Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Chris Albertson]

I think that even with a rudimentary and incomplete knowledge of the road
network one could detect spoofing a car navigation system.   The car would
show up inside buildings and farm fields and lakes.   You'd see this even
on a very poor map.

If the spoofer moved the signal even 200 yards the match to the roads would
be total rubbish and non sense.  It would be detectable even using very old
maps with many segments missing



On Mon, Aug 14, 2017 at 3:10 PM, Ron Bean <t...@rbean.users.panix.com>
wrote:

> >In a car it is even easier.  The car nav system KNOWS it must be on a
> >roadway.  The car's ground track (positional history) must be on a road.
>
> That's assuming the GPS company keeps their maps up to date (it doesn't
> matter how often you update the maps in the device if the company's maps
> don't keep up with reality). New roads appear, old ones occasionally get
> moved.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Chris Albertson]

Detecting a spoof is not really so hard.  What you need to redundancy.
When the two navigation methods diverge then you know one of them is acting
up.  (that is broken or being spoofed or just buggy)

On a ship you have magnetic compass and knot log and almost certainly gyros
and all these are typically NMEA connected.   Then of course there is a
paper based backup.   But just using the available electronics you could
detect divergence.

A large ship that is long enough could use two GPS receivers one at each
end.  The ship knows it's magnetic heading and the distance between the two
GPS receivers.  When the GPS solution is wrong the ship knows to ignore
GPS.An attacker would have to spoof so that both receivers are moved
the exact same direction and distance.   I'mhaving some trouble seeing how
that could be done. (not that it can't be done)   But in any case the first
method (divergence from expected location) would work eventually and not
requires any extra hardware.

In a car it is even easier.  The car nav system KNOWS it must be on a
roadway.  The car's ground track (positional history) must be on a road.
When this is no longer true the navigator can turn the screen red and say
"invalid gps signal".

I more sophisticated car such as a Tesla with autopilot sensors can do a
more sophisticated form of visual navigation and compare the observed road
type (multilane divided highway or residential) and it can notice when it
crosses intersections.   It should notice divergence from GPS more quickly
can could fail back to dead reckoning with visual updates.  Yes an
expensive to develop software system but not science fiction either.

In a way cars have it good because they know they can't drive though
building.

Commercial aircraft have even better data available that could be used to
compare with GPS, Ground based radar being one but many on-board systems as
well.

In short it is REALLY HARD to spoof information a person can  know from
other sources.



On Mon, Aug 14, 2017 at 11:29 AM, Bob kb8tq <kb...@n1k.org> wrote:

> HI
>
> Since multi path is a real issue in a mobile environment, defining what an
> “abnormal”
> change is could be quite tricky. A reasonable “spoof” would start with
> feeding the correct
> data and then slowly capture the target (still with correct data). Once he
> is are “in charge”
> signal wise, start doing whatever …. If you are talking about a ship, you
> have *lots* of time.
>
> Bob
>
> > On Aug 14, 2017, at 1:40 PM, ken Schwieker <ksw...@mindspring.com>
> wrote:
> >
> > Wouldn't monitoring the received signal strength and noting any
> non-normal increase (or decrease) level change indicate possible spoofing?
> The spoofing station would have no way to know what the target's
> > received signal strength would be.
> >
> > Ken S
> >
> >
> > ---
> > This email has been checked for viruses by AVG.
> > http://www.avg.com
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Chris Albertson]

The trouble with spoofing location is that in theory every ship is using
more than one method of navigation.   They would notice their GPS is acting
up and turn it off.

I'm far from a professional but I've taken the  six week class and I'm
reasonably certain I could find a place on the other side of the pacific
ocean with no GPS.   The GPS is far easier to use and more accurate but no
one uses just GPS alone, they alway compare several methods.

On Mon, Aug 14, 2017 at 10:12 AM, Clint Jay <cjaysh...@gmail.com> wrote:

> I guess it would depend on the level of infrastructure available to the
> attacker, clock distribution is a reasonably well solved problem isn't it?
>
> There would, I suppose also be the issue of receiver swamping, you could
> monitor received signal levels as it's my understanding that the signals
> from the satellites are weak enough that they're indiscernible from noise
> floor without some rather complex processing?
>
> Authentication via signing could be another feasible way to prevent
> spoofing except we are potentially talking about interference from state
> actors who may even be the very people who run one of the satellite
> networks
>
> On 14 Aug 2017 5:51 pm, "Attila Kinali" <att...@kinali.ch> wrote:
>
> > On Mon, 14 Aug 2017 12:09:43 -0400
> > Tim Shoppa <tsho...@gmail.com> wrote:
> >
> > > I think if you are only trying to spoof a single receiver it would be
> > > possible to walk a spoofed time/space code in a way that time moved
> > without
> > > so obvious of a discontinuity. I'm sure there would be effects a
> time-nut
> > > could notice still.
> >
> > Not really. Unless you have a multi-antenna setup (see jim's email),
> > you have nothing to compare the signal to. Even an ideal reference
> > clock in your GPS receiver does not help, as the attacker could be
> > tracking you in such a way that you will never see a discontinuity
> > in time or position and that all the other sanity checks you do
> > still don't show anything.
> >
> > With a two antenna setup, you can already check whether the phases
> > add up to what you expect them to be, given your position relative
> > to the satellites position. You do not need 3 antennas as a potential
> > attacker can spoof the phase of some satellites correctly, but not
> > of all at the same time. This at least gives you a spoof/no-spoof signal.
> >
> > With an antenna array you can do some masking of spoofers (ie placing
> > a null where the spoofer comes from). But this increases the cost and
> > complexity of the system super-linear with the number of antennas.
> > Maybe one way to do it, would be to use a single receiver with a stable
> > reference clock and switch between antennas in short succession. Ie
> similar
> > to how the early single channel GPS receivers worked, but for antennas
> > instead of SVs. But I have no idea how easy/difficult this would be
> > to do and how well it would work against spoofers.
> >
> > Attila Kinali
> > --
> > It is upon moral qualities that a society is ultimately founded. All
> > the prosperity and technological sophistication in the world is of no
> > use without that foundation.
> >  -- Miss Matheson, The Diamond Age, Neil Stephenson
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Trimble Thunderbolt no longer determines the correct date

[Chris Albertson]

On Thu, Aug 10, 2017 at 10:24 AM, Brad Dye <b...@braddye.com> wrote:

>
> I read here on the Time Nuts messages that some are considering: "some
> in-line device that re-writes the serial data as it comes out of the
> Thunderbolt”
>

An in-line device makes sense if you don't have control of whatever you
have the T-Bolt plugged into.  This would be the case in a cell tower.

But if the T-Bolt is plugged into a computer in your own house, I'd think
it would be far easier to modify the software your computer runs.   LH and
NTP are the only two most of us would run and both are open source and easy
to change.   Four of five lines of code, max.

Building an inline device would be easy, even an Arduino could work but it
would need more software and time to write it than a simple patch to NTP or
LH.

Patches are free, and thousands of people can use them just by downloading
but an in-line device has to be built for each user.

-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Can Lady Heather set PC time directly from a TrimbleThunderbolt?

[Chris Albertson]

On Fri, Aug 4, 2017 at 7:39 AM, Chris Wilson <ch...@chriswilson.tv> wrote:

>
> Thanks  to  everyone  for the replies, so basically would you say that
> with  a permanent internet connection I should forget using GPS time to
> set  the  PC  clock  and  just use Meinberg or NTP (which is what I am
> currently using and seems to work just fine)?

You'd be using the same NTP software in either case.  The difference
is it you were to add a GPS reference clock to the current setup.
Even with GPS you's till want to keep the internet based reference
clocks.

Currently your PC clock might be accurate that the few milliseconds
level.  Adding a GPS receiver into the mix will improve accuracy to
the tens of microseconds level.   You'd gain abut two orders of
magnitude over the current setup.

Do you need this?  I can think of uses for a highly accurate clock in
amateur radio.  Perhaps you are measuring propagation delay.  Doing
this 100 times more accurately might be helpful.On the other hand
maybe you only need log files time stamps to be with a second or so of
correct? When I got into this may application was pointing
telescopes and measuring the light from variable stars.Usually you
can start with you application and work backwards to place a
requirement on time accuracy

On the other hand this is a "time nuts" list and some people here just
want the BEST they can get.

I'm not a fan of Meinberg because of the way they market freely
available software.


-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Can Lady Heather set PC time directly from a Trimble Thunderbolt?

[Chris Albertson]

This idea keeps coming up.   "Jamming" the time from a GPS into a
computer is NEVER the best idea.  When you "jam" the time the PC
internal clock moves in  jerks and jumps where it will move forward
and even backward.

The only way that works well is to discipline the PC's clock using the
same method you'd use to discipline the crystal inside A GPSDO.You
compare the phase between the GPS and the local PC clock then adjust
the RATE of the PC clock to keep the peas in sync.   That is what NTP
does.

I say all of the above because this is a "timeouts" list.   If you
only care that the PC clock by "close enough" that the time printed on
the screen matches your wristwatch then a 50 millisecond error is
acceptable as that is about the limit of human perception.But it
you are a "nut" and want each millisecond of time to be reasonably
equal, that means with "tick" of the PC's clock to advance in time
about the same amount then you can't "jam" the PC's clock from GPS.
You will need to adjust the PC clock's RATE not the PC clock's PHASE.

On Thu, Aug 3, 2017 at 6:54 AM, Chris Wilson <ch...@chriswilson.tv> wrote:
>
>
>   03/08/2017 14:50
>
> I use an NTP client to set my Windows 7 64 bit PC time for digital
> mode amateur radio activities, but I was wondering if my Trimble
> Thunderbolt and Lady Heather can do the same job? If it can, how do I
> do it please, and can the PC show GMT and not UTC, and finally does
> the date glitch affect this? Lady Heather communicates with the GPS
> via a true serial port. Thanks!
>
> --
>Best Regards,
>Chris Wilson. 2E0ILY
> mailto: ch...@chriswilson.tv
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Local System Time Sync

[Chris Albertson]

You should be using NTP for that.

Simply "syncing" the local clock to GPS is never the best thing to do.   If
you think about it 50% of the time the local clock would have to go
backwards and 50% forwards.  This means you could have the system time be
at the same time twice or you have missing time intervals.

The correct way is to adjust the RATE of the local clock so you never have
missing or double time.   This is exactly the same as building a GPSDO.
Every adjustment period you compare there PHASE of the local clock to GPS
then adjust the RATE if required. NTP does this.

On Tue, Jul 25, 2017 at 7:45 PM, Lee - N2LEE via time-nuts <
time-nuts@febo.com> wrote:

> I have what I believe is a simply question. Especially for this
> illustrious brain trust. :)
>
> How can I force Lady Heather to time sync the local computer system it is
> interfaced to ?
>
> Isn’t this what the /ts[odhm] command accomplished or I am
> misunderstanding ?
>
> - Thunderbolt is interfaced to a Mac laptop running LH5
> - Connection is USB to Serial cable (might be the issue because of no PPS)
> - Turn off Internet NTP sync on laptop
> - Purposely set laptop time 15 seconds ahead
> - Enter / then after the dash(-) I enter tsm to sync system time every
> minute.
>
> I thought this would force the system to sync ever minute with Thunderbolt
> time.
> But it doesn’t it. It never corrects the laptop time, it is always wrong.
>
> What am I missing here ?
>
> Thanks,
>
> Lee
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] DAC performance [WAS: Papers on timing for lunar laser ranging]

[Chris Albertson]

What about josephson standards?   After all, this is "Time Nuts" and we are
allowed to propose silly-complex solutions to simple problems if it
improves performance even a little.

But seriously I thought the issue of making a perfect voltage standard was
solved because the Volt is defined to be whatever the Josephson array
produces. Yes expensive because to runs at nearly absolute zero.

On Sun, Jul 16, 2017 at 4:10 PM, Bob kb8tq <kb...@n1k.org> wrote:

> Hi
>
> > On Jul 16, 2017, at 6:33 PM, Richard (Rick) Karlquist <
> rich...@karlquist.com> wrote:
> >
> >
> >
> > On 7/16/2017 1:51 PM, Bob kb8tq wrote:
> >> Hi
> >> One gotcha with any ADC or DAC is going to be the reference. There, you
> are in the same
> >> “get what you pay for” dilemma. Stable and noisy, can do. Quiet and not
> very stable, can do.
> >> Both stable and quiet, not so easy if you want it cheap.
> >> Noise can also be the sigma delta ADC’s weak point. Even at slow rates,
> some of them need
> >> a lot of averages to quiet down.
> >
> > The reference initially used in the E1938A turned out to be too
> noisy/unstable.  It was non trivial to find an upgrade.  The
> > HP Smart Clocks of 20 years ago were limited in their performance
> > by the reference used.
> >
> > Has there been much improvement in references in the intervening
> > 20 years?
>
> They still don’t seem to have the hysteresis problem licked. Yes, you can
> do an oversized reference
> and take care of the issue. More or less that’s what you would have done
> 20 years ago.
>
> Bob
>
>
> >
> > Rick N6RK
>
> _______
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Thunderbolt Monitor Kit by KO4BB

[Chris Albertson]

The Raspberry Pi idea is good because for your $100 it can do a few other
tasks at the same time.

It can run LH but also maybe she other services like  NTP,  a small web
server and also a WiFi based backup server that backs up any notebook
computers you have (it such a hassle to plug in an external drive to a
notebook that few people do it.   So I have mine do an hourly backup over
WiFi.)

I have a Pi3 on my desk right now and yes, it is more than powerful enough
and would be under utilized even with a half dozen light weight servers
running.

So a $100 t-bolt monitor is rather expensive but if you can get four of
five other functions at the same price, maybe worth it.

On Mon, Jul 3, 2017 at 9:50 AM, Mark Sims <hol...@hotmail.com> wrote:

> The K04BB device is a great little relatively inexpensive and compact
> Thunderbolt monitor.
>
> Another option is to use a Raspberry PI and the 7" color LCD touchscreen
> along with the latest Lady Heather code.   I've added touchscreen support
> and some optimizations to the screen code for better display on smaller
> screens.  The combo makes for a very nice package that shows pretty much
> everything and lets you control the unit from the touchscreen.   The PI +
> touchscreen does cost around $100 though.  I've seen some really nice
> builds, such as Willis Hendly's,  with the Tbolt, power supply, and
> PI/touchscreen (I think he actually uses a Beaglebone) mounted in a box.
> Perhaps he will do a post showing his implementation.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] PI Zero W LED Desktop Clock with 10ths of Seconds / NTP disciplined

[Chris Albertson]

There already exists an NTP for ESP8266.   At least a simple one.   Look
over on GitHub.

On Sun, Jul 2, 2017 at 5:27 AM, Tim Shoppa <tsho...@gmail.com> wrote:

> I have been thinking about doing similar with an ESP8266 controller


-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Power connectors continued

[Chris Albertson]

These expensive and exotic connectors are nice but are over kill for most
projects which live their entire lives on a lab bench and never fly to Mars
or even Low Earth Orbit.

I found out about "GX" style connectors a while back.  They are multi-pin
circular connectors with screw down locking rings with from 2 to 8 poles
and size either 12mm or 16mm diameter They are not suitable for use on
airplanes or the like but good enough for machine tools and any hobby
project that needs straight (no coax)  pins that are rated to 5 amps
continuous.

The really good part is the cost.   About $1 per mated pair.   Find them on
eBay searching for gx16 for the 16mm version of gx12 for the smaller one.
here is an example:
http://www.ebay.com/itm/10-Pcs-8-Pin-16mm-GX16-8
<http://www.ebay.com/itm/10-Pcs-8-Pin-16mm-GX16-8-Aviation-Plug-Power-Chassis-Male-Female-Panel-Connector-/272702764391?hash=item3f7e59f567:g:UA8AAOSwi7RZNQDE>

I think these win the bang per buck contest.

For a buck each, these are not machined from brass, I think molded pot
metal and chromed.


-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPScon running on Raspberry Pi 3b

[Chris Albertson]

On Sun, Jun 25, 2017 at 3:04 PM, Mark Sims <hol...@hotmail.com> wrote:

> Heather's configuration priority is to process:  hard coded defaults,
> then the config file,  and finally the command line options.  This lets you
> set your preferred settings in the config file and then override your
> config file options from the command line.
>


If that is the desired behavior and I think it is reasonable and what most
people would expect,  then the correct implementation of that behavior is
to NOT ACT on any config setting until the command line options are read.
Or in general never act on an instruction that might be overridden

So the bug reported below seems to be a bug.


>
> 
>
> > When I ran it with ./heather -4u, it first told me that it was unable to
> open /dev/ttyUSB0 and
> then told me it was unable to open /dev/ttyUSB3. This is probably due to
> the
> configuration file containing "-1u", but if that option is given on the
> command line then the configuration file value should be ignored - or at
> the
> least it should be tried after the command line option.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Latest Lady Heather

[Chris Albertson]

Any chance of this getting hosted in say Giithub?   If people arguing to to
contribute changes having each contributor hold his own changes is not what
that call "best practice". If you make it easy enough by using git, you
will see more contributions by users.

On Sun, Jun 25, 2017 at 1:43 PM, Wes <w...@triconet.org> wrote:

> I asked about this before but got no response.
>
> I know of John Miles' site where I downloaded v5 but I've seen a post by
> Mark Sims about further enhancements and wonder where I might get the
> latest.
>
> Mark seems to have an "unlisted number."
>
> Thanks,
>
> Wes
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Chris Albertson]

You are correct about 9V batteries.  A 10A short is about 90 Watts.   But
have you seen the specs on a LiPo Battery?

I have a 18 volt nominal 8,000 mAH LiPo battery that is rated "40C".  This
battery is safe and within design limits to discharge at 40 x 8,000 mA.
Yes, taking 320 amps out of the battery is acceptable, the battery is
designed for that.

The battery can continuously supply 5.7 Kilowatts over 2 times more power
then can a standard AC mains wall outlet.  Of course at that rate it runs
out of power in roughly one minute.  But you can do a LOT in one minute.

When you short the leads you get a LOT more than 320 amps

A battery like that costs only about $50 today so they are available to
almost anyone who wants one.




> (1) A common 9V (NEDA1604 style) battery should never be left where it
> might contact a metal short, and should never be left in a pocket. I
> knew better, but temporarily slipped an alkaline 9V battery into a
> trouser pocket, where it was shorted by my keys and became extremely hot
> very rapidly. The peak current might reach 10 A (depending on the
> battery chemistry and how it's shorted), so the battery heats up very
> rapidly!

-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPScon running on Raspberry Pi 3b

[Chris Albertson]

I've got a Pi3 here on my desk.   I only see one UART that connects to GPIO
pins.   But it turns out if you actually need to use serial you use the USB
to serial dongles.  If you need four serial ports use four dongles.   That
is just the way the Pi3 is.

You can level the 3.3 volt serial port but then you are into a MAX chip and
some passives or maybe just a couple transistors but the =USB-Serial dingle
is easier then level shifting.

If you want a Pi-like device that is better for real-time embedded use look
at the Beagle Bone Black.  But it was limited CPU and RAM compared to Pi3
but better IO.

If you are building a NTP server, look at the Pi Zero version 1.3.  $5 each.



On Thu, Jun 22, 2017 at 7:51 PM, Orin Eman <orin.e...@gmail.com> wrote:

> On Thu, Jun 22, 2017 at 5:36 PM, Mark Sims <hol...@hotmail.com> wrote:
>
> >
> > The PI does have a couple of logic level serial ports on the expansion
> > connector you can connect a level shifter two.  One port is normally the
> > Linux serial console which you can configure to be a general purpose

-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Power connectors continued

[Chris Albertson]

I think they call these "16mm aviation plugs" in the CNC machine tool
world.  They are common for connecting servo or stepper motors to their
controllers.

they have any number of poles from 2 to 6 or more and screw rings that
secure them.   Usually really good quality even from Chinese eBay vendors.
But they are really used only for a cable to chassis and only up to a few
amps.  here is one
<http://www.ebay.com/itm/5pcs-Aviation-Plug-4-Pin-16mm-GX16-4-Metal-Male-Female-Panel-Connector-New/172271528592?_trksid=p2047675.c19.m1982&_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D44840%26meid%3D1f63ff61ed134f628c9629d26b2690b1%26pid%3D19%26rk%3D1%26rkt%3D1%26sd%3D281469838889>

Why so many connecter types?   So you don't cross stuff up.

Power poles are great for low-tech 12 volt buss systems that don't need any
kind of engineering and are tolerant of connecting "anything to anything."
 Amateur radios and lead acid batteries are OK.  Not good for high tech
battery or their chargers or loads.

Th XT60 or if you need 90  amps, the XT90 is ok because it is gendered and
you can't accidentally connect two sources.

The aviation type are perfect for cabling four or six lead motors.

I would not use 3-pin XLR for anything but audio.  Don't make it easy to
connect line level audio to a battery.

A really dumb idea was this guy, I heard this story secondhand.  He used
A/C extension cords for speaker cables because they work well for that
purpose, but then someone plugged a speaker into a 120vac well outlet.   I
assume it made a load 60 Hz tone for a few cycles.Best to follow
industry conventions because that is what people expect.

Even though it would work well electrically, no one uses a mini-USB jack
for Ethernet and for good reason



On Thu, Jun 22, 2017 at 11:42 AM, Mark Spencer <m...@alignedsolutions.com>
wrote:
> Sorry if I have caused any un due confusion thru my perhaps incorrect use
of the terms "cannon" and "XLR."
>  The green connector with 4 separate female contacts is what I perhaps in
correctly referred to as a "cannon" connector.  The silver connector with 3
separate female contacts was what I perhaps incorrectly referred to as a
"XLR" connector.
>
> Both were in use in my lab powering time nuts gear.
>
>
>
>
>
>
>
>
>
>
>
>
> Mark Spencer
>
> m...@alignedsolutions.com
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Chris Albertson]

Get the "real ones" not the knock-off clones.  Better plastic and
better precision molding.   There are lots of cheap ones on eBay.

HobbyKing has the best prices for authentic, higher quality ones.
Still only 80 cents.

On Thu, Jun 22, 2017 at 11:15 AM, Brent <brent.ev...@gmail.com> wrote:
> Never seen the XT60.  Thanks for the heads up - looks promising - and cheap.
>
> Brent
>
> On Thu, Jun 22, 2017 at 12:48 PM, Chris Albertson <albertson.ch...@gmail.com
>> wrote:
>
>> One of the problems of power poles is they are expensive.  Not a
>> problem if you only need a few of them.   I've been buying DC
>> connectors by the bag full as I've working on some battery powered
>> mobile robots  I robot does not need many but for every finish one
>> you've build maybe four breadboard systems and then you have the
>> battery charging systems and the cables that connect battery chargers
>> to power supplies. (LiPo battery charging is complex when you get into
>> 18 volt 10 amp hour sizes.
>>
>> Power poles are also rather bulky.  OK if the equipment is stationary
>> but not good for something that flies or drives around where weight
>> and volume matter a lot.
>>
>> I've standardized on XT60 type connectors  These very compact and
>> rated for 60 amps continuous.  Much easier to assemble and they cost
>> about 80 cents per mating pair.They are common in the electric
>> power drone industry as battery connectors
>> the XT60 is easy to use because they don't come apart.  the metal pins
>> are permanently molded into the shell, you simply solder the wires on.
>> The shell is high temperate plastic and withstands even unskilled
>> soldering.
>>
>> I did something stupid last might and assembled power distribution not
>> as designed with a mosfet switch and diode in backwards then connected
>> a high power density battery.  I had an open flame along an entire run
>> of #18 cable but finally the coper conductor failed (the metal
>> vaporized) and the circuit opened and the flame stopped.   I have some
>> chared remains of wires and crunchy black melted plastic.  But the
>> XT60 connectors are still good.  The metal parts inside are still
>> shiny gold plated and the nylon shells are good as new, after cleaning
>> the soot off.
>>
>> I was actually holding the connecter in my hand when the thing went
>> off like a bomb, but just minor burns.  Still amazed the connecter is
>> fine after unsoldering the little stubs of burned wire from the pins.
>>
>>
>>
>> On Thu, Jun 22, 2017 at 12:19 AM, Tom Van Baak <t...@leapsecond.com> wrote:
>> > Wes, Don,
>> >
>> > I am quite surprised at the negative reaction to Anderson Power Pole
>> connectors. I have found them the best DC connector out there. I have used
>> them for a decade or two for all my DC feeds and have never had a problem:
>> in my home lab, my car, even for my laptop charger. They are inexpensive,
>> reliable, genderless (hermaphroditic) and easy to crimp. I use them for my
>> 5V, 12V, 24V, and 48V supplies as well as my DC backup systems.
>> >
>> > What on earth are you doing with them that causes them to disconnect? I
>> mean, they are not meant for towing or lifting or rappelling. For critical
>> applications there is a plastic gizmo that keeps them mated; or just use a
>> square or figure 8 knot on the cables.
>> >
>> > /tvb
>> >
>> > ___
>> > time-nuts mailing list -- time-nuts@febo.com
>> > To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>> > and follow the instructions there.
>>
>>
>>
>> --
>>
>> Chris Albertson
>> Redondo Beach, California
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] How to love your Power Poles.

[Chris Albertson]

No, there are more problems.   Being non-gendered that apply
connections mistakes like connecting to power sources together.
Could you imagine how bad it would be if all power connectors were
not-gendered?   then you could connect two wall AC mains outlet
together.  Kind of a problem if there were out of phase (US 120VAC
wiring is like that)   Bad enough that it allows tow DC power supplies
to be connected.

What is is good for is it you are in a hurry.  non-genet connections
were invented for firemen so after laying dow 300 feet of hose that
NEVER find the have it backwards and have to flip a 300 foot hose end
for end.   Ive done this a few times with outdoor AC extension cords.

There is an advantage to gendered connectors.  Typically the source
are female and you can't plug two outhouse together by mistake.   If
you need N-way connections yo make and test the power harness before
hand.

That said I do have some power pole cables.  They work good for 12VDC
lead acid battery type stuff.  But NEVER use then for exotic battery
chemistries.   Fires are not good.  and it WILL happen if you use PP
on Lithium type batteries, an accident waiting to happen.




On Thu, Jun 22, 2017 at 7:11 AM, James Robbins <jsrobb...@earthlink.net> wrote:
> I’ve used Power Poles for some years.  I have a proper crimper intended for 
> PP.  Color coding is very useful.
>
> I think the complaints about them are due to two things:  (1) improper 
> crimping of the contacts and (2) heavy gauge wire.
>
> The PP15/30/45 use the same plastic housing while changing the size of the 
> contact.  A wire gauge suitable for 30 to 45 amps is quite large physically 
> and puts a great deal of mechanical strain on the plastic connectors.  So, 
> when such a gauge of wire moves (or doesn’t move), it tends to disconnect the 
> plastic housings.  If the connections are from one set of wires to another, a 
> two prong plastic jumper plug can successfully hold the four connectors 
> together through the mating holes in the pair during movement.
>
> The problem is that when one set of connectors is mounted in a chassis, it is 
> often not really possible to use a two prong plug (or Ty-Wrap) to physically 
> hold them together.  Move the chassis and if the wire doesn’t want to follow, 
> you get disconnected.
>
> Two solder lugs mounted to the chassis and a few small Ty-Wraps will fix most 
> of this “heavy wire” issue.
>
> Jim Robbins
> N1JR
>
> PS:  Make up a pair of PP with an LED to test your future PP builds.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Chris Albertson]

One of the problems of power poles is they are expensive.  Not a
problem if you only need a few of them.   I've been buying DC
connectors by the bag full as I've working on some battery powered
mobile robots  I robot does not need many but for every finish one
you've build maybe four breadboard systems and then you have the
battery charging systems and the cables that connect battery chargers
to power supplies. (LiPo battery charging is complex when you get into
18 volt 10 amp hour sizes.

Power poles are also rather bulky.  OK if the equipment is stationary
but not good for something that flies or drives around where weight
and volume matter a lot.

I've standardized on XT60 type connectors  These very compact and
rated for 60 amps continuous.  Much easier to assemble and they cost
about 80 cents per mating pair.They are common in the electric
power drone industry as battery connectors
the XT60 is easy to use because they don't come apart.  the metal pins
are permanently molded into the shell, you simply solder the wires on.
The shell is high temperate plastic and withstands even unskilled
soldering.

I did something stupid last might and assembled power distribution not
as designed with a mosfet switch and diode in backwards then connected
a high power density battery.  I had an open flame along an entire run
of #18 cable but finally the coper conductor failed (the metal
vaporized) and the circuit opened and the flame stopped.   I have some
chared remains of wires and crunchy black melted plastic.  But the
XT60 connectors are still good.  The metal parts inside are still
shiny gold plated and the nylon shells are good as new, after cleaning
the soot off.

I was actually holding the connecter in my hand when the thing went
off like a bomb, but just minor burns.  Still amazed the connecter is
fine after unsoldering the little stubs of burned wire from the pins.



On Thu, Jun 22, 2017 at 12:19 AM, Tom Van Baak <t...@leapsecond.com> wrote:
> Wes, Don,
>
> I am quite surprised at the negative reaction to Anderson Power Pole 
> connectors. I have found them the best DC connector out there. I have used 
> them for a decade or two for all my DC feeds and have never had a problem: in 
> my home lab, my car, even for my laptop charger. They are inexpensive, 
> reliable, genderless (hermaphroditic) and easy to crimp. I use them for my 
> 5V, 12V, 24V, and 48V supplies as well as my DC backup systems.
>
> What on earth are you doing with them that causes them to disconnect? I mean, 
> they are not meant for towing or lifting or rappelling. For critical 
> applications there is a plastic gizmo that keeps them mated; or just use a 
> square or figure 8 knot on the cables.
>
> /tvb
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] TruePosition on the Arduino

[Chris Albertson]

Yes,   It is easy if you have an Arduino handy.  Write a scratch to
try  EVERY address one at a time.  Print the currently attempted
address top the screen

In fact there is a pre-written sketch in the IDE's I2C examples
folder.  You can run that and it will report what it finds.  It just
tries reads on every possible address.



On Tue, Jun 20, 2017 at 6:02 PM, Tom Miller <tmiller11...@verizon.net> wrote:
> Has anyone been able to get the Packrat software to work with a display? I
> have been successful getting the Arduino board to initialize the
> Trueposition board but can't get the display right.
>
> The problem seems to be getting the I2C addressing correct. There are
> several 16x2 line displays available but they address at 0x20 to 0x27 and
> 0x38 to 0x3F. Neither of these work.
>
> Since we do not have the source, is there any way to find out what address
> is in use?
>
> Regards
>
> - Original Message - From: "Gregory Beat" <w...@icloud.com>
> To: <time-nuts@febo.com>
> Sent: Tuesday, June 06, 2017 8:44 PM
> Subject: Re: [time-nuts] TruePosition on the Arduino
>
>
>> Ben -
>> I assume that you never received the Arduino "C code"
>> written by Bruce, WA3YUE for the original project?
>>
>> Club's Powerpoint presentation indicated that source code was available.
>> http://www.packratvhf.com/techinal.htm
>>
>> Packrat GPS Project (Gary, WA2OMY; Bruce, WA3YUE; George, KA3WXV) with
>> TruePosition GPSDO and Arduino
>> by The Mt. Airy VHF Radio Club "Pack Rats" (Southampton, PA).
>> http://www.qsl.net/wa2omy/A%20Packrat%20GPS%20Receiver%20Project.pdf
>>
>> greg, w9gb
>> ==
>>>
>>> original message / digest <
>>
>> I'm getting to the point that once I've got the button logic working, I'll
>> send out my source to anyone who wants to take a look at it or use it.
>> I will stipulate one condition - you can't make too much fun of how poorly
>> programmed it is.  ;)
>> thanks much and 73,
>> ben, kd5byb
>> ==
>> Sent from iPad Air
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPScon running on Raspberry Pi 3b

[Chris Albertson]

it looks to me like Olgierdhas a working INTEL linux
os running on the Pi3.   He installed Wine on the Intel Linux not on
the ARM Linux

It looks like maybe Michael has an ARM version of linux running native
on the Pi3  Wine will not run on that
If you need to run Wine, you need to fist  have an INTEL lInux
running.   Remember "WINE= Wine Is Not an Emulaor" and it will not
run Intel binaries on Arm.

I'm skeptical it would be more then a stunt a triple stack of virtual
environments.  But if the final Windows app is not really doing
anything with the CPU, maybe fast enough.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Hints on PPS Buffer design...

[Chris Albertson]

Why 100R?   If using a 74xxx logic part as the driver is has a maximum
drive current.  100R limits current in case of a short to ground or 5V
supply  to only 50mA  It is about the lowest value resister i'd want to use

If you need 50 ohm output them go with an small RF amplifier or a
transistors driver.  These can drive a 50R load without burning up.

On Sat, Jun 17, 2017 at 1:15 AM, Clay Autery <caut...@montac.com> wrote:

> Trying to pin down a reasonably optimal buffer design for bringing PPS
> out...  I've looked at all the references, like the i3detroit.org site
> et al.
>
> Of the few schematics and devices I see, most are using a hex inverter
> (1 into the other 5 paralleled with series resistors for "balance" and
> setting output impedance?
>
> Q:  Why does everyone pick FIVE x 100 Ohm resistors?  That's 20 Ohm out,
> not counting the gate impedance on the hex inverter...
>
> Q2:  Anyone have a reference to the math for choosing the resistors for
> setting a 50 Ohm nominal out INCLUDING determining and including the
> gate impedance of a particular part.
> (Right now, I am going to use the TI SN74AC04 Hex Inverter)  I saw a
> refernence in the archive referring to a 4 gate setup using a different
> part needing 187 Ohm resistors... thus I can only include that I need to
> use something slightly more than 250 Ohms on a 5 gate parallel setup)
>
> Q3: It's only a 1Hz frequency, but is low inductance a desired trait of
> the chosen resistors?
>
> I'm sure there are others...
>
> Thanks!
>
> --
> __
> Clay Autery, KY5G
> MONTAC Enterprises
> (318) 518-1389
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS splitter

[Chris Albertson]

On Fri, Jun 16, 2017 at 8:54 PM, Clay Autery <caut...@montac.com> wrote:

> This brings up some interesting questions:
>
>
> I am assuming since this is a receive only situation, it will follow
> approximately the same rules of physics that dealing with satellite
> antenna installations.
>

And guess what?  Satellite TV splitters work.  They even have the answer to
"how much attenuation" printed right on the splitter and they come with F
type connecters you can use the recommended TV type antenna cable too.
You can buy them with DC blockers too.  All this stuff is low cost because
it is mass produced  by the billions

Yes, it's 75 ohm not 50 and the splitters a 2+ GHz but it works just fine
if your antenna has the right gain. The splitters don't high pass the
signal.Trimble actually recommends using the 75 Ohm TV cable and
supplies it with their kits.

Sometimes a GPS receiver will raise an "Antenna Alarm" if it does not see a
DC load but you can turn those off with a serial command
-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Control Systems (was: uC ADC resolution)

[Chris Albertson]

On Sun, Jun 11, 2017 at 9:28 AM, Attila Kinali <att...@kinali.ch> wrote:

> Hi,
>


>
> You are asking a lot of question regarding control systems.
> But, there are no easy answers there. Especially if you want
> to build it cheap. The cheaper you want to be the more you
> need to know and understand the problem.
>

This has been my opinion for a LONG time.  It is easy to come up with good
solutions if to just throw money at the problem.So you see here people
proposing just going top of the line all across but an engineer earns his
money
by comping up with cost effective solutions that meet all the stated
requirements.

This is my interest in mechanics too.  Can a $200 3D printed plastic robot
arm
with poor absolute repeatability place an M6 screw into an M6 nut?
Certainly
not if it runs open loop.  But what if you add visual feedback?
Yes everything requires more expertise if you reduce the budget

So you understand my questions are all like this:  "If you back down from
top of the line solution how does that effect real world performance?"
No one answers.


>
> I suggest you reading an introductory text into control systems
> like e.g. "Feedback Control of Dynamic Systems", by Franklin, Powell,
> Emami-Naeini.




-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] uC ADC resolution (was: Poor man's oven)

[Chris Albertson]

On Sat, Jun 10, 2017 at 12:59 PM, Poul-Henning Kamp <p...@phk.freebsd.dk>
wrote:

> 
>
> Delta-Sigma strategies for spreading the noise-spectrum are
> interesting, but will not save you if the required heater power
> ends up being a small rational fraction (1/2, 1/3, 1/4 ...) of the
> full scale.
>

How many output bits are required?  Most uPs have quite a few digital
output pins.  Each pin could drive a heater resister.  Values of the
resisters organized by power of two.   Again note the title (poor mans...)
 resisters cost almost zero.  Even of driver transistors are needed you'd
get change back from a dollar bill.

The reason I ask "how many bits" is because the above is reasonable with 4
to 6 effective bits but not reasonable with 24

I say "effective" because we can dither the low order bits to gain maybe 6
effective bits form 4 real bits (we can filter the switching noise from a
low frequency dither)

-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] uC ADC resolution (was: Poor man's oven)

[Chris Albertson]

On Sat, Jun 10, 2017 at 11:33 AM, Magnus Danielson <
mag...@rubidium.dyndns.org> wrote:

> Hi,
>
> I was about to make this very point myself. The resolution of the ADC
> needs to be higher than the limit you try to achieve. There is several ways
> to reason about it, but one is that the system is a bit slugish you want to
> have higher resolution in order to react of changes before they overshot
> the limits you want to keep. Another benefit is that you get away from the
> bang-bang behavior you get when having too few bits.
>
> For an oven you can however cheat some by not requiring linearity in the
> "too cold" region of temperature. You do want some linearity as you start
> to come into the right range in order to slow down the heating in order not
> to do a big overshot.
>
> I have seen a little too much cases where there been too few bits both on
> ADC and DAC sides. Some of it you can overcome, but it runs into trouble.
> Get good dynamics, it makes the rest of the design easier.
>




OK, following the advice both above and below.  Let's try some real-world
numbers...

 Lets say my goal is regulation within 0.1C.  After filtering I have 10
"good" bits in my ADC.  That is 1024 counts.   My set point is S.

I scale the ADC so that 0 == (S - 0.5) and 1023 == (S + 0.5)This means
that each ADC count is 0.001 degree C and within the 0.1C range there are
100 ADC counts.

But what if there are only 8 good bits after filtering   The each count is
 0.004 degree C and there are 25 counts within the 0.1C range.

The uP's ADC is nominally 12 bits.   Getting 10 "good" noise free bits
might be asking to much but 8-bits is pretty reasonable.





>
> Cheers,
> Magnus
>
> On 06/07/2017 08:32 PM, Bob kb8tq wrote:
>
>> Hi
>>
>> There is a gotcha with the initial assumption: You want the loop to be
>> *quiet* at a level well below 0.1C. If it is bouncing around that much,
>> the second order (rate defendant) tempco of a normal crystal will
>> become a pretty major issue.
>>
>> Simple rule of thumb - add at least two bits past whatever the target is.
>> More or less, if you *are* after 0.1C and that comes out to 6 bits, you
>> need
>> eight solid bits to get things to work properly.
>>
>
-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] uC ADC resolution (was: Poor man's oven)

[Chris Albertson]

One question for the control theory experts.

Assume me goal is to regulate temperer of an aluminum block to within 0.1C,
how good must my ADC be?   Is an effective 6-bits good enough?

It seems to me the problem with fewer bits is only quantization noise.
Lets assume 6-bits.  This is 1 part in 64.   If I scale the input to the
ADC such that it os 1.0C from 0 to 63 counts then each cunt is 1/64 C
 which is about 6 times better then my allowed error of 0.6 C.

My gut-feel is that this is marginal but could work ("work" is defined as
holds temperature within the range) but I'd be happier using 8 bits.  Im
pretty sure I can get 8-bits by over sampling and filtering.

I don't know how to analyze this but I'm guessing with n-bits each each
sample has a 1/2 bit error so my I and D terms in the PID controller will
accumulate lots of 1/2 bit errors.   I thing I want them "a couple orders
of magnitude" smaller then the  allied temperature range.

Of cose one could buy the best ADC on the market.   But this is POOR MAN's
project.   So he asks, "What is the lowers performance/cost part that will
allow the system to meet its specification?

BTW, a related story.I'm on another couple lists that deal with vacuum
tube audio.  We see the same things there people correctlypointing out how
to make something better but the question is always how much better and at
what cost an does it matter.   So a fun project was proposed.  Set a budget
of $200 to build a tube based stereo Hi Fi amplifier.  Who can do the
best.  Youhade to publish the BOM with prices and suppliers.   Extra points
if you came in under budget. This eliminated all the suggestions to buy
high end hand made transformers from Sweden.

IT turrets out that you see MUCH more interesting designs when you lower
the budget.  Anyone can make a high performance system even enough money.
They waste half the cost on useless stuff and the product costs double what
it should and is over complex but is works real, really well.   That's
easy.  Harder and more interesting is "Can you make something just as good
at 1/2 the price?"   Answer is usually Yes.  Then you say "what much do you
loose if I set the price to 1/4?   The answer is surprisingly little if you
get smart about sourcing parts.  Turns out about $180 is the minimum
for pretty decent quality HiFi vacuum tube.

An interesting graph would be Oven Specification vs. Price.  What is the
minimum cost for keeping temperature to within 1.0 C, for 0.1C, 0.01 C?
 Can you do 1.0C for under $5?   or 0.1C for under $10.I bet yes.

I did an exercise a while back to see what is the minimum price and
complexity to build a GPSDO that was good enough only to drive the lab
bench instruments I have.   I implements only 1/2 od Lars W's design and
cut his lines of code by about 90%.  Turns outhe cost is the XO and about
$10.   Compared to my Thunderbolt, performance was not nearly as good but
the ratio of performance over parts cost might be better.



On Tue, Jun 6, 2017 at 2:39 PM, Mark Sims <hol...@hotmail.com> wrote:

> Another thing to watch out for on processor ADCs is their performance near
> the supply rails...  the AVR ADCs are particularly entertaining below
> around 300 mV (with a 5V Vref).
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] uC ADC resolution (was: Poor man's oven)

[Chris Albertson]

On Tue, Jun 6, 2017 at 2:17 PM, Attila Kinali <att...@kinali.ch> wrote:

> On Tue, 6 Jun 2017 16:37:27 -0400
> Bob kb8tq <kb...@n1k.org> wrote:
>



> . Heck, the STM32F4xx have so much internal noise that the ENOB
> of their ADC is below 6bit... so low that they even had to write an
> appnote on how to do averaging to get back to the 12 bits the ADC is
> spec'ed for. (but don't mention that to an ST sales person, they will
> hate your guts afterwards).
>

Can you actually get back all of those bits?   How many samples would you
need?   My current use case for the STM32 ADC is to track battery voltage
and maybe 6 bits is enough but if I can get to 12 with a software-only fix
I'll take it.  Batteries volts charge slowly so I'd have time to take many
samples.   It's a rather mundane application.  Controlling a battery
powered motor and I can't let theLiPo battery dichange below a limit so I'm
sampling voltage at 1Hz.   Got a link to or the name of the app note?

>
>
-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Poor man's oven

[Chris Albertson]

> There are more sophisticated control loop designs that can handle this
> better, eg by using two temperature sensors, one at the crystal and
> one at the heater. But designing them correctly is more difficult
> than the normal PID loop.
>

Keeping with the thread topic, I think this is the key.For the cost of
only one more cheap sensor you gain a lot.   Harder design as you say but
getting help on-line seems to be free.

I have gotten PID to work myself with linear systems (motor speed) and I
reading up on Kalman Filters as I need them for navigation using multiple
sensors.

I guess one could use the crystal frequency as a measure of its temperature
to tune the system.  Is there a name to Google to read up on using two
sensors and a pid-like algorithm?
-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Poor man's oven

[Chris Albertson]

Yes, as I wrote.  I would not mess with AREF.  At most you can only get a
multiplication about 4.   Use an op-amp.   Signal conditioning really
almost alway is required in the analog domain before any A/D conversion

Also like the uP is not inside the oven and has a cable of some length so
you'd want a buffered analog signal on the cable, the op-amp can do that
to.

Those $2 parts I linked to have the ADC referenced to 3.3 volts but have 12
bits as compared to the arduino which has 10 bits

The next step up the complexity scale would have you place an I2C
interlaced ADC inside your oven.  These don't cost much and have several
ADC channels.  then your oven has full digital interface and a much higher
quality DAC.  But this adds another 2 or 3 dollars to the design.   Maybe
worth it as now all the analog stuff is inside a temperature stable metal
tin can. But you have to watch this feature-creep as you can drive up
cost with little to show for it.

Also I'd not want the analog stuff designed to work only with ADC built
into one specific development board.  The I2C serial interface is pretty
much universal

I'm thinking something like this:
http://www.ebay.com/itm/12-Bit-I2C-4-CH-ADS1115...
<http://www.ebay.com/itm/12-Bit-I2C-4-CH-ADS1115-ADS1015-Module-ADC-Development-Board-for-Arduino-/112192172479?hash=item1a1f2cb1bf:g:kQEAAOSwA3dYGrZp>
Notice that the chip has programmable gain, it can scale the input over a
small range before sampling.
For $2 it's still a "poor man's part and you do NOT need to make a PCB to
use it.

On Tue, Jun 6, 2017 at 10:08 AM, Jim Harman <j99har...@gmail.com> wrote:

> On Tue, Jun 6, 2017 at 10:00 AM, Riley, Ian C CTR NSWC Philadelphia, 515 <
> ian.riley@navy.mil> wrote:
>
> > Is there a practical minimum for what voltage you can feed into AREF?
> >
>
> It is hard to find on the data sheet, but the minimum voltage for an
> Arduino's AREF is the internal analog reference voltage - 1.1V for the Uno,
> 2.56V for the Leonardo or Micro. The 32U4 chip in the Leo and Micro has
> options for differential analog input and gains of 10, 40, or 200 but they
> are not supported by the Arduino IDE - you have to set the internal
> registers directly to use them. Also the input amplifier is pretty slow.
>
>
> --
>
> --Jim Harman
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Poor man's oven

[Chris Albertson]

On Tue, Jun 6, 2017 at 7:34 AM, Attila Kinali <att...@kinali.ch> wrote:

>
> 1) You want the control loop as stable as possible
> 2) Stability is directly related to controllability
> 3) The larger the heat flow, the better the controllability
> 4) therefore the outside temperature should be as low as possible


I think you are correct but within reason of course.   It is easy to see
that the extremes can't work. If the internal set point is very close to
ambient the oven is uncontrollable.  because you only use the first bit of
the DAC to control the heater and after a few seconds you have overshoot.
Moving the set point up lets us use the full range of current on the heater
can gives us 8 or 10 bits of control and the rate of change is slow enough
that we have time take thousands of samples and see a rate of change in
temperature.  The PID algorithm needs something that is slow to change
compared to the control loop cycle.  So you want a good size thermal mass
compared to the amount of heat.


At the other extreme, where the set point to far above ambient we would
need to run the heater full time and also loose control.  So I disagree
with #4 above.   The heater would have to run full-on at 100% duty cycle.
 (In other words avoid using liquid nitrogen baths)

There is an optimum were it peaks but I don't know how to find it.Look
at the specific heat of the thermal mass (likely you are using aluminum)
and multiply that by the mass and I think you want that to be large
compared to the heat from a full-on heater so that the rate of change looks
slow compared to your control loop cycle.





-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Poor man's oven

[Chris Albertson]

On Mon, Jun 5, 2017 at 3:38 PM, Charles Steinmetz <csteinm...@yandex.com>
wrote:

> Chris wrote:
>
> Today all you need is a reliable way to measure the error
>> between the crystals' current temperature and the set  point.
>>
>
> That's all that's ever been needed.  But it is devilishly difficult to
> measure the actual quartz temperature, or even to find a good proxy that is
> easier to measure.
>
> There is a fair body of published research on these topics, including
> Rick's (et al.) work on zero-gradient ovens.
>
> Keep this in mind when someone says they are controlling the "oven
> temperature" to 0.001C (or even 0.1C).  They are measuring *something*, and
> may even be holding whatever it is "constant" within fairly tight
> tolerances.  But they have no idea what the quartz temperature is, and no
> way to know with precision the relationship between the measured
> temperature and the actual quartz temperature.
>

How much does this matter?  What we measure is the ambient temperature
inside the insulated box that contains the crystal.   The assumption is
that given some time the temperature will be uniform. OK, so the assumption
is not 100% correct but lets say the crystal is held to a range of 0.1C
 This is a reasonable goal for a home shop made controller.

Here is another question:
Lets assume we place the operating point on the flat part of the curve with
say a 1.0 C absolute error and can hold the relative temperature to 0.1C
 What does this mean in terms of frequency.?

This is a "Poor Man's" oven.   So really the question is this:  I have a
$10 budget, shouldI blow half my budget on a better sensor or is the 75
cent part good enough.  Or is it worth buying a second 75 cent sensor so I
can detect a temperature gradient  With a poor man's budget, I think the
trick is to use a good size thermal mass, chunks of scrap meter are cheap.




>
> Some years ago, I consulted for a research group that was using a number
> of non-contact technologies to measure the temperature of oscillating
> quartz crystals.  The results were promising, but there were some issues
> with measuring the temperature (which is, essentially, quantifying tiny
> random molecular motions within the crystal lattice) against the background
> of the hugely greater macro motion of the vibating quartz.  I never knew
> the final conclusions, nor am I aware of any systems designed using these
> principles or methods.  But it is something to think about if you *really*
> want a temperature-stable oscillator.
>
> Best regards,
>
> Charles
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Poor man's oven

[Chris Albertson]

Look at the dates on the uses of these exotic temperature controllers.
Organic compounds and positive temp coefficients and so on.  All these were
used before the current era.  Today all you need is a reliable way to
measure the error between the crystals' current temperature and the set
point.

Those exotic methods were good back when controllers were analog devices
build with op-amps and precision resisters and every math operation cost
you one more op-amp.   Today we can do a million floating point operations
per second for the cost of one kind good op-amp.

The trick with using a uP and it's built-in A/D converters is scale.  You
want the limited 10-bits of revolution to fall over the operating range
which is very narrow, like 1C.   Anything outside of that is either  or
 and only seen at start-up.,  So at start up the the controller is on
"bang-bang" mode then later you have milli-degree resolution over your 1C
range.   Basically you are measuring noise. but your $2 uP can take 100,000
measurments per second and putt tour a digital filter.

Today we can do things the old-time designers even as recent as the 1980's
would not even dream of doing and it cost under $10.

On Mon, Jun 5, 2017 at 1:35 AM, Ulf Kylenfall via time-nuts <
time-nuts@febo.com> wrote:

>   The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand
> they were marketed by Murata.
> I once purchased a small amount of theseand used them as "poor man's
> ovens".
> Although not perfect by far, they did theirjob and kept my UHF gear stable.
> Murata dropped that product many yearsago and I have not been able to
> findany similar product. The Posistors arelisted by eg. Digi-key but they
> do not stock them.
> Ulf - SM6GXV
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] PPS sync

[Chris Albertson]

I did not finish the sawtooth explanation.  One of the units is designed
such that the PPS is always on the raising edge of an internal 10MHz clock.
   If the 10MHz clock were perfect this means the maximum error is 1/2
cycle.   The software in the GPS choose site best edge to minimize error.
 the jump you see it when it selects a different cycle and jumpsThe
software tracks the error and outputs an estimate of the root on the serial
channel.

You can verify this by plotting the sawtooth correction vs.time and see
that it lines up with your observation of the jump back to zero error.

There might still be errors cause by other things, like improper self
survey but the results you reported are exactly like what one would expect
from a unit that uses an oscillator edge to trigger PPS.  It other words
what you see is a design feature not an error.

On Mon, Jun 5, 2017 at 6:40 AM, Jerry Hancock <je...@hanler.com> wrote:

> It was off 7.5KM, that’s a little beyond groggy, no?  More like a trip to
> Vegas.
>
> I’ll let it rerun the survey and see if it gets closer.
>
> > On Jun 4, 2017, at 9:50 PM, Mark Sims <hol...@hotmail.com> wrote:
> >
> > Be careful when using one unit's location to set a different model's
> location...  particularly the altitude.   Some devices report altitude in
> MSL, others in AGL... and different units may use different models for the
> ellipsoid.   You are always better off using coordinates generated by the
> particular device (either the built-in self survey or something like Lady
> Heather's precision survey).
> >
> > I did some tests while developing Lady Heather's precision survey code.
>  I got pretty consistent lat/lon/alt results on the same units but
> consistent offsets between different models of receivers.
> >
> > I would suggest letting the Motorola re-surevy itself...  it may have
> been a bit groggy after first being powered up after a few years of
> sleep... I know I am...
> >
> > ---
> >
> >> I then set the M12 reference location to the Lucent location as I know
> it to be correct.
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] poor-man's oven

[Chris Albertson]

Yes,  Agree.  I wrote tin the first post that "for your use a resistive
heater would be better"

But everything else, I'd do over.  Drill the aluminum block and use thermal
epoxy to hold the sensor in place.   Use a vacuum insulated mug or bowl for
a cover and let a micro controller run a PID loop to control temperature..
  You can keep it within 0.1C without the need to be a control theory
expert. Another order of magnitude would really hard and expensive

The last temperature controller I made was not as good but keeps a rubidium
oscillator within about a degree.   I put a thruster in the Rb's heat sink
and a micro controller adjusts the fan speed.  The self heat from the Rb
unit is enough. The Rb is about the size and shape of an old 3.5 inch
disk drive so I put it n an old disk drive enclosure that already had a
place for a fan.As crude as this is, it is much better then what I had
which was not control.  The Rb output is better then I have means to
measure now.

So same with the poor man's oven.   It can be very good with very little
effort.What has happened is that now we have nearly free micro
controllers and can use daily sophisticated control algorithms that HP
could not use back in the day. We can actually model non linearities in
the sensor.   We can use a full on PID solution rather then the simple
on/off thermostat.

But no you don't want to cool a crystal, I was not suggesting that.   We
happened to have a high gain amplifier that was in effect counting
electrons.

On Mon, Jun 5, 2017 at 2:15 AM, Attila Kinali <att...@kinali.ch> wrote:

> On Sun, 4 Jun 2017 22:01:45 -0700
> Chris Albertson <albertson.ch...@gmail.com> wrote:
>
> > Voltage is proportional to the product of resistance and absolute
> > temperature.   As an experiment place a voltage across a high value
> > resister like say one 1M  raise the volts until you are near the limit of
> > the resister and connect it via a coupler cadaster to an audio amplifier.
> > You will hear white noise in the speakers.
>
> Yes, Johnson noise increases by about 20% (or about 0.8dB)
> when going from 25°C to 90°C. But Johnson noise is usually
> not the first limiting noise one runs into when designing
> a crystal oscillator. I would rather use a simpler,
> "high temperature" oven and invest the time saved into a
> desgining better oscillator structure.
>
>
> > There is a similar effect in semi conductors.  The best example of this
> is
> > visual noise in digital camera, when you tern the gain way up (set the
> ISO
> > high) you can see it in the photo.
> >
> > All of this is proportion; to absolute.
> >
> > As I remember we ran the "oven" at -20C There was a valve used to flash
> out
> > the air inside with inert welding gas to reduce ice.
>
> If the -20°C was used on the camera, then this is not to reduce Johnson
> noise, but the dark current noise. While the former is due to thermal
> vibration of the atom lattice, the later is due to spontaneous forming
> of electron-hole pairs in the p-n junction region. Thus also their
> temperature characteristics differ: While Johnson noise is linear
> in temperature, dark current noise is (almost) exponential in temperature.
> Going down from room temperature to 0°C is something like a factor 100
> (IIRC, from memory, could be wrong) in noise for a CCD. While for
> a resistor, the difference is almost negligible.
>
> Attila Kinali
> --
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering.  -- The Doctor
> _______
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] PPS sync

[Chris Albertson]

One of the GPS units is likely sending a saw-tooth message out the serial
line that exactly describes the 0 to 100ns drift.   This is why they call
it "saw tooth" the function ramps up slowly then falls to zero.  A device
like a GPSDO that uses the PPS would need access to the serial data to read
the sawtooth correction,

On Sun, Jun 4, 2017 at 9:36 PM, Jerry Hancock <je...@hanler.com> wrote:

> 1) I have my TAPR M12 Kit working now next to my lucent RFTG-U REF0/1
> pair.  I was comparing the PPS outputs triggering on the Lucent as channel
> 1 and the M12 as channel 2.  I can’t tell which is moving around but the
> symptoms are that at T0 (not the top of the minute or hour) they are in
> sync within a nanosecond.  From T1 to T20 they move progressively out of
> sync until hitting around 100ns and then snapping back to being in sync. I
> would think that if both were moving that it wouldn’t be that consistent,
> no?
>
> Since I can’t tell which is moving, most likely both,  I plan to take the
> disciplined 10Mhz out of the Lucent and divide it down with my TAPR TADD-2
> to 1PPS.  I would think that would be more stable on a PPS by PPS basis and
> compare again.
>
> Any other ideas?
>
> 2)  When I first fired up the M12 and let it do a survey, it was off for
> some reason by 7KM.  I then set the M12 reference location to the Lucent
> location as I know it to be correct.  I was thinking though, would the PPS
> phase comparison in 1, above, be impacted by the reference locations being
> off?  Both GPS cables are the same length.  The only thing I don’t know is
> the internal processing delay of the units.  The SynTac software allows you
> to take this into consideration for PPS timing when using the M12.
> Interesting unit by the way.  Lots of configuration options exposed with
> the Syntac software.  Not that I would replace Lady Heather or anything,
> I’m just using it while I get some of these issues figured out.
>
> Jerry
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] poor-man's oven

[Chris Albertson]

Voltage is proportional to the product of resistance and absolute
temperature.   As an experiment place a voltage across a high value
resister like say one 1M  raise the volts until you are near the limit of
the resister and connect it via a coupler cadaster to an audio amplifier.
You will hear white noise in the speakers.

There is a similar effect in semi conductors.  The best example of this is
visual noise in digital camera, when you tern the gain way up (set the ISO
high) you can see it in the photo.

All of this is proportion; to absolute.

As I remember we ran the "oven" at -20C There was a valve used to flash out
the air inside with inert welding gas to reduce ice.

Some people use vacuum and get to cryogenic temperatures.  But that is
expensive and way-hard without an institutional size budget.





> What is the reason why you'd expect less noise with a TEC?
>
> Attila Kinali
>
> --
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering.  -- The Doctor
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] poor-man's oven

[Chris Albertson]

Look at the temperature coefficient of your XO.  Then figure a very simply
control loop and a thermistor will keep a block of aluminum within 0.1C of
a set point.  Use a decent size block and insulation

We drilled a deep hole then epoxied the thermistor.  I think this step is
important as you want to measure the center of the black, not the surface..
   Then epoxied a TEC (aka Peltier device) to the Al Block.  TECs are nice
because they can both cool and heat.   On the other side other TEC was a
rather large heat sink (or heat source depending on the polarity) a uP and
a PID loop controlled the output current.   Place an insulator over the
controlled end of the block.   I think a stainless steel vacuum insulated
coffee mug works well.

I think cheap thermistors are OK as they will never, in use, see
temperature swings of more then 0.1C so who care if they are linear or not.
They are all linear enough over a short range.  What you pay for is being
perfect over a 100C range, you don't need that.


We used the pelter because we preferred a cool "oven" to a hot one.   The
theory has that we get less electronic noise so we ran the TEC in cooling
mode.   But for your use a resistive heater would be cheaper.   But in
either case you see a coffee mug with a round chunk of Al shoved in and
heat sink fins showing.

When I was doing some contraction work, I thought of it would be fun to
toss an XO in the big hole that was going to get a truckload of concrete
poured into it.  The temperature down there would be very stable.



On Sun, Jun 4, 2017 at 5:13 AM, jimlux <jim...@earthlink.net> wrote:

> I recall some years ago folks were talking about putting a PTC thermistor
> on the TCXO of a FlexRadio SDR1000 to stabilize the frequency as a sort of
> poor-man's OCXO.
> It's also referenced at
> http://www.setileague.org/askdr/xtaloven.htm
> where he says "order of magnitude improvement" with no numbers (from 1% to
> 0.1% or from 1 ppb to 0.1 ppb?)
>
> I wonder how well that actually works.
>
> Say you bought an inexpensive (perhaps non TC) XO and an equally
> inexpensive thermistor, glued on on the other, hooked em both up to 3.3 or
> 5V.
>
> Yeah, there's issues with room air blowing on it, and tolerances in both
> the XO and thermistor, so your absolute frequency accuracy may not be so
> hot. But what sort of medium to long term performance can one expect.
>
> I did some searches, because I'm sure we've discussed this before, but I
> couldn't find it.  There was some stuff from Oct 2007, but that was in the
> context of a more complex circuit, and the thermistor was the sensor.
> (discussions of TE devices too)
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] The future of Telecom Frequency Standard surplus

[Chris Albertson]

I think there will be fewer useful parts.

The reason is integration.   In the old days they would buy off the shelf
equipment like a GPS receiver that was inside its own box and was cabled to
something else.  A better newer design would be to use a "GPS Chip" can
route the output not using a cable but with PCB traces.   An even better
design is to move the GPS on-chip And one day you get a "cell phone tower
on a chip"  THAT day may never come but you get the point.   The trend is
that the sub-parts will be be separable.

Going back a few years in technology.   I bought a broken 1950's vintage
Hammond organ (no, not a classic B2) because I wanted to build a guitar
amplifier.  The dead organ has good transformers, tubes and tube sockets
and so on.  In other words it was built entirely from generic parts that
could have been used to build their day to build any kind of audio
equipment.   50's vintage guitar amps used the same parts, just wired up
differently.

You can no longer to this with audio gear.  Just try taking an AV receiver
apart so you can build your own iPod.  Today all the parts are specialized
and there are few generic parts in most phones, TV sets and the like.

The good news is that making you own specialized parts is now much easier.
FPGAs are cheap and the actual designs are in software that can be pushed
around for free over the Internet, kept on GitHub or whatever.As an
example I needed a logic analyzer.  These used to be big expensive beasts
but today one can use a generic FPGA development board and somefware for
less than the cost to ship the beast via UPS.

In short, my prediction:  Less surplus gear but better ability to get new
gear so less need of the old stuff.

On Wed, May 31, 2017 at 8:47 AM, Tom Knox <act...@hotmail.com> wrote:

> I think many of us Time-Nuts have played with the wide range of frequency
> standards surplussed from the Telecom market.
>
> My questions is, will the quality of future surplus offerings go up or
> down as 4G and in the more distant future 5G surplus Frequency Standards
> hit the market? It seems with higher data rates stability and phase noise
> demands will increase, but will other advances find ways around the expense
> of a high end Frequency Standard. I know some early telecom systems even
> want as far as Cesium Standards, but more robust network tolerances seems
> to have reduced the need for that level of performance. So which way are we
> headed?
>
> Any thought? I imagine some members are actually involved in design and
> implementation of the next generation telecom technologies and will have
> direct knowledge.
>
> Thanks;
>
>
> Thomas Knox
> 1-303-554-0307
> act...@hotmail.com
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Machining some aluminum help!

[Chris Albertson]

That is one reason people have been recommending heilicoils.   The
drill an tap size is about 30% larger than for #4 screws without the
inserts.  It is easier to do and when you are done there are stainless
female threads that are much stronger.

On Thu, May 25, 2017 at 3:57 PM, ed breya <e...@telight.com> wrote:
> ..., you can save a lot of grief by using a slightly larger bit than the
> standard tap drill. You're not really too concerned with optimal fit and
> strength here - it's more about being able to make a whole lot of usable
> screw holes without losing too many bits and taps,
-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Machining some aluminum help!

[Chris Albertson]

Why not make the enclosure with a round, not square cross section then
the end plate can screw in.  Only one hole to thread that way.  Of
course there is plumbing pipe but also stainless steel water bottles,
fly rod cases and all kinds of ready  made metal enclosures with
thread caps that can hold pressure.A stanley wide mouth thermos
would be excellent for making a temperature controlled metal
enclosure.  The vacuum insolation is pretty good, and of course they
already hold pressure.

On Thu, May 25, 2017 at 2:08 PM, ed breya <e...@telight.com> wrote:
> This is the first time I've looked at time-nuts in about a month, and I
> noticed the run about this project. I'm very late to the party, but have a
> few suggestions that may help - if it's not too late. I quickly scanned many
> of the posts, and agree with many of the ideas. Please forgive if my
> suggestions are redundant to what's already been said.
>
> First, I assume that the aluminum box is a simple extrusion, so it will
> likely be a soft alloy that will tend to gall horribly with machining -
> especially bad for anything that needs high precision. With these kinds of
> material, go big, starting with bigger fasteners. With 1/4" walls, you can
> easily up it to 6-32 or 8-32, as long as the holes are fairly shallow, and
> you can jig it up for good centering and plumbness. With 4-40 and blind
> holes, you're just asking for trouble - especially taking a chance 40 times.
> The tap drill will be quite skinny, and prone to deform and wander as it
> goes in, and can easily be snapped off when it stalls due to the galling -
> and that's just the drilling stage - the tapping will be worse.
>
> Bigger threads give you a chance to get it done with fewer fasteners and
> holes, and much less grief. The thread depth should allow for at least one
> pitch-diameter of penetration for strength, but preferably two or more, so
> you don't have to worry about finding exact right screw lengths that won't
> bottom out. Depending on the thickness of the end plates, you could get down
> to two or three fasteners per side to hold the small pressure needed.
>
> If you're using a drill press, punch mark the hole centers, then use a
> center drill to make the pilot holes for the tap drill. If you're freehand
> drilling, put the piece on the floor and drill downward, keeping it as plumb
> as possible. Definitely use an oil or other lubricant for all the drilling
> and tapping operations.
>
> For sealing, I'd recommend against fancy o-ring features and such - these
> are also harder to machine cleanly in soft aluminum, and add unnecessary
> complexity. If the end caps need regular remove and replace operations, then
> go with a pliable gasket, have more fasteners to get more uniform
> compression, and make the threads deeper so they'll last longer. If the
> sealing is one-time, or seldom needs to be broken, I'd recommend using a
> gasket sealing goop that will work fine with few fasteners and even rough
> surface finish. My favorite is Permatex #2 "Form-A-Gasket Sealant," which
> I've used for all sorts of stuff over fifty years (back then it was Radiator
> Specialties brand). Don't use a silicone goop unless you want to spend a lot
> of time scraping off the old stuff if it needs to be opened. If you do use a
> goop, it's a good idea to machine in features for prying the lids off, such
> as gasket-plane screwdriver slots, or extra tapped through-holes in line
> with the mounting holes on of the lid.
>
> Ed
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GNSS Disciplined Clock

[Chris Albertson]

The long term stability of GPS is very good.  Some one here will point
out exactly how one measures it.   But roughly when speaking of
accuracy you always need to specify a time interval. For example
if the 1PPS is "off" by 15ns that is not bad and yes there are much
better systems if you need to measure time intervals on the order of
one second.   But if the signal is "off" by 15 ns over 100,000 seconds
that is well, 100,000 time better.

This is a basic reference and for some specialized end use case you
might couple it with other equipment.  Many of the concerns you had,
such as effects of the atmosphere get averaged out because the unit is
looking at satellites from all over the sky.  (averaging over space)
And you do git better results with better antenna locations that are
away from multi-path and have a 360 degree view of the horizon.  But
notice the unit has an temperature stabilized crystal oscillator that
is stable over many seconds. an is much more stable in the short term
then is a GPS receiver.  Trimble uses this crystal to average over
time

You also have to ask where is the tine data going to be used.  Are you
synchronizing a computer's internal clock or trying to measure the
frequency of a microwave transmitter

SO it falls back to the old thing about there being no "better" only
better for a specific use case.

Some of use were lucky enough to buy Trimble Thunderbolts, a previous
version of this unit when they were on eBay for $100 each.   For those
without 5 digits budget they ar pretty much the Gold Standard.  I have
mine installed with a good filtered DC power supply and an outdoor
antenna on mast well above the roofs of surrounding buildings. I
get long term stability of about one part in 10E13.   Yes 13 digits
over long periods.   (I think?)  It is really hard to know because my
measurement system is a little circular referenced

On Thu, May 25, 2017 at 6:27 AM, Ebrahim Roghanizad
<e.roghani...@gmail.com> wrote:
> Dear members
>
> I am a new amateur member in your group. Maybe my question has been asked.
> Recently I found Trimble Mini-T GG, whose data sheet is attached, as a good
> GNSS disciplined time reference. I would like to know if there exists a
> more accurate one, since it does not employ dual frequencies to compensate
> ionospheric delay, though it handles both GPS and GLONASS. Besides, could
> anyone guide me about the presented accuracy in the datasheet? There, it is
> stated that "When operating in Over Determined Timing Mode, the accuracy of
> pulse per second (PPS) is within 15 nanoseconds of GNSS/UTC." Does it mean
> that it includes both bias and the noise? In other words, is it true to say
> that "The time-synchronization error between two of them with a long
> distance is less than 2*15 ns"?
>
> Best Regards
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] TruePosition and Arduino Progress

[Chris Albertson]

The root of the problem is that he is doing all the parking at once
and ignoring inputs from both the serial line and the 1PPS

Even if the iPPS were connected to an interrupt (and it should be) he
is still busy parking input when the ISR sets the flag.

He needs to read the data fro the serial line one character at a time
and not wait to start parsing.

Either that or he needs to insert calls to some kind of CHECKINPUTS()
every few lines in the parser and that just look ugly.

On Sun, May 21, 2017 at 11:56 AM, Jim Harman <j99har...@gmail.com> wrote:
> Another way to do is to use the 1 PPS to trigger an interrupt on the
> Arduino. Look at the documentation for attachInterrupt(). In the interrupt
> routine, have it set a flag. The flag variable should be declared up front
> as volatile.
>
> Then in your main loop, do all your parsing then loop waiting for the flag
> to be set. When set, update the clock then clear the flag and repeat.
>
>
>
> On Sun, May 21, 2017 at 2:32 PM, Chris Albertson <albertson.ch...@gmail.com>
> wrote:
>
>> To add to my last message.
>>
>> You CAN collect all the data then parse it like you are doing if you
>> were to move to an interrupt driven serial port reader.   Each
>> character is then read by the interrupt handler anyplace in a large
>> circular buffer.   The parcer then reads out of the other and of this
>> buffer.
>>
>> The phlegm with the current code is the parse ingnores serial input
>> and will drop data, in also ignore the PPS and will as you found drop
>> pulses.
>>
>> Typically in real time processors like your that must be interrupt
>> driven or they must poll MANY times laster then the data arrives
>>
>> so as I wrote before, parsing the data stream one character at a tie
>> is in effect pooling the serial port much faster then characters
>> arrive.Adding a ring buffer and interrupts guarantees yo never
>> miss a character and certainly you need to interrupt in the PPS to
>> handle the case there three s serial data and the PPS at the same
>> time.
>>
>> The ring buffer is like you big string except you data data onto one
>> end at the same time as soured data off the other.  Hopefully the ring
>> buffer never has much data in it as the parser should be fathers then
>> the serial line.  BUT if a PPS happens then the parser in interrupted
>> while the display updates so th ring buffer might get filled up a
>> little.  But the ISR terminals the parser clears the buffer.
>>
>> On Sun, May 21, 2017 at 11:20 AM, Chris Albertson
>> <albertson.ch...@gmail.com> wrote:
>> > The problem is that you get the ENTIRE string then parse it.  This is
>> > not going to work well as you found out.   Your CPU spends almost the
>> > entire time waiting for characters to come in slowly off the serial
>> > line.  You are just waiting on bits and wasting CPU cycles
>> >
>> > What you need to do is parse one character at a time.   I bet your
>> > parser reads one character at a time from the string.   Have it read
>> > one character at a time directly from the serial port.   (Use a state
>> > machine.  It will work for such a simple  job as this)
>> >
>> > Yes if your CPU was MUCH faster your plan could work.  But on some
>> > GPSes the data never has a break.   You are trying to do ALL the work
>> > in the break but actually most of the down time when you should be
>> > working is between the characters.There is not a lot of work a
>> > finite state machine needs to do between characters, just move state
>> > based on a 'character class" table.   I you ever studied this
>> > formally, what you are building here is a "lexer" not a parcer.   The
>> > "Language" is not recursive and you never need to backtrack so it can
>> > be de-coded literally one character at a time.
>> >
>> > You DO really want the 1PPS to drive an interrupt.   Thisway you just
>> > continue working on the data stream and don't wait for the PPS.   When
>> > the PPS happens you do something QUICK. never do anything time
>> > consuming in the ISR or you will miss the next serial character.
>> > increment a seconds count and write two bytes the the LCD and exit
>> >
>> > On Sun, May 21, 2017 at 6:45 AM, Ben Hall <kd5...@gmail.com> wrote:
>> >> Good morning all,
>> >>
>> >> A quick update for those interested on my Arduino code development for
>> the
>> >> TruePosition boards.  I've got Arduino code together than can read in
>> the
>&g

Re: [time-nuts] TruePosition and Arduino Progress

[Chris Albertson]

To add to my last message.

You CAN collect all the data then parse it like you are doing if you
were to move to an interrupt driven serial port reader.   Each
character is then read by the interrupt handler anyplace in a large
circular buffer.   The parcer then reads out of the other and of this
buffer.

The phlegm with the current code is the parse ingnores serial input
and will drop data, in also ignore the PPS and will as you found drop
pulses.

Typically in real time processors like your that must be interrupt
driven or they must poll MANY times laster then the data arrives

so as I wrote before, parsing the data stream one character at a tie
is in effect pooling the serial port much faster then characters
arrive.Adding a ring buffer and interrupts guarantees yo never
miss a character and certainly you need to interrupt in the PPS to
handle the case there three s serial data and the PPS at the same
time.

The ring buffer is like you big string except you data data onto one
end at the same time as soured data off the other.  Hopefully the ring
buffer never has much data in it as the parser should be fathers then
the serial line.  BUT if a PPS happens then the parser in interrupted
while the display updates so th ring buffer might get filled up a
little.  But the ISR terminals the parser clears the buffer.

On Sun, May 21, 2017 at 11:20 AM, Chris Albertson
<albertson.ch...@gmail.com> wrote:
> The problem is that you get the ENTIRE string then parse it.  This is
> not going to work well as you found out.   Your CPU spends almost the
> entire time waiting for characters to come in slowly off the serial
> line.  You are just waiting on bits and wasting CPU cycles
>
> What you need to do is parse one character at a time.   I bet your
> parser reads one character at a time from the string.   Have it read
> one character at a time directly from the serial port.   (Use a state
> machine.  It will work for such a simple  job as this)
>
> Yes if your CPU was MUCH faster your plan could work.  But on some
> GPSes the data never has a break.   You are trying to do ALL the work
> in the break but actually most of the down time when you should be
> working is between the characters.There is not a lot of work a
> finite state machine needs to do between characters, just move state
> based on a 'character class" table.   I you ever studied this
> formally, what you are building here is a "lexer" not a parcer.   The
> "Language" is not recursive and you never need to backtrack so it can
> be de-coded literally one character at a time.
>
> You DO really want the 1PPS to drive an interrupt.   Thisway you just
> continue working on the data stream and don't wait for the PPS.   When
> the PPS happens you do something QUICK. never do anything time
> consuming in the ISR or you will miss the next serial character.
> increment a seconds count and write two bytes the the LCD and exit
>
> On Sun, May 21, 2017 at 6:45 AM, Ben Hall <kd5...@gmail.com> wrote:
>> Good morning all,
>>
>> A quick update for those interested on my Arduino code development for the
>> TruePosition boards.  I've got Arduino code together than can read in the
>> serial stream, parse it, and display time, date, number of satellites, and
>> TFOM on a 2x16 LCD display.  It does not do multiple screens, handle survey,
>> or display lat/long yet.
>>
>> What I'm having issues with is handling the 1 PPS.  Ideally, I want to use
>> the 1PPS signal to trigger the display update.  IE:
>>
>> void loop()
>> {
>> getSerialString()  // uses serial.available to pull in the serial data
>>
>> parser()  // this parses the data
>>
>> wait for 1PPS tick to go high
>>
>> if there has been a clock message, updateDispay()  // update the display
>> }
>>
>> This works great when there is a just a clock message.  But when there is a
>> clock message, an extstatus message, and a status message, it seems like it
>> is still parsing when the 1PPS tick comes in...so it will display seconds as
>> follows:  30, 31, 33, 34, 35, 36, 37, 39, etc...
>>
>> (If I don't wait for the 1PPS tick, it seems that my clock is one second
>> fast.  I say "seems" to be fast, as the time agrees with an NTP clock on one
>> computer, but seems a half second slow per GPSCon's time display on the
>> Z3801.  I think I need to put up the antenna and check against WWV.)
>>
>> I've got one of those cheap little USB logic analyzers on order to figure
>> out how much time elapses between the clock, extstatus, status, and 1PPS
>> tick.  I may need something faster than an Arduino Uno to do this.
>>
>> I'm sure there is a way to do this with an interrupt...but

Re: [time-nuts] TruePosition and Arduino Progress

[Chris Albertson]

The problem is that you get the ENTIRE string then parse it.  This is
not going to work well as you found out.   Your CPU spends almost the
entire time waiting for characters to come in slowly off the serial
line.  You are just waiting on bits and wasting CPU cycles

What you need to do is parse one character at a time.   I bet your
parser reads one character at a time from the string.   Have it read
one character at a time directly from the serial port.   (Use a state
machine.  It will work for such a simple  job as this)

Yes if your CPU was MUCH faster your plan could work.  But on some
GPSes the data never has a break.   You are trying to do ALL the work
in the break but actually most of the down time when you should be
working is between the characters.There is not a lot of work a
finite state machine needs to do between characters, just move state
based on a 'character class" table.   I you ever studied this
formally, what you are building here is a "lexer" not a parcer.   The
"Language" is not recursive and you never need to backtrack so it can
be de-coded literally one character at a time.

You DO really want the 1PPS to drive an interrupt.   Thisway you just
continue working on the data stream and don't wait for the PPS.   When
the PPS happens you do something QUICK. never do anything time
consuming in the ISR or you will miss the next serial character.
increment a seconds count and write two bytes the the LCD and exit

On Sun, May 21, 2017 at 6:45 AM, Ben Hall <kd5...@gmail.com> wrote:
> Good morning all,
>
> A quick update for those interested on my Arduino code development for the
> TruePosition boards.  I've got Arduino code together than can read in the
> serial stream, parse it, and display time, date, number of satellites, and
> TFOM on a 2x16 LCD display.  It does not do multiple screens, handle survey,
> or display lat/long yet.
>
> What I'm having issues with is handling the 1 PPS.  Ideally, I want to use
> the 1PPS signal to trigger the display update.  IE:
>
> void loop()
> {
> getSerialString()  // uses serial.available to pull in the serial data
>
> parser()  // this parses the data
>
> wait for 1PPS tick to go high
>
> if there has been a clock message, updateDispay()  // update the display
> }
>
> This works great when there is a just a clock message.  But when there is a
> clock message, an extstatus message, and a status message, it seems like it
> is still parsing when the 1PPS tick comes in...so it will display seconds as
> follows:  30, 31, 33, 34, 35, 36, 37, 39, etc...
>
> (If I don't wait for the 1PPS tick, it seems that my clock is one second
> fast.  I say "seems" to be fast, as the time agrees with an NTP clock on one
> computer, but seems a half second slow per GPSCon's time display on the
> Z3801.  I think I need to put up the antenna and check against WWV.)
>
> I've got one of those cheap little USB logic analyzers on order to figure
> out how much time elapses between the clock, extstatus, status, and 1PPS
> tick.  I may need something faster than an Arduino Uno to do this.
>
> I'm sure there is a way to do this with an interrupt...but I couldn't make
> that work yesterday.  More to follow.
>
> thanks much and 73,
> ben, kd5byb
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Machining some aluminum help!

[Chris Albertson]

I worked on a project like this once.  No screws at all.  Rather then a 0.1
PSI over pressure. the interior was flush with dry gas then pumped out with
to  a crude vacuum with a hand pump.  Air pressure alone force the cover
plate on.  OK a couple screws where there just to aid in assembly but the
cheap $12 hand pump was good enough.

"high vacuum" requires expensive equipment and is a black art but "crude
vacuum" is easy, easier then holding a pressure because the forces are
pushing the seal together for you.

On Thu, May 18, 2017 at 2:46 PM, jimlux <jim...@earthlink.net> wrote:

> On 5/18/17 1:34 PM, cdel...@juno.com wrote:
>
>> Well that generated a lot of advice and thanks for it!
>> I think I might do it myself and go with a 1/2" hole depth and 1/4"
>> threaded depth.
>> I'll get some of that Aluminum Tap magic, some new taps and new drill
>> bits.
>> Good idea about drilling the end plates first and drilling thru to match.
>> Between the end plate and the tube is a gasket that needs to seal
>> pressure and moisture tight. That's why I used 5 per side.
>>
>
> I would make the end plate "real thick",with a machined groove for the
> o-ring, and use some sort of latches to hold it in place, rather than "lots
> 'o screws".  Unless you've got a real tight space constraint. How much
> pressure do you have to hold? That will determine the clamping force needed
> on your gasket (and potentially, on your fasteners).  Do you need the full
> 4.5x4.5" inside clear space? A 1/4-20 bolt in the corner might be a good
> way to go.
>
> There's also inexpensive surplus vacuum equipment around, as well as run
> of the mill plumbing. Unless Steel (stainless or not) isn't an option.
>
>
>
>
>
>
>> Will let you know how it turns out.
>>
>> Cheers,
>>
>> Corby
>>
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Machining some aluminum help!

[Chris Albertson]

Yes, threaded inserts.  There are many kinds but they are used almost
universally for cases where the material to be threaded is soft, like
aluminum.   They also eliminate or reduce galvanic corrosion which is an
issue with steel screws in aluminum.  (that said, as long as you keep water
away you are OK.)Still these inserts are the "class" way to go and will
save some broken taps.

As for a seal, it is hard to beat o-rings.  A proper designed o-ring seal
does not need much clamping pressure as it depends on the pressure inside
to force the ring in place and hold it there.

On Fri, May 19, 2017 at 12:51 PM, Lincoln <linc...@ampmonkeys.com> wrote:

>
> >
> > There are a lot of variables involved. Run the screws in and out of the
> aluminum a number of times and
> > the holes will fail first ….There are other gotchas as well.
> >
> > Bob
> >
>
> This is where helicoils come in to play. They are used a lot on the CVD
> furnaces that I used to make parts for. They are not just for un-buggering
> a thread. They would be installed form the get go and could be replaced
> should something gall.
>
> Link
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Machining some aluminum help!

[Chris Albertson]

To tell the truth I had not worked this out.But I wonder of the screws
fail first on
they are in aluminum holes with only 1/4 of thread.

Which fails depends on the material and the number of engaged threads,

But if what you say is right for this case.  It strengthens my case for
using self threading screws.  I try and use these when I can.

What you do is center punch the screw location around the end plate.  Then
glue the end plat in place using blue lock tight. (or even two tiny daps of
"Super Glue")  then go to the drip pressed drill through the endplate into
the edge of the wall and insert one screw.  The right size the type screw
will cut its own thread as you screw it in.  Then drill neither hole and
put in another screw.   It is imported to place the screw as you drill to
keep alignment, even when using the glue.   Later take out the screw and
break the glue, reassemble.



On Thu, May 18, 2017 at 5:13 PM, jimlux <jim...@earthlink.net> wrote:

> On 5/18/17 2:36 PM, Chris Albertson wrote:
>
>> It would be easy to re-design the job for cheaper machining..  Do you
>> really need to tap the holes?  You might use self taping screws.  Id the
>> would work then you can do the work yourself with just a hand drill.
>>
>> OK it you must use machine threads and they must be #4 size try "rivets"
>> these work like pop rivets but leave a hollow thread insert in the hole
>> that will take screws.  Takes all of 5 seconds to install a thread hole.
>>
>> Think again about threading aluminum.  It is not very strong, it would be
>> easy for an end user to strip the #4 threads.  Better to use the rivet or
>> other steel thread insert.Even native nuts  installed with flush
>> rivets
>> is better
>>
>
> Interestingly enough, for 4-40 hardware, the screws fail before the
> aluminum does.  The area of the thread engagement is quite a bit larger
> than the cross section of the fastener that is not thread.
>
> For large fasteners, where the thread depth is a smaller fraction of the
> fastener diameter, this may not be the case (as anyone who has stripped the
> threads on an aluminum cylinder head with a steel sparkplug will know, in a
> deep and visceral way).
>
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Machining some aluminum help!

[Chris Albertson]

So the goal is not to attach end plates, that is the solution. The real
goal is a sealed container that can be re-opened.I suggest a trip to
the plumbing supply store.Why not just use screw-on end caps

It you need it sealed 4-40 screw are not able to provide any reasonable
clamping force.   The weak link is the aluminum threads.  You need enough
force to deform the gasket material and those little screws are not going
to do it.

If you need a gas tight chamber, look at plumbing parts.  They make
screw-on end caps with both make and female threads.

There is also a system for brazing alumni that work almost as well as
celiac welding and you can do it with a propane lumber's torch.   They sell
the rods at Harbor Freight.

Why not post a specification (enclose with x,y,z inside dimension,
water/gas tight/ ends on one end,) and ask people for ideas on the
lowest cost way to make that using simple tools.

There are SO MANY solutions, one is double sided, coper clad PCB material.
You can cut it with a wood saw and then solder the panels together to make
a box.   I find that I can solder brass screws to copy PCB material and
make thread posts or studs.

On Thu, May 18, 2017 at 4:13 PM, Andy ZL3AG via time-nuts <
time-nuts@febo.com> wrote:

>
> Why are my eyes watering?
>
> On 19/05/2017, at 5:03 AM, Bob Darlington wrote:
>
> >  I had
> > to soak my cavity ring in nitric acid for a month to get the tap out.
> >
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Machining some aluminum help!

[Chris Albertson]

It would be easy to re-design the job for cheaper machining..  Do you
really need to tap the holes?  You might use self taping screws.  Id the
would work then you can do the work yourself with just a hand drill.

OK it you must use machine threads and they must be #4 size try "rivets"
these work like pop rivets but leave a hollow thread insert in the hole
that will take screws.  Takes all of 5 seconds to install a thread hole.

Think again about threading aluminum.  It is not very strong, it would be
easy for an end user to strip the #4 threads.  Better to use the rivet or
other steel thread insert.Even native nuts  installed with flush rivets
is better

So try self threading screws first them go to threaded inserts, you could
install 100 4-40 inserts in one hour using just hand tools.


On Thu, May 18, 2017 at 9:54 AM, <cdel...@juno.com> wrote:

> Hi,
>
> I have a square aluminum tube 5" X 5" with a .25" wall it's 8 1/2" long.
>
> I need 20 holes in each end tapped for 4/40 and 1/2" deep.
>
> This is for a Rubidium project.
>
> The local machine shop want's $360.00
>
> Anyone have a machining setup that could do the work a bit cheaper?
>
> If not I'll give it a try myself.
>
> Please contact me off list.
>
> Thanks!
>
> Corby Dawson
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Machining some aluminum help!

[Chris Albertson]

Yes, generally when something is expensive to manufacture it is because the
designer was not thinking about costs.  A design with 40 size "tiny" thread
holes in just not cost-effective.  A redesign could save hours work.

On Thu, May 18, 2017 at 11:16 AM, Tim Shoppa <tsho...@gmail.com> wrote:

> I'm very dubious that you need a tapped 4-40 hole to be threaded any deeper
> than 0.25". If you work with the machinist I'm sure you can come up with
> some reasonable spec that does not require a bottoming tap and will save
> you a lot of money.
>
> I bet you went to 0.25" wall square tubing only because you want to tap the
> walls for 4-40. Alternative designs can let you use much thinner material
> and a very different flange on the ends, but the costs will likely move
> towards welding/brazing rather than machining.
>
> Tim N3QE
>
> On Thu, May 18, 2017 at 12:54 PM, <cdel...@juno.com> wrote:
>
> > Hi,
> >
> > I have a square aluminum tube 5" X 5" with a .25" wall it's 8 1/2" long.
> >
> > I need 20 holes in each end tapped for 4/40 and 1/2" deep.
> >
> > This is for a Rubidium project.
> >
> > The local machine shop want's $360.00
> >
> > Anyone have a machining setup that could do the work a bit cheaper?
> >
> > If not I'll give it a try myself.
> >
> > Please contact me off list.
> >
> > Thanks!
> >
> > Corby Dawson
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS seconds conversion on an Arduino

[Chris Albertson]

On Mon, May 15, 2017 at 1:49 PM, Ben Hall <kd5...@gmail.com> wrote:

> Hi Chris and list,
>
> On 5/15/2017 1:22 AM, Chris Albertson wrote:
>
>> Are you still going for Sidereal time?  If so that is floating point
>>
>
> I'm not sure how Sidereal time came up...it wasn't one of my goals and
> after reading the discussion, it's going to be way past what I think I can
> understand, never mind program onto *anything*.  ;)
>
> This is my favorite under $2 boards now - http://r.ebay.com/9UasSq
>>
>
> That blows my mind!  $1.62 shipped.  Amazing!  I read what you wrote on
> different boards and I've got a lot of poking around and reading to do. The
> idea of dropping a file onto a USB-looking drive is very appealing to me.
> And they seem to be very cheap.  To be honest, being more towards the
> "idiot" end of the embedded programming spectrum, I'm really thinking I
> should stay with slower, simpler, and more well documented stuff.  If I
> knew what I was doing...I'd probably be ordering up some of cheaper, more
> off-the-beaten-path stuff that's way less expensive.
>
> One more bit of advice.  Buy a logic analyzer.   I was using one today and
>>
>
> I've been on the lookout for a dedicated bench one at a good price...but
> nothing has tickled my fancy.  I'm going to order one of those $10 Saleae
> clones this evening.  That Saleae clone analyzer would be just the ticket
> to see if the time information is coming from the serial port before the
> 1PPS tick.  This is what is written in the little TruePosition information
> we have and would be nice to verify.  :)
>
> Thanks much and 73,
> ben, kd5byb
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS seconds conversion on an Arduino

[Chris Albertson]

That Chinese guy selling boards shipped for $1.67 is buying the boards,
paying for postage and 10% commission to eBay and STILL earning some
income.It's an insane price and the unit is dramatically more powerful
than Arduino and $1.67 is so close to "free" that I don't care about the
difference.

But if you are looking for the simplest thing you can find, the genuine
made in Europe Arduino Uno for $30 is that.  All of the "how to use your
Arduino" examples assume you have an "Uno"  and those examples are targeted
at people who can't read schematics so they use pictures of components and
of the wire.  With an Uno you can match up the pictures to make say a LED
blink. But then you pay $30 for a slow 8-bit computer with very little
memory.

This is the level of instruction you find with Arduino
http://fritzing.org/media/fritzing-repo/projects/l/led-blinking
<http://fritzing.org/media/fritzing-repo/projects/l/led-blinking-using-arduino/images/fritzing_bb.png>

But on the "mbed" tutorial you'd expect this
https://developer.mbed.org/cookbook/Motor

Which level do you need? I've used the $1.67 part with both Arduino and
mbed.



On Mon, May 15, 2017 at 1:49 PM, Ben Hall <kd5...@gmail.com> wrote:

> Hi Chris and list,
>
> On 5/15/2017 1:22 AM, Chris Albertson wrote:
>
>> Are you still going for Sidereal time?  If so that is floating point
>>
>
> I'm not sure how Sidereal time came up...it wasn't one of my goals and
> after reading the discussion, it's going to be way past what I think I can
> understand, never mind program onto *anything*.  ;)
>
> This is my favorite under $2 boards now - http://r.ebay.com/9UasSq
>>
>
> That blows my mind!  $1.62 shipped.  Amazing!  I read what you wrote on
> different boards and I've got a lot of poking around and reading to do. The
> idea of dropping a file onto a USB-looking drive is very appealing to me.
> And they seem to be very cheap.  To be honest, being more towards the
> "idiot" end of the embedded programming spectrum, I'm really thinking I
> should stay with slower, simpler, and more well documented stuff.  If I
> knew what I was doing...I'd probably be ordering up some of cheaper, more
> off-the-beaten-path stuff that's way less expensive.
>
> One more bit of advice.  Buy a logic analyzer.   I was using one today and
>>
>
> I've been on the lookout for a dedicated bench one at a good price...but
> nothing has tickled my fancy.  I'm going to order one of those $10 Saleae
> clones this evening.  That Saleae clone analyzer would be just the ticket
> to see if the time information is coming from the serial port before the
> 1PPS tick.  This is what is written in the little TruePosition information
> we have and would be nice to verify.  :)
>
> Thanks much and 73,
> ben, kd5byb
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS seconds conversion on an Arduino

[Chris Albertson]

Sorry for the email with zero new content.  It was a "mis-click".

Don't bother with a stand-along logic analyzer.   They were designed for
the old days with people built stuff using about a hundred or so 74xxx TTL
chips.No one does that any more.Today we use micro controller and
FPGA and only enough small scale logic a needed for glue.  Mostly none at
all.

The features you need, those old analyzers can't do.  You want to do stuff
like de-code the data off a I2C or SPI or serial link and reverse engineer
a protocol.   The old units are useless for this and they have horrible
user interfaces.  the PC based ones are better now.

This is NOT true for oscilloscopes.  Those are better to have the dedicated
unit.   I looked to replace my aging Tektronix 365 and found it was not
worth buying another used scope.  The new ones are THAT much better.


On Mon, May 15, 2017 at 1:49 PM, Ben Hall <kd5...@gmail.com> wrote:
>
>>
>> One more bit of advice.  Buy a logic analyzer.   I was using one today and
>>>
>>
>> I've been on the lookout for a dedicated bench one at a good price...but
>> nothing has tickled my fancy.  I'm going to order one of those $10 Saleae
>> clones this evening.  That Saleae clone analyzer would be just the ticket
>> to see if the time information is coming from the serial port before the
>> 1PPS tick.  This is what is written in the little TruePosition information
>> we have and would be nice to verify.  :)
>>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS seconds conversion on an Arduino

[Chris Albertson]

Are you still going for Sidereal time?  If so that is floating point

The ARM processor unlike the Arduino does not have fixed pin assignment.
Typically there are many UARTS, I2C interfaces, ADC units and so on more
than there are physical pins.  Within some limits you assign functions to
pins in software.Some you don't need to make a special board at OSHPark
with three serial ports.   You can move the serial function to the pins you
like.

That said, moving functions to pins is an "advanced" software art.  So to
make it easy for normal people the development environment will have some
easy way to do this and some limits too.

You can program most ARM M boards using Arduino but that IDE while day to
use is limited.   The next step up is "mbed" which is much more capable and
lets you move some functions to some pins the IDE is web based so there is
no software to install.   (OK you can work locally if you like.  There are
several ways to do that.

This is my favorite under $2 boards now
http://www.ebay.com/itm/STM32F103C8T6
<http://www.ebay.com/itm/STM32F103C8T6-ARM-STM32-Minimum-System-Development-Board-Module-For-Arduino-/192181979870?hash=item2cbef04ade:g:pBgAAOSwvihY8r-0>
The specs are literally an order of magnitude over Arduino and at under $2
shipped thrice is right.   These are Arm Cortex M3 in the size of a large
1970's vintage DIP chip.  Google the P/N for loads of informationThis
parts works on bed and arduino IDEs   as well as simply using the gcc arm
compiler.

The other one I use is Nucleo F401RE
These are $13 each and unlike the above have loads of 1st rate
documentations written by a US company ST Micro.
https://developer.mbed.org/platforms/ST-Nucleo-F401RE/
Yes you can snap off the programmer and reconnect it with jumpers or leave
it on.   Even if you leave it on you can use it to program the STM32F103.
Saves you from having to buy an Chinese clone ST-Link dongle.

TheF401RE is the "classic" part that most example programs have beed tested
on but I'd buy the F446RE for $1 more.  It's twice as fast and has more RAM.

The mbed IDE lets  you use most C source code you can find and it runs a
real time OS.Arduino is still hands down the easiest environment to
learn and it runs at 5 volts.  I keep one for testing 5V hardware.  All the
arm stuff is 3v3

Most any ARM board can run with the Arduino IDE it some one wrote a boot
loader for it.  The mbed boards don't use bootloders.  They "look" like a
flash drive to your PC so all you do is drag and drop the BIN file to the
flash drive and the board then runs whatever case to dropped there.


One more bit of advice.  Buy a logic analyzer.   I was using one today and
mad it save a LOT of time debugging when you can see what data is on the
pins.  Logic analyzers used to be expensive but one god enough for this
kind of work is now under $10 for a Saleae clone
http://www.ebay.com/itm/24MHz-8CH-USB-Logic-Analyzer-24MHz-8-Channel-Compatible-to-Saleae
<http://www.ebay.com/itm/24MHz-8CH-USB-Logic-Analyzer-24MHz-8-Channel-Compatible-to-Saleae-ARM-FPGA-M100-/272337085235?hash=item3f688e2333:g:RNcAAOSwPCVYBD2b>
They work like a scope for digital and can do protocol decoding show the
data going over a cable.


On Sun, May 14, 2017 at 2:16 PM, Ben Hall <kd5...@gmail.com> wrote:

> Hi Chris and list,
>
> My original goal was to duplicate, more or less, what the PackRat guys did
> to get the TruePosition boards up and functional as described here:
>
> <http://www.packratvhf.com/A%20Packrat%20GPS%20Receiver%20Project.pdf>
>
> I did get in touch with them and they forwarded the HEX files.  I haven't
> tried them yet, but another list member did try them without success.
>
> I figured, as a learning exercise, I'd program up my own interface.  The
> boards do not talk NMEA...but output their own format of message.  One
> message contains GPS time in seconds...plus the number of leap seconds that
> have elapsed, so my goal there was to convert the GPS time from the unit
> into normal UTC date and time.
>
> On 5/14/2017 12:38 PM, Chris Albertson wrote:
>
>> Unless this is an educational exercise I'd move to a different processor.
>> One of those $3 Arm M3 units has enough  memory AND a more standard
>> development environment that you could use a standard library function to
>> do what you need.
>>
>
> It is an educational exercise...but I'm still going to look into this.
> Another list member suggested a different Arduino board that had two real
> serial ports, as right now the Uno board I'm using only has one hardware
> serial port with a second duplicated in software.  (one port talks to the
> TruePosition board...the other is debugging output port)
>
> I did happen to recall that I included a Teensy-LC board (Cortex M0) in a
> recent OSHPark PCB order...and it appears to have three 

Re: [time-nuts] GPS seconds conversion on an Arduino

[Chris Albertson]

On Sun, May 14, 2017 at 9:15 AM, Nick Sayer via time-nuts
<time-nuts@febo.com> wrote:
>
> I wouldn’t expect floating point to enter into it.


The question here was about conversion to Siderial Time.   The mean
sidereal day is 23.9344699 hours but that is the MEAN.  The length of
the day continuously changes.  So depending on how accurate you need
to be this can use a LOT of 64-bit floating point math.


-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS seconds conversion on an Arduino

[Chris Albertson]

Unless this is an educational exercise I'd move to a different processor.
One of those $3 Arm M3 units has enough  memory AND a more standard
development environment that you could use a standard library function to
do what you need.   For more money ($13) you can get the Arm M4 on an
arduino-like PCB and this unit has floating point hardware and even more
memory.   Still about the size of an Arduino Uno but 1/2 the price and 10X
processing power.

Then use nothing like this
http://cosmos-project.org/docs/core/1.0.2-/group__timelib__functions.html

But what is your "big Picture" goal?   Do you just need a sidereal clock
display.  Then you only need precision up to the number of digits displayed
up up to human perception. 50ms more or less is about all we can detect
by eyeball or ear.

But are you looking to aim a telescope and need sub-arcsecond precision?
The last time I needed to write software to aim a 'scope we had a wide
angle camera so I only needed to car about milliseconds but some people
today even with backyard telescope want better than that.


On Sat, May 13, 2017 at 6:58 PM, Mark Sims <hol...@hotmail.com> wrote:

> Converting GPS seconds to Gregorian date/time on the Arduino will be an
> arduous task.  You take GPS seconds and add it to the GPS starring epoch to
> get a Julian date.  Then add in the number of leap seconds as a fraction of
> a day to get UTC and possibly add in a time zone offset for local time.
> Don't forget to do daylight savings time conversion...  Then convert the
> result to Gregorian date/time for display.
>
> The problem is the Arduino floating point library is single precision only
> and does not have the resolution needed to handle the numbers involved.
> Doing it with integer arithmetic (long longs) opens up a whole new can of
> worms.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Looking for a HP-58503 display

[Chris Albertson]

I've read about people making a replacement using a large LCD graphic
screen.   A micro controller reads the data lines going to the old display
and draws characters on the modern screen.Not total rocket science to
implement but still  it would easier to buy try the easy fixes first (check
cap, transistors and such or even buy a "for parts not working " unit from
eBay.But the only units do look nice with a new cell phone screen

On Tue, May 9, 2017 at 12:42 PM, Gregory Beat <w...@icloud.com> wrote:

> Mark -
>
> Option 001 for the HP-5803B GPSDO
> featured a 12-character (alphanumeric) Vacuum Fluorescent Display (VFD).
> It appears to have been a custom VFD for HP / Agilent (Colons used in time
> display).
> http://www.leapsecond.com/museum/hp58503a/097-58503-13-iss-1.pdf
>
> Noritake Itron Corp. (Ise Electronics Corp.) of Japan invented the VFD
> technology in 1967.  Noritake, Newhaven, Futaba, Samsung, and a Chinese
> mfg. are the 5 major mfg.
> Three of these companies have their North American HQ offices here in
> Chicago area.
>
> Futaba in Schaumburg
> http://www.futaba.co.jp/en/display/vfd/lineup.html
>
> Noritake Itron Company in Arlington Heights
> https://www.noritake-elec.com/
>
> Newhaven Display in Elgin
> Company is more of an East Asian importer, but handles custom runs.
> http://www.newhavendisplay.com/vfd-c-586.html
>
> VFD do have a finite life, and darken as they age.  Samsung states 30,000
> hours to reach it 80% level (brightness).  You stated your unit has 83,000
> hours.
> DOUBLE CHECK DC Power and electrolytic capacitors associated with circuit,
> this has been known issue with commercial consumer appliances with VFD.
> The mfg. date on your unit may have been during "bad caps" decade.
>
> greg
> w9gb
> ==
> > I recently got in an HP-58503B GPSDO from a local equipment liquidation
> auction.
> > The unit has 83,000 hours of run time.  I think it was last powered up
> in 2013.
> >
> > The display (VFD) is a bit dim and blotchy.
> > Does anybody have a replacement display that would look better?
> > - Mark
> --
> Sent from iPad Air
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] How get FEI-Zyfer 380 GPSDO to talk with computer?

[Chris Albertson]

Yes, "gpsmod" is a name that make have been used of by many developers.
There might be many programs called gpsmon around.   But I think all this
one does is respond to NMEA sentences.   So it might be useful.

The first step in figuring this out is to look if there is any data coming
out.   Put a scope on the TX pin and see if there is data.  Then if there
is data pipe it to a terminal

On Wed, May 3, 2017 at 7:24 PM, Bob kb8tq <kb...@n1k.org> wrote:

> Hi
>
> I have a nasty suspicion that the “GPSMon" Zyfer is talking about is not
> the same
> program that is part of the Linux package. It’s a fairly obvious name. I’d
> bet it got
> re-used a couple of times. The docs on gpsd refer to it’s own tangled
> history in this
> regard.  It’s certainly worth trying. I simply would not chuck the GPSDO
> in the trash
> if it does not work :)
>
> Bob
>
> > On May 3, 2017, at 9:49 PM, Chris Albertson <albertson.ch...@gmail.com>
> wrote:
> >
> > gpsmon is part of the gpsd package.  http://www.catb.org/gpsd/
> >
> > But you can try simply connecting the serial data to a terminal window
> and
> > reading what comes out.
> >
> > On Wed, May 3, 2017 at 4:40 PM, James Robbins <jsrobb...@earthlink.net>
> > wrote:
> >
> >> Has anyone gotten an FEI-Zyfer 380 to talk to a control program?  Can't
> >> seem
> >> to get it to talk to GPSCon or TAC32.  Supposedly, it wants a program
> >> called
> >> "GPSMon" but I do not find the program with Google.
> >>
> >>
> >>
> >> Jim Robbins
> >>
> >> N1JR
> >>
> >> ___
> >> time-nuts mailing list -- time-nuts@febo.com
> >> To unsubscribe, go to https://www.febo.com/cgi-bin/
> >> mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >>
> >
> >
> >
> > --
> >
> > Chris Albertson
> > Redondo Beach, California
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] How get FEI-Zyfer 380 GPSDO to talk with computer?

[Chris Albertson]

gpsmon is part of the gpsd package.  http://www.catb.org/gpsd/

But you can try simply connecting the serial data to a terminal window and
reading what comes out.

On Wed, May 3, 2017 at 4:40 PM, James Robbins <jsrobb...@earthlink.net>
wrote:

> Has anyone gotten an FEI-Zyfer 380 to talk to a control program?  Can't
> seem
> to get it to talk to GPSCon or TAC32.  Supposedly, it wants a program
> called
> "GPSMon" but I do not find the program with Google.
>
>
>
> Jim Robbins
>
> N1JR
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] TAPR Oncore M12+ kit

[Chris Albertson]

On this product people are going to want holes drilled and I think a "D"
shape hole for the DB type connector.   The holes would allow easy clamping
but in a two step operation.If I were making these I'd first clamp the
stock over a pair of 123 blocks, mill the holes, then after I hade a batch
of these made,  hole the holes to hold the part a fixture and then mill the
edges.

But that said, I could make a pair of these by hand with hack saw, file and
drill press in about 15 minutes.



On Fri, Apr 28, 2017 at 1:41 PM, Jerry Hancock <je...@hanler.com> wrote:

>
> Generally, the way I mill plates such as these is I surface a piece of
> scrap and then glue (using superglue) the stock down onto the scrap.  I can
> then machine around the edges without worrying about clamping.  With
> pockets though, the torque even when ramping down might break the part
> loose.
>

-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] TAPR Oncore M12+ kit

[Chris Albertson]

org%2Fimages%2FM12-MB.jpg=01%
> 7C01%7Cart%40synergy-gps.com%7C4dc2f4b8f72f4e2fc73108d47615ead3%
> 7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1=VnOToRye%
> 2Be6pu62p6Os1ohPVVa%2FzDEFh1%2F0vo%2Fi5ag4%3D=0
> >
> > greg
> > w9gb
> >
> > Sent from iPad Air
> >
> >> On Mar 28, 2017, at 12:18 PM, Larry McDavid <lmcda...@lmceng.com>
> wrote:
> >>
> >> What "OEM supplier?" Do you mean from Synergy Systems? Or, is there an
> enclosure supplier to Synergy?
> >>
> >> Do you know if there is a schematic of the Synergy interface board
> available?
> >>
> >> Larry W6FUB
> >>
> >>> On 3/27/2017 9:31 AM, Gregory Beat wrote:
> >>> The TAPR offering is a "partial kit" from the Synergy's SynPaQ/E
> product.
> >>> Here is that data sheet:
> >>> https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.s
> >>> ynergy-gps.com%2Fimages%2Fstories%2Fpdf%2Fsynpaq%2520product%2520data
> >>> %2520sheet%2520040110.pdf=01%7C01%7Cart%40synergy-gps.com%7C4dc2
> >>> f4b8f72f4e2fc73108d47615ead3%7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1
> >>> data=WF1IWYKvN5q6C0WMToPljgax2dpKhBqLxTAyhvKrYzw%3D=0
> >>> Blank aluminum end-plates can be fabricated, or purchased from the OEM
> supplier.
> >>>
> >>> w9gb
> >> --
> >> Best wishes,
> >>
> >> Larry McDavid W6FUB
> >> Anaheim, California  (SE of Los Angeles, near Disneyland)
> > ___
> > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
> https://na01.safelinks.protection.outlook.com/?url=
> https%3A%2F%2Fwww.febo.com%2Fcgi-bin%2Fmailman%
> 2Flistinfo%2Ftime-nuts=01%7C01%7Cart%40synergy-gps.com%
> 7C4dc2f4b8f72f4e2fc73108d47615ead3%7Cc81f9fdec0e04d8c95779afaa0ca
> d9ed%7C1=aHBSvpbaodwO9tAMMGXMstwLQuQ5KqO3pPlWTuUypn4%3D=0
> > and follow the instructions there.
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Frequency counter questions

[Chris Albertson]

On Mon, Apr 24, 2017 at 10:13 AM, Bob kb8tq  wrote:

> Hi
>
> Some of the process below is “not trivial”. One example:
>
> You have a “gate” from the GPSDO and a “signal” from somewhere else. If you
> want the STM to do the whole thing, the “gate” pin needs to get the job
> done in
> X +/-  1 cycles of the “signal” pin. Delay X (if it’s consistent) isn’t a
> problem. Having a
> > +/- 1 cycle delay *is* a problem. The interrupt servicing structure in
> the MCU
> may or may not be able to hit things +/- 10 ns or even +/- 100 ns.
> Sometimes a
> “lower power” MCU with simple code is better at this than a multi core
> gizmo running
> a high level operating system.

-- 

C

The STM32 is in fact a low level micro controller that does not run an OS.

The chips contain counters and other hardware so most of the real-time
stuff is not done in software.  You need to set this up so the on-chip
hardware outside of the CPU is used.

There are two basic types of ARM computers, the "Cortex A" is what is in
your phone and these have multi cores, GHz class clock speeds, gigabytes
class memories and run an OS.   The other is ARM "Cortex M".  These are
much smaller and run on about 100 uA of current with clocks about 100 MHz
and kilobyte class memories and don't support running an OS.  These are
used in embedded applications such as the throttle control in your car or a
high end battery charger.  These cost about $1 each and the physical chip
is about 3/8 inches square.I buy them quality one as a "Nucleo" board
for about $12.  It is like an Arduino but about (literally) 100X better
specs and half the cost.  About the same physical size.But for this
counter project I'd use a generic STM32 board from eBay.  They sell for
about $2 shipped

Take a look at this device.  It has a lot of power.  It can even be
programmed using the Arduino IDE or the gnu toolchain and others.  You
can't beat the price or the size.
...ebay.com/itm/New-STM32F103C8T6-ARM-STM32...





hris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Frequency counter questions

[Chris Albertson]

On Sun, Apr 23, 2017 at 6:25 PM, Jerry Hancock <je...@hanler.com> wrote:

>
>
> So to summarize, if I limit my high resolution to 99,999,999.999hz and use
> a gate of 1000 seconds, would that get me to .01hz?  If not, then what
> would the possible resolution be?
>

It is best to keep this kind of discussion on the list.  That way if some
one like me sys something dumb, it will get noticed and called out.

OK, so it seems you

(1) are interested in measuring frequency up to 100 MHz but no higher.
(2) want to use an STM32 ARM uP to
(3) Are using the older (and simpler) design that simply counts cycles and
divides by the gate time to measure frequency

If the above assumptions are wrong.  STOP reading now and post corrections
or additions

OK so we are good to go

I assume you know about and intend to use the built in counter/timmer on
the STM32.   You first step is to find out the maximum pule rate you can
place on that pin.  Lets guess it is 48 MHz. But you are a conservative
engineer an want to de-rate it to 24 MHz.

This means to measure up to 100 MHz you will need a prescaler that can
divide by 4.This will transform you maximum 100 MHz to a maximum of 25
MHz.   It will force you into using 4X longer gate time.   This is the only
reason to pre-scale, because you can't otherwise process the signal.

Now it is very simple.   You write software that starts the counters on the
desired pin and then your GPS sends a signal every one second (You do NOT
need to divide down the 10MHZ from a GPSDO because the GPS already has a
one pulse per second output that feeds the DO.)   SO every one second you
read the number of counts and keep doing this for as many seconds as you
need   After the gate time which might be one second or 4,000 seconds you
add up all the one second readings and compute the answer.

Actually you can do better given the excess computer power you have:  You
can output a frequency estimate after the first send and then each second
you can output a more accurate value until finally after 4,000 seconds out
have 0.001 Hz.   So in the first second you put up a display that is good
for +/- 4 hZ and then four seconds later you can be a 1.0 Hz and after an
hour 0.001 Hz

As I wrote before.   I use the "trigger" output of my old Tektronix scope
as input to my counter because the scopes trigger is MUCH better.   If you
own a 'scope this will save you a LOT of work as all you would need to
build is a voltage converter to take the trigger output to 3v3 volts for
the STM32.  The STM already can do rescaling and counting.Connect an
I2C display and you are done with the hardware.  For a better and cheaper
display, the STM32 can serve a web page and then you see the frequency on
your phone.






Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Frequency counter questions

[Chris Albertson]

Confusion comes about because there is a ton of on-chip hardware an
addition to the CPU.  An edge detector, prescaller and a few hardware
counters on the STM32.   So I said he'd likely not be actually counting in
software but just setting up the desired tiger condition, loading the
prescaler then letting it run for a gate interval and finally reading out
the count. The hardware is good for some tens of MHz.  But you really
have to be careful in your programming to get this exactly right.  Easy to
by off by one.

The chip has all kinds of other devices that greatly off load the CPU for
example making PWM outputs.

But you are right, we don't know what the OP wants to do.  Is he a ham what
needs to monitor the output of a transmitter and is this HF or microwave.
We's need to know the real world use case in order to suggest a solution.



On Sun, Apr 23, 2017 at 12:48 PM, Bob kb8tq <kb...@n1k.org> wrote:

>
> >
> > Yes, But I assume he is not going to do the actual counting in software.
>
> Except that’s not what he *said* he was trying to do. Thus the confusion
> and attempt
> to clarify what he’s trying to do. We now have a half dozen people who are
> equally
> confused about the task and no further input from the only person who
> actually
> *knows* what he’s trying to do. If indeed you have registers and the like,
> then they
> are probably in an FPGA. If you already have an FPGA doing the high speed
> stuff,
> the need for the F7 is even more questionable. Yes it’s a $12 or so chip,
> what needs
> to be done can be done with a $2 chip. Not only is would it be cheaper. It
> likely
> would be faster and easier to get working.
>
> Bob
>
>
> > He will likely be using the CPU to set and read some registers and
> control
> > the user interface.
> >
> > The time stamping idea is not bad.  But today you do NOT need to "post
> > process".  Your little processor could do this in nearly real-time and
> > you'd have results on the screen in seconds.
> >
> >
> >
> > --
> >
> > Chris Albertson
> > Redondo Beach, California
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Frequency counter questions

[Chris Albertson]

On Sun, Apr 23, 2017 at 7:38 AM, Bob kb8tq <kb...@n1k.org> wrote:

>
>
> If you want to do something like the 53131 or even the 5335, you will need
> something a bit different
> than the F7 to do it. They are wonderful MCU’s but not really fast enough
> to do the fancy stuff.
>


Yes, But I assume he is not going to do the actual counting in software.
He will likely be using the CPU to set and read some registers and control
the user interface.

The time stamping idea is not bad.  But today you do NOT need to "post
process".  Your little processor could do this in nearly real-time and
you'd have results on the screen in seconds.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Frequency counter questions

[Chris Albertson]

 Assuming you are counting every cycle with no pre-scaler and can't measure
the period, the answer is easy.

If you want to measure Hz then the gate needs to be 1 second.  If you want
to measure too 0.1 Hz then you need a 10 second gate.  In your case 0.001
Hz you need to count for 1,000 seconds.

If you use a prescaler let's say it is a "divide by N" then you multiply
the gate time by N.

If the frequency is high and you want to measure to .001 Hz then you need a
really large maximum count and will overflow a 32 bit integer  You want 12
digits so you need to use a 64 bit integer counter.

The STM32 has some pre-scalers built in and a built in counter too, I
think.  I don't know what their maximum speed is.   You don't need the
compute power is an STM32 but "why not" as they cost only $12, I use the
Nucleo boards and mbed.

The problem with counting to 12 digits is that you are only measuring the
average frequency over a very long interval.  The signal is likely not that
stable.   Lets say during that 10 second gate the signal was DC or zero Hz
for 5 seconds then went to 2 MHz.  You meter would read 1.000 MHz but the
signal was NEVER 1 MHz.


The OTHER way to measure frequency is harder but faster.  You measure the
period.   A perfect meter could mere the unknown frequency in one cycle.
It would not be an average.   But there are no perfect meters.

On Sun, Apr 23, 2017 at 12:14 AM, Jerry Hancock <je...@hanler.com> wrote:

> Hello,  I would like to find a person that would be able to answer some
> frequency counter questions I have.
>
> Basically, I am thinking of building my own using one of the high end
> STM32F7 boards as the counter.  I would like it to count reliably to 12
> digits (e.g. 30,000,000.001x hz).  I am not worried about input
> conditioning as I have a circuit that is suitable for my needs.  Most of my
> questions have to do with using a prescaler on the front (divide by N where
> what is N) to get to the desired resolution when using multiples of the PPS
> coming from my GPSDO.  Gate times could be as long as needed to get the
> resolution.  So what prescaler do I need and what gate time is required are
> the first two questions.  I suggest if someone is willing to help that they
> either reply here with an email address or send a note to meters at hanler
> dot com.  This is for my own non-commercial use.
>
> Thanks!
>
> Jerry
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork

[Chris Albertson]

I worked on a project once where a part was temperature sensitive.  Another
engineer, not me stuck a Peltier device on the part along with a
temperature sensor  and a crude servo using an op amp.   This was not
complex, a simple design and it held to about 1/2 degree C.Basically
made an oversized part with JB Weld epoxy and $15 in parts. Something
like that wold have put your clock spot-on.

Yes you can design very sophisticated controls and insolation and get
marginally better results at 100x cost.Did that one too.   Used water
cooling and a vacuum chamber for insulation.  That was more of a plumbing
job than an electrical job, getting the signals and water lines and vacuum
lines not to leak.

I learned to be a fan of designs that to 90% of perfect with 10% of the
cost.  On my Rb oscillator I took the cheap/easy route this time.  There is
a temperature sensor on the heat sink and a fan has its speed controlled to
keep the heatsink at constant temperature.Used just one chip to build
the fan controller an 8-pin AVR running an Arduino sketch.   The Rb is now
pretty stable

Those cheap 32K crystals might be really good if you find a low cost why to
temperature control them.  Strapping it so some one's wrist seems the best
and lowest cost way, just don't remove it.

On Tue, Apr 11, 2017 at 12:21 AM, Morris Odell <vilgo...@bigpond.net.au>
wrote:

>
> > Most wristwatches do not have any temperature compensation. If worn, the
> wristwatch is pretty close at the 25°C (the human body is a quite good and
> temperature stable oven). The difference only starts to > show when the
> watch isn't worn for long periods of time.
>
> That explains my experience with the first microcontroller based clock I
> built years ago. I used a commercial module with a micro and some
> accessories including a watch crystal for timing. It's on a window ledge
> facing west in Australia where the temp varies during the year by 40°C. It
> was always a bit fast and I spent a lot of time checking my code to make
> sure I was dividing it by the right amount. I eventually tamed it by
> programming a short pause at 3:00 am. I'm sure the temp of the watch
> crystal is very rarely 25°C!!
>
> Morris
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork crystal specs

[Chris Albertson]

On Sun, Apr 9, 2017 at 4:45 AM, Tim Shoppa <tsho...@gmail.com> wrote:
> I've had only a few different cars over the past 25 years but I've been
> impressed with how accurate their mass-market built-in clocks are,

Have you always lived in the same place.  What is the average year
round temperature there?

What I live the clocks always gain time, a minute every could mounts.
It seems I always have to set the time back a minute or two.  But then
it really never gets cold here, maybe a dip below 50F at night in the
winter



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Time Dilation tinkering

[Chris Albertson]

"flight" there is the word.Why drive up a mountain?   Take the clock
with you inside the pressurized cabin of a commercial airliner next time
you are on one of those 10 hour trans=pacific flights.   You be taller then
any mountain and it is actually cheaper then a weather balloon.

Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask
first.  There must be a way to hand cary specialized equipment.



On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak <t...@leapsecond.com> wrote:

>
> But attached is one of the first plots where I put a SA.32m in a home-brew
> vacuum chamber and pulled down to a few inches of Hg for a few hours to
> simulate the low pressure of a flight up to 50 or 90,000 ft. For a high
> altitude relativity experiment -- where you'd like your clock to remain
> stable to parts in e-13 and not accumulate too many stray ns -- it's not a
> good sign when your clock changes by 2e-11 (that's more than 1 ns per
> minute) just because of ambient pressure changes.
>
-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Time Dilation tinkering

[Chris Albertson]

 the same surplus market here as the US, so purchasing
> >> a Caesium based standard is well beyond my means.
> >>
> >> This got me to wondering if a Rubidium based standard might do the trick
> >> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> >>
> >> Clearly there'd need to be a bunch of extra gubbins [2] added to the
> >> 10MHz standard to turn it into an actual clock/counter including battery
> >> backup and so forth.  And would need a pair of everything.
> >>
> >> Before I delve too far into the planning, I'd be interested in feedback
> >> as to whether this style of Rb standard is likely to be up to the task
> >> of being the core of such an endeavour or not ?
> >>
> >> Oh I should add - my plan was to build the systems such that they
> >> function as nice standalone time/frequency references once this
> >> experiment is concluded :)
> >>
> >> Thanks in advance,
> >>
> >> Kind Regards/73,
> >> Hugh
> >> VK3YYZ/AD5RV
> >>
> >>
> >>
> >> [1] gh/c^2 x 3600 x 24  Where h is 1500, g and c the usual values :)
> >>
> >> [2] I presume at a minimum a counter running at a 5ns or less "tick" fed
> >> from a frequency source locked to the 10MHz of the Rb standard.  This
> >> counter would need to be latched for reading from an external signal so
> >> that it can be compared to the second clock.  Not sure but seems the
> >> TAPR TICC might have role here :)
> >> ___
> >> time-nuts mailing list -- time-nuts@febo.com
> >> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> >> and follow the instructions there.
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

[Chris Albertson]

I built one of these using a PWM DAC also.   The design was posted to this
list so I can't take credit for the idea.   But we used two PWM output
pins.   The PWM provides more voltage range than is needed by the OXO's
EFC.  To the output was scaled by a voltage divider.  This also scaled down
thew step size. The second PWN output was scale down even more, like
maybe 100X more.  The two PWM outputs were added.  One does course
adjustment the other fine.   The software first sets the course PWM and
then the fine one takes over.

But the PWM output was just run through an RC filter with a very long time
constants low pass filter with corner freq. < 1 Hz.   The goal was to build
a VERY low cost GPSDO and adding a good external DAC would add to the cost.

Someone here recently suggested that one could do as well by simply
adjusting a good oversized crystal with a screw driver as they could using
a simple GPSDO.   Well, before building the GPSDO I tried keeping my OXO in
sync with my Tunderbolt using just a screw driver and a dual trace analog
tektronix scope.  It is REALLY hard to do with a screw driver.   Some tines
I'd think I had it right then I'd look at the scope after 30 minutes and
fine one sine wave had gained 1/4 cycle on the other.  Lots of reason for
this, perhaps one of my voltage regulators are temperature sensitive,
"stiction" in the screw I was turning.  Who knows. But my simple GPSDO
would notice the 1/4 cycle error and fix it automatically

It real life for practical purposes I use the Rb clock, was lucky to get
one at the old $35 price.

On Mon, Mar 20, 2017 at 4:43 PM, Mark Sims <hol...@hotmail.com> wrote:

> The "DAC" was PWM based, but used a separate voltage regulator for the
> "reference".  I never tried it using the USB power as the reference.
>
> The OCXO (+board) uses less than 500 mA warming up (which it does rather
> quickly).  It's in a small hermetic package about twice the size of a
> standard DIP-14 oscillator package.  There was a Ebay seller several years
> ago offering them at $15 each or 10 for $100.
>
> The Chinese "Arduino" board (it's not really and Arduino,  just a MEGA 328
> and a proto area)  has a micro-USB connector for power input but does not
> implement USB data.   I used the processor serial port with a level shifter
> dongle.   The firmware was a cheap and dirty hack and I didn't implement
> much in the way of control or monitoring... never got around to improving
> it.  The project was basically "Hey, I forgot I had those parts...  Hmmm,
> one could build a simple GPSDO... why not?
>
> -
>
> > Did you use the Arduino's PWM output plus a LPF for the DAC, or a
> separate
> DAC? If PWM, did you have problems with noise or sensitivity to the
> USB-provided supply voltage?
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Four hour cycle in GPS NMEA jitter

[Chris Albertson]

Wow.   350 nS.  I had not been following this for the last few years.   It
seems the ARM is a simply CPU with much more predictable interrupts timing.


One might ask way you'd need such good internal timing.   What got me into
this years ago was scientific data acquisition.  I wanted to time stamp the
data.   So I had a Linux based PC connect periodically to the Internet
using a dial-up phone modem and run NTP.   It worked well enough.A GPS
receiver at $10,000 each was out of the question.



On Mon, Mar 20, 2017 at 5:06 PM, Gary E. Miller <g...@rellim.com> wrote:

> Yo Chris!
>
> On Mon, 20 Mar 2017 15:19:25 -0700
> Chris Albertson <albertson.ch...@gmail.com> wrote:
>
> > I've only hear of 1 uS being broken with hardware.
>
> A Raspberry Pi can get down to a Standard Deviation of about 350 nano
> seconds
> using NTPsec..
>
> https://blog.ntpsec.org/2017/02/01/heat-it-up.html
>
>
> RGDS
> GARY
> 
> ---
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
> g...@rellim.com  Tel:+1 541 382 8588
>
> Veritas liberabit vos. -- Quid est veritas?
> "If you can’t measure it, you can’t improve it." - Lord Kelvin
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Four hour cycle in GPS NMEA jitter

[Chris Albertson]

> Does this sound like something that one would expect with the NMEA output of 
> a non-timing GPS?  Is it related to satellite orbits?  Or perhaps is has 
> something to do with the design of the SiRFStar IV?
>

Remember the phone based time service? "At the tome time time will be
 BEEP"  With a GPS the NEMA sentence take the place of the spoken
words on the phone.   The NEMA specification allows the sentences to
up to one second "off".   That said most GPS receivers do MUCH better
than the NEMA spec but you should never count on non-specified
performance in a professional design.   The PPS is of course doing the
job of the BEEP on the old phone system.  Set you watch based on the
beep, not NEMA.

If you have an FPGA available then you could significantly improve
system time keeping.   Currently the PPS interrupts the CPU to
snapshot internal counter.   Unpredictable interrupt latency lifts NTP
timekeeping to about 1 or 2 microseconds but is the counter snap
shooting could be moved out to FPGA hardware there would be no unknown
latency and you could get NTP to break a "magic" 1uS barrier.   I've
only hear of 1 uS being broken with hardware.You would actually
not ned to write much software to make this happen, just move the
counter outside the CPU to the FPGA and you about have it.


Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Smart Phone time display accuracy...?

[Chris Albertson]

> AndroiTS GPS Test (V 1.48 Free) is good, but a battery hog I find.   On
> my Moto G, I find that it can handle not only the US GPS system, but
> three other systems too, including Glonass, and I think the new Chinese
> system.  I don't recognise the last symbol, maybe Galileo.  Not bad for
> a consumer gadget.

THIS is why the phones don't really track time so well.  Not that they
can't but doing so requires battery power. It would need to keep
receivers and internal oscillators powered up full time.   These
phones have an incredible degree of fine grained power management.
Processors can slow their clocks, graphic units can power off.  The
best clocks required stable conditions and even temperature controlled
ovens for their crystals.

Bt the question raised here was more interesting:  How accurate is the
DISPLAYED time.   No need for an internal probe you can look at the
screen.The problem is that human eyes are not good at this and I
doubt anyone could detect even a 100 ms error.   You need to rig up a
photo detector aimed at the screen.

One question was if the software stack from GPS/Cell receiver to
screen added any delay.  Of course it does but did the designers
account for any fixed delay?   You have to measure to know.

Only one manufacturer, Apple seems to give a worst case spec and they
only give it for a phone pared to a watch, 50 ms.  But it might be
much better.  I guess it is most of the time.   Again, to answer what
was asked, you'd need some kind of optical sensor.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Smart Phone time display accuracy...?

[Chris Albertson]

> Not to gloat, but my Android phone is always spot on.  I have a GPS time
> app that shows the difference between GPS and phone time and it's always in
> the tenths of a second area.

"tenths of a second" is "spot on"?   No way.   That is a difference
that is perceivable to humans.

Apple claims in their spec that the iPhone when paired with a watch is
worst case within 50 milliseconds which is not really that good but is
acceptable for a watch because it is just under what most people can
notice.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Smart Phone time display accuracy...?

[Chris Albertson]

Apple Support claims "within 50 milliseconds of the definitive global
time standard".  At least that is what Apple gives in their spec.

It might use difference source depending on which radios are enabled.
The phone does have GPS and a cell network radio and both can be used
for time.But on a phone these radios are powered up and down as
needed.   I think best just to accept Apple's spec.

Again it would be fun to measure.  There is an API call to get the
system time.  One could write a simple app to send this out

Harder to know the specs on Android as there are so many manufactures
and versions and price points

On Thu, Mar 16, 2017 at 10:06 AM, Mike Garvey <r3m...@verizon.net> wrote:
> CDMA mobile telephony needs system synchronization to +/- 10 uS in order to 
> smoothly handoff a moving client from one cell to the next. Most systems use 
> GPS to maintain this 10 uS.  This says nothing about how bad it could get 
> after that.
> Mike
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Baker
> Sent: Wednesday, March 15, 2017 22:33
> To: time-nuts@febo.com
> Subject: [time-nuts] Smart Phone time display accuracy...?
>
> Hello, Time-nutters--
>
> Any thoughts on what the likely accuracy of smart phone time
> displays might be?   I am thinking that the stacking of delays
> along the path to its receive antenna plus any internal processing delays 
> would accumulate to some unknown degree.  Any thoughts on this?
>
> Mike Baker
> *
> ___
> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Smart Phone time display accuracy...?

[Chris Albertson]

It COULD be very good.   It would be easy for them to run NTP inside
the phone.   But I don't think they do as battery life is "everything"
  I think on IOS  they periodically run SNTP.

I just as interesting question is how to measure the phone's display?
 The biggest problem with all visual displays is the refresh rate.
Typically the screen is only updated at something like 60 Hz.  You
have to establish a network connection to be able to see higher
resolution time.Not hard to do as Android is running Linux inside
and iPhones a Unix derivative  You can


On Wed, Mar 15, 2017 at 7:32 PM, Mike Baker <mp...@clanbaker.org> wrote:
> Hello, Time-nutters--
>
> Any thoughts on what the likely accuracy of smart phone time
> displays might be?   I am thinking that the stacking of delays
> along the path to its receive antenna plus any internal processing
> delays would accumulate to some unknown degree.  Any
> thoughts on this?
>
> Mike Baker
> *
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] WTB: GPSDO

[Chris Albertson]

On Wed, Mar 15, 2017 at 1:09 AM, Attila Kinali <att...@kinali.ch> wrote:

> IMHO it's much easier to just
> get a known-good GPSDO and a rubidium for verification.

Yes, for sure it is easiest to buy something that already works.
But the question was how to bootstrap from scratch?  In other words,
if the only oscillator you own is one you built, how would you know
that it is working?


I actually did use your method.  I have a Rb and Thunderbolt, a pair
of freq. counters and so on.But still I wanted to see if I could
build from scratch and verify proper operation and keep the budget
under say $50 for everything from antenna to power cord. I think
it can be done but one can only verify longer term stability.

(Yes you were correct a GOOD oversized XO is not sensitive to the
environment.  But notice the above budget.)

-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] WTB: GPSDO

[Chris Albertson]

Yes, that is a problem.  How to test a 10 MHz oscillator of any kind
(GPSDO or not) if you only have one oscillator.

I call it the "bootstrap problem"  and I think it's worth some
discussion.  The easy way is to buy a few known good clocks before you
set out to make a clock but that is the "easy way".   that

It is not hard to test its long term stability.  Simply count how may
cycles your new device makes in (say) 10 seconds.   Now all you need
is a way to measure 10 seconds.GPS receivers are good at this.
For short term stability you have yo have some faith.  Buy a $25
oversized crystal oscillator that was made by the name brand with a
decent reputation and it will likely be reasonable

All the GPSDO does is adjust the electronic frequency control of that
$25 eBay oscillator until there are EXACTLY 10,000,000 counts between
every 1 Hz pulse.   The GPSDO is self testing.  Every second it
decides if that $25 crystal is running to fast or to slow and then
does something.   One of the things it should do it tell its owner if
the crystal is reusing much to fast or slow or if it is just right.
You will know the GPSDO has decent long term stability because the
green :just right" LED stays on all the time.

You can also verify the GPSDO is working correctly by looking at the
EFC voltage.  That is the control signal the controller sends to that
$25 eBay crystal.  You'd expect that the ESFC volts follows some kind
of theory and tracks the environment and you'd not expect a random

In short you can verify the correct operation of a home build GPSDO
because you can see inside of it.  When you see the inside parts are
working as expected you can have high confidence it is all working
well. But for proof you need at least to more known-good
oscillators and you can measure beat frequencies between them.



On Tue, Mar 14, 2017 at 3:33 PM, Tim Lister <lister...@gmail.com> wrote:
> On Fri, Mar 10, 2017 at 2:35 PM, Chris Albertson
> <albertson.ch...@gmail.com> wrote:
>> A GPSDO is not hard to make.  All you need is some way to compare the
>> phase of two signals, an XOR gate can do that.  Then a small $2
>> process moves the control voltage on the crystal.I tried one to
>> build the simplest GPSDO that could still work.   Got the parts count
>> down to about four or five and the cost well under $10 plus the OXO
>> which was about $20.  The simplest dumb one I could make keeps about
>> e-10.  Not great but enough for many uses.   I compared to my
>> Thunderbolt and I could see the phase advance and retreat.  Just a
>> little most sophistication and I likely could do much better but my
>> goal was to prove to myself that a GPSDO could be build VERY simply
>> with cheap parts
>>
>
> Hi Chris, that's good news that a GPSDO is that easy to make (at least
> a basic one) as that is exactly my medium term plan ! The issue of
> course is having something to test the newly built GPSDO against... I
> got one of the rehoused Trimble UCCM-based GPSDOs off ebay a while ago
> but haven't been super happy with it. It's quite a bit less sensitive
> than more modern GPS receivers and it often struggles to get even 1
> satellite with the indoor patch antenna. At one point both red alarm
> LEDs came on and stayed on despite power cycles - I eventually fixed
> that by taking it apart and finding and hitting a reset button on the
> board. Currently although I can talk to the unit over serial and it
> seems to respond, Lady Heather is not seeing any output from it.
>
> Combined these things don't give me a great deal of confidence that
> this unit will act as a stable master reference. I was wondering if a
> second GPSDO like Russ linked to would work better (I have a ublox
> LEA-6T GPS already which I plan to use as the basis of the homebuilt
> GPSDO and it consistently sees many more satellites than the UCCM
> with a similar indoor antenna)  or put the money to getting an outdoor
> antenna mounted (don't feel happy drilling holes in the house myself)
> by someone. Do 2 GPSDOs tell you much more or just that each is
> different and you need a third to adjudicate ? (I can see a slippery
> slope looming from here...)
>
> Cheers,
> Tim
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Chris Albertson]

e the collection of prior 
> postings to ...
>
>
>
>>>> and follow the instructions there.
>>>>
>>>
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> time-nuts Info Page - American Febo 
> Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
> www.febo.com
> time-nuts is a low volume, high SNR list for the discussion of precise time 
> and frequency measurement and related topics. To see the collection of prior 
> postings to ...
>
>
>
>>> and follow the instructions there.
>>
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> time-nuts Info Page - American Febo 
> Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
> www.febo.com
> time-nuts is a low volume, high SNR list for the discussion of precise time 
> and frequency measurement and related topics. To see the collection of prior 
> postings to ...
>
>
>
>> and follow the instructions there.
>>
>>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] WTB: GPSDO

[Chris Albertson]

A GPSDO is not hard to make.  All you need is some way to compare the
phase of two signals, an XOR gate can do that.  Then a small $2
process moves the control voltage on the crystal.I tried one to
build the simplest GPSDO that could still work.   Got the parts count
down to about four or five and the cost well under $10 plus the OXO
which was about $20.  The simplest dumb one I could make keeps about
e-10.  Not great but enough for many uses.   I compared to my
Thunderbolt and I could see the phase advance and retreat.  Just a
little most sophistication and I likely could do much better but my
goal was to prove to myself that a GPSDO could be build VERY simply
with cheap parts

On Fri, Mar 10, 2017 at 1:39 PM, al wolfe <alw.k...@gmail.com> wrote:
> Jeff,
> I have been using a TrueTime XL-AK purchased on eBay a few years
> ago. It has worked flawlessly for the last five years. It seems to
> work well with most amplified antennas that I have tried. Supposedly
> accurate to better than 10 -12 but I have nothing to compare it to. It
> will supposedly control an external oscillator. Mine has five 10 mhz.
> sine wave outputs as well as IRIG-B out.
>
> I paid around $150 for mine, but it seems they are asking around
> $500 these days. With patients they can be had for less.
>
> Al, k9si
>
>
>> On 3/9/2017 3:45 AM, Jeff AC0C wrote:
>>> We had a small tornado come through north of our house about 1/2 mile on
>>> Monday.  Really did a number on the antennas.  Only electronics impacted
>>> was my old Nortel GPSDO.  It’s pretty much deaf now, as far as I can tell.
>>>  The Nortel always had a hard enough time obtaining the initial lock in
>>> the past on startup, but since “the event” it’s been no joy.
>>>
>>> So I’m in the market for a GPSDO.  Key application here is as a bench
>>> precision frequency reference.  Something with good composite noise
>>> performance close in.
>>>
>>> If you have a suitable GPSDO in solid operational condition, kindly
>>> contact me off list.  Thanks!
>>>
>>> 73/jeff/ac0c
>>> www.ac0c.com
>>> alpha-charlie-zero-charlie
> _______
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] advice

[Chris Albertson]

I'm curious about what you are trying to find out with this
experiment.   Certainly it is not to prove that time does in fact
dilate.Are you planning on using time to measure relative
differences in gravity?   That seems reasonable because as it turns
out times is the physical quantity that can be measured to the highest
precision.   It might be interesting to see how the rate of time
changes as a result of Earthquakes, magma circulating deep underground
or as the moon orbits the earth and the tides change.

I think the record for detecting time dilation using clocks in a 1
meter difference in elevation.   I'm sure someone here knows where
this was published.

On Tue, Feb 21, 2017 at 9:13 AM, Rhoderick Beery <rjbe...@gmail.com> wrote:
> Greetings Time-Nuts!
>
> I'm a physics theorist interested in performing an experiment to measure
> the gravitational time dilation beneath the surface of the Earth. Boulby
> Labs in the UK is 1.1 km down which would generate a time differential from
> the surface on the order of 1 part in 10^15 -- not much to work with!
>
> I've investigated measuring redshift/blueshift from lasers but our
> wavemeter technology is no where near accurate enough. I've concluded that
> my best solution is to use atomic clocks, of which I know very little
> about. I thought a clock-enthusiast mail group would be a fantastic way for
> me to learn about the subject as well as possibly spur ideas on the lab
> test design itself.
>
> Thanks in advance!!
> ---
> Rhoderick Beery
> direct: 402-817-9363
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

> 73,
> David GM8ARV
> --
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

Sorry, I conflated terms.   NTP uses offset and delay differently.  In
NTP speak "delay" is the round trip time.  "offset" is the difference
from local system clock to reference clock after accounting for delay.
   It is like cause by asymmetric trans time.

But still, I think my main point is correct:  what you care about in
the uncertainty in the process, not the numbers like delay and offset,
it's the error bars in those numbers

On Sat, Feb 18, 2017 at 9:14 AM, Chris Albertson
<albertson.ch...@gmail.com> wrote:
> You are plotting "offset".  This is simply the communications path
> delay.   It does not measure your system's deviation from UTC.   NTP
> takes into consideration the offset.
>
> Here is the way to understand what NTP does with offset.   Let's say
> we lived 200 years ago and wanted to set a grandfather clock to match
> the one in your friend's house and you have no other clocks.  Let's
> say the friend lives one mile away.    The best option is to walk
> round trips to your friend's house and measure the time and standard
> deviation of the round trip time.  Divide this time in half and call
> it "offset".   Then walk to your friend's house, write down the time
> and take it home.  Set your clock to this time PLUS the offset.
>
> What you care about is the uncertainty of this process NOT the offset
> but the standard deviation of the offset.
>
>
>
> On Sat, Feb 18, 2017 at 1:53 AM, David J Taylor
> <david-tay...@blueyonder.co.uk> wrote:
>> Hi,
>>
>> I was wondering whether there is some data/information available on the
>> claimed +/- 100 ns jitter?
>>
>> Regarding the PPS -> USB (using the CTS line of a FTDI FT232R), I
>> plotted, using some lines of Python, the time offset as attached. Just
>> to get an overview how it is 'worst case', i.e., user program, python,
>> etc. The 1PPS signal comes from a GPS rx.
>> Looks like a standard deviation of around 150 us.
>> y-axis:  measured pps offset from full second (computer time) in us,
>> x-axis pps pulse number.
>>
>> On the long term it looks interesting (while measuring I played with the
>> NTP server on this computer)
>> Until ca. second 1: ntpd synchronization via internet
>> Until ca. second 17000: made an additional LAN NTP server (GPS) available
>> Until the end: replaced ntpd with chrony (still using internet and local
>> servers)
>>
>> Interesting points:
>> -It looks surprisingly bad with using the normal ntpd (especially, there
>> is not really an improvement having an local GPS based server
>> available, did I do something wrong? Only the offset changes by ca. 3
>> ms.)
>> -It looks surprisingly good with chrony. But there are continuously
>> outliers of up to 4500 us, is this a result of the chrony control loop?
>> The time is wandering around with ntpd, but has less jitter.
>>
>> Conclusion:
>> Despite the 150 us stddev, the using PPS over USB gives some interesting
>> inside of what the local ntp server is actually doing. It looks to me
>> like it would be an improvement to use it when using ntpd, but not when
>> using chrony.
>>
>> Best regards,
>>   Thomas
>>   DK6KD
>>   SA6CID
>>
>> PS:
>> Raw data is here, if you want to zoom in: (1.7 MiB, one row per PPS
>> offset in us)
>> http://petig.eu/pps-usb.txt
>> =
>>
>> Thomas,
>>
>> I've done some tests with PPS over USB with Windows some time back, which
>> showed that PPS?USB could be better than LAN-sync alone, but that also
>> included a reduction of the poll interval from possibly 64 seconds for LAN
>> sync to 16 seconds for PPS sync, which may have influenced the results.
>>
>> It would be helpful to have some units on the axes - 1 what?
>> I'm guessing microseconds
>>
>> For comparison, here is a Raspberry Pi running NTP, with the reported offset
>> plotted against time.
>>
>>  http://www.satsignal.eu/mrtg/raspi14_ntp_3.html
>>
>> This Raspberry Pi (running a seismic detector) is using an Ethernet
>> connection via Power-line Ethernet (yes, I know, QRM etc. etc.), and a
>> couple of switches to a very good stratum-1 server.  I would estimate from
>> your graph that the jitter in offset is about 1 millisecond peak-to-peak,
>> but it seems that I get less than that - perhaps 100 microseconds
>> peak-to-peak with occasional excursions outside that.  This is with the
>> latest reference version of NTP.
>>
>> remote   refid  st t when poll reach   delay   offset jitter
&

Re: [time-nuts] Installing GPS Antenna

[Chris Albertson]

Copper?  What an expensive material to use.   Galvanized iron pipe is
cheaper and very strong.   But even the thinner "type M" copper pipe
is strong enough if it is 1 1/4" diameter.

You should not need guy wires on such a short mast.   You will need
likely the proper threaded adaptor to fit the antenna mount.   Run the
coax antenna lead down the center of the pipe.  Also be sure and
ground the pipe to a ground rod.   The ground wire needs to be (from
memory) #8 or larger.   You don't want a 20 foot tall ungrounded
lightening rod up on the roof.  Electric code requires the ground.

One thing, because you used copper pipe use either copper wire for the
ground or if using aluminum wire use the special fittings/clamps
designed for connecting aluminum to copper.

I assume this is an unused chimney?

On Fri, Feb 17, 2017 at 9:57 PM,  <time...@metachaos.net> wrote:
> I have finally ordered a GPSDO (probably get here in April). In the meantime,
> I have the GPS antenna (Luctel, 26Db). I picked up a 20' solid section of 1 
> 1/4"
> copper pipe at the plumbing store with the intention of mounting it to my
> chimney.
>
> My question is about the stability of that mounting. I expect that 16 or 17
> feet of the pipe will be above the chimney. The weight of the GPS antenna is
> trivial. The effective cross section area of the pipe is very small as well,
> so I would think that wind effects would be pretty small even for a good
> breeze.
>
> Will that be sufficiently stable, or will I need to include guy wires? If so,
> are there any recommendations in that area. I don't really have any experience
> putting up antennas. I know that TV antennas are much heavier and, even though
> not mounted as high, still 10' or so is common without guy wires.
>
> Thanks.
>
> Michael
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

Yes,  that is the normal "best practice case".   But the OPand myself
some years go
both have a difference use case. In this case no other machine
needs to know the time.
I only care about one computer.

The reason I used NTp back then and he is using it now is to calibrate
the rate of a real-time process running on that one computer.   In
this special case it makes sense to connect GPS PPS to the computer
and use no other source of time.



On Thu, Feb 16, 2017 at 10:58 AM, Gary E. Miller <g...@rellim.com> wrote:
> Yo Chris!
>
> On Wed, 15 Feb 2017 23:48:39 -0800
> Chris Albertson <albertson.ch...@gmail.com> wrote:
>
>> An ntpd that is running as
>> strum one that has no other ntpd connected to it has VERY little to do
>
> That would be a marginal configuration.  I have yet to see a GPS that
> did not lose sat lock, or lep second, or UTC offset now and then.  Best
> practice is to have at least 3 other network chimers configured.
>
> RGDS
> GARY
> ---
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
> g...@rellim.com  Tel:+1 541 382 8588
>
> Veritas liberabit vos. -- Quid est veritas?
> "If you can’t measure it, you can’t improve it." - Lord Kelvin
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

sub Millisecond is EASY.   my Apple 27" iMac is doing that right now
using just Internet pool servers.   Yes I have a very good Internet
connection.  100 Mbit fiber and then the last meter is 1000BaseT

But still, milliseconds are really EASY.  It is sub microseconds that
requires things like PTP and special hardware.   It's at the uS level
where you have to work hard

If anyone needs to break a millisecond, just run the PPS to the
machine that needs it edit /etc/ntp.conf and you are now in the "few
uS" level.  It costs nothing (if PPS is available.)  But breaking that
uS barrier is not easy


On Thu, Feb 16, 2017 at 9:59 AM, shouldbe q931 <shouldbeq...@gmail.com> wrote:
> On Thu, Feb 16, 2017 at 7:55 AM, Chris Albertson
> <albertson.ch...@gmail.com> wrote:
>>
>> But PTP requires special hardware.   You may not have this.
>>
>
> I have to disagree.
>
> I run PTP on a Raspberry Pi using its onboard USB connected NIC, and
> onboard NICs on HP and Dell servers, I see +- 5 microsoconds jitter in
> the one way delay across 4 fanless HP switches, and when PTP is
> running on a Pi with a GPS hat with PPS, I see +50 -30 microseconds
> jitter in the reported offset from master across the slaves.
>
> If the requirement is for sub millisecond then PTP on commodity
> hardware is a _workable_ solution.
>
> If sub microsecond accuracy is required, then the NIC, Ethernet switch
> and time source hardware requirements change.
>
> Cheers
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

Your processing machine is going to be running NTP with a reference
clock being your local status 1 NTP server

I think the processing machine would see a lighter load if it's NTP
was using GPS as the reference rather thennother NTP server.   In
other words the processing box, the one with the 4Hz work load could
be an isolated strum 1 NTP server with no other connected computers.
 Servicing the GPS interface is nearly trivial, much simply then going
over the network to another server.An ntpd that is running as
strum one that has no other ntpd connected to it has VERY little to do

BTW I first learned about NTP formerly this same reason.   I was
writing firmware for an astronomical CCD camera and we wanted to know
EXACTLY when exposures started and stopped.

On Wed, Feb 15, 2017 at 7:09 PM, MLewis <mlewis...@rogers.com> wrote:
> On 15/02/2017 1:17 PM, Chris Albertson wrote:
>>
>> Why set up a dedicated NTP server if you only have two computers that will
>> use it? ... You could save some money and just run NTP on the two computers.
>> ... NTP is almost zero load on the CPU and the best thing is the NTP
>> accuracy is not effected by CPU load...
>
> My application cycles between a low background load to a full CPU load on
> hex cores four times a second on the quarter-second. Each quarter-second
> load, for each of 22 datasets, first takes a data snapshot, then does some
> processing, which for any or all of the datasets may trigger more
> processing, and when all dataset processing treads are complete, this is
> followed by some house-keeping tasks. Therefore the duration of those full
> loads varies, and one of the four quarter-second loads has more to do and is
> significantly longer than the other three. To get the quarter-second loads
> done as fast as possible, the bios is set to run the CPU in turbo
> continuously, otherwise power saving 'features' start dialing back core
> speed and shutting down cores, resulting in the longer quarter-second task
> not getting done within 250 ms in time for the next quarter-second's start.
>
> The rate of accumulating lag on system time varies from 2 ms a minute to 16
> ms a minute, depending on the load. The result is that the quarter-second
> data snapshots don't start on the actual quarter-second, off more and more
> as lag accumulates, until they're off their target time by more than a
> second, then seconds, etc..
>
> With NTP polling six pool sources while my application is cycling between
> load levels four times a second, the observed quarter-second start drifts
> within roughly 300 ms, sometimes 600 ms.
>
> That wasn't exactly a surprise. The base application I'm working from used
> Apache's NTPUDPClient to maintain an offset from system time from a single
> NTP source.  After expanding the design to use multiple NTP sources, I found
> that the reported offsets from pools were stable when my CPU load was
> stable, but when it was cycling in/out of the heavy loads, the reported
> offsets became more variable between sources and the number and offset of
> reported offsets that were outliers became ridiculous. As much fun as it was
> to design custom cascading outlier filters, this led me to abandon the
> underlying base application's offset to system time and use NTP to maintain
> system time.
>
> To be able to move forward with my original application:
> By going to a separate box running NTP and a GPS reference, I will have a
> reference time that is entirely independent from whatever is going on with
> my working box. With microsecond accuracy and precision, it will be more
> than sufficient for my needs. With a dedicated ethernet connection between
> the working box and the NTP box, NTP on the working box should be able to
> have system time within 1 ms of that reference. If it's observed that isn't
> happening, then I'll remove NTP from the working box and I already have code
> than can monitor the system time against the NTP box and reset it every time
> it lags more than 1 ms. Brute and crude, but it will work for keeping my
> application within 1ms.
>
> Or, so I think...
> I've been surprised and changed direction enough times since I headed down
> this time rabbit-hole.
>
> Michael
>
> _______
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

On Wed, Feb 15, 2017 at 11:48 PM, Chris Albertson
<albertson.ch...@gmail.com> wrote:
> On Wed, Feb 15, 2017 at 10:30 PM, Ruslan Nabioullin
> <rnabioul...@gmail.com> wrote:
>> On 02/15/2017 01:17 PM, Chris Albertson wrote:
>>>
>>> Why set up a dedicated NTP server if you only have two computers
>>> that will use it?Your server will be accurate to a few
>>> microseconds but your two computers will only by good to a few
>>> milliseconds because ethernet is not nearly as good as PPS.
>>
>>
>> Well Ethernet can be *extremely* accurate if PTP is used (a whitepaper
>> specifies <= 100 ns accuracy if the LAN is optimized for it).

But PTP requires special hardware.   You may not have this.

A cheap why to distribute time is use PPS on a back channel.   You
build a little amplifier and rig it so all computers receive PPS from
the same GPS source.  NTP runs on all these computers and you add the
"Atom" ref clock.   The trouble is you need to run more wires,
Ethernet and PPS.But notice that only 1/2  of the wires in a
standard Ethernet cable are in use.

-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

The desktop PCs can each be configured with as many reference clocks
as you like.   That is independent of how many stratum 1 NTP servers a
company needs to operate.Maybe you are running some stratum 2
servers on your routers and using more from the Internet.All these
choices are independent of each other.

If you are serving Windows PCs then, I think those are all running
SNTP and then use just one NTP server

For most companies there really is no need to even have a GPS
receiver.  Being within 10  milliseconds is just fine so pool servers
will do.

> I would argue that you need at least three servers (and more like five). When 
> given only two
> servers NTP simply dithers back and forth between them. It does not have
> a way to figure out which of two clocks is wrong. It will detect a missing 
> clock, but
> not one that is simply off time by a bit.
>
-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

On Tue, Feb 14, 2017 at 9:38 PM, MLewis <mlewis...@rogers.com> wrote:

> That dual set model is new to me. Interesting to see its fall-back on
> failures. And the offline model.
>
> It's the poor-man's version of that model that I was aiming for (and one,
> not two sets of receiver-with-server):
> - A small box as "GPS receiver" with NTP, receiving the PPS from a GPS
> timing module.
> - That box as a source to an NTP Server that also looks at six internet pool
> sources (pools are the 'backup' if GPS/receiver-box fails).
> - My systems (two boxes) look to the NTP Server for their time reference.

Why set up a dedicated NTP server if you only have two computers that
will use it?Your server will be accurate to a few microseconds but
your two computers will only by good to a few milliseconds because
ethernet is not nearly as good as PPS.

You could save some money and just run NTP on the two computers.   A
dedicated server does not get you much because you can't get GPS level
accuracy out of it to your other devices. But this is a hobby and
setting it up is educational  And maybe you find other uses for the
server like maybe it can keep backups or store media files (videos) or
host a small web site   NTP is almost zero load on the CPU and the
best thing is the NTP accuracy is not effected by CPU load  SO you can
run other service without degrading the NTP server.  (All the time
critical stuff happens inside a tiny interrupt handler, not in user
space)

-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

On Tue, Feb 14, 2017 at 7:31 AM, MLewis <mlewis...@rogers.com> wrote:

>
>
> - a dedicated machine/box for unencumbered acceptance of PPS, and
> - for systems with a business need, a dedicated NTP server/box disciplined
> by the PPS source (with dedicated communication), while maintaining
> internet NTP sources as backup for when the PPS source fails?
> Is there a better way?
> Other considerations?


Don't ever think about "backup servers".  NTP will always select the "best"
reference clocks.   The best ones are defined as the subset of references
that track each other.

Best practice today is to have two independent NTP servers and two GPS
receivers.   It is best if these are independent as you can make them,
different buildings if you can.   I would even use different brands of
hardware to protect against a bug.   Then throughout your company all your
PCs are configured to look at both NTP servers

Each server is configured to use the GPS reference clock, the other "twin"
NTP server as well as about five Internet "pool" servers.

If your location does not have an Internet connection. ( YES this can
happen.  I've worked on computers that process classified information and
these computers never have Internet access.)  You can configure them so
they run in "orphan mode" that is they all use each other as reference
clocks.  Then when GPS is lost thenoormal NTP clock selection algorithm
will select the subset of PCs that all agree on what the time is.   The
outliers tent to get ignored.    When GPS comes back up the system makes a
gradual and graceful recovery.





Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

Here is a something that could work.  It has a real serial port and you
could add more ethernet controllers, uses very little power and cost only
$60.
www.newegg.com/
<https://www.newegg.com/Product/Product.aspx?Item=N82E16813157497_re=j1900-_-13-157-497-_-Product>

There are other boards like this that use the same J1900 CPU.   I'm
thinking about using this as th machine tool (milling machine) controller.

On Tue, Feb 14, 2017 at 4:26 AM, Bob Camp <kb...@n1k.org> wrote:

> Hi
>
> A direct port might be a +/- 100 ns sort of thing most of the time and a
> +/-10 us
> thing every so often under some OS’s. Most desktop operating systems are
> not
> designed to prioritize random pin interrupts. A dirt cheap MCU coded with
> a few
> (hundred) lines of assembly code may be a better option than a typical
> desktop.
> Complicating this further is the degree to which some OS’s can be directly
> or
> indirectly optimized. Install *this* package and it all goes nuts. Install
> that package
>  and not much happens ….
>
> Bob
>
> > On Feb 13, 2017, at 11:07 AM, Ruslan Nabioullin <rnabioul...@gmail.com>
> wrote:
> >
> > Hi, generally speaking, what are the performance differences between the
> following: 1. direct RS-232 (i.e., what I believe is a standard PCI card
> offering RS-232---essentially UARTs interfaced more-or-less directly to the
> PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI cards (which might also
> have an IRIG input or even an onboard GNSS receiver).
> >
> > Thanks in advance,
> > Ruslan
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Chris Albertson]

Pretty dramatic difference between a "real" serial port and USB.  Like two
orders of magnitude or more.

If you computer lacks a serial port, just buy a new computer.  The
Raspberry Pi or the like costs about $40.   But the money you save on
electric power will pay off that $40 in less than a year.

Why is this?  the serial port has a pin that is tied to an interrupt.  If
you read the code associated with that interrupt it is like maybe 4 or 6
lines of C and VERY simple.   USB on the other hand is packetized.
Nothing happens on till a block of data comes in and then it is quite
complex so the time from the pin going active to the internal counter being
sampled is quite variable   I said "two orders of magnitude"  it might even
be three orders.


On Mon, Feb 13, 2017 at 8:07 AM, Ruslan Nabioullin <rnabioul...@gmail.com>
wrote:

> Hi, generally speaking, what are the performance differences between the
> following: 1. direct RS-232 (i.e., what I believe is a standard PCI card
> offering RS-232---essentially UARTs interfaced more-or-less directly to the
> PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI cards (which might also
> have an IRIG input or even an onboard GNSS receiver).
>
> Thanks in advance,
> Ruslan
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Chris Albertson]

So far all the answers are about high-end expensive equipment.   There were
also low cost frequency meters.  I have one 40 years ago that was not
expensive.  It wa a simple "frequency to voltage" circuit that drove an
analog meter.   It was made just before the digital multimeters came out,
maybe in the 70's  Sold for well under $100.   I think these were the most
common type.The others being described here were WAY behind the
hobbyist's budget

On Sun, Feb 12, 2017 at 5:39 AM, Dan Rae <dan...@verizon.net> wrote:

> On 2/11/2017 10:08 PM, Scott Stobbe wrote:
>
>> I was inspired recently coming across a Lampkin 105 frequency meter, as to
>> how  frequency measurement was done before counters.
>>
>> Certainly zero-beating a dial calibrated oscillator, would be one
>> approach.
>>
>>
>> Google BC-221 and you may get some idea of how those worked.  I just wish
> I could find the one hidden in my garage :^)
>
> Dan
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] WWV Receivers

[Chris Albertson]

On Mon, Feb 6, 2017 at 11:27 PM, Hal Murray <hmur...@megapathdsl.net> wrote:

>
> > esp. if one uses a Chinese $6.50 incl. shipping HF  receiver off eBay;
>
> Could somebody give me a lesson in receivers appropriate for extracting
> time
> from WWV?
>
> Is $10 a realistic price?
>

Yes, this would not need to be tunable as WWV is at a fixed frequency.  I
have seen a receiver that uses a 10MHz crystal in the front end and then
mixes the signal to baseband then samples it with a PC "sound card".   $10
in parts easy

You extract the time in the PC software.   I say "PC" but a really low-end
computer like a Rasperry Pi would be perfect for this, maybe over kill but
you'd want the features of the OS to send the time some place
-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Li-ion Battreries

[Chris Albertson]

No way will an ammo box explode and send shrapnel flying.  Even if filled
with machine gun bullets and tossed in a fire.  The rubber gasket fails and
the pressure escapes.  A slow burning object like a battery will never
cause steel to fragment.   If someone made a video it was faked

The purpose of the box is that first it offers mechanical protection in
storage and transport and second it is a heat sink.  If a few hundred watts
of energy is put into a small part of the box, the heat conducts to a
larger area and you have a lower temperature.

The box is designed to store ammo in a combat area, the box will not
explode if something inside of it catches fire.  The gasket would fail
first or it not the wire bail holding the lid would fail under minimal
pressure.   The lid opens LONG before the steel can bursts

If I wanted to make a dramatic video, I'd fill the entire box with gun
powder.  The lid would fly open and burning powder would to ejected into
the air and it would LOOK like an explosion

On Sun, Jan 22, 2017 at 6:25 PM, Mark Sims <hol...@hotmail.com> wrote:

> They can be if you store them in something like an ammo box.   If they "go
> off" in the sealed box the pressure builds,  the reaction rate increases
> exponentially,  and voila... shrapnel time.   There's a video out there
> showing the results.
>
> Most people recommend storing them in nomex/kevlar "cell bags".   I keep
> mine, bagged,  in an unused/unplugged oven!  If one goes off,  hopefully
> the flames won't spread to the rest of the property and the hinged oven
> door allows pressure to escape.
>
> Hobby RC packs are one of the most dangerous type of rechargeable lithium
> cells out there... even from "reputable" sources and brands.   A local
> hobby shop twice had  brand new name brand packs sitting on the shelf go
> off.  A friend of mine had the same thing happen carrying a just purchased
> pack home in his car.
>
> 
>
> > They aren't bombs, guys.  Use sensible precautions and get on with it
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] purpose of time of day display units

[Chris Albertson]

I do stuff like that too.   I always like to use an I2C connected LCD
display while developing code on any micro processor project.  I might take
the actual LCD off at the end but I always leave the signal pins in place.
I might need to debug the device again some time and then I can find
another display.  I see a lot of this in commercial products, for example a
USB connection on the back of my TV, only for diagnostic use.

Same with "heartbeat" LEDs, they let you know the device is cycling through
its main pressing loop and not hung.

On Sun, Jan 22, 2017 at 4:26 PM, Hal Murray <hmur...@megapathdsl.net> wrote:

>
>
> Is there a term similar to "eye candy" for geeks?
>
> Many years ago, I designed network gear.  That was back when a controller
> was
> a board full of small and medium sized chips rather than a single big chip.
> I always put a few LEDs on the board wired up where the microcode could get
> at them.  Most of the time they were just eye candy.  But occasionally I
> would borrow one and hack the microcode so a LED would be interesting on a
> scope.
>
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Li-ion Battreries

[Chris Albertson]

On Sun, Jan 22, 2017 at 9:36 AM, Mark Sims <hol...@hotmail.com> wrote:

> I have a LOT of experience in testing and using 18650 cells.   It is a
> horrible place for the un-initiated to be.  The market is so saturated with
> dangerous fakes and inferior, over-speced cells that finding a genuine cell
> is a vanishingly small probability.  Hopefully the seller mentioned before
> pans out and sticks around.


I agree, many fakes.  But you CAN buy through reputable distributes like
Amazon.com  for maybe $16 per cell.

When I buy a battery packs the cells are already shrink wrapped and who
knows what is really inside, so I test the pack.  I charge it up and then
discharge it through a dummy load and track the power over time (actually
my programable charger can do this for me) then I recharge it ti to "stage
age voltage" and check that the self-discharge rate is reasonable.  I've
not had a problem with hobby type drone batteries and if I did I'd be
covered by even a 30 day warranty or failing that by PayPall's chargeback
policy.

I'd 100% recommend that anyone who buys a lithium battery place it inside a
fire proof enclosure then run it through a few charge/discharge cycles and
very the seller's specifications.   If you are not set up to do this kind
of acceptance testing don't buy lithium.

I can say first hand that once the lion battery fails, boiling electrolyte
and white smoke will continue to come out of the battery no batter what you
do, just take it outdoors and set it on the concrete and let it finish,
dropping the assembly in a bucket of water will not help, they will
generate a few hundred watts of heat until they run out of energy.  One
started it is a positive feedback loop.  But not dangerous if you thought
ahead to place the thing inside some metal container.  Just carry the
smoking mess outdoors and leave it there for a while.(I tried salvaging
lithium cells for Milwaukee power tools with only about 50% success rate)


-- 

Chris Albertson
Redondo Beach, California
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.