Re: [time-nuts] PLL/GPSDO/etc learning resources for mere mortals

[Hal Murray]

hol...@hotmail.com said:
> Besides temperature compensation for holdover conditions you should also
> include drift compensation for OCXO aging.   The Trimble GPSDOs,   HP 38xx
> and 53xxx GPSDOs, and Oscilloquartz Star-4 do this.

Does any of the HP gear have a temperature sensor?  If so, how do I read it?

-- 
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Re: [time-nuts] Lots of Off Topic discussion,

[Pete Lancashire]

One way I like to put it is like you when I start it in ham radio I
immediately considered WWV as the answer to everything TimeWise.

But for me around about 1975 I worked at General Electric space flight
systems. One could say I became a Time nuts then and discovered that what I
thought what is a Accurate Way of determining how much in error I was
between NBS and my clock Waze and amount that was totally useless to
anybody else other than maybe a ham and someone that owned a watch.

So I went from 1/100th to at least at work 1/100 and now today that
is considered totally useless. Put about 20 zeros and you're getting closer.

The only way to put it is the world has changed

On Tue, Sep 4, 2018, 7:15 AM Scott McGrath  wrote:

> Hi Joe
>
> Like myself you are not a RECENT ham.  Your first radio like mine was
> probably a Heathkit with Glassfet technology.   Like me you learned how to
> use WWV to set clocks and your VFO accurately
>
> Fast forward to the ‘current’ generation of hams.  Most have been licensed
> 15 years or less.   They are interested in SDR, digital modes,  ‘The World
> Above 50 Mhz’ and to a lesser extent coherent CW.   This generation ‘knows’
> WWV as a question in the exam pool and they never met W2NSD.
>
> This is the generation of hams who DONT use WWV.   At many large tech
> companies you would be surprised at the number of hams but most of them
> don’t advertise the fact as I’dont because of the undeserved reputation of
> hams being behind the technology curve.   But everyone is gaga because i
> have a GROL+RADAR+GMDSS maintainer.
>
> Content by Scott
> Typos by Siri
>
> On Sep 1, 2018, at 8:12 PM, Joe Hobart  wrote:
>
> Scott McGrath
>
> I am an amateur radio operator (62 years), and I have accurate 1 PPS and
> 10 MHz
> available.  I also coordinate emergency communications for this very large
> county.
>
> I use WWV:
>
>   To judge propagation during normal and other than normal times
>
>   To set clocks after a power outage
>
>   To calibrate relatively new amateur radio transceivers (not Collins)
>
>   To set my computer clock to better than 1/10 second for FT8 digital mode
> and
> when I was recovering faint asteroids that were in danger of being lost
>
> It is easy to set clocks within 1/10 second while watching the digital
> display
> and listening to the WWV/WWVH tics.  I tend to get the wrong second when I
> use a
> GPS clock.
>
> Best,
> Joe Hobart
>
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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Hal Murray]

I'm in Silicon Valley.  I'm logging some data from a Z3801A and a KS-24361.

I have a poor antenna location.  I'm used to the Z3801A dropping into holdover 
every few days when it can't find any satellites.  Less often for the KS-24361.

I noticed some strange activity in the past few days.  The FFOM is bumping up 
to 1 for a while while it says it has several satellites.  I don't see 
indications of holdover, but maybe I'm not looking in the right place.

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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

Actually. I have 6...   And a large assortment of directional antennas of many 
flavors LPDA, Horn etc,I have to get out there and find the interfering 
source.

Cable company has been having problems with ‘booster’ amplifiers installed by 
homeowners to ‘clean up’ noisy DTV signals.   So just imagine a cheap 
unshielded amp driven into clipping.

I live in the sticks so LightSquared or its successor  is unlikely to be the 
source in my case.



On Sep 4, 2018, at 3:18 PM, Dana Whitlow  wrote:

Scott & John,

Do either of you have any activity by "Light Squared" (or whatever it's now
called) in your area.  Jamming does not always have to be in-band to be
effective.

Dana


> On Tue, Sep 4, 2018 at 1:11 PM Scott McGrath  wrote:
> 
> My TrueTime DC-XL has lost lock since yesterday as has my Z3805 and my
> car’s onboard GPS will not lock since the 2’nd.  I need to get about a mile
> from home before Car’s nav system reports ready.
> 
> There has been a great deal of repair work on the local cable system so
> this is almost certainly related to that
> 
> But it proves my point about the fragility of GPS
> 
> 
> 
> 
> 
> On Sep 4, 2018, at 12:31 PM, John Sloan  wrote:
> 
> Folks:
> 
> GPS jamming and spoofing isn't really my area of expertise, but it's
> something I worry about, not just for its impact on geolocation and
> navigation applications, but also because GPS has become critical as a high
> precision timing reference in the telecommunications realm, which *is* my
> area of expertise.
> 
> Yesterday (2018-09-03) afternoon (about 22:00UTC, 16:00MDT) I noticed one
> of my three home-made GPS-disciplined NTP servers had lost its GPS lock.
> After some forensics on my part, this (2018-09-04) morning (about 16:00UTC,
> 10:00MDT) I replaced the amplified antenna, and the device reacquired its
> lock. I figured it was just an antenna failures; this is an amplified
> filtered antenna so it has active electronics.
> 
> Then just an hour or so later, I noticed one of my commercial
> GPS-disciplined NTP servers (TimeMachines) had lost the GPS 1PPS timing
> signal, but indicated it still had GPS lock. (I question now what this
> actually means in the context of this particular device). As a
> troubleshooting step, I power cycled the device, and it reacquired 1PPS.
> But as I did that, the second commercial GPS-disciplined NTP server
> (Uputronics) right next to it lit up with a red warning on its display,
> indicating it had lost GPS lock. A minute or so later it also reacquired
> lock and indicated 1PPS, with no action on my part.
> 
> All of these devices are completely independent, have different software
> (and probably hardware), have separate amplified antennas sitting side by
> side in the window of my home office, and are not all on the same
> electrical outlet (but may be on the same household circuit).
> 
> I lit up the LCD display on my little GPS monitoring tool I built that
> runs Lady Heather 24x7 and see on the graphical display sudden jumps of
> reduced timing accuracy of a factor of 10^2 (from nanoseconds to hundreds
> of nanoseconds) in the recent past. But I’m thinking this can also be
> caused just by the dynamic satellite geometry, and might be normal. It’s
> not like I watch this graph all the time (even though it does sit right in
> front of me on my desk).
> 
> No clue what's going on in my suburb near Golden Colorado. But I’m a
> little freaked out. Trying to figure out which rule, [1] It’s something
> stupid I’ve done, or [2] I am not unique, to apply.
> 
> :John
> 
> --
> J. L. SloanDigital Aggregates Corp.
> +1 303 940 9064 (O)3440 Youngfield St. #209
> +1 303 489 5178 (M)Wheat Ridge CO 80033 USA
> jsl...@diag.comhttp://www.diag.com 
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Re: [time-nuts] Trimble Thunderbolt Start Up RS-232 Communications Glitch

[Artek Manuals]

You using a mother board serial port or a USB adapter? Not all USB/RS232 
adapters are created equal. Drivers for brand "X" vs brand "Y"  can make 
a difference,. I would go down in the lab to see what I have that is 
currently working but it is at least 5 years old and you wouldn't likely 
find it anyway. How your operating system handles the drivers and the 
polling process will also make a difference. They are not generally 
expensive so you may have to play mix and match till you get a combo 
that is stable.


Tell us what operating system and how the COM port is derived for starters

-DC
manu...@artekmanuals.com

On 9/4/2018 3:54 PM, skipp via time-nuts wrote:

Re: Trimble Thunderbolt Start Up RS-232 Communications Glitch

Hello to the Group,

Would anyone be able to help provide a bit of insight
or experience in dealing with what I call the an initial
Trimble Thunderbolt GPSDO RS-232 communications glitch
(during initial power on/up).

I've noticed some of the programs (Lady Heather) and
external status monitor devices (my own), sometimes
seem to initially stutter, freeze or even lock up if
the RS-232 cable connection is made (as one would expect
to be normal).

Establishing a working initial power on/up, serial
port monitor function can require a physical disconnect
from the GPSDO. Once everything is on, the physical RS-232
connection can be made and monitor functions operate
well going forward.

Would there be a hardware or software "serial comm
preamble" or power-on sequence, best order of
operation?  The physical disconnect RS-232 comm
reset is more than casually inconvenient.

Thank you in advance for your replies

Cheers,

Skipp

skipp025 at jah who dot calm.

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--
Dave
manu...@artekmanuals.com
www.ArtekManuals.com


---
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https://www.avast.com/antivirus


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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Graham / KE9H]

The following are active GPS NOTAMs.
Data Current as of: Tue, 04 Sep 2018 19:16:00 UTC
GPS   GLOBAL POSITIONING SYSTEM [Back to Top] !GPS 09/009 (KNMH A0020/18)
GPS NAV PRN 02 OUT OF SERVICE 1809061455-1809070255

ZAB   ALBUQUERQUE (ARTCC),NM. [Back to Top] !GPS 08/259 (KZAB A0367/18) ZAB
NAV GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL
WI A 359NM RADIUS CENTERED AT 45N1063840W (TCS054036) FL400-UNL, 311NM
RADIUS AT FL250, 215NM RADIUS AT 1FT, 223NM RADIUS AT 4000FT AGL, 169NM
RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230

ZDV   DENVER (ARTCC),CO. [Back to Top] !GPS 08/260 (KZDV A0287/18) ZDV NAV
GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A
359NM RADIUS CENTERED AT 45N1063840W (TCS054036) FL400-UNL, 311NM
RADIUS AT FL250, 215NM RADIUS AT 1FT, 223NM RADIUS AT 4000FT AGL, 169NM
RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230

The military does testing that can cause GPS jamming down in New Mexico.
Are you within range of these NOTAMS?
You might have to plot the Lat-Long co-ordinates

--- Graham

==


On Tue, Sep 4, 2018 at 1:10 PM Scott McGrath  wrote:

> My TrueTime DC-XL has lost lock since yesterday as has my Z3805 and my
> car’s onboard GPS will not lock since the 2’nd.  I need to get about a mile
> from home before Car’s nav system reports ready.
>
> There has been a great deal of repair work on the local cable system so
> this is almost certainly related to that
>
> But it proves my point about the fragility of GPS
>
>
>
>
>
> On Sep 4, 2018, at 12:31 PM, John Sloan  wrote:
>
> Folks:
>
> GPS jamming and spoofing isn't really my area of expertise, but it's
> something I worry about, not just for its impact on geolocation and
> navigation applications, but also because GPS has become critical as a high
> precision timing reference in the telecommunications realm, which *is* my
> area of expertise.
>
> Yesterday (2018-09-03) afternoon (about 22:00UTC, 16:00MDT) I noticed one
> of my three home-made GPS-disciplined NTP servers had lost its GPS lock.
> After some forensics on my part, this (2018-09-04) morning (about 16:00UTC,
> 10:00MDT) I replaced the amplified antenna, and the device reacquired its
> lock. I figured it was just an antenna failures; this is an amplified
> filtered antenna so it has active electronics.
>
> Then just an hour or so later, I noticed one of my commercial
> GPS-disciplined NTP servers (TimeMachines) had lost the GPS 1PPS timing
> signal, but indicated it still had GPS lock. (I question now what this
> actually means in the context of this particular device). As a
> troubleshooting step, I power cycled the device, and it reacquired 1PPS.
> But as I did that, the second commercial GPS-disciplined NTP server
> (Uputronics) right next to it lit up with a red warning on its display,
> indicating it had lost GPS lock. A minute or so later it also reacquired
> lock and indicated 1PPS, with no action on my part.
>
> All of these devices are completely independent, have different software
> (and probably hardware), have separate amplified antennas sitting side by
> side in the window of my home office, and are not all on the same
> electrical outlet (but may be on the same household circuit).
>
> I lit up the LCD display on my little GPS monitoring tool I built that
> runs Lady Heather 24x7 and see on the graphical display sudden jumps of
> reduced timing accuracy of a factor of 10^2 (from nanoseconds to hundreds
> of nanoseconds) in the recent past. But I’m thinking this can also be
> caused just by the dynamic satellite geometry, and might be normal. It’s
> not like I watch this graph all the time (even though it does sit right in
> front of me on my desk).
>
> No clue what's going on in my suburb near Golden Colorado. But I’m a
> little freaked out. Trying to figure out which rule, [1] It’s something
> stupid I’ve done, or [2] I am not unique, to apply.
>
> :John
>
> --
> J. L. SloanDigital Aggregates Corp.
> +1 303 940 9064 (O)3440 Youngfield St. #209
> +1 303 489 5178 (M)Wheat Ridge CO 80033 USA
> jsl...@diag.comhttp://www.diag.com 
> ___
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> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
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[time-nuts] Trimble Thunderbolt Start Up RS-232 Communications Glitch

[skipp via time-nuts]

Re: Trimble Thunderbolt Start Up RS-232 Communications Glitch

Hello to the Group,

Would anyone be able to help provide a bit of insight
or experience in dealing with what I call the an initial
Trimble Thunderbolt GPSDO RS-232 communications glitch
(during initial power on/up).

I've noticed some of the programs (Lady Heather) and
external status monitor devices (my own), sometimes
seem to initially stutter, freeze or even lock up if
the RS-232 cable connection is made (as one would expect
to be normal).

Establishing a working initial power on/up, serial
port monitor function can require a physical disconnect
from the GPSDO. Once everything is on, the physical RS-232
connection can be made and monitor functions operate
well going forward.

Would there be a hardware or software "serial comm
preamble" or power-on sequence, best order of
operation?  The physical disconnect RS-232 comm
reset is more than casually inconvenient.

Thank you in advance for your replies

Cheers,

Skipp

skipp025 at jah who dot calm.

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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Dana Whitlow]

Scott & John,

Do either of you have any activity by "Light Squared" (or whatever it's now
called) in your area.  Jamming does not always have to be in-band to be
effective.

Dana


On Tue, Sep 4, 2018 at 1:11 PM Scott McGrath  wrote:

> My TrueTime DC-XL has lost lock since yesterday as has my Z3805 and my
> car’s onboard GPS will not lock since the 2’nd.  I need to get about a mile
> from home before Car’s nav system reports ready.
>
> There has been a great deal of repair work on the local cable system so
> this is almost certainly related to that
>
> But it proves my point about the fragility of GPS
>
>
>
>
>
> On Sep 4, 2018, at 12:31 PM, John Sloan  wrote:
>
> Folks:
>
> GPS jamming and spoofing isn't really my area of expertise, but it's
> something I worry about, not just for its impact on geolocation and
> navigation applications, but also because GPS has become critical as a high
> precision timing reference in the telecommunications realm, which *is* my
> area of expertise.
>
> Yesterday (2018-09-03) afternoon (about 22:00UTC, 16:00MDT) I noticed one
> of my three home-made GPS-disciplined NTP servers had lost its GPS lock.
> After some forensics on my part, this (2018-09-04) morning (about 16:00UTC,
> 10:00MDT) I replaced the amplified antenna, and the device reacquired its
> lock. I figured it was just an antenna failures; this is an amplified
> filtered antenna so it has active electronics.
>
> Then just an hour or so later, I noticed one of my commercial
> GPS-disciplined NTP servers (TimeMachines) had lost the GPS 1PPS timing
> signal, but indicated it still had GPS lock. (I question now what this
> actually means in the context of this particular device). As a
> troubleshooting step, I power cycled the device, and it reacquired 1PPS.
> But as I did that, the second commercial GPS-disciplined NTP server
> (Uputronics) right next to it lit up with a red warning on its display,
> indicating it had lost GPS lock. A minute or so later it also reacquired
> lock and indicated 1PPS, with no action on my part.
>
> All of these devices are completely independent, have different software
> (and probably hardware), have separate amplified antennas sitting side by
> side in the window of my home office, and are not all on the same
> electrical outlet (but may be on the same household circuit).
>
> I lit up the LCD display on my little GPS monitoring tool I built that
> runs Lady Heather 24x7 and see on the graphical display sudden jumps of
> reduced timing accuracy of a factor of 10^2 (from nanoseconds to hundreds
> of nanoseconds) in the recent past. But I’m thinking this can also be
> caused just by the dynamic satellite geometry, and might be normal. It’s
> not like I watch this graph all the time (even though it does sit right in
> front of me on my desk).
>
> No clue what's going on in my suburb near Golden Colorado. But I’m a
> little freaked out. Trying to figure out which rule, [1] It’s something
> stupid I’ve done, or [2] I am not unique, to apply.
>
> :John
>
> --
> J. L. SloanDigital Aggregates Corp.
> +1 303 940 9064 (O)3440 Youngfield St. #209
> +1 303 489 5178 (M)Wheat Ridge CO 80033 USA
> jsl...@diag.comhttp://www.diag.com 
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[time-nuts] Lost GPS lock or 1PPS recently?

[John Sloan]

Folks:

GPS jamming and spoofing isn't really my area of expertise, but it's something 
I worry about, not just for its impact on geolocation and navigation 
applications, but also because GPS has become critical as a high precision 
timing reference in the telecommunications realm, which *is* my area of 
expertise.

Yesterday (2018-09-03) afternoon (about 22:00UTC, 16:00MDT) I noticed one of my 
three home-made GPS-disciplined NTP servers had lost its GPS lock. After some 
forensics on my part, this (2018-09-04) morning (about 16:00UTC, 10:00MDT) I 
replaced the amplified antenna, and the device reacquired its lock. I figured 
it was just an antenna failures; this is an amplified filtered antenna so it 
has active electronics.

Then just an hour or so later, I noticed one of my commercial GPS-disciplined 
NTP servers (TimeMachines) had lost the GPS 1PPS timing signal, but indicated 
it still had GPS lock. (I question now what this actually means in the context 
of this particular device). As a troubleshooting step, I power cycled the 
device, and it reacquired 1PPS. But as I did that, the second commercial 
GPS-disciplined NTP server (Uputronics) right next to it lit up with a red 
warning on its display, indicating it had lost GPS lock. A minute or so later 
it also reacquired lock and indicated 1PPS, with no action on my part.

All of these devices are completely independent, have different software (and 
probably hardware), have separate amplified antennas sitting side by side in 
the window of my home office, and are not all on the same electrical outlet 
(but may be on the same household circuit).

I lit up the LCD display on my little GPS monitoring tool I built that runs 
Lady Heather 24x7 and see on the graphical display sudden jumps of reduced 
timing accuracy of a factor of 10^2 (from nanoseconds to hundreds of 
nanoseconds) in the recent past. But I’m thinking this can also be caused just 
by the dynamic satellite geometry, and might be normal. It’s not like I watch 
this graph all the time (even though it does sit right in front of me on my 
desk).

No clue what's going on in my suburb near Golden Colorado. But I’m a little 
freaked out. Trying to figure out which rule, [1] It’s something stupid I’ve 
done, or [2] I am not unique, to apply.

:John

--
J. L. SloanDigital Aggregates Corp.
+1 303 940 9064 (O)3440 Youngfield St. #209
+1 303 489 5178 (M)Wheat Ridge CO 80033 USA
jsl...@diag.comhttp://www.diag.com 
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[time-nuts] PLL/GPSDO/etc learning resources for mere mortals

[Mark Sims]

Besides temperature compensation for holdover conditions you should also 
include drift compensation for OCXO aging.   The Trimble GPSDOs,   HP 38xx and 
53xxx GPSDOs, and Oscilloquartz Star-4 do this.  Oscilliquartz calls it ATDC 
(Automatic Temperature and Drift Compensation).   For many OCXOs the magnitude 
of the temperature and drift values are of similar importance in predicting 
holdover compensation corrections.

Teasing out and modeling the independent effects of temperature and drift can 
be quite a challenge in operational systems.
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Re: [time-nuts] PLL/GPSDO/etc learning resources for mere mortals

[Jim Harman]

> The challenge seems to me to be

how to temperature stabilize the entire DAC chain without putting it all in
an oven

Hi Forrest,

Generally you don't have to temperature stabilize the DAC because it is
inside the phase-locked control loop and the loop will adjust for
temperature dependencies, just as it adjusts for drift and temperature
dependencies in the oscillator. You will want your phase detector to be
reasonably temperature stable however.

In the time-nuts archives you will find posts from Lars Walenius and myself
with schematics and code for Arduino-based GPSDOs which you might want to
study.
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Re: [time-nuts] PLL/GPSDO/etc learning resources for mere mortals

[Forrest Christian (List Account)]

Thanks to everyone who has responded so far.

My underlying interest is learning about 1PPS holdover methodologies in the
presence of environmental changes (think outdoor day/night temperature
cycles).  My thoughts are that there are two ways that seem obvious to me
to implement a temperature-stable holdover:

1) Discipline an OCXO using some sort of control loop to a known frequency
(using an appropriate GPS receiver) and divide that down to 1 Hz.   This
solution has large parts in the analog domain, with a bit of a PID or other
similar control loop implemented in a micro, and the divider perhaps in a
FPGA or implemented with standard logic.  The challenge seems to me to be
how to temperature stabilize the entire DAC chain without putting it all in
an oven - on the other hand, it seems that this might not be quite as
critical as I think it is, due to the relatively limited frequency control
range of many OCXO's in comparison to the voltage range of that signal. But
I just don't know enough to be able to say for sure.  I probably need to
get a few surplus (or new) OCXO's and play with them.

2) Use a non-disciplined OCXO as a temperature-stable clock and feed this
clock into a FPGA where one could implement a 1Hz PLL or similar.   It
would seem to me that even measuring the OCXO's average frequency over a
long period using a GPS 1PPS source as a gate would get me somewhere toward
where I am headed, but I'm guessing that there's a lot of complexity I'm
not aware of.

I realize that a lot of what I just mentioned above contains a lot of
naivete.  I'm sort of at the stage that I sort of know what building blocks
I might be able to use (and perhaps these aren't even the right blocks),
but need to understand more about the internal workings of each.   There's
also the distinct possibility that I'm missing key building blocks that I
don't even know exist (or that they're needed).

I'm going to dig through "Deans Book" and see about obtaining a non-scarily
priced copy of the Phase Lock Techniques by Gardner.   Both seem like
excellent resources that will take me some time to digest.  Any other
suggestions would be happily received.

On Mon, Sep 3, 2018 at 12:49 AM, Hal Murray  wrote:

>
> li...@packetflux.com said:
> > I'm trying to fill in some gaps in my knowledge about PLL's, GPSDO's,
> etc.,
> > with the goal to eventually implement some of these either in a
> > microcontroller or fpga or some combination thereof.
>
> An FPGA is unlikely to be the way to go for a GPSDO.  There is lots of
> time to
> do it in software and the tools for micros are generally easier to work
> with
> than FPGA tools.  (But if you like FPGAs, don't let me scare you away.)
>
> One thing to keep in mind for GPSDOs is that the time constants for
> filters
> are very long relative to what is reasonable to build with Rs and Cs that
> are
> readily available.  The usual way to go is a D/A connected to a micro.
> That
> moves the filter time constant into software.  Thus you will see lots of
> discussion on this list about which D/A to use.  Generally, you would like
> more bits than you can get.  For a one-off project, you can trade a
> reduced
> tuning range for better resolution if you are willing to use a pot (or
> soldering iron) for the coarse adjustment, aka the high bits on the tuning
> range.
>
> Another thing to add to your list is hanging bridges and sawtooth
> correction.
>
> Another magic term associated with PLLs is PID controller - Proportional,
> Integral, Differential.  You may find some web articles that tell you
> enough
> to be helpful without using complicated math.
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
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-- 
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com
  

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