Re: [time-nuts] S200 PS

[Lists via time-nuts]

I should have said, I’m based in the UK, so pointers to US suppliers aren’t 
much help, but thanks for taking the time to reply.

I’ve replaced the opto-coupler, it was an 817 device, got a couple off ebay 
brand new for pennies, still not working though :-(

I’ve also ordered a new MOS FET which should be here by the weekend, so we’ll 
see if that helps. At this rate It will be a whole new PSU by the time I 
replace the faulty part! Assuming of course it’s not the transformer, in which 
case I’m stuffed.

The problem with buying a new PSU is finding one that fits, all the ones with 
suitable outputs I’ve found so far are the wrong shape/size.

Regards,
Chris



> On 3 Oct 2017, at 04:54, mart...@soundtech-lg.com wrote:
> 
> 
> Chris,
> 
> There is a PowDec Tech SMPS PCBA on ebay PTE43-34 ebay item
> 322751890408
> The S200 PS is a PTE43-31. +5V+12V-12V. The one listed is 5V+15V-15V
> $20 Probably few components need to be swapped.
> 
> Here is the spec sheet for the PTE43 series with a nice photo...  oem
> for sure:
> https://www.sager.com/_resources/pdfs/product/PTE43.pdf
> 
> Martin
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Re: [time-nuts] Symmetricom S200 PSU

[Lists via time-nuts]

Thanks for the reply Clint. I spent some time on it today with no luck, I do 
have some more info though…

The primary seems ok, there is a steady 329volts DC across the big cap after 
the rectifier diodes.

When you power it up under its normal load you can hear the transformer 
whistle, which you could not hear when it was working, also measuring the DC 
outputs gives almost exactly half the expected output, i.e.

+2.54v
+6.02v
-5.88v

Unfortunately I only have a multimeter and no ‘scope so any further fault 
finding is difficult. I guess the next step is to replace the mos fet that 
drives the transformer, or I guess it could be the feedback loop, which looks 
like an opto-isolator, doubt that the isolator itself would die, but there’s a 
PNP transistor driving it…

If anyone has any other ideas I’m listening !

Thanks,
Chris


> On 18 Sep 2017, at 20:21, Clint Jay <cjaysh...@gmail.com> wrote:
> 
> Hi Chris, if it's not blowing fuses and you're sure you've got all the 
> capacitors ( low value ones in the primary specifically) then check all the 
> high value resistors on the primary and continuity from reservoir capacitor 
> to switching transistor. 
> 
> The average SMPSU usually doesn't deviate wildly from the application notes 
> of the switching controller so if there's no specific schematic that might be 
> a lifeline.
> 
> 
> 
> On 18 Sep 2017 20:08, "Lists via time-nuts" <time-nuts@febo.com 
> <mailto:time-nuts@febo.com>> wrote:
> Hello Fellow Time Nuts,
> 
> Does anyone know where I can get either a circuit diagram or a replacement 
> PSU for a symmetricon S200 NTP server?
> 
> I’ve fixed the original one twice before by replacing all the electrolytic 
> caps, this time it’s popped something more critical and refuses to come back 
> to life.
> 
> So I either need a new PSU or a circuit diagram so I can fault find on the 
> original.
> 
> I’m in the UK.
> 
> Thanks,
> Chris
> 
> 
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[time-nuts] Symmetricom S200 PSU

[Lists via time-nuts]

Hello Fellow Time Nuts,

Does anyone know where I can get either a circuit diagram or a replacement PSU 
for a symmetricon S200 NTP server?

I’ve fixed the original one twice before by replacing all the electrolytic 
caps, this time it’s popped something more critical and refuses to come back to 
life.

So I either need a new PSU or a circuit diagram so I can fault find on the 
original.

I’m in the UK.

Thanks,
Chris


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Re: [time-nuts] Symmetricom experts?

[Lists]

Thanks to all who replied. Turns out it was the cap in the PSU (3,300uF 10v). I 
replaced it with a 3,300uF 16v and all seems well.

It was a bit strange because I had already checked the PSU with a multimeter 
and all rails read fine. It wasn’t until I put a ‘scope on the supply rails out 
of interest that I noticed the 5v rail had a massive high freq ripple on it (I 
guess from the switch mode osc).

Anyway it’s back up and running now.

Thanks again,
Chris


> On Thu, Sep 24, 2015 at 1:21 AM, G1FEF  wrote:
> 
>> Do we have any Symmetricom experts on this list?
>> 
>> I've had a Symmetricom Syncserver S200 GPS+PPS with rubidium clock running
>> for several years until we had a power cut and the UPS battery failed, on
>> powering back up it won't boot at all.
>> 
>> I suspect the flash is corrupt but they protect it in some way, so one
>> can't just copy the o/s onto a new card, and the company want 's to fix
>> it for me!
>> 
>> Thanks in advance,
>> Chris
>> 
>> 
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[time-nuts] Wenzel oscillator - L1 value?

[lists]

Hi,
I'm currently playing around with crystal oscillators (specifically a homebrew 
OCXO) and came across the Wenzel low-distortion crystal oscillator:
http://www.wenzel.com/pdffiles1/pdfs/xtalosc.pdf

This uses an inductor (L1) to trim the crystal frequency, with the note that a 
varactor/varicap could be added to allow the frequency to be trimmed 
electronically.

Has anyone built one of these oscillators?

How would you pick a value for L1? I've been reading up on other crystal 
oscillator types (Colpitts, Clapp,...) and have yet to find anything which uses 
this style of frequency trimming.

Where would I add the varactor if I wanted to add EFC? Across C3?

Thanks.
-- 
Phil.
phil...@philpem.me.uk
http://www.philpem.me.uk/
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[time-nuts] Blank email test message

[lists]

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Re: [time-nuts] raspberry pi, adafruit gps ntp

[lists]

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Re: [time-nuts] Beaglebone NTP server

[lists]

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Re: [time-nuts] Cheap 1588 cards Was: Re: Net4501

[lists]

Well you sent me on a search. I know virtually zip about ptp, but this page 
lists a few ethernet cards that allow time stamping. Is this the same as having 
a 1588 card?

https://github.com/richardcochran/linuxptp-as/blob/master/README.org

-Original Message-
From: Doug Calvert dfc-l...@douglasfcalvert.net
Sender: time-nuts-boun...@febo.com
Date: Fri, 7 Jun 2013 20:58:20 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Cheap 1588 cards Was: Re:  Net4501

On Thu, Jun 6, 2013 at 8:48 PM, Bob Camp li...@rtty.us wrote:

 1588 compatible network cards are capable of time stamping everything
 that goes in and out. They are pretty common these days both as stand
 alone cards and as peripherals on MCU's. There's no real need to do
 hardware, just come up with drivers (and all the other software goop)
 to make them work with NTP. More or less the same work you would have
 had to do once the FPGA was done and debugged.

 Bob



Can anyone recommend a cheap 1588 compatible card? I just recently saw
that the linux kernel PPS support for the cards.
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[time-nuts] E-loran article

[lists]

http://mobile.reuters.com/article/idUSBRE94T0MO20130530?irpc=932

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Re: [time-nuts] RPi NTP was Net4501's cheap...

[lists]

Flightradar24 is using beagle bones in their ADS-B/mode-s system and will be 
incorporating MLAT soon. I suspect they work well in timing applications.

That said, the Allwinner they sell on Sparkfun will probably be my next SBC. 
Though not listed on the wiki, they have opensuse running on it. 

BTW, on some linux dists, there is a way to get around the clock speed 
stepping. It may not be universal, but selecting performance works on 
opensuse for Arm.


-Original Message-
From: Paul tic-...@bodosom.net
Sender: time-nuts-boun...@febo.com
Date: Sat, 25 May 2013 12:47:38 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] RPi NTP was Net4501's cheap...

On Sat, May 25, 2013 at 2:43 AM, David J Taylor wrote:

  Paul,

 Just what devices were you hot-plugging to produce this problem?  One with
 an initial current surge outside the USB spec I could understand.


I was plugging in a USB to RS232 adapter.  If you read the various bits
you'll find about the USB on Rev.B boards you'll see all the work-arounds
suggested here as well as an implication that Raspberry intends to fix the
problem in a later release.


 NTP performance on the three Raspberry Pi cards here can be of the same
 order as FreeBSD running on an Intel Atom PC:


Yes, I've looked at your stats.  As I said earlier you put me onto the Pi
and the Sure boards.  The offsets on the Pi are fine. I just don't like the
weak network  performance which you can see in the ntpq output for the
Pi.  Since I'm still testing bits all four of my clocks are on the same
gigabit switch so I don't expect to see simultaneous negative and positive
offsets.  The Laureline is jittery too but at least it always presents the
same offset polarity.  I'll see how the Beaglebones do, check out the
next rev. of the Laureline and then dither some more.
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Re: [time-nuts] Good (cheap) PIC chip choice for project?

[lists]

If you go arm cortex and linux, you will need to make your code a service. 
You will want it to start up by itself and if for some reason it crashes, you 
will want it to restart itself. The buzzword is harden and the techniques 
vary depending on the distribution.

You should check the architecture of the system. I didn't realize many of these 
boards run the ethernet off the usb hub. My recollection is the a10 used by 
Allwinner does not do that.

Opensuse has JEOS, which stands for Just Enough OS. Less is more!

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Re: [time-nuts] Net4501's cheap...

[lists]

My solution is not to use the R Pi. An extra $20 gets you any number of 
superior arm SBCs. Go cortex-A7 type cpu. 

The Beagleboard XM I'm using has a bug in the built-in usb hub (patchable), but 
it has no issues with hot plugging.  

The R Pi is designed to be cheap, but you spend a lot of time doing 
work-arounds, hardware and software. At some point, an extra $20 looks like a 
bargain.

-Original Message-
From: Dan Kemppainen d...@irtelemetrics.com
Sender: time-nuts-boun...@febo.com
Date: Fri, 24 May 2013 09:44:46 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Net4501's cheap...

This may be way off topic, but the inrush current problem is probably 
with devices not meeting the USB specification. As it turns out, a lot 
of low end devices do not meet this spec.

I spent some time redesigning the power supply system of one such device 
I was using. This time was covered by the company that built the device, 
and eventually it went into production. High speed clamp on probe showed 
2Amps inrush, where it was supposed to be much smaller than that. That 
caused all sorts of havoc. It worked fine on a PC USB, where the 5V line 
is very stiff. USB hubs were a different story.

My bet is a workaround would be a stiff cap (ceramic, not 'lytic) at the 
USB on the Pi board to counteract empty filters on the hot plugged 
device may help. Maybe a small impedance between the 5V supply of the Pi 
board and the cap would help.

Dan


On 5/23/2013 8:37 PM, time-nuts-requ...@febo.com wrote:
 by mahjongg ? Mon Nov 19, 2012 12:09 am
 Don't hot plug USB devices directly into the PI, if you must hot plug
 plug into a hub instead!

 Its called the rush in current problem, and it makes that the
 current PI itself is non hot pluggable, note that the revision 1 PI
 was hot pluggable, as the two polyfuses prevented any rush in current
 because the fuses had a non zero resistance. But in the current board
 there is literally zero resistance between the PI's 5V supply, and any
 USB device you plug in, that means that if you plug in any USB device
 with empty power decouplers, (which act as a complete short for a very
 small time) then you are actually simply shorting the 5V when you plug
 de USB device in.

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Re: [time-nuts] time transfer over USB

[lists]

I suspect the idea is to use a port where no other devices, that is internal, 
are on the hub.

Like you, I never saw a usb port not on a hub.

-Original Message-
From: Jim Lux jim...@earthlink.net
Sender: time-nuts-boun...@febo.com
Date: Mon, 20 May 2013 06:14:12 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] time transfer over USB

On 5/20/13 2:43 AM, Attila Kinali wrote:

 Oh.. and connect the whole thing to a port on the PC that does _not_
 have an internal USB hub.

That's a bit of challenge, I suspect.. A casual look at the PCs  I have 
around here running windows all seem to have on-mobo hubs when you 
check Device Manager.  I suspect they are integrated into one of the 
peripheral chips.



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Re: [time-nuts] Can I get 1 millisecond accuracy with a USB GPS-18

[lists]

Note that MAX232 type chips add jitter. The charge pumps make substrate noise 
and that leaks into the receivers/transmitters.

I like that addafruit solution. 

Note the beagle XM has a bug in the USB that RCNelson fixed. I have managed to 
get it in opensuse, but can't say for sure yet if it is in the distribution.

-Original Message-
From: George Lu l...@goodxense.com
Sender: time-nuts-boun...@febo.com
Date: Mon, 13 May 2013 10:04:59 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Can I get 1 millisecond accuracy with a USB GPS-18

On Mon, May 13, 2013 at 9:25 AM, Chris Albertson
albertson.ch...@gmail.comwrote:

 On Mon, May 13, 2013 at 9:04 AM,  li...@lazygranch.com wrote:
  You might want to avoid the older Atom boards at this point. I think
 28nm or 22nm is due soon.
 
  I have.an ARM board handy with serial and usb, but never set up NTS
 with a GPS. Is it just NEMA commands?
 

 TO work well with NTP the borad needs a low latency PPS interrupt
 handler.  THis means that you need both (1) the DCD line on the rs232
 port tied to a CPU interrupt pin, with not much between the DCD and
 the CPU pin and (2) The OS has a simple low latency handler.

 Linux x86 has a good PPS handler.  I don't know about Linux ARM.  Also
 I don't know how the interrupt hardware works on the ARM board.  But
 if it is as described above it will work well enough.

 You do need access to a hardware interrupt pin.


Hi, I am a newbie on this list. I had tried to do PPS via a USB serial
dongle that supported DCD. I could not get under 1ms jitter.  I found that
since kernel 3.2 there is a PPS-GPIO module which you could use to register
an available GPIO pin for PPS interface. I had successfully implemented PPS
though GPIO pin on Linux ARM (first on a beagleboard-xm, then a
beaglebone). ntpq -p shows:

 remote   refid  st t when poll reach   delay   offset  jitter
==
*SHM(0)  .GPS.0 l4   16  3770.000  -19.922   9.783
oPPS(0)  .GPIO.   0 l2   16  3770.000   -0.281   0.002
-vhost.cohesivel 128.249.1.10 3 u   50   64  377   56.110   13.134   2.715
-clock01.laca02. 216.119.63.113   2 u   16   64  377   25.002   17.157   1.003
+cheezum.mattnor 129.7.1.66   2 u   20   64  377   57.517   11.404   1.817
+gatekeeper.tss. 173.13.85.5  2 u   31   64  377   39.604   15.033   0.929


This was done first using the Garmin 18x LVC then later changed to the GPS
breakout from Adafruit http://adafruit.com/products/746 which is already
on 3.3V logic and the NMEA output does not need inversion.

I had recently shared a more detailed write-up at
https://groups.google.com/d/topic/beagleboard/bU_xZ9tWoiA/discussion(second
post under that topic).

George


 It might be NMEA or it might be some other serial protocol like TSIP.
 The better timing type GPS receiver avoid NMEA because NMEA lacks soe
 commands and timing data sentences.  NMEA was designed for boat and
 ship navigation, not timing.
 --

 Chris Albertson
 Redondo Beach, California
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[time-nuts] Imagery position accuracy

[lists]

Bing birdseye tech uses Pictometry. They have a few papers on their position 
accuracy. Perhaps conflicting papers. One shows the RMS error of 0.6ft. Another 
shows a 95% confidence level at 2.8ft. This is on 4 inch resolution imagery.

In any event, if your city uses the service, you possibly could get the 
planning department to provide accurate position data.  

http://www.pictometry.com/index.php?option=com_contentview=articleid=75Itemid=84

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Re: [time-nuts] Imagery position accuracy

[lists]

Eh, I just recalled the original question a day or so ago and was curious if 
any of the imagery services had statistics on their position accuracy. It was 
an interesting question.

This is the server with the marker data. 

http://www.ngs.noaa.gov/cgi-bin/ds_radius.prl



--Original Message--
From: Chris Albertson
To: li...@lazygranch.com
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Imagery position accuracy
Sent: May 5, 2013 7:21 PM

After you get the position, how does the OP (or anyone else) put the
location data into the Trimble GPS receiver so that it can be used in
the time solution.  This is for NTP remember.

Assuming there is some way, will the Trimble GPS receiver remember
the location over a power cycle?

In other words, is there a way to program a Trimble receiver to NOT do
the self-survey on power up and instead to use some survey location
you got by some other method, like possibly hiring a survey team.

If there is a why to make that work, I might even modify the NTP
driver to do it.



On Sun, May 5, 2013 at 7:01 PM,  li...@lazygranch.com wrote:
 Bing birdseye tech uses Pictometry. They have a few papers on their position 
 accuracy. Perhaps conflicting papers. One shows the RMS error of 0.6ft. 
 Another shows a 95% confidence level at 2.8ft. This is on 4 inch resolution 
 imagery.

 In any event, if your city uses the service, you possibly could get the 
 planning department to provide accurate position data.

 http://www.pictometry.com/index.php?option=com_contentview=articleid=75Itemid=84

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-- 

Chris Albertson
Redondo Beach, California

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Re: [time-nuts] GPS position survey

[lists]

Isn't the other half of the question how useful the information is to the OS? 
That is how is the time integrated with the application using it. Even if the 
RTCs had perfect sync, would two apps attempting to read the clock get the same 
time value in a multitasking system?

I've been looking for the stat on the London stock exchange, which runs on Suse 
Enterprise. I recall they claimed 100us time stamp accuracy, but can't find a 
source.

I thought PTP would be more accurate than NTP, but the consensus of the hive is 
they are equally good.

If you follow ADS-B/mode-s aircraft tracking, a number of vendors are using 
MLAT techniques to detect the aircraft location in the case of mode-s, and to 
detect spoofing in the case of ADS-B. Some use a transmitter that all the sites 
can receive, that is they make their own time sync scheme. But others are using 
 GPSDO. But I assume they time stamp the aircraft signal reception in their own 
hardware.


-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Sun, 5 May 2013 20:40:41 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] GPS position survey

So this is different from the Thunderbolt, even if they both use the
same serial protocol or can the t-bolt also have it's flash rom
programmed from a PC?

The bottle neck in the system in the uncertainty in the interrupt
latency on the PC where NTP runs.  After all this I doubt you can
captures the PPS to better than 1 uS.

For a long time I've been wnting to build an external counter for NTP.
  But it would have to use some very fast logic family.

On Sun, May 5, 2013 at 6:26 PM, Miguel Barbosa Gonçalves m...@mbg.pt wrote:
 Hi Chris!

 On 06/05/2013, at 01:21, Chris Albertson albertson.ch...@gmail.com wrote:

 If you are talking about using this with NTP.  I don't know if you
 have a choice.  The Trimble receiver is going to do whatever it is
 going to do when you power it up.Software running on a PC can
 perform a 24 hour survey and report the location but the Type 29
 driver in NTP has no way to tell the Trimble receiver what to do on
 power up.  And there is no way to specify a location you have surveyed
 by some other means.

 What I am doing at the moment is connecting Trimble's port A (timing
 port) to NTP and configuring the receiver using a Windows laptop
 through port B. I can connect to port B occasionally to check the
 receivers health. The receiver has its configuration stored in an
 EPROM so it will just work anytime unless the configuration gets
 corrupted.

 After the survey ends the position can be optionally stored to the
 EPROM. Also, if the antenna changes its position more than 1000 meters
 a new self-survey will run automatically.

 Perhaps the Trimble GPS has some way to program it's FLASH Rom with
 changed parameters but NTP only reads the packets.  It does not send
 any.  Can LH download a surveyed location r change the length of the
 survey?   NTP can't do any of that

 It does. It is available on the Trmble's FTP site.

 Other NTP drivers such as the Type 30 Motorola driver are more
 flexible.  Those alow you to specify a lat, long that was surveyed or
 have the receiver do a survey.  The type-30 Motorola driver is a lot
 more configurable.

 The Trimble software is very nice and allows one thing the Motorola
 NTP driver doesn't allow if I remember correctly. On the Trimble I can
 choose the number of fixes for the survey and can watch it run while
 NTP is receiving time. I can't do this on an Oncore because it only
 has one port.

 But as was said, light travels about 30cm/nanosecond and NTP works in
 microseconds.  So your location can be off by 1000 times 30cm before
 NTP will care.  So 3 or 4 meters of location error will not matter and
 the 2,000 point self survey will be good enough.

 When surveying accuracy of the PPS will be around 1 us. The accuracy
 will obviously increase when the survey ends.

 But if yo really so want nanosecond level timing, then you need to
 care about the survey

 Agree!

 Cheers,
 Miguel
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Precise positions for GPSDOs

[lists]

Actually, wouldn't you need a satellite visible mark to use google earth? Not 
every marker can be seen on google earth.

Then often these markers are in places you can't use safely, such as in the 
middle of a road. 

Note that google earth does orthorectification on the imagery. If you knew 
where the imagery had the least correction, that might be a place where the 
position data is accurate. If a tall structure looks tilted, then you know the 
image has had a lot of post processing.



-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Thu, 2 May 2013 08:19:17 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Precise positions for GPSDOs

Google maps is NOT that good, it can be off by a lot, tens of meters.

I had to have my property line surveyed some years ago to get a city
building permit. So now I have two brass markers at know position.
The survey crew used traditional transits from a brass benchmark.
Google Earth thinks these brass markers are a few meters from here the
survey crew said. (Yes I know about WGS84, we are all working in that
system)

I think the problem is that the lland is not flat here.   If I lived
in Kanas the Google system might work.   But I don't think Google
warps the images to account for hills and even slopes.  I don't know
the source of Google's error.  The 1 Sigma on the self survey is about
.5 meters more or less.

I think the best why to measure is to let the self survey run for a
full 24  hours so you get two full orbital periods of each satellite.
And also to  make sure you have 360 degree view of the sky.I think
a view in only one direction might be biased.

But yu can check Google.  Find a few brass government benchmarks near
your house and have Google locate them and if you got a match go with
Google

On Thu, May 2, 2013 at 2:29 AM, Stewart Cobb stewart.c...@gmail.com wrote:
 A GPSDO typically makes the assumption that the position of its antenna is
 fixed and well-known. That removes position uncertainty from the navigation
 equations, and allows all the information from the satellite measurements
 to be used to improve the time estimate. Errors in this position create
 errors in timing, with a magnitude scaled by the speed of light (one ns per
 foot, three ns per meter).

 Most GPSDOs do some sort of position averaging when they are first turned
 on, to come up with a good-enough estimate of antenna position. For a true
 time-nut, that might not be good enough.

 GPS surveying equipment can easily determine the position of your antenna
 to within a few centimeters (~20 ps). Unfortunately, such equipment is
 expensive and difficult to borrow.

 A high-end GPSDO designed today should have the ability to record phase
 data into RINEX files, which could be sent to a service like OPUS to find
 the antenna position.

 http://www.ngs.noaa.gov/opus/

 But few do, so far.

 The next best idea is to locate your antenna on Google Maps. Type in the
 self-surveyed position to the Google search box, either as decimal degrees
 or as DMS, formatted like this but without the quote marks:

 37.384542, -122.005526

 37 23 4.35, -122 0 19.89

 Click on the map and zoom in. Click on the Map box in the upper right and
 uncheck the 45 degree view icon. Then right-click on the spot on the
 picture where your antenna is actually located, and select What's here?
 from the pop-up menu. A green arrow marker will appear, pointing to your
 antenna. Left-click on the arrow, and read your latitude and longitude in
 both formats. Enter one of them into your GPSDO, replacing the self-survey,
 and enjoy increased accuracy.

 A true time-nut will take one more step to improve accuracy. (Sorry, but
 the rest of this is specific to North America. Similar details apply to
 other parts of the world, but I only know the recipe for the place I live.)

 Google Maps photos are registered (quite accurately) to the North American
 Datum NAD83. Unfortunately, your GPSDO operates in a different datum
 known variously as WGS84, ITRF, or IGS (these are all essentially the
 same). The difference between these two datums can be a couple of meters,
 easily visible on the map photos and worth 5 ns or more of time error.
 Fortunately, you can convert NAD83 to ITRF2008 at this website:

 http://www.geod.nrcan.gc.ca/apps/tmobs/tmobs_e.php

 For ITRF epoch, just enter today's date. For ellipsoidal height, use
 the value from your self-survey if you don't have a better one. You might
 be able to get a better one from Google Earth, or by finding a nearby
 benchmark from this site (US only) and extrapolating to your antenna
 location.

 http://www.ngs.noaa.gov/cgi-bin/ds_radius.prl

 Note that the WGS84 ellipsoid is tens of meters higher than sea level
 through most of North America, so if you live near the ocean, 

Re: [time-nuts] Measuring Phase diference between different GPSDO

[lists]

Meditating on this a bit, I assume in a strict sense, you can only consider 
GPSDOs phase locked if they are disciplined from the same GPS.

Or is this being pedantic?

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Re: [time-nuts] Time nut newbie

[lists]

A bit OT, but back in the day there was what amounted to an X-prize for a real 
accurate chronometer for navigation.

Make that way back in the day.
http://en.m.wikipedia.org/wiki/John_Harrison

Somehow I suspect everyone knows this story. ;-)
-Original Message-
From: Tim Bastiann7...@yahoo.com
Sender: time-nuts-boun...@febo.com
Date: Tue, 30 Apr 2013 13:49:43 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Time nut newbie

Hi all,

I'm a time nut newbie. My obsession started with the search for an accurate 
chronometer to carry on my boat for celestial navigation. Yes there still are a 
few of us left that practice the art.

My current project is a quartz chronometer using a DS32Khz tcxo oscillator and 
two 74HC4060s (+ or- 10 seconds / year).  

For my next project I'm looking at an Abricon Part Number AOCJY2-10.000MHZ  
ocxo 5 ppb running through a pic and using the algorithm posted on 
http://www.romanblack.com/one_sec.htm. I'm shooting for + or - 1 seconds / 
year.  

 Is there an archive of old posts that might be helpful in answering some of my 
questions and for getting ideas. 

Thanks,

  Tim KK4FQB

Sent from my Motorola ATRIX™ 4G on ATT
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Re: [time-nuts] Radio with GPSDO

[lists]

In a world of digital comms with very capable competition, AOR has been looking 
for a reason to exist. They have turned to high end gear. For some time now, 
their radios were DDS and capable of running from an external 10MHz. I suspect 
they are used in a rack of gear to direction find. The black box SDR version is 
the next obvious step since nobody was actually playing with the knobs anyway.

I would be surprised if there were vans with 3 or 4 of these black box radios 
as part of a stingray or silent ping set up using correlation techniques to 
RDF cellular users. It has enough bandwidth to cover all known cellular 
providers. It could probably RDF wifi.




-Original Message-
From: Jim Lux jim...@earthlink.net
Sender: time-nuts-boun...@febo.com
Date: Wed, 24 Apr 2013 04:33:26 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Radio with GPSDO

On 4/23/13 6:54 PM, li...@lazygranch.com wrote:
 http://www.aorusa.com/receivers/ar2300.html

 Just a FYI.


Interesting..

I see they use the OEM GPS from Garmin.  I wonder what kind of DO 
performance they get, and whether they actually discipline the 
oscillator or just measure it.  Since they've got a DDS, they could use 
a quiet fixed OCXO, undisciplined, and just adjust the DDS control word.


Fascinating, also, that they provide a raw I/Q sample output.  Clearly, 
that's the way of the future, and it makes sense.

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Re: [time-nuts] S743 Marketplace Fariness Act

[lists]

There are limitations for low volume sellers. Ebay could easily write a program 
to compute sales tax. My problem with the seller collecting tax is do they 
really send it off to the tax authority.

Technically, there is no sales tax on used items, at least in most states. 
Certain high value items do get taxed when bought used, like cars and planes.

-Original Message-
From: Tom Knox act...@hotmail.com
Sender: time-nuts-boun...@febo.com
Date: Tue, 23 Apr 2013 16:51:33 
To: Time-Nutstime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] S743 Marketplace Fariness Act

The eBay emails appear real since it can also be accessed on my actual eBay 
site. I cannot imagine what a pain it would be to sell 20 items on eBay each to 
a buyer in a different state and be required to file the paperwork to pay taxes 
on each of those sales. This is a formula for disaster. 

Thomas Knox



 To: time-nuts@febo.com
 From: johncr...@aol.com
 Date: Tue, 23 Apr 2013 16:04:58 -0400
 Subject: Re: [time-nuts] S743 Marketplace Fariness Act
 
 The ebay message re this law is probably legit. In any case
 the congress IS considering such a law. In essence it forces
 all internet sellers to collect the sales tax due in the buyers state. If you 
 live in a state with a law requiring that sales tax be paid on all out of 
 state purchases (internet or not), often called a use tax, as the buyer you 
 are required to pay this tax. The taxes already are on the books, they are 
 often not enforced.
 
 You can learn all about this with a Google search which will reveal all sorts 
 of opinions. Here is one that is not too
 bad:  
 
 http://www.forbes.com/sites/beltway/2013/04/23/five-things-you-should-know-about-the-long-overdue-online-sales-tax-bill/
 
 If you already comply with the law and do a lot of internet purchases; 
 passage will relieve you of a pain in the ass accounting job at tax time. If 
 your state has no such tax or if you avoid paying it, though your state 
 requires it, passage will cost you some sale taxes you would have otherwise 
 escaped.
 
 One nasty consequence is that the software to pull this off is non-trivial 
 since local sales taxes in many states vary by county, school district, local 
 bond issues and so on. How that is handled should be amusing.
 
 -73 john k6iql
 
 
  
 
 
  
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[time-nuts] Radio with GPSDO

[lists]

http://www.aorusa.com/receivers/ar2300.html

Just a FYI.

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Re: [time-nuts] OT: eBay Contact Congress

[lists]

I didn't get the email, but I generally use www.ip2location.com to track 
addresses. Look for demo at the top of the page.

A long story, but this is my Moroccan hacker.
41.143.64.233

A long story, but I was hacked for Morroco.

-Original Message-
From: Christopher Quarksnow cquarks...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Mon, 22 Apr 2013 15:55:56 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] OT: eBay Contact Congress

Just check the mail header (viewing message source in your mail client) and
look for the originating ip address.
Then go to arin.net and see if e-bay owns that block ; if the ip address is
from Nigeria, arin will refer you to Afrinic, or whatever RIR it's under.

Hope this helps,

Chris


On Mon, Apr 22, 2013 at 2:41 PM, Donald Henderickx
wa9...@sandprairie.netwrote:

 On 4/22/2013 12:21 PM, Max Robinson wrote:

 I received one but I don't know if it's legit.

 Regards.

 Max.  K 4 O DS.

 Email: m...@maxsmusicplace.com

 Transistor site 
 http://www.funwithtransistors.**nethttp://www.funwithtransistors.net
 Vacuum tube site: http://www.funwithtubes.net
 Woodworking site http://www.angelfire.com/**electronic/funwithtubes/**
 Woodworking/wwindex.htmlhttp://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
 Music site: http://www.maxsmusicplace.com

 To subscribe to the fun with transistors group send an email to.
 funwithtransistors-subscribe@**yahoogroups.comfunwithtransistors-subscr...@yahoogroups.com

 To subscribe to the fun with tubes group send an email to,
 funwithtubes-subscribe@**yahoogroups.comfunwithtubes-subscr...@yahoogroups.com

 To subscribe to the fun with wood group send a blank email to
 funwithwood-subscribe@**yahoogroups.comfunwithwood-subscr...@yahoogroups.com

 - Original Message - From: J. Forster j...@quikus.com
 To: armyrad...@yahoogroups.com
 Cc: time-nuts@febo.com
 Sent: Monday, April 22, 2013 8:13 AM
 Subject: [time-nuts] OT: eBay Contact Congress


  Hi,

 I recieved a very odd communication, apparently from eBay, this morning.
 It is a request to contact Congress about sales taxes on internet sales.

 It APPEARS to be genuine, but I'm unconvinced.

 Has anybody else received this email, and is it for real?

 Puzzled,

 -John

 

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 mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.


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 mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.

  Go to eBay. go to my eBay. messages, log into your account.If the
 message in question is not there it did not come from eBay. (run away run
 away)
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Re: [time-nuts] antennas was Re: Common-View GPS Network

[lists]

But the pan is just a ground plane. It isn't a reflector based on the type of 
antennas I saw in the photograph.

Sent via BlackBerry from T-Mobile

-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Wed, 17 Apr 2013 12:18:00 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] antennas was Re: Common-View GPS Network

Another way to ask this question is what is the effect of a small
deviation form the ideal dimensions?

If we assume deviations of about 1/20th of a wavelength are OK then we can
allow about 1cm of dimensional error.  Almost anyone using simple hand
tools can do better.

With care using primitive garage equipment we can do much better.  The
old-school hand method for precision sheet metal work was to make a
hardwood form and then bend and cut the metal around the wood form.

I think if a cake pan would work is a matter of luck.  You'd just have to
find one within about 2cm of the correct diameter.  If not then you be
better off starting with flat sheet and hand shears.


On Tue, Apr 16, 2013 at 10:46 PM, David J Taylor 
david-tay...@blueyonder.co.uk wrote:

 From: Sarah White
 I just have to ask though... cake pans? really? I can't imagine it would
 even be possible to modify a cake pan with enough accuracy to get a
 usable antenna.


-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] GPS antenna??

[lists]

Aren't GPS birds all over the sky. South facing is for the Clarke belt. 
-Original Message-
From: Bob Camp li...@rtty.us
Sender: time-nuts-boun...@febo.com
Date: Mon, 8 Apr 2013 15:28:14 
To: 'Discussion of precise time and frequency measurement'time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] GPS antenna??

Hi

Is the proposed window south facing? If not, you will need enough cable
outdoors to get your second antenna to a south facing location. 

Assuming it's south facing and reasonable sky view, have you tried a patch
antenna on / at the window? That should at least give you some idea of how
likely the signal is to get through it. It's not uncommon to run GPSDO's
with window mounted antennas. 

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Alan Melia
Sent: Monday, April 08, 2013 1:00 PM
To: time-nuts measurement
Subject: [time-nuts] GPS antenna??

Hi all an interesting problem you may have encountered, I want to use a GPS 
frequency standard inside a building with no opening windows (opening 
windows are known as air conditioning in the UK :-))  )
This is part of a two day amateur microwave conference so we should have the

expertise.

I intend to try and pass the signal through a a double glazed glass window 
unit (hopefully not metalised) using a couple of patch antennas. The outer 
GPS antenna is active so will need  a 5v supply via an inserter. Inner patch

active, outer patch passive to avoid problems of feedback. Main antenna can 
be shielded from the coupling either physically or with a slab of 
absorber.

Has anyone tried this? does it work?.any gotchas?

Thanks
Alan
G3NYK 

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Re: [time-nuts] Photodiodes for high frequency OPLL

[lists]

This thread has already drifted a bit, but as an aside, the sky UV filters 
sold for photography are a joke. (Easily verified with UV diodes and any 
material that reacts to UV.) The Andover 400nm long pass actually DOES filter 
UV. A 400nm is nearly cast free. A 420nm does have a bit of a cast, but can be 
useful at times. These UV filters reduce the effect of airborne water vapor in 
long distance photography/remote-sensing.



-Original Message-
From: Attila Kinali att...@kinali.ch
Sender: time-nuts-boun...@febo.com
Date: Mon, 1 Apr 2013 11:12:26 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Photodiodes for high frequency OPLL

On Sun, 31 Mar 2013 20:31:58 -0700
gary li...@lazygranch.com wrote:


 On 3/31/2013 5:52 AM, Attila Kinali wrote:
 
  Probably. But as steep filters for optics are kind of hard to come by,
  i think a super heterodyne design isn't realy going to work.

 I've bought optical filters from Andover. They are pretty cheap, at 
 least compared to the rest of the industry.
  http://www.andovercorp.com/Web_store/index.php

Yes, but the usual optical filters are not steep enough for this application.
They are specified to a few nm, while we are talking here about GHz.
At those wavelengths this is IIRC a factor 100'000.

But thanks for the page anyways.. they might come handy as an ambient
light filter for the photodiodes.

Attila Kinali

-- 
The people on 4chan are like brilliant psychologists
who also happen to be insane and gross.
-- unknown
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Re: [time-nuts] Photodiodes for high frequency OPLL

[lists]

You lose me at damping per decade? Is damping the right word? Do you mean high 
frequency rolloff?

Most texts on photodiodes go into bootstrapping them to reduce the effect of 
capacitance. But if you design fully differential amplifier circuits, they have 
the same effect as bootstrapping. Jerald Graeme's Photodiode Amplifiers goes 
into this. I'm not a fan of Gain technology as a company, but Graeme's book are 
good texts. 

The bootstrapping circuits use simpler buffers to keep the voltage potential 
across the diode low, while the fully differential circuits depend on gain 
bandwidth product to do the same.

-Original Message-
From: Attila Kinali att...@kinali.ch
Sender: time-nuts-boun...@febo.com
Date: Sat, 30 Mar 2013 12:48:01 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Photodiodes for high frequency OPLL

Moin,

I'm currently reading up some stuff on optical PLLs and am stuck with some
details i cannot find any data on.

The goal is to make two lasers locked with about 7GHz of offset to eachother.

So far, i figured out that PIN photodiodes can go up to several 100MHz
transition frequency and avalanche photodiodes are available up to 2GHz.
The only photodiodes that go higher are those for the telecom range
at 1-1.5um, which is a bit low for my needs.

But, i have seen descriptions of such OPLL that work with multi GHz
offsets in the 700-800nm range.

Now the question is: Do these use special made photodiodes with a very
high transition frequency or do they just treat the transition frequency
as a 3dB point and amplify the signal after detection?
(They do not describe the detection circuit at all, so i guess it must
be something readily available)

If it's the former, any idea where i could get such photodiodes?

If it is the later, how much damping can i assume with PIN or avalanche
photodiodes per decade?


Thanks in advance!

Attila Kinali


-- 
The people on 4chan are like brilliant psychologists
who also happen to be insane and gross.
-- unknown
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Re: [time-nuts] Photodiodes for high frequency OPLL

[lists]

I forgot to mention if you use the bootstrap technique, you can keep a negative 
bias on the photodiode, which improves bandwidth by reducing capacitance. That 
is, you drive the AC signal across the diode to zero, but not the DC bias. If 
you use the fully differential amplifer, then the bias voltage is zero, hence 
more capacitance. 
I've looked into transformer coupling for photodiodes as a way to go fully 
differential and still apply a bias. A few years ago, the idea would be silly, 
but RF applications have created a supply of really high frequency 
transformers. 

The UDT diodes with the BNC attached are pretty common on ebay. I think the 
company was bought out. 


-Original Message-
From: jmfranke jmfra...@cox.net
Sender: time-nuts-boun...@febo.com
Date: Sat, 30 Mar 2013 13:46:51 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Photodiodes for high frequency OPLL

I used UDT PIN10 photodiodes to observe the mode spacings in HeNe lasers. 
The typical mode spacings were around 600 MHz.

John  WA4WDL

--
From: ed breya e...@telight.com
Sent: Friday, March 29, 2013 8:20 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Photodiodes for high frequency OPLL

 I don't think that you can effectively directly mix two laser wavelengths 
 in a semiconductor light detector and get a useable IF - it's hard enough 
 just to get the tens of GHz modulation signals out above the noise floor, 
 let alone a tiny difference signal between hundreds of THz. You need an 
 optical interference or nonlinear device up front to do the mixing and 
 get the wavelength discrimination, while the optical detector(s) serve as 
 the first IF O-E transducer.

 My knowledge of this stuff isn't up to date - maybe nowadays there are 
 detector devices and methods that take care of this directly, but I don't 
 think so.

 Most really high speed diodes are optimized for the 1550 nm region where 
 EDFAs work, but maybe they have usable response at other ranges. It 
 depends on your particular application and wavelength. I think detectors 
 are usually specified over the entire IR region, so datasheets may tell 
 enough.

 Here's link to some good info, but not current state of the art:

 http://e-collection.library.ethz.ch/eserv/eth:28429/eth-28429-02.pdf

 There are various methods that use lower frequency modulation techniques 
 so that regular detectors can be used directly. If you study up on related 
 patents, you may find some ideas and leads to appropriate actual devices.

 Ed

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Re: [time-nuts] Photodiodes for high frequency OPLL

[lists]

The circuit is something like the instrumentation amplifier. The description 
starts on page 207 with a schematic on page 208. I can scan it later, but the 
circuit is easy to describe. Think of two op amps in the classic current 
multiplication (I to V)  circuit, that is positive input to ground and a 
resistor from output to negative input. Now place the diode between the two 
negative inputs. The current flow will cause the outputs of the op amp to move 
differentially, which can then be made single ended with an op amp circuit. But 
the thing to keep in mind is that the voltage potential across the photodiode 
has been kept to zero, so the capacitance doesn't matter. But it is only held 
to zero as long as the amplifier has loop gain, that is create the virtual 
ground, hence you need a high GBP for the capacitance to be neutralized. 

Now I haven't seen this published, but it seems to me if you wanted a negative 
bias across the diode, you could just use a transformer. I ran into a patent on 
transformer coupled photodiode circuitry. It was for high speed flash 
detection. (Amazing was common sense obvious design technique can be patented.) 

The bootstrap technique basically takes the virtual ground signal of the  
current multiplier circuit and replicates the AC portion of the virtual ground 
on the other side of the photodiode, keeping the AC signal across the diode at 
zero volts, but letting the current flow into the circuit to be multiplied by 
the op ampresistor. 

Since the bootstrap needs to sample the virtual ground, it itself can't steal 
any current from that point, so it usually employs a JFET. 

These amplifier circuits usually go down to DC, so they will also have response 
to ambient light, which could eat into the dynamic range of the circuit. 

Linear Technology app notes use the bootstrap often. They use a common low 
noise JFET from NXP. Noise from the bootstrap adds right to the diode, so the 
bootstrap components need to be low noise.  The fully differential circuit 
doesn't have the bootstrap noise source, but it has two amplifiers on the front 
end, hence two uncorrelated noise sources. 

Going back to the fully differential circuit, you could bias the diode by 
placing the positive inputs of the I to V circuits at different potentials, 
then reject the DC components at the double ended to single ended converter by 
capacitive coupling. You would probably want to meditate on start up issues if 
the DC bias is large, that is use clamping diodes on the double ended to single 
ended converter if it looks like something will be stressed on start up.

When you read the photodiode literature, bandwidth is stated into an impedance, 
so I think they just treat the capacitance as the limiting factor. Maybe that 
is real life, or maybe it is oversimplified. At that point this is a solid 
state physics problem and not a circuit design issue. (I'd have to crack a book 
on the physics.)

--Original Message--
From: Attila Kinali
To: li...@lazygranch.com
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Photodiodes for high frequency OPLL
Sent: Mar 30, 2013 12:03 PM

On Sat, 30 Mar 2013 17:29:45 +
li...@lazygranch.com wrote:

 You lose me at damping per decade? Is damping the right word?
 Do you mean high frequency rolloff?

Er.. yes. Frequency rolloff... Sorry, my native language got the better of me.


 Most texts on photodiodes go into bootstrapping them to reduce the
 effect of capacitance. But if you design fully differential amplifier
 circuits, they have the same effect as bootstrapping. Jerald Graeme's
 Photodiode Amplifiers goes into this. I'm not a fan of Gain technology
 as a company, but Graeme's book are good texts. 

Thanks! I just ordered this book.
Although i will have to build a discrete amplifier for the first stage
until i can mix the signal down to something that can be handled easier.

 The bootstrapping circuits use simpler buffers to keep the voltage
 potential across the diode low, while the fully differential circuits
 depend on gain bandwidth product to do the same.

Well, as i currently lean torwards using an avalanche photodiode,
which needs an operating voltage in the range of 100V, keeping the
potential accross the diode low is not really an issue :-)

How do the fully differential circuits get to keep the potential low?
As far as i can tell, from the circuits i've seen so far, the differential
circuits just use the single ended signal from the diode take the difference
to a bias voltage.


Attila Kinali
-- 
The people on 4chan are like brilliant psychologists
who also happen to be insane and gross.
-- unknown

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Re: [time-nuts] Photodiodes for high frequency OPLL

[lists]

If I can rephrase that it it, the diode needs to see the difference signal of 
the mixer? 
-Original Message-
From: Bruce Griffiths bruce.griffi...@xtra.co.nz
Sender: time-nuts-boun...@febo.com
Date: Sun, 31 Mar 2013 11:43:48 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Photodiodes for high frequency OPLL

The detectors don't have to be fast enough to keep up with optical 
carrier frequency as long as the incident optical power has a component 
at a much lower frequency.

Bruce

ed breya wrote:
 Ooops - never mind. I wrote before my memory was updated. My 
 experience in E-O stuff was years ago using AM at relatively low 
 frequency, and nowhere near the lasers and microwave/gigabit/sec stuff 
 - I didn't think the detectors were fast enough to actually keep up 
 with the optical carrier frequency. I was also picturing 
 wavelength/spatial separation with interference in order to allow 
 relatively slow detectors to see it, or mixing in nonlinear optical 
 materials.

 Ed

 Bruce Griffiths wrote:

 A photodiode is in fact a nonlinear device for optical fields as it is
 essentially a linear optical power detector.
 The output is proportional to the incident optical power not the field
 amplitude.
 Photomixers are routinely used in wide range of diverse application such
 as translating the frequency fluctuations of the (Mie) scattered light
 due to Brownian motion of the colloidal particle sizes to baseband. The
 size of the scattering particles can be inferred from the shape of the
 resultant frequency spectrum.

 An interferometer of itself (without a detector) is a linear device that
 merely superimposes optical fields and will of itself produce no
 difference frequency output.

 Bruce

 ed breya wrote:
  I don't think that you can effectively directly mix two laser
  wavelengths in a semiconductor light detector and get a useable IF -
  it's hard enough just to get the tens of GHz modulation signals out
  above the noise floor, let alone a tiny difference signal between
  hundreds of THz. You need an optical interference or nonlinear device
  up front to do the mixing and get the wavelength discrimination,
  while the optical detector(s) serve as the first IF O-E transducer.
 
  My knowledge of this stuff isn't up to date - maybe nowadays there are
  detector devices and methods that take care of this directly, but I
  don't think so.
 



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Re: [time-nuts] Photodiodes for high frequency OPLL

[lists]

OK, so if you just need to detect the mixer difference, the band limiting of 
the photodiode is a feature. ;-)
-Original Message-
From: Bruce Griffiths bruce.griffi...@xtra.co.nz
Date: Sun, 31 Mar 2013 12:28:59 
To: li...@lazygranch.com; Discussion of precise time and frequency 
measurementtime-nuts@febo.com
Subject: Re: [time-nuts] Photodiodes for high frequency OPLL

Yes, the beat (difference) frequency of the 2 lasers has to lie within 
the photodiode electrical passband.

With a suitable low noise tunable LO (laser) the frequency spectrum 
beyond the photodiode electrical bandwidth can be explored.

Bruce

li...@lazygranch.com wrote:
 If I can rephrase that it it, the diode needs to see the difference signal of 
 the mixer?
 -Original Message-
 From: Bruce Griffithsbruce.griffi...@xtra.co.nz
 Sender: time-nuts-boun...@febo.com
 Date: Sun, 31 Mar 2013 11:43:48
 To: Discussion of precise time and frequency measurementtime-nuts@febo.com
 Reply-To: Discussion of precise time and frequency measurement
   time-nuts@febo.com
 Subject: Re: [time-nuts] Photodiodes for high frequency OPLL

 The detectors don't have to be fast enough to keep up with optical
 carrier frequency as long as the incident optical power has a component
 at a much lower frequency.

 Bruce

 ed breya wrote:

 Ooops - never mind. I wrote before my memory was updated. My
 experience in E-O stuff was years ago using AM at relatively low
 frequency, and nowhere near the lasers and microwave/gigabit/sec stuff
 - I didn't think the detectors were fast enough to actually keep up
 with the optical carrier frequency. I was also picturing
 wavelength/spatial separation with interference in order to allow
 relatively slow detectors to see it, or mixing in nonlinear optical
 materials.

 Ed

 Bruce Griffiths wrote:

 A photodiode is in fact a nonlinear device for optical fields as it is
 essentially a linear optical power detector.
 The output is proportional to the incident optical power not the field
 amplitude.
 Photomixers are routinely used in wide range of diverse application such
 as translating the frequency fluctuations of the (Mie) scattered light
 due to Brownian motion of the colloidal particle sizes to baseband. The
 size of the scattering particles can be inferred from the shape of the
 resultant frequency spectrum.

 An interferometer of itself (without a detector) is a linear device that
 merely superimposes optical fields and will of itself produce no
 difference frequency output.

 Bruce

 ed breya wrote:
  
 I don't think that you can effectively directly mix two laser
 wavelengths in a semiconductor light detector and get a useable IF -
 it's hard enough just to get the tens of GHz modulation signals out
 above the noise floor, let alone a tiny difference signal between
 hundreds of THz. You need an optical interference or nonlinear device
 up front to do the mixing and get the wavelength discrimination,
 while the optical detector(s) serve as the first IF O-E transducer.

 My knowledge of this stuff isn't up to date - maybe nowadays there are
 detector devices and methods that take care of this directly, but I
 don't think so.




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Re: [time-nuts] Releasing sources (was Re: Brooks Shera)

[lists]

You can simply set up a phpbb forum. Most questions cam be answered by users of 
the software, who in turn can write a better FAQ because they DIDN'T write the 
program. This sounds counter intuitive, but you need outsiders to do 
documentation. What is obvious to the designer is not obvious to the user.

 
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Re: [time-nuts] Win XP and NIST time

[lists]

SDR isn't as taxing as you think. I'm running 4 of those rtlsdr type dongles on 
an A8-cortex. Granted under linux, but this is a single core Arm. 

The multimedia versions of linux don't get much press these days since the 
kernel itself now is rather low latency. But if you google linux musicians or 
windows musicians, there are tips for latency reduction. 

One of the nicest things you can do to a computer is turn off the stupid file 
indexing. On windows, the program everything is faster than windows file 
search ever was, and doesn't need the index.

-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Wed, 27 Mar 2013 08:38:32 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Win XP and NIST time

The appearent conflict here is in the definition of real time.

For the video capture application we only need to keep up with the
average data rate and if the system stops reading data for a few tens
of milliseconds and lets it buffer in the capture hardware then it is
OK because nothing is lost.   The only criteria for success is
nothing is lost.

The SDR application is a little more time critical because it needs to
play the proceed audio.  But again it can be buffered and we'd never
notice a 50 millisecond lag in audio and for radio  a 100 ms lag might
go unnoticed

But there is a category of what engineers ca hard real time.  Home
computer users don't normally use their PCs for hard real time
applications.  This would be things like controlling a walking robot,
guiding an anti aircraft missile or just about any time a computer is
inside the feedback loop of a control system.  These are all
engineering and science applications that home users wouldn't see.


A harder real time use that people DO see in home use is music.  If
you try to do multi-track recording in a home music studio with
windows.  This can be done but people have to do thinks like (1)
remove everything non music related from the PC and disconnect it from
the network.  (2) replace the audio subsystem software with special
real-time ASIO audio drivers.  Then it can work

So real-time has a wide range of meanings, video capture is about
the easiest to do and being embedded in a servo control loop the
hardest

On Tue, Mar 26, 2013 at 6:08 PM, David I. Emery d...@dieconsulting.com wrote:
 On Tue, Mar 26, 2013 at 07:39:51PM +0100, Alberto di Bene wrote:
 On 3/26/2013 7:21 PM, Dan Kemppainen wrote:

 Keep in mind, we are after all, taking about windows. An operating
 system that IS NOT real time operating system. (You think it is, try
 move a continuous stream of a few 6+ MBytes/Sec data to it!)

 Well, the Perseus SDR, when set to its maximum sampling rate after the DDC,
 sends
 the I and Q continuous streams (24 bit/sample each), to the PC at a rate of
 2 MHz. This
 means 12 MBytes/sec via a high speed USB2 port. Using one the many
 available SDR
 programs, those 12 MBytes/sec are received, FIR and FFT are applied,
 demodulation
 algorithms are used, and there are no glitches in the final audio...  if
 even a single sample
 would be lost, you would ear immediately the artifact

 Windows is not as bad as somebody would depict it... :-)

 I have been using Windows for digital video analysis and
 capture for years... often capture multiple 70-80 mb/s transport streams
 by the hour from USB and PCI sources and output similar for testing.

 It works.

 Does take buffering and tuning in the code, and some in the
 hardware.



 --
   Dave Emery N1PRE/AE, d...@dieconsulting.com  DIE Consulting, Weston, Mass 
 02493
 An empty zombie mind with a forlorn barely readable weatherbeaten
 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
 celebration of what could have been, but wasn't and is not to be now either.

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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Win XP and NIST time

[lists]

The timing/logging of events can benefit from precise time, even if the 
processing of such data is not real time. MLAT/TDOA for example. But I believe 
stock trading uses precise timing in order to queue orders.

On my list of sdr hacks is a radio interferometer. Precise event timing there 
would be key. (I will have to hack the sdrs to use one time source.)

-Original Message-
From: Dan Kemppainen d...@irtelemetrics.com
Sender: time-nuts-boun...@febo.com
Date: Wed, 27 Mar 2013 12:46:08 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Win XP and NIST time

Good explanation. I guessed, since the list is time nuts I assumed 
real time in reference to an OS would be understood. :)  My bad.

Because windows is not a real time operating system (RTOS), I lack 
seeing the purpose in getting the windows clock synchronized to within 
microseconds or nanoseconds of anything. Even if you could do it, you 
won't get much out of doing so.

I've seen windows regularly stall critical code loops for more than a 
second at a time, when the loops would normally take a few milliseconds 
to run. If reading data down a USB connection, with limited buffering on 
the USB peripheral, data can and will be lost in streaming applications. 
(I suspect the SDR mentioned has a good bit of buffering in it!)

As for timing things on windows, check out how to read the performance 
counters in windows. I believe these are QueryPerformanceCounter and  
QueryPerformanceFrequency in kernel32. In most modern systems these 
should give a time stamp from the system start, at the native core clock 
frequency.

Now, using these with interrupts on some sort of input, one should be 
able to get some really good resolution on measurements from a PC.  If 
the CPU clock frequency was locked to a really good source, you could 
get quite a system out of it...


Dan




On 3/27/2013 12:00 PM, time-nuts-requ...@febo.com wrote:
 The appearent conflict here is in the definition of real time.

 For the video capture application we only need to keep up with the
 average data rate and if the system stops reading data for a few tens
 of milliseconds and lets it buffer in the capture hardware then it is
 OK because nothing is lost.   The only criteria for success is
 nothing is lost.

 The SDR application is a little more time critical because it needs to
 play the proceed audio.  But again it can be buffered and we'd never
 notice a 50 millisecond lag in audio and for radio  a 100 ms lag might
 go unnoticed

 But there is a category of what engineers ca hard real time.  Home
 computer users don't normally use their PCs for hard real time
 applications.  This would be things like controlling a walking robot,
 guiding an anti aircraft missile or just about any time a computer is
 inside the feedback loop of a control system.  These are all
 engineering and science applications that home users wouldn't see.


 A harder real time use that people DO see in home use is music.  If
 you try to do multi-track recording in a home music studio with
 windows.  This can be done but people have to do thinks like (1)
 remove everything non music related from the PC and disconnect it from
 the network.  (2) replace the audio subsystem software with special
 real-time ASIO audio drivers.  Then it can work

 So real-time has a wide range of meanings, video capture is about
 the easiest to do and being embedded in a servo control loop the
 hardest

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Re: [time-nuts] Win XP and NIST time

[lists]

I think using satellite Dave's plot routines is the way to tweak NTP. If you 
update too often, you can see the disturbance. This isn't a scientific 
solution, but a practical one.


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Re: [time-nuts] About metastability

[lists]

Epic fail:
Not fancy SPICE simulations.

Note there are many situations where you force the result (if you call 
hysteresis a biased scheme) simply because to do otherwise is a more serious 
problem.

-Original Message-
From: Azelio Boriani azelio.bori...@screen.it
Sender: time-nuts-boun...@febo.com
Date: Mon, 25 Mar 2013 14:09:54 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] About metastability

Thomas Cheney, October 1979:

In closing, there is a great deal of theoretical and experimental
evidence that a region of anomalous behavior exists for every device
that has two stable states. The maturity of this topic is now such that
papers making contrary claims without theoretical or experimental support
should not be accepted for publication.


Philip Freidin 8/27/2003:

Nothing improves the MTBF of a metastable synchronizer better than
just waiting longer. Not clocking the intermediate signal on the
negative clock edge. Not voting. Not threshold testing. Not adding
noise. Not fancy SPICE simulations. Not predicting circuits. Not
circuits designed to bias the outcome to either 1 or 0. Not
clocking it twice as fast through twice as many flip flops.
Nothing.
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Re: [time-nuts] Metastability (was Brooks Shera)

[lists]

There is an AMD patent where they actually drive the input pin to make it 
decide rather than hang. I have no first hand knowledge with the design (well 
other than knowing the designer) since I couldn't use the scheme in my own 
designs.

-Original Message-
From: Bob Camp li...@rtty.us
Sender: time-nuts-boun...@febo.com
Date: Mon, 25 Mar 2013 18:02:33 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Metastability (was Brooks Shera)

Hi

In normal operation, the counter is clocking back and forth across the 1024 / 
24,000,000 boundary. It has to do this for the control loop to see anything. 
Put another way, if it's always 1024 / 24,000,000 the loop does nothing at all. 

It's the race between things like enable and clock or data and clock that 
generates metastable conditions. If the data is changing as the clock fires, 
the flip flop oscillates rather than goes to a single state. In this case 
oscillation is not a good thing…..

Bob

On Mar 25, 2013, at 5:43 PM, Chris Albertson albertson.ch...@gmail.com wrote:

 First off we have the answer.  This thing works very reliably well.
 The question is why?
 
 In the normal steady state case the phase of the VCXO is held to be
 1024/24,000,000 seconds.  This means the plus from pin 15 of the 4046
 would be about 4,000 nanoseconds long and would never be anything so
 much as a factor of ten away from 4 uSec.
 
 One thing I notice is that I think the QST artcle has the pins on the
 4520 mislabeled.  Pins 9 and 10 are the two inputs to an AND gate.
 The 24MHz counter is being anded with the phase detector and the
 result of the AND is then fed to the counter.  My data sheet shows
 pins 2 and 10 as being called enable.  So what we have as a pulse
 that is about 4uSec wide gating a 24MHz square wave.
 
 There might be a race to see if the enable pin or the clock pin gets
 a pulse first and it would be a coin flip now and then but it's only
 an off by one problem.
 
 In the no-steady state case, when power is first applied before the
 loop is closed.  I don't think we care about glitches and and if the
 VXCO is stable but as soon as it does locj the pulse going to pin the
 4520's pin-10 will be 1024 times longer than the the period of the
 signal at pin-9  Again, pins 10 and 9 are the two inputs to an AND
 gate (after pin-10 is inverted)
 
 On Mon, Mar 25, 2013 at 2:04 PM, Bob Camp li...@rtty.us wrote:
 Hi
 
 With the 24 MHz clock in the circuit, and the logic families shown, the most
 likely metastability issues are edge rather than clock pulse width related.
 When you hit the magic window (think picoseconds) there is a probability
 of going metastable. It's not a 100% thing. Even with multiple synchronizer
 stages *not* being metastable is also not a 100% guarantee.
 
 The real question is - does a once every X seconds / hours / centuries event
 bother me in the application? Once you get to a multi stage synchronizer,
 the dimensions on the time are large enough that the answer is generally no.
 The event is so rare that you will never see it with these data rates. Being
 sure it's fixed is easy.
 
 It's the flip side - error rate without the synchronizer that is a bit
 harder to quantify. Things could run for weeks outside the threat window. Is
 it a several times a minute (every few days) or once an hour (every few
 weeks) problem? In the first case, you probably do care. Multiple hits per
 minute will mess up the loop. In the second case, you will never notice the
 issue.
 
 Of course, boost the clock, change the logic family, mix logic families,
 fiddle this or that and you probably should look at things again...
 
 Bob
 
 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of Bruce Griffiths
 Sent: Monday, March 25, 2013 4:38 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Metastability (was Brooks Shera)
 
 Both edges of the 24MHz clock gating pulse are asynchronous with respect
 to the signal being gated.
 Metastability can result with clock pulse widths that lie within a
 critical range.
 
 Bruce
 
 Chris Albertson wrote:
 On Mon, Mar 25, 2013 at 12:45 PM, David McGawn1...@alum.dartmouth.org
 wrote:
 
 S/LS logic was introduced in the mid 70's, F/AS/ALS around 1980, HC was
 early 80's.  By the third 7400 generation (F/AS/ALS) the problem was well
 known with parameters available and the logic fairly hard to it
 
 I think this is all moot because as I just wrote in another email the
 PPS signal never gets out of the 74hct4046 chip.   What gets out is
 the output of  Phase Detector #3.  You've have to know in some
 detail how the 4046 chips' PD3 works.
 
 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] Win XP and NIST time

[lists]

MS has/had a program to verify if your hardware would run win7. It has been too 
many years for me to recall the name. But if you are running really old 
hardware, it makes sense at some point just to dump it if you run it 24 and 7, 
if only for the cost of electricity (well depending where you live.) 

MS does not make OS switching economical. I'd say the cheapest version of win7 
you should get is PRO since it has all the XP fallback hook.

Win7 is missing a few features of older MS operation systems. The search 
feature is gone, but you can run a free program called everything. It is so 
fast, you can turn off indexing. Also gone is hyperterminal, but you can run 
terraterm, also free.

I have a dual core intel atom for 24/7 use. With SSD and 4G of Ram, it used 25 
watts. D525 processor. 

I've also been running linux on Arm. Even less power.
  
-Original Message-
From: James Harrison ja...@talkunafraid.co.uk
Sender: time-nuts-boun...@febo.com
Date: Sun, 24 Mar 2013 10:39:09 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Win XP and NIST time

-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1

On 24/03/2013 06:27, David J Taylor wrote:
 
 I'm surprised by how many time-nuts are not using the reference
 NTP port for Windows, considering the many advantages it has over
 the simple (non conformant and non-manageable) client built into
 Windows).  I made some notes here:
 
 http://www.satsignal.eu/ntp/setup.html
 
 You can then use the same management tools (ntpq) and
 configuration expertise you have on you UNIX, Linux, FreeBSD etc.
 systems. Serial-port PPS devices are supported, allowing you to
 make stratum-1 clocks on Windows with performances down to the
 100-200 microsecond level:
 
 PCs Alta Bacchus Feenix and Stamsund 
 http://www.satsignal.eu/mrtg/performance_ntp.php
 
 and with Windows-8, network synced PCs with offsets typically below
 250 microseconds even over Wi-Fi sync, PC Bergen: 
 http://www.satsignal.eu/mrtg/performance_ntp.php
 
 Cheers, David

+1 to this - on the Windows boxes I used to have running at a radio
station (including playout machines, which needed good time
synchronization) we ran Meinberg's NTPd port on all the machines and
had no issues. That's with XP under a support contract, though - I
suspect some people without said contracts via work etc will be
hitting issues.

http://windows.microsoft.com/en-GB/windows/products/lifecycle#section_2
suggests
end of extended support April 2014, though - so only just over a year
until even businesses can't get updates.

Happily migrated everything to Win7 or Linux now so no more headaches
on that front here. If you've not looked into 7 and are on XP still, I
do recommend at least considering a migration - 7 is stable now and
will be supported at least until 2020, but I'd wager longer than that
the way Windows 8 appears to be crashing and burning in the market.

Cheers,
James
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Version: GnuPG v2.0.17 (MingW32)

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upkAniM5ga/4e+96/mEGKVjpx4LMoSb+
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Re: [time-nuts] Brooks Shera

[lists]

Just send me the link relative to archive.org of where the code should be 
found. 
-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Sun, 24 Mar 2013 11:31:50 
To: step...@tompsett.net; Discussion of precise time and frequency 
measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Brooks Shera

On Sun, Mar 24, 2013 at 4:12 AM, Stephen Tompsett (G8LYB)
step...@tompsett.net wrote:
 Here's a copy of the source package (that claims to be for version 1.28)
 that he sent me when I enquired about it many years ago.

That's great.  It needs to be some how linked to an archive of his
article.  No better memorial to an engineer than to have is work
preserved in a public place.   I read the assembly source code.  I'm
not a PIC expert but I've been doing software for 25+ years I and see
that it is well written and easy to understand.   Some day I'll
transliterate this to run on a TI launchpad and will have to credit
the author.
-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Brooks Shera

[lists]

Uh WTF. I am preserving his legacy.


-Original Message-
From: WB6BNQ wb6...@cox.net
Date: Sun, 24 Mar 2013 16:38:06 
To: li...@lazygranch.com; Discussion of precise time and frequency 
measurementtime-nuts@febo.com
Subject: Re: [time-nuts] Brooks Shera

Really ? 
Well   li...@lazygranch.com,   I don't mind telling you I think your statement 
is rather crass and quite disrespectful.  The gentleman is not even cold in his 
grave and all you can demonstrate is to grab his efforts for your own selfish 
purposes. 
Truly shameful, 
BillWB6BNQ 
li...@lazygranch.com wrote: Just send me the link relative to archive.org of 
where the code should be found. 
-Original Message- 
From: Chris Albertson albertson.ch...@gmail.com 
Sender: time-nuts-boun...@febo.com 
Date: Sun, 24 Mar 2013 11:31:50 
To: step...@tompsett.net; Discussion of precise time and frequency 
measurementtime-nuts@febo.com 
Reply-To: Discussion of precise time and frequency measurement 
    time-nuts@febo.com 
Subject: Re: [time-nuts] Brooks Shera 
On Sun, Mar 24, 2013 at 4:12 AM, Stephen Tompsett (G8LYB) 
step...@tompsett.net wrote: 
 Here's a copy of the source package (that claims to be for version 1.28) 
 that he sent me when I enquired about it many years ago. 
That's great.  It needs to be some how linked to an archive of his 
article.  No better memorial to an engineer than to have is work 
preserved in a public place.   I read the assembly source code.  I'm 
not a PIC expert but I've been doing software for 25+ years I and see 
that it is well written and easy to understand.   Some day I'll 
transliterate this to run on a TI launchpad and will have to credit 
the author. 
-- 
Chris Albertson 
Redondo Beach, California 
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Re: [time-nuts] Brooks Shera

[lists]

I know someone at archive.org. I can probably get the website patched if 
someone can supply the missing files. 

I never built Brooks most accurate clock, but of course wanted to so. When I 
found some NOS symetricoms and got them going, the plug and play experience was 
kind of a let down. 
 
-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Sat, 23 Mar 2013 15:00:44 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Brooks Shera

On Sat, Mar 23, 2013 at 1:41 PM, Joseph Gray jg...@zianet.com wrote:
 Sad news. I wonder if his web pages will survive him. If not, the
 Internet Archive has archived the information. The latest is at:
 http://web.archive.org/web/20120823060601/http://www.rt66.com/~shera/

The webarchive seems to be complete except that there is no link to
the assembly language source code.  Only the hex file is available.
The QST article said thew source was available but I don't think it is
unless perhaps some one here has a copy.


-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Don't use cheap cables -- a cautionary tale (Bob Camp)

[lists]

At what frequency do these problems appear?  And how bad it bad?
 
-Original Message-
From: David Kirkby david.kir...@onetel.net
Sender: time-nuts-boun...@febo.com
Date: Tue, 5 Mar 2013 18:16:54 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale (Bob
Camp)

On 5 March 2013 17:08, Gregory Muir engineer...@mt.net wrote:
 When I compare the typical easily-obtained Jameco
 or Marlin P Jones type of connector to a better made product such as a
 true MIL item on a network analyzer, one can see a noticeable difference
 between the impedance and VSWR characteristics. It has been long known that
 the simple nickel-plate connector can cause problems over time in an
 installation from changing contact resistance and such.  The manufacturer
 RF Industries still uses silver  gold plating on their types of RF
 connectors as compared to the cheaper nickel-plated types and I have found
 these to be very reliable with a cost slightly higher than the cheaper
 nickel plated types.

I've recently been playing with some N adapters from various
manufacturers. I was particularly keen to find a decent male to male
adapter to include with a low-cost N calibration and verification kit
I am sellling.

http://www.vnacalibration.co.uk/sales/

If you read the specs on that, I state if the male to male adapter is
used, it limits performance. I've tried various makes, from the cheap
to fairly expensive (Huber and Suhner), although I am not considering
metrology grade devices, given the price I am selling the kit for.

I don't have all the data in front of me, but certain things stick in my mind.

1) The Huber and Suhner female-female N barrel was the most expensive
of any I tried. The qualtiy of the threads was excellent. But when I
stuck it on the VNA, the performance was really poor. I was intending
to phone H+S to ask what was wrong, but before doing so I looked at
the specification sheet. The spec was indeed poor, and the one I had
met it.

2) Someone recently sent me a couple of RF Industries male to male N
barrel adapters. RF performance was higher than I had seen on any
connector of its type with the exception of metrology grade devices.
However, it felt as though there was sand between the threads when
tightening these up.

3) I found some pretty decent female-female Ns that were really cheap
( $5). RF performance was good, mechanically well made. They did not
have the best RF performance of those I found, but they were cheap.

For a male-male adapter in that cal kit, I have settled on the Radiall
component for now, but I'd like to find a better one. The RF
Industries unit would do, as long as I supply a lubricant to make
screwing the things on better.

So to me, there does not appear to much correlation between cost and
performance. I've seen poor expensive items and fairly decent very
cheap items.

Dave
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Re: [time-nuts] Don't use cheap cables -- a cautionary tale

[lists]

I use Ponoma cables that have the strain relief. However, I don't know about 
the cable construction itself. 

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Re: [time-nuts] webcam app to watch for and time stamp changes

[lists]

My fob only outputs a code on demand, that is after I push the button.

Any of the motion detection programs that use webcams would detect the change 
in display, but with a multiplexed  display, I'm not sure how well.
 
-Original Message-
From: Jim Lux jim...@earthlink.net
Sender: time-nuts-boun...@febo.com
Date: Sat, 02 Mar 2013 11:33:02 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] webcam app to watch for and time stamp changes

I am interested in the timing behavior of my RSA fob, which changes 
every 60 seconds.  Since I'm not about to open it up and probe inside, I 
was wondering if someone had a clever way, say using a USB web cam, to 
log the changes over a 48 hour period.  You'd point the web cam at the 
fob, and it would log the time when the display changes
Or one might even be able to look at the blinking 1 pps indicator using 
a light and photocell or something..
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Re: [time-nuts] webcam app to watch for and time stamp changes

[lists]

If you think about it, there would have to be some time correction if only 
because these fobs can't be all that accurate in maintaining time. That is, 
they would be no better than a watch. 

I'm not so keen on wearing out the internal battery since these things are now 
$30 instead of $5 when paypal introduced them. 
-Original Message-
From: Jim Lux jim...@earthlink.net
Sender: time-nuts-boun...@febo.com
Date: Sat, 02 Mar 2013 13:18:36 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] webcam app to watch for and time stamp changes

On 3/2/13 1:10 PM, Peter Gottlieb wrote:
 I had one for work a while back and asked the IT security guys about it
 and was told that the change was on a fixed schedule but of course each
 fob was a little different due to temperature, over time, etc and that
 the system automatically learned the fobs and opened or tightened its
 tolerance for when the fobs updated.  So if you had a slow one the
 system would adapt over time and just learn to expect that but if the
 timing got too far off they would replace the fob.  I suppose if you
 kept messing with the timing by leaving in the sun or freezer eventually
 you would get rejected logins and your IT people would want to replace
 it, unless they manually really loosened up the timing windows.  The
 people I asked didn't mind my inquiries and seemed eager to chat but
 some places might be a bit more paranoid.


The explanation in RSA's manuals is more like..

You set a tolerance window.. how many codes before/after are you willing 
to accept.  When it accepts your code, it resynchronizes it's master 
timer (for your fob) to whatever you just entered.It doesn't go so 
far as to try and adjust the rate, just the offset.



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Re: [time-nuts] lightweight webserver for, e.g., NTP widget

[lists]

I think those SBCs have insufficient RAM (128M on the biggest board.) . 512M 
seems to be OK (which is where most community boards are at). The Panda ES is 
double that. 

Now those SBC have sata ports, so swap space isn't quite as detrimental as on 
SBCs that use the SDHC for swap. Still, I rather have the RAM.


-Original Message-
From: Didier Juges shali...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Tue, 12 Feb 2013 13:47:41 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] lightweight webserver for, e.g., NTP widget

If you decide to go with one of the SBCs at embeddedarm.com, I have a Wiki page 
on my web site documenting how I have set mine up.

Didier

Www.ko4bb.com


Sent from my Droid Razr 4G LTE wireless tracker.



-Original Message-
From: Jim Lux jim...@earthlink.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Mon, 11 Feb 2013 4:02 PM
Subject: [time-nuts] lightweight webserver for, e.g., NTP widget

I'm intrigued by the possibility of using a lightweight web server to 
provide a management/user interface to test equipment or appliances 
(e.g. like the NTP server recently discussed, or a box with mixers and 
counters).

I've built some web interfaces to very small things using Arduinos and 
Rabbits, and it works ok for simple stuff (turning on and off switches), 
but as soon as you start looking at a bit more complexity (e.g. you want 
to move files around), a bit more sophistication on your server seems 
useful.  Or, for instance, if you have a DDS you want to program to 
follow a particular sequence of frequencies (e.g. to match a particular 
Doppler profile, in my case). Or a data acquisition application.

The appeal that the user client is that any old web-browser is pretty 
generic.

I've done this sort of by exposing a directory as a public share (SMB) 
and then browsing to that file, using the file:// mechanism, but it 
seems that actually having a real server might be useful (for things 
like POST from a form, for instance)

But, on the other hand, it seems that something like Apache is a bit 
much to manage.

Is there something that runs under Linux on a lightweight single board 
PC (Raspberry pi or Intel Mini-ITX Atom mobos) that isn't too much of a 
pain, and doesn't require you to be a full time web server administrator 
to make it work?

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Re: [time-nuts] NTGS50AA Power supply

[lists]

Are the two diodes really back to back? I have use two in parallel to enhance 
the time the diodes will conducting. Due to current hogging, the diodes will  
effectively turn on one at a time.

-Original Message-
From: EB4APL eb4...@cembreros.jazztel.es
Sender: time-nuts-boun...@febo.com
Date: Sun, 10 Feb 2013 02:08:17 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] NTGS50AA Power supply

Nate,

I have it already connected to a 48 V supply according to the vendor 
instructions (fluke.l is a vendor with technical knowledge)and now I 
removed the PCB from the case that I furnished and found that my unit 
doesn´t have such bridge.  Instead it have a quite elaborate reversal 
power protection (a series diode, two fuses and a pair of back connected 
diodes which will blow the fuses if the power is reversed and the first 
diode fails shorted) so I think that there are dual supply models 
(according to my documentation) and single supply ones, as my unit 
appears to be.
Thank you for the suggestion to change the 1/2PPS to 1PPS by software,
I'll try it.

Regards,
Ignacio EB4APL


El 09/02/2013 17:54, Nathaniel Bezanson wrote:

 Open it up, you'll find a bridge rectifier as the first component on the 
 incoming power.
 It's actually much easier to solder straight to the pins of that component, 
 rather than trying to bodge something together that would poke into the 
 backplane connector. :)
 I know there's a TSIP command for *other* units to change their PPS into PP2S 
 (even second), so try throwing 8E-4E at this unit and see if you can change 
 it the other way. Haven't had a chance to try it on the local one.
 -Nate-
 EB4APL  wrote:
  Hello,

 According to a Nortel specification document (Dual Voltage Global
 Positioning System Timing Module (GPSTM) OEM General Specification
 Dataset Name: GSBW50AA), this GPSDO is dual voltage and can be powered
 either from -48 V or + 24 V systems.  Mine is working from a 48 V power
 supply but I´m afraid to test it at 24 V because the polarity should be
 reversed and if my assumption is not true I can damage the unit.
 Do you know if these units are dual voltage or my documentation refers
 to other model?.  Has anybody operated it at 24 V?.
 Another question, is there any internal 1PPS signal available?
 Of course, my unit is of ebay - China origin.

 Regards,
 Ignacio EB4APL
 ___

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Re: [time-nuts] NTGS50AA Power supply

[lists]

OK. I have the circuit now. Normally you would want to limit the reverse 
condition to one diode drop. At two silicon diodes, the chips themselves would 
start to turn on.
 
Odd, but I assume the designers had a reason.




-Original Message-
From: EB4APL eb4...@cembreros.jazztel.es
Sender: time-nuts-boun...@febo.com
Date: Sun, 10 Feb 2013 03:01:13 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] NTGS50AA Power supply

Maybe I didn't explained this quite well, I'm not good writing in English.
So I try again: In the negative input first there is a forward biased 
diode, then a pair of fuses in parallel, and then the two diodes in 
series connected to the positive in the back direction, so if the input 
is reversed and the first diode became shorted, the two series connected 
diodes makes the fuses blow,(one after another or at the same time, 
giving the current involved). The diodes are schottkys and maybe they 
need two in series due to reverse voltage limits, since the 48 volts 
unit must withstand 100 V transients without failure.

Regards,
Ignacio, EB4APL


On 10/02/2013 2:17, li...@lazygranch.com wrote:
 Are the two diodes really back to back? I have use two in parallel to enhance 
 the time the diodes will conducting. Due to current hogging, the diodes will  
 effectively turn on one at a time.

 -Original Message-
 From: EB4APL eb4...@cembreros.jazztel.es
 Sender: time-nuts-boun...@febo.com
 Date: Sun, 10 Feb 2013 02:08:17
 To: Discussion of precise time and frequency measurementtime-nuts@febo.com
 Reply-To: Discussion of precise time and frequency measurement
   time-nuts@febo.com
 Subject: Re: [time-nuts] NTGS50AA Power supply

 Nate,

 I have it already connected to a 48 V supply according to the vendor
 instructions (fluke.l is a vendor with technical knowledge)and now I
 removed the PCB from the case that I furnished and found that my unit
 doesn´t have such bridge.  Instead it have a quite elaborate reversal
 power protection (a series diode, two fuses and a pair of back connected
 diodes which will blow the fuses if the power is reversed and the first
 diode fails shorted) so I think that there are dual supply models
 (according to my documentation) and single supply ones, as my unit
 appears to be.
 Thank you for the suggestion to change the 1/2PPS to 1PPS by software,
 I'll try it.

 Regards,
 Ignacio EB4APL


 El 09/02/2013 17:54, Nathaniel Bezanson wrote:

 Open it up, you'll find a bridge rectifier as the first component on the 
 incoming power.
 It's actually much easier to solder straight to the pins of that component, 
 rather than trying to bodge something together that would poke into the 
 backplane connector. :)
 I know there's a TSIP command for *other* units to change their PPS into 
 PP2S (even second), so try throwing 8E-4E at this unit and see if you can 
 change it the other way. Haven't had a chance to try it on the local one.
 -Nate-
 EB4APL  wrote:
   Hello,

 According to a Nortel specification document (Dual Voltage Global
 Positioning System Timing Module (GPSTM) OEM General Specification
 Dataset Name: GSBW50AA), this GPSDO is dual voltage and can be powered
 either from -48 V or + 24 V systems.  Mine is working from a 48 V power
 supply but I´m afraid to test it at 24 V because the polarity should be
 reversed and if my assumption is not true I can damage the unit.
 Do you know if these units are dual voltage or my documentation refers
 to other model?.  Has anybody operated it at 24 V?.
 Another question, is there any internal 1PPS signal available?
 Of course, my unit is of ebay - China origin.

 Regards,
 Ignacio EB4APL
 ___

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Re: [time-nuts] Low noise power supplies?

[lists]

Ok, but open loop as I described?

I bicmos design, there are two common junk buffers. The junkiest (sp?) is 
going up a PNP and down a NPN. No feedback. You live with the vbe mismatch. 
Next up the food chain is the long tail pair (diff amp) with emitter follower. 
With one gain stage, it is reasonable stable. 

-Original Message-
From: John Miles jmi...@pop.net
Sender: time-nuts-boun...@febo.com
Date: Fri, 1 Feb 2013 01:30:24 
To: 'Discussion of precise time and frequency measurement'time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Low noise power supplies?

 Are 4 and 5 regulated? Or is the zener picked to compensate for the VBE
 drops?
 
 Any of these circuits where the output transistor is in an emitter
 follower configuration will have its noise effected by the load current,
 since that current directly effects the output transistor
transconductance.

The load in all cases was a couple hundred mA worth of resistance at the
voltage in question, as I recall.  It's been a few years since I captured
these plots.

The Zeners were just whatever parts came to hand, 1N474x parts basically.  I
didn't care about the 1.4V drop across the Darlington, just the resulting
noise.

-- john
Miles Design LLC



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Re: [time-nuts] Low noise power supplies?

[lists]

Well the Tek current probe that goes in the power supply wasn't low cost. They 
also had a nice bench supply that went in the box. But a lot of the instruments 
weren't so fancy.
 
-Original Message-
From: Max Robinson m...@maxsmusicplace.com
Sender: time-nuts-boun...@febo.com
Date: Fri, 1 Feb 2013 13:39:14 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Low noise power supplies?

Well, I stand corrected.  Weren't the TM 500 instruments marketed as low 
cost?

Regards.

Max.  K 4 O DS.

Email: m...@maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
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- Original Message - 
From: David davidwh...@gmail.com
To: Discussion of precise time and frequency measurement 
time-nuts@febo.com
Sent: Thursday, January 31, 2013 11:10 PM
Subject: Re: [time-nuts] Low noise power supplies?


I have seen it used in a couple of Tektronix TM500 instruments but the
 purpose may have been to generate a lower voltage power supply rail
 instead of noise reduction.  Tektronix often added LC sections on
 their switching power supply outputs and distributed smaller LC
 sections to prevent coupling between different circuits.

 On Thu, 31 Jan 2013 22:12:42 -0600, Max Robinson
 m...@maxsmusicplace.com wrote:

You haven't seen it used because it doesn't work very well.  It appeared 
in
a few pieces of Heathkit equipment but I don't think HP or Tek used it at
all.  Any AC component of base to collector voltage has a small but 
definite
effect on Vbe which transfers voltage in the reverse direction from
collector to emitter even though the base is held at AC ground.  A three
terminal regulator does a better job of suppressing ripple from a power
supply.

Regulators use a zener diode as the reference and there are circuits in
which a zener is used as a noise source.  What does that tell you?  The
quietest power supply is an analog regulator followed by one or more RC
filter sections.  The inductor in an LC filter is likely to pick up more 
hum
and noise than it filters out.  My presumption is that a low noise power
supply is likely to be providing a small amount of power to the load and
load regulation is probably not a problem.
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Re: [time-nuts] OT, looking for a good science forum

[lists]

If the intent is surface mount work, get an old BL Stereozoom 3. I'd suggest 
getting one with any attached illuminator, even a broken one, since the fitting 
to hold the illuminator is about $30. Later model stereozooms had plastic parts 
in the focus mechanism.  If you need more magnification, you can always get 
stronger occulars.

-Original Message-
From: J. Forster j...@quikus.com
Sender: time-nuts-boun...@febo.com
Date: Sat, 26 Jan 2013 09:04:59 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: j...@quikus.com, Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] OT, looking for a good science forum

For microscopes and all related topics, the Yahoo Microscope Group is very
knowledgeable. It has over 3500 members now.

-John

=



 This is by definition Off Topic

 I'm looking for a forum where people are about as technically
 competent as here but where an amateur scientist can ask questions
 like

 1) What is a cost effective way to measure temperatures at around -80C
 (about the temperature of dry ice)  Thermocouples, NTC thermisters?
 2) Is brand X microscope as good as brand Y, they look identical to me.

 All I'm finding is either places that cover science news or some
 forum filled with nonsense about cloning dinosaurs and time travel.

 --

 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] OT, looking for a good science forum

[lists]

Eh, I'd spend the extra $200 and get a BL unless you don't expect to use it 
much. At around $300, you would get a Stereozoom 3, heavy table and long arm. 
The Stereozoom dates back to the days they built magnetic RAM. It is designed 
for all day use. The working distance is kind of important if you expect to 
work on a PCB, since they are 3D. 

But maybe the Chinese stuff would work for occasional use. However, the BL can 
go in your will!


--Original Message--
From: Chris Albertson
To: li...@lazygranch.com
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT, looking for a good science forum
Sent: Jan 26, 2013 1:36 PM

On Sat, Jan 26, 2013 at 10:00 AM,  li...@lazygranch.com wrote:
 If the intent is surface mount work, get an old BL Stereozoom 3. I'd suggest 
 getting one with any attached illuminator, even a broken one, since the 
 fitting to hold the illuminator is about $30. Later model stereozooms had 
 plastic parts in the focus mechanism.  If you need more magnification, you 
 can always get stronger

This is really OT for the TN list.  But no.  I'm looking to equip a
biology lab.  Need a compound microscope that has on the high side a
1000x magnification.  Pretty much your Standard university lab
microscope that all freshmen bio students would use.  These are a
little hard to know what's best to get

But I think in addition I want a stereo microscope too.   There are
decent new ones from China for under $100 and older ones like you
mentioned for about the same price.   New ones are attractive because
of advances like battery powered LED illumination.  This kind of
microscope is pretty easy to find compared to the other.
-- 

Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Lady Heather survey accuracy

[lists]

If you go onto alt.sci.satellite-nav, there are many technical threads about 
why averaging GPS position readings has its limitations. It isn't like 
averaging an electronic measurrment where you are filtering random noise. Or 
maybe it is like an electronic measurement where you have to deal with drift.



-Original Message-
From: John Nelson honey...@outlook.com
Sender: time-nuts-boun...@febo.com
Date: Thu, 24 Jan 2013 16:13:36 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Lady Heather survey accuracy

I hesitate to ask this question on here since it's perhaps more one for
position-nuts rather than time-nuts. My excuse is that it involves a
Thunderbolt ;-) 

I've been a happy user of a Thunderbolt for a while as an accurate time and
frequency source but until recently I hadn't got round to mounting it in a
proper enclosure with its PSU and finding a permanent home for the result in
the office. Having done so I asked Lady Heather to carry out a 48h
'precision survey' and got a result which although close to that done when I
first acquired the unit was about 10m different. I then carried out two
further surveys which gave similar disparate results.  

LH reports latitude and longitude results to eight decimal places, which in
principle suggests centimetre accuracy. I don't know enough about the finer
points of GPS to know whether this is actually achievable over a 48h period
but the results I'm seeing suggest that it's not.  

So the question amounts to this -- how reliable is the position produced by
LH after a 48h 'precision survey' and what level of accuracy is achievable
in practice? I'm guessing it's more like four places of decimals than eight.


John

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Re: [time-nuts] Better gps antennas than a Symmetricom 58532A

[lists]

For a single frequency use like GPS, the impedance should be close to the 
target. It is true for scanners and such, 50 ohms is quite nominal. (This 
notion of DC to daylight and maintaining 50 ohms is fantasy. ) But for a GPS, 
you know exactly the application. 

The loading could effect the antenna pattern if it were not for the preamp.
-Original Message-
From: Jim Lux jim...@earthlink.net
Sender: time-nuts-boun...@febo.com
Date: Wed, 23 Jan 2013 06:07:49 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Better gps antennas than a Symmetricom 58532A

On 1/23/13 12:41 AM, Hal Murray wrote:

 mspencer12...@yahoo.ca said:
 This URL goes into some of the issues involved in using 75 ohm coax in a gps
 system.  I do acknowledge that several GPS manufacturers have promoted the
 use of 75 ohm coax so some of the conclusions might be arguable..

 If the coax is short, the loss due to mismatch dominates.  If the coax is
 long, the attenuation per X meters will dominate.

And it's not clear that there's actually loss due to mismatch.  Most 
antennas/preamps/receivers don't have exactly 50 ohm impedances.  75/50 
is only 1.5:1, and there's an awful lot of antennas and receivers out 
there that only claim 2:1 VSWR.  The usual spec for the antenna is 
1.5:1, so for all you know the Antenna and Receiver is already 75 ohms, 
and RG6 will give you a better match than 50 ohm LMR400.



probably a bigger issue *might* be that reflections will create 
synthetic multipath from the signal reflecting back and forth in the cable.


 There should be a crossover length  What is it for 50 ohm RG-58 and 75 ohm
 RG-6?


 If you are designing your own antenna, you have the option of making one that
 matches 75 ohm rather than 50.





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Re: [time-nuts] Better gps antennas than a Symmetricom 58532A

[lists]

I doubt the impedance would be designed so nobody gets a right match. Anyway, 
the geometric mean, which is how you would do such a compromise is 61.24 ohms.


-Original Message-
From: Jim Lux jim...@earthlink.net
Sender: time-nuts-boun...@febo.com
Date: Wed, 23 Jan 2013 20:50:00 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Better gps antennas than a Symmetricom 58532A

On 1/23/13 7:26 AM, li...@lazygranch.com wrote:
 For a single frequency use like GPS, the impedance should be close to the 
 target. It is true for scanners and such, 50 ohms is quite nominal. (This 
 notion of DC to daylight and maintaining 50 ohms is fantasy. ) But for a GPS, 
 you know exactly the application.


You assume that the antenna designer actually tried to hit a particular 
Z.  They may have been going for about 60 ohms which would be about 
1.2:1 for both 50 and 75 ohms.  Or, they were more worried about 
optimizing the pattern or axial ratio, and the Z could be good enough.

I've got a SWR plot from a passive L1/L2 antenna here (specified as 
better than 1.5:1) and it varies somewhat randomly with no apparent 
pattern between 1.5:1 and 1.1:1, and is about 1.3:1 at L1.  Another 
antenna (same mfr, same model, slightly different installation and 
cable) ripples between 1.45:1 and 1.05:1, mostly oscillating around 
1.2:1. At L1 it's about 1.1:1

It meets the spec everywhere.

 The loading could effect the antenna pattern if it were not for the preamp.

It is unlikely that the impedance presented at the feedpoint of an 
single feed antenna will change the pattern, particularly for something 
low gain like a GPS. That is, there's no physical way it could affect 
it.  The pattern is determined by the currents distributed around the 
physical antenna, and they have a fixed (complex) ratio to the current 
at the feedpoint. all an impedance change would do is change that 
current, but then everything changes together and the pattern is unchanged.



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Re: [time-nuts] Raspberry Pi Competition...

[lists]

It is hard to say which Arm is best for time nuts. The Cortex-A8 is  what the 
Beagleboard XM uses. That CPU has neon, which is Arm's version of MMX. That 
is, not fully kosher floating point, but fast parallel processing good enough 
for DSP. The Raspberry Pie uses a fancier GPU and a simpler CPU (no DSP in the 
CPU). If you are compiling your own code with gcc, there are many options 
specific to the neon architecture. (It is on the TI website.) I've been doing 
some SDR on the Beagleboard XM, and the difference can be a factor of 3 in CPU 
utilization.


--Original Message--
From: Rob Kimberley
Sender: time-nuts-boun...@febo.com
To: 'Discussion of precise time and frequency measurement'
ReplyTo: Discussion of precise time and frequency measurement
Subject: [time-nuts] Raspberry Pi Competition...
Sent: Jan 21, 2013 7:26 AM

http://www.electronicsweekly.com/Articles/28/09/2012/54676/raspberry-pi-gets
-a-competitor.htm

Rob K



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Re: [time-nuts] Better gps antennas than a Symmetricom 58532A

[lists]

There was a thread on RF absorbing material a few months ago to get rid of 
reflections.. That might be a way to spend spme money. I'd like to see before 
and after results.
-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Mon, 21 Jan 2013 09:20:44 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Better gps antennas than a Symmetricom 58532A

I'd say that if you have some extra money to spend, first spend it of
improving the antenna's location.  Unless it already is on top of a tall
mast with a clear view of the horizon and far from any radio reflectors.
 The Heliax will only do good if the length of the run is long.

Another good use of excess funds is to improve the ground system.  Do you
have a #8 wire going from the mast to a ground rod using the most direct
route and is this rod tied to the building ground system?




On Mon, Jan 21, 2013 at 9:01 AM, Mark Spencer mspencer12...@yahoo.cawrote:

 Greetings:

 I'm contemplating upgrading my GPS antenna.   Does anyone have any
 suggestions for an antenna that would be significantly better than a
 Symmetricom 58532A for typical time nuts applications.  (As a side note if
 I upgrade the antenna I will also upgrade the feed line to LMR style cable
 or Heliax.)  At this point I don't envision owning any receivers that would
 use bands other than L1.

 Immunity to other transmitters is also a consideration for me, and this
 may push me towards staying with the 58532A.

 Regards
 Mark Spencer
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Better gps antennas than a Symmetricom 58532A

[lists]

It is possible that the noise figure of the preamp is better than that of the 
gps. This is especially true if the GPS predates SiGe parts being common place.

I never ran any heliax, but isn't the idea also that it will last longer than 
coax.

-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Mon, 21 Jan 2013 20:19:47 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Better gps antennas than a Symmetricom 58532A

On Mon, Jan 21, 2013 at 6:59 PM, Hal Murray hmur...@megapathdsl.net wrote:


 albertson.ch...@gmail.com said:
   The Heliax will only do good if the length of the run is long.

 I don't understand that.  What does the type of antenna have to do with the
 length of the run?


You are confusing heliax with helix.The latter is an antenna type
the former is a way to build coax cable with a hard copper later in place
of the coper braid.

For most normal cable runs of say 20 to 40 feet using exotic cable is not
just ified be cause the difference in signal strength is only a dB or two
but if you are building a tall microwave tower where the equipment room is
100+ feet from the antenna then the losses add up and things like Haliax
might be worth it.

Yes you could use an amplifier and cheaper cable, most everyione facing a
longer run would do that.  It works.  But in theory amplifiers always add
some noise so in theory if you can sawp out and amplifier of some big-bucks
cable you migh gain something.   But at short distances it is moot because
there is nothing to gain.This is why I said it only makes sense for
longer runs where cable loss matters

Of course the cheaper way to deal with cable loss is to move the GPS
receiver.  Maybe place it in the attic right under where the antenna cable
comes through the roof?


-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] YIG oscillators

[lists]

If you need that mixer for a LNBF, I believe that is close to the international 
C-band. Google around for a Norsat that ends in I. They use it in India.

-Original Message-
From: Lizeth Norman normanliz...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Fri, 4 Jan 2013 14:12:55 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] YIG oscillators

Double balanced mixer!  Sorry for the silly overuse of abbreviations..
Norm

On Fri, Jan 4, 2013 at 2:10 PM, gary li...@lazygranch.com wrote:
 dbm?



 On 1/4/2013 9:45 AM, Lizeth Norman wrote:


 I've actually purchased several of these with the thought of using
 them to drive the LO port of a dbm so that I can rx at 5.84GHz (as
 well as some other freq's)


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Re: [time-nuts] noisy varactor diodes

[lists]

Paralleling devices reduces noise. Why do you think otherwise? Noise will be 
reduced by the square root of the number of devices you parallel.

-Original Message-
From: cdel...@juno.com
Sender: time-nuts-boun...@febo.com
Date: Wed, 19 Dec 2012 14:43:02 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] noisy varactor diodes

The HP sceme in the patent refers to an array of series and parallel
diodes to reduce noise.

Just paralleling them does not reduce the noise!

The 4 paralleled in the 5065  are to give enough phase deviation for the
low modulation level applied.  (150mv)

The symptom was a fluctuating 2nd harmonic meter reading and coresponding
fluctuations at the A7 TP2 test point.

John I could not see the info you refered to?

Corby

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Re: [time-nuts] noisy varactor diodes

[lists]

But putting the diodes in series should increase the noise. They are 
noncorrelated, so I would say increase the noise in a RMS fashion. 

HP has made at least one radio with switched varactors in the prefilter. They 
made a SIGINT rack for I presume three letter agencies, though it was in the 
catalog in the 80s IIRC. The radio was offered to me from a destruct house that 
wasn't clear on the definition of destruction. It was even GPIB.



-Original Message-
From: John Miles jmi...@pop.net
Sender: time-nuts-boun...@febo.com
Date: Wed, 19 Dec 2012 15:37:29 
To: 'Discussion of precise time and frequency measurement'time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] noisy varactor diodes

 The HP sceme in the patent refers to an array of series and parallel
 diodes to reduce noise.
 
 Just paralleling them does not reduce the noise!

Still, the patent claims seem pretty obvious.  Paralleling n diodes would
reduce their noise contribution by the usual 3 dB * log2(n) factor, but
would also multiply their max/min capacitance ratings by n... which in turn
can be restored to the original value by putting n blocks in series.  Yes, I
can totally see where HP is entitled to a government-enforced monopoly on
this valuable intellectual property.  We wouldn't want to discourage
innovation, would we? :-P

In practice, low-noise synthesizers made with bulk LC components often use
banks of parallel varactors, but they maintain the necessary tuning range by
switching between multiple inductors.  I'm sure that particular stroke of
genius was patented by someone as well...
 
 The 4 paralleled in the 5065  are to give enough phase deviation for the
 low modulation level applied.  (150mv)
 
 The symptom was a fluctuating 2nd harmonic meter reading and
 coresponding
 fluctuations at the A7 TP2 test point.

I see.  That symptom isn't one that I've been observing.

 John I could not see the info you refered to?

Here's a direct link to the attachment:
http://www.ke5fx.com/5065a.png

-- john
Miles Design LLC


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Re: [time-nuts] Cell timing error

[lists]

I can assure you the GSM shacks have GPS timing in them. I can dig up the 
photos if you want.

-Original Message-
From: Joseph Orsak jor...@nc.rr.com
Sender: time-nuts-boun...@febo.com
Date: Sat, 15 Dec 2012 18:24:20 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Cell timing error

ATT uses UMTS in most areas which is a self-synchronizing modulation 
scheme. Supposedly one of the selling points is no dependence on GPS. All 
the extra sync channels and sync messaging is a capacity hog, not a very 
spectrally efficient standard in my opinion.

About 85 maximum simultaneous voice calls in a 5Mhz UL / 5 Mhz DL 
sector/carrier before it starts to fall apart. A big step backwards from 
good old CDMA2000 (also just my opinion).

But hey, you can surf the web while you talk on the same device.



-Joe W4WN


- Original Message - 
From: Jim Lux jim...@earthlink.net
To: Discussion of precise time and frequency measurement 
time-nuts@febo.com
Sent: Saturday, December 15, 2012 5:43 PM
Subject: Re: [time-nuts] Cell timing error


 On 12/15/12 2:16 PM, Scott McGrath wrote:
 In a prior life we had a CDMA timing receiver for NTP which used VZ for 
 its source

 On Dec 15, 2012, at 12:18 PM, Graham / KE9H time...@austin.rr.com 
 wrote:

 You should switch to Verizon.
 They are inherently accurate to milliseconds.
 Sub micro-seconds inside the base stations.


 On 12/15/2012 12:51 PM, Greg Troxel wrote:
 In central mass, ATT and tracfone (? carrier) are showing phone times 
 very close to 1 min slow.  Virgin/sprint is ok.   I've never seen this 
 before - usually it's a few s slow.



 The time *displayed* on the phone might not reflect the time from the 
 network.

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Re: [time-nuts] Fw: Cell timing error

[lists]

Yeah, the TruePosition website is quite interesting. It seems they do a bit 
more than 911 service. ;-) 

Feel free to change the #3 in the file name to whatever for more shots of the 
interior. 


-Original Message-
From: Dennis Ferguson dennis.c.fergu...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Sat, 15 Dec 2012 22:58:39 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Fw:  Cell timing error


On 15 Dec, 2012, at 21:30 , gary li...@lazygranch.com wrote:
 This is a shot of the GPS timing rack in an ATT shack.
 http://www.lazygranch.com/images/att/att_3.jpg

Yes, the TruePosition box helps compute handset locations for
E911 and whomever else wants to know where your phone is.  This
isn't a unit you would necessarily see in cell closets in other
countries.

Dennis Ferguson

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Re: [time-nuts] Comparing PPS from 2 GPS units

[lists]

They make frequency difference meters. I never used one, but it seems to me a 
frequency difference meter would just use the two input signals to toggle up 
and down respectively on a counter, then display the result over a fixed period.

Would this do what you want?

--Original Message--
From: Hal Murray
Sender: time-nuts-boun...@febo.com
To: time-nuts@febo.com
ReplyTo: Discussion of precise time and frequency measurement
Subject: [time-nuts] Comparing PPS from 2 GPS units
Sent: Dec 13, 2012 1:57 AM


Suppose I want to compare the PPS outputs of 2 GPS units.  The problem is 
that I don't know which one will happen first.

If I feed them into the start/stop inputs of a typical timer/freq box, I 
don't know which is which.  If I get them wrong, the answer will be 
0.99xx seconds rather than the -0.00xx that I want.

Is there a simple solution for this?

My straw man is to use the antenna cable delay setting to offset one of the 
PPS pulses a long way.

Plan B would be a physical delay unit.  But they are probably temperature 
sensitive, and I'm not setup to keep anything at a constant temperature.

Do any of the counter/timer boxes have a mode for this?  If so, is there a 
buzzword I've overlooked?


-- 
These are my opinions.  I hate spam.




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Re: [time-nuts] B-1B bomber time reference

[lists]

They routinely redact stuff in the awards. Usually the names of the individuals 
that picked the vendor. It is a silly game since you can and do FOIA much of 
the redacted information if you lost the bid. 

Some of the crypto comm schemes need time of day to work. Usually the pilot 
will say give me a Micky, as in (I guess) a Micky Mouse watch. Then a chirp 
goes out over the UHF radio system. But I always assumed they had a GPS time 
reference since talking on UHF radio isn't too stealthy.


-Original Message-
From: Peter Bell bell.pe...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Fri, 14 Dec 2012 10:57:16 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] B-1B bomber time reference

It's quite amusing that they decided to redact the quantity and unit price
from the sole source letter - but the other document says we are going to
buy 14 of these - sort of makes you wonder why they bothered...



On Fri, Dec 14, 2012 at 9:26 AM, gary li...@lazygranch.com wrote:

 If you are curious about how the B-1B bomber sets its time reference, go to
 www.fbo.gov
 and search for
 F1S0AF2321B001
 in the box next to keyword.

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Re: [time-nuts] 31bit ADC, 1000 samples per second

[lists]

It is 31 bits with no missing codes. Usually missing codes is of concern in 
feedback systems, but I don't see the use in a geophone. Perhaps they will 
average the digital signal further to reduce the noise, hence the noisy bits.



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Re: [time-nuts] 31bit ADC, 1000 samples per second

[lists]

Regarding feedback loops, I had a brain fart. I mean monotonic and no missing 
codes, not no missing codes in general.

I think it was Fluke or Analog that had a small booklet on understanding data 
converter specifications. 





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Re: [time-nuts] Switching oscillators

[lists]

You would probably want to see when the external oscillator frequency is close 
to the internal oscillator. I suppose than could be done with a mixer and glue 
circuitry. I don't think this is cheap though. 
 

-Original Message-
From: Joseph Gray jg...@zianet.com
Sender: time-nuts-boun...@febo.com
Date: Sun, 9 Dec 2012 14:12:51 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Switching oscillators

I have a device that has an internal TCXO. I want to feed it with an
external OCXO, but I don't want to completely replace the TCXO.

Here is the scenario. On initial power on, or after a power loss, I
want the internal TCXO to be used. Once the OCXO is up, I want to
switch to it. How could this be done easily and cheaply?

Joe Gray
W5JG

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Re: [time-nuts] Switching oscillators

[lists]

I don't know if this makes things easier or not, but the act of sampling itself 
is like a mixer. If you sample one clock with the other, it would produce a 
beat frequency. Sampling here just means a strobing a D flip flop. The output 
will be low frequency, so the error could be measured with a uP.

This is just a variant on the decimation demodulators that were used before 
DSPs were powerful.
 



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Re: [time-nuts] UK: GPS Jamming Notices

[lists]

Relative to the last notice, a CW jammer would be at a single frequency, so it 
seems odd they specify a band. Perhaps a CW anywhere in that band.

I talked to the USAF about their jamming, and they use white noise over the 
band. A certain COTS Marconi (IIRC) signal generator produces the band limited 
noise and puts it on the carrier. 

-Original Message-
From: David J Taylor david-tay...@blueyonder.co.uk
Sender: time-nuts-boun...@febo.com
Date: Mon, 3 Dec 2012 12:16:12 
To: Time-nuts mailing listtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] UK: GPS Jamming Notices

I have received the three following notices:


NOTIFICATION OF GPS JAMMING EXERCISES STANFORD TRAINING AREA, EAST ANGLIA, 
FEBRUARY 2013

Dates: Between 11 and 15 February 2013.
Times: 0900 -1600 GMT.
Location of MULTIPLE jammers: Land based within 5km of N52° 29.0’ E000° 45.0’.
Frequency: A 24 MHz band centred around 1575.42MHz (GPS L1).
Total Power: Up to 10 Watts EIRP.
It is stressed that, as in previous exercises, Safety of Life operations 
will at all times take precedence over exercise activities.





NOTIFICATION OF GPS JAMMING EXERCISES OFF THE COAST OF EAST ANGLIA, 
FEBRUARY/MARCH 2013

Dates: 25 to 26 February and 28 February to 1 March 2013.
Times: Intermittently for a 90 minute period in each time slot 0930-1200 GMT 
and 1400-1630 GMT.
Location of jammers: Sea based omni-directional jammer onboard a vessel 
sailing within the Experimental Buoys area, as charted, but no further North 
than 51°55’N in the area bound by following boundary positions (WGS84):
* 51.916667°N 1.453745°E  (51° 55.0’N  1°27.2’E)
* 51.883980°N 1.445504°E  (51° 53.0’N  1°26.7’E)
* 51.883607°N 1.397795°E  (51° 53.0’N  1°23.9’E)
* 51.916667°N 1.421994°E  (51° 55.0’N  1°25.3’E)
Frequency: 24 MHz bands centred around 1575.42MHz.
Total Power: 0.0005 Watts ERP maximum so as not to effect vessels outside 
the area bounded by the co-ordinates above or aircraft flying above 2500ft.
It is stressed that, as in previous exercises, Safety of Life operations 
will at all times take precedence over exercise activities.





NOTIFICATION OF GPS JAMMING EXERCISES RAF SCULTHORPE AIRFIELD, EAST ANGLIA, 
MARCH 2013

Dates:   25th and 29th March 2013.
Times: 0700 -1700 BST.
Location of SINGLE jammer: Land based within 2km of 52° 50′ 54″ N, 0° 45′ 
38″ E
Frequency: A 20 MHz band centred around 1575.42MHz (GPS L1).
Power: Up to 0.3 Watts EIRP (300mW).
Jammers: Omni-directional jammers radiating CW.
It is stressed that, Safety of Life operations will at all times take 
precedence over exercise activities.



David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 


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Re: [time-nuts] Time security musing - attacking the clock itself

[lists]

Or you just hack the SCADA. Far nastier.



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Re: [time-nuts] Time security musing - attacking the clock itself

[lists]

I have one of those key fobs. Does the code somehow inform the power the be 
about the drift in the built in clock? Or is the time element of the code so 
sloppy that the drift is acceptable?


-Original Message-
From: Jim Lux jim...@earthlink.net
Sender: time-nuts-boun...@febo.com
Date: Mon, 03 Dec 2012 15:45:24 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Time security musing - attacking the clock itself

On 12/3/12 9:32 AM, dlewis6767 wrote:
 I agree, Bob.

 Like the billboard on the side of the highway says: - Does Advertising
 Work? JUST DID -

 The bad guys can read this list same as the good guys.



Security through obscurity never works in the long run.  Much better to 
discuss vulnerabilities in the open, and discuss countermeasures that 
are robust.


Clock synchronization is of great interest in a variety of crypto 
systems where keys are changed on a predetermined schedule (the RSA two 
factor authentication key fob is an interesting instance).

It's even trickier when you have to distribute time in a secure way 
(in the sense that not only is the at the tone, the time is message is 
reliable, but also that the timing of the tone is reliable).

The various redundancy and reasonableness checks (e.g. for GPS) are in 
this area as well.

The question is: Can I distribute timing information through a network 
reliably


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Re: [time-nuts] GPS antenna in attic?

[lists]

If you were going to add a pipe for coax purpose, wouldn't you want something 
like the electrical service inlet? They have a bit of a hook on the top to 
reduce water penetration.



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Re: [time-nuts] Warning if buying from directly from Agilent via eBay with Paypal.

[lists]

I'm just amazed Aligent doesn't take credit cards directly. Paypal is for small 
time players.



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Re: [time-nuts] Is it sensible to update every few seconds from NTP server?

[lists]

Based on a sample of one (my NTP), I can hold the clock frequency to 0.1PPM. 
Seems to me you could compute the adjustment requirements from such a number.

 
-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Wed, 7 Nov 2012 15:02:41 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Is it sensible to update every few seconds from NTP
server?

Sure enough every 4 seconds would work, as would every 2 seconds.  But I
bet every 1000 seconds would work as well.

We need some more details but it seem he has something badly misconfigured
if 4 seconds updates are required.

On Wed, Nov 7, 2012 at 1:41 PM, David Kirkby david.kir...@onetel.netwrote:

 Someone at my radio club uses some mode of operation where accurate
 time is required. He said the standard Windoze clock does not keep
 sufficiently accurate, so he has software which updates from an NTP
 server every 4 seconds or so.




-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] For my whole life timezones have been weird

[lists]

Microsoft also does updates regarding the day daylight savings time changes, 
similar to that Apple message.

I suspect I'm not following this thread correctly. What I got from the orignal 
thread is Microsoft will thunk the RTC during the switchover. I'm going to 
make it a point to insure NTP is logging correctly, and then look for a time 
error at the switch over. (2AM I think.)

-Original Message-
From: Edgardo Molina xe1...@amsat.org
Sender: time-nuts-boun...@febo.com
Date: Sat, 3 Nov 2012 02:02:47 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] For my whole life timezones have been weird

Dear Sarah,

Good morning. I just returned home from a long and difficult customer data 
center migration. I thought of sharing that I feel the same way as you do 
regarding your thread. Things should always behave like a Mac or Linux, in 
which if there is a glitch, the OS responsible party jumps into scene with a 
solution. Not the way it happens and builds your frustration with Windows.

Food for thought, just an example of someone supporting their OS user base on a 
similar topic. To err is human, to fix the errors should also be: 
http://support.apple.com/kb/TA24568?viewlocale=en_US

Cheers,



Edgardo Molina
Dirección IPTEL

www.iptel.net.mx

T : 55 55 55202444
M : 04455 20501854

Piensa en Bits SA de CV



Información anexa:




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este mensaje, le suplicamos se lo notifique al remitente mediante un correo 
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retener una copia de los mismos. Queda estrictamente prohibido copiar este 
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NON-DISCLOSURE OF INFORMATION

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On Nov 2, 2012, at 11:32 PM, Sarah White kuze...@gmail.com wrote:

 So, at or around 1981 (the year I was born) there was a cool concept.
 IBM was selling personal computers (IBM-PC compatible later became a
 thing) and by the time I was old enough to operate a modem, I had one
 myself. Life was good.
 
 Wonder if there is any sensible way to petition microsoft to fix this
 stupid mistake dating back to the DOS era. Windows 8 / metro is out now,
 and I can't bloody stand the changes. Would be nice if windows 7 had an
 update to fix this issue:
 
 http://support.microsoft.com/kb/2687252
 
 Article ID: 2687252 - Last Review: March 13, 2012 - Revision: 4.0
 
 APPLIES TO
 Microsoft Windows XP Home Edition
 Microsoft Windows XP Professional
 Microsoft Windows XP Service Pack 3
 Windows Vista Business
 Windows Vista Enterprise
 Windows Vista Home Premium
 Windows Vista Ultimate
 Windows Vista Service Pack 1
 Windows Vista Service Pack 2
 Windows 7 Enterprise
 Windows 7 Home Basic
 Windows 7 Home Premium
 Windows 7 Professional
 Windows 7 Ultimate
 Windows 7 Service Pack 1
 Windows Server 2008 Datacenter
 Windows Server 2008 Enterprise
 Windows Server 2008 Standard
 Windows Server 2008 Service Pack 2
 Windows Server 2008 R2 Datacenter
 Windows Server 2008 R2 Enterprise
 Windows Server 2008 R2 Standard
 Windows Server 2008 R2 Service Pack 1
 Microsoft Windows Server 2003 Service Pack 2
 
 ... Pretty sure that's 100% of all recent versions of windows. The whole
 thing started because windows 3.1 / 95 / 98 / 2000 / ME / etc. etc. etc.
 were all targeted with being backward compatible with the previous OS
 leading all the way back to DOS (first versions of DOS were coming out
 in 1981 the year I was born)
 
 For where I live, this weekend is the change your clocks for the
 fall... or don't, or do something else... petition microsoft maybe?
 
 I'd love for windows 7 to have a fix for this since I'm not upgrading to
 the horrible looking windows 8 --- windows 7 will be in extended support
 until 2020 (( reference: http://goo.gl/unxvj )) so I figure let's try to
 get them to fix it in the next few years. I'm serious about this.
 
 Let's fix this timezone problem!!!
 
 Pretty much every other operating system vendor out there (various POSIX
 platforms including more than one version of BSD, linux and even mac OSX
 since under the hood it is a POSIX based operating system) it is an
 option to leave the hardeware real-time-clock (bios clock) on UTC.
 
 Ok that's all I'm typing on this.
 
 Angry at several of my clocks today,
 Sarah White
 
 ___
 

Re: [time-nuts] Sulzer 5A 5P PSU/battery question

[lists]

It has been my experience with nicad and NiMH, the higher the cell capacity, 
the shorter the battery life. Not for cycles, but in terms of years.

I designed a charger chip for bridging applications. Bridging batteries are 
used to maintain a system while you swap battery packs. The batteries used in a 
bridging scheme have poor volumetric energy density. (Capacity based on 
volume.) These bridging batteries come equipped with leads, that is they are 
intended to last the life of the device.

My gut feeling is if you want nicad or NiMH batteries that last a long time, go 
for batteries designed for fast charging like those used in remote control 
cars. 

Stating the obvious, but just in case, any pack you roll yourself should use 
batteries with tabs on them. Never solder directly to a battery. If the battery 
doesn't come with tabs attached, you need to get them from a battery house with 
electroweld capability.
 
I've use TNR Technical for battery pack construction. But I wouldn't rule out 
other vendors. This isn't exactly rocket science unless you need to mount a 
thermistor in the pack. 
-Original Message-
From: paul swed paulsw...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Thu, 1 Nov 2012 17:21:11 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Sulzer 5A  5P PSU/battery question

Nimh is indeed the answer to replacing nicads but they are not inexpensive.
The other thing is that the energy densities have gone up over the years so
you can use a smaller footprint. But you have to check the charge rates.
Typically .1c for slow.

I have old nicads from HP that indeed still work pretty well after 30
years. The modern batteries will last 5. Could be lots of reasons. But
thats what I see. Whatever you do, don't buy nicads they are still sold.
Issue is they have been on the shelf for a long time and are a waste of
money.
Regards
Paul

On Thu, Nov 1, 2012 at 5:11 PM, Tom Knox act...@hotmail.com wrote:


 Hi Magnus;
 I have looked several times for an article that explains charging
 perimeters for the various types of batteries on the market.  So many freq
 standards have outdated battery technology. It would be nice to find an
 modern alternative battery that does not require much modification to the
 charge circuit.
 Best Wishes;
 Thomas Knox



  Date: Thu, 1 Nov 2012 21:51:21 +0100
  From: mag...@rubidium.dyndns.org
  To: time-nuts@febo.com
  Subject: [time-nuts] Sulzer 5A  5P PSU/battery question
 
  Fellow time-nuts,
 
  Yesterday I picked up a Sulzer 5A + 5P without batteries. It is supposed
  to have 21 D-cell NiCd batteries, but today those are not easy to come
  by, so I wonder if I can either run the PSU safely without battery or if
  I can swap in lead-batteries.
 
  I know that some of you have these, so I would value your input.
 
  I did try to run it a short time without batteries, but the 5 MHz output
  did not work very well, so I turned it off.
 
  Cheers,
  Magnus
 
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Re: [time-nuts] Timing performance of servers

[lists]

The GPS seeing the horizon isn't required. Those satellites are filtered out by 
software. The timing GPSs are designed to be less sensitive to the horizon.


-Original Message-
From: Chris Albertson albertson.ch...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Thu, 25 Oct 2012 10:04:43 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Timing performance of servers

On Thu, Oct 25, 2012 at 9:44 AM, Sarah White kuze...@gmail.com wrote:

 Regardless of if I run linux vs bsd vs windows (will be testing multiple
 configurations of each, and doing writeups over the next few years as I
 test more and learn) I'll need a good external antenna for the new GPS
 I'm going to run.

 Anyone think I can get by with anything cheaper than a symmetricom
 58532a antenna? I can probably get one (used) for less than $50 on ebay,
 but I'd really prefer to source something more entry-level for closer to
 $5 or $10 if possible. Any suggestions?

Chris Albertson
Redondo Beach, California

Location matters a LOT more than the brand of antenna.

In an ideal world a GPS antenna needs to see all the way to the
horizon in all directions AND it needs to be far way from reflective
objects that can cause multi path.   Some times moving a foot or
some is enough for an improvement.

You will notice that the best timing mode antenna come inside
enclosures made to shed water and snow.  They are pointy or round on
top.   You don't need this feature if the antenna is looking out a
window.  In fact the small patch type antenna might be able to be
place close to a window and get a better view of the sky.

All that said.  These are good and not expensive.  ebay #270881742870
I have one of these on a mast and the cable fits inside the pipe/mast.
the patch antenna is cheaper see #290739284641

One thing to watch is the kind of connectors.  You don't want to have
to use a chain of adaptors, N to F to BNC.   Those can cost $5 each
and certinly do not help the signal.  For outdoors I like N type as
they are 100% water proof.   Some types of F are too but not all of
them.

Watch that you get a 5V volt antenna (unless you really want a 3.5
volt type) and get a co-axial type cable.  Some have odd-ball
multi-pin cables

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Re: [time-nuts] Timing performance of servers

[lists]

The 20 degree cutoff is what I recall the starloc uses as a default. Now I 
don't know how important it is to filter those out by the response pattern of 
the antenna versus by software.  

-Original Message-
From: Rob Kimberley robkimber...@btinternet.com
Sender: time-nuts-boun...@febo.com
Date: Thu, 25 Oct 2012 20:24:58 
To: 'Discussion of precise time and frequency measurement'time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Timing performance of servers

We used to filter out anything 10 - 20 degs above the horizon when setting
up timing receivers. Typically there's a lot of noise down low (multipath
and tropo effects). As long as you've got plenty of SVs you don't need to go
way down to the horizon.

Rob Kimberley

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Albertson
Sent: 25 October 2012 20:09
To: li...@lazygranch.com; Discussion of precise time and frequency
measurement
Subject: Re: [time-nuts] Timing performance of servers

On Thu, Oct 25, 2012 at 11:02 AM,  li...@lazygranch.com wrote:
 The GPS seeing the horizon isn't required. Those satellites are filtered
out by software.

OK, technically it needs to see down to within 10 degrees of the
horizon.   But when you are choosing a location for the mast to the
horizon or withing 10 degrees of it looks pretty much the same.   I
don't want a huge tree of building due south of the antenna.  But for
timing all you really need is to see most of the sky.   It depends
on if you want it to work or work as well as it can.


Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Timing performance of servers

[lists]

Just a FYI here, using Dave's logging program, I found large errors in NTP when 
the antivirus did its thing. I don't know if it was due to CPU activity 
interfering with NTP or the cabinet heating up when the antivirus was running.
  
-Original Message-
From: David J Taylor david-tay...@blueyonder.co.uk
Sender: time-nuts-boun...@febo.com
Date: Thu, 25 Oct 2012 06:03:44 
To: Time-Nutstime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Timing performance of servers

Fellow time-nuts,

When spending time on a conference last week, I heard one interesting
comment that they lost data due to bad timing on their Windows servers.
[]
If you need better performance than that, you should use NTP (and then
download and install Meinbergs Windows-client for NTP).

Then again, I would point out that for this type of data, it would most
probably be better served on a Linux box.

What should be a nice wake-up call for them would be a summation of how
different strategies would give them clock precision of sufficient
grade. So, does anyone know of such measurements presented anywhere?
[]
Cheers,
Magnus


Magnus,

If it helps, I have my own measurements of the Meinberg NTP port and later 
versions running on Windows here:

  http://www.satsignal.eu/mrtg/performance_ntp.php

Strategy:
1  - have one FreeBSD (not Linux) server, although this is now not 
essential, but it's nice as a confirmation that the rest is working OK.

2 - Configure some Windows PCs as stratum-1 servers fed from GPS.  On the 
plots above, PCs Alta, Bacchus, Feenix and Stamsund are acting as stratum-1 
servers.  These all have serial port connections, and cover the OS range 
Windows 2000, XP, Win-7/32 and Win-7/64.  All are using the kernel-mode 
serial port driver patch developed by Dave Hart.  PC Pixie is the FreeBSD 
box.

3 - For the client PCs, use a fixed 32-second polling interval to the local 
stratum-1 servers, with Internet servers as a backup polled at 1024 seconds, 
resulting in a configuration file something like:

___
# Use drift file
driftfile C:\Tools\NTP\etc\ntp.drift

# Use specific local NTP servers
server 192.168.0.3iburstminpoll 5 maxpoll 5 prefer# Pixie
server 192.168.0.2iburstminpoll 5 maxpoll 5# Feenix
server 192.168.0.7iburstminpoll 5 maxpoll 5# Stamsund

# Use pool NTP servers
pool uk.pool.ntp.orgiburstminpoll 10
___


The client performance varies, with some of the best results being on a 
Windows-8 Wi-Fi connected PC which seems to have very good drivers (PC 
Bergen).  Jitter is 40 - 110 microseconds.  Windows XP also shows low 
jitter, but greater offset (within 250 microseconds).

Windows Vista was the worst performer I had, but that PC has now been 
retired.  There are discussions in progress at the moment about improving 
Windows-Vista and Windows-7 as a Windows time interval setting and reporting 
bug has been discovered, particularly affecting NTP.

Cheers,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 


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Re: [time-nuts] documentation for beginners

[lists]

A bit OT, no way OT, but I found Bev as useful as tits on a boar hog. 
Planeplotter was trying doing illegal memory acesses and Bev wouldn't provide a 
copy of the program with debugging enabled.

Worse yet, after paying for the program, my credit card got hacked all over 
France. 

Planeplotter is easily the worst software I ever bought. Yeah I tested it, but 
it didn't crash until all the features were enabled. Oh, and Bev keeps your 
money if the software works or not. Further, you can't sell your license since 
it would cost Bev a new sale. 

Now Planeplotter is timenut related since it requires accurate time from the 
host feeding a server. Dave's NTP analyser allowed me to get my timing as good 
as it could get.  


-Original Message-
From: David J Taylor david-tay...@blueyonder.co.uk
Sender: time-nuts-boun...@febo.com
Date: Sun, 21 Oct 2012 18:10:46 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] documentation for beginners

I started a small Wiki for the Plane Plotter program, using the free pbworks 
site:

  http://planeplotter.pbworks.com

The site is easy to use, and you can have multiple authors and as many 
readers as you like.  I could start a Wiki for Time Nuts, if you like, or 
anyone else could start one of course.

Cheers,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 


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Re: [time-nuts] Up And Running

[lists]

Looks good, but I would have gone for a different GPS antenna. The timing 
antennas are weather proof. I have a Marine grade GPS antenna, also weather 
proof, but the timing antennas are probably a little better since they have 
less response to GPS birds on the horizon. 
  
-Original Message-
From: George Race geo...@mrrace.com
Sender: time-nuts-boun...@febo.com
Date: Fri, 28 Sep 2012 10:53:25 
To: time-nuts@febo.com
Reply-To: geo...@mrrace.com,
Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Up And Running

Hello to all the Time-Nuts: 

 I Have been acquiring parts for a few weeks and finally have a
Thunderbolt-Trimble system up and running.

Though I would share a few pictures of what I did and how it looks now that
it is all together and working.

 

First, here is an overall look at what I have put together.

 

http://www.mrrace.com/TrimbleGPS/TrimbleParts.jpg

 

I had to use the attenuator to reduce the amplitude of the 10MHz signal from
the Trimble.  It was overdriving the Extron causing distortion in the output
waveform.  The 6db attenuator is just what was needed.

 

I was running on a temporary old GPS antenna mounted on the edge of my
garage roof for a while.  I ordered a Trimble antenna from China, took about
10 days to get here.  What a difference that made in the overall signal
strength and stability of the unit.

Here is a Lady Heather shot after running on the antenna over night.

 

http://www.mrrace.com/TrimbleGPS/MyLadyH.jpg

 

I am still having trouble knowing what all the indicators on the screen
mean, but it appears that everything is working.

Sure wish there was an index somewhere that told what each and every thing
on that screen means!

 

As I mentioned, the antenna arrived yesterday and I built a mount and
installed it yesterday afternoon.

Though you might like to see what I ended up doing.  We have a lot of rain,
snow, and ice here in Michigan, so I wanted to do something to protect the
antenna and connectors the best that I could from the elements.  First, here
is a picture of the antenna from China, along with the adaptor cable to get
it to an “F” connector to hook to my 50 foot RG6U cable with “F” connectors
on each end.

 

http://www.mrrace.com/TrimbleGPS/TrimbleAnt.jpg

 

Here is the mount that I built.  I am going to put it on my TV antenna mast
that is mounted on the house.  The 10 degree elevation pattern should see
open sky in all directions.

The mount is a piece of aluminum angle with a mast clamp on one end, the a
sealable tea container on the other.  The container is one of those push
button kitchen containers that has a very tight air seal when the button on
the lid is pressed in.  It really holds well, and you cannot remove the lid
when it is locked into place.  Also this configuration makes it really easy
to get to the antenna and connectors if necessary.  Just release the button
on the bottom and lift off the unit.  The “F” barrel connector through the
side of the container makes it easy to just unscrew the cable if necessary.
The seal on the container is about ¾ of an inch wide, and really holds on to
the inside of the container.

 

http://www.mrrace.com/TrimbleGPS/BuildingTheMount.jpg

 

To hold the GPS antenna in place at the top of the container, I cut a small
aluminum plate, carefully drilled 3 holes for 2-56 hardware through the top
of the container, using the aluminum plate as a template.  The antenna is
“clamped” into place by bolting the plate up against the bottom of the
antenna, inside of the container.  You can see from the next picture how the
cable connectors and antenna wire is coiled up in the bottom of the
container, and terminates on the “F” barrel connector inside.  Looks like it
is all ready to put up on the roof and connect to the cable.

 

http://www.mrrace.com/TrimbleGPS/ReadyToPutUp.jpg

 

Here it is, mounted about 25 feet above the ground, below the TV antenna.

 

http://www.mrrace.com/TrimbleGPS/MountedHigh.jpg

 

And here is a close up of the finished installation.

 

http://www.mrrace.com/TrimbleGPS/UpAndWorking.jpg

 

A lesson to be learned, about “F” connector barrels!

 

When I hooked up the basement end of the cable, total disappointment!  On
the screen it said in yellow letters, “Antenna Open.”

As I had tested the system end to end, BEFORE I put it all in the container,
the only place that could be a problem was that “F” connector barrel.

I brought the container back down to the bench and carefully looked at the
connections.  It was so simple, and I had caused the problem during early
bench testing of the cables.  The jumper cable from the antenna to the inner
part of the “F” connector has a extremely small diameter center conductor.
On the other hand, the RG6U cable has a greatly oversize, compared to RG59U
cable, center conductor.  In testing I had pushed the RG6U center conductor
into both ends of the “F” barrel.  This pushed the center 

Re: [time-nuts] usb gps devices

[lists]

If they have FCC ID numbers, you may be able to find photographs of the inside 
of the devices, which in turn could reveal the chipset if the photo was clear, 
then with the chipset you could determine if a 1 second pulse is available.

Years ago I got a GPS board from Asin or something like that. It had a 1 second 
pulse, but absolutely not locked to gps time. So you need to beware of what 
looks like a timing pulse but might not be.

-Original Message-
From: Don Latham d...@montana.com
Sender: time-nuts-boun...@febo.com
Date: Wed, 26 Sep 2012 14:11:10 
To: time nutstime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] usb gps devices

Have any of the 'nuts hacked one of the very simple very cheap GPS USB
devices for your car top to see if there is an available 1 sec tick
inside one of them somewhere? I have one that I intend to look at, but
I'll have to get a scope and teenyweeny probe outside to do it, so, if
there is a readily available something, I'd like to know. Thanks!
Don



-- 
Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind.
De Erroribus Medicorum, R. Bacon, 13th century.
If you don't know what it is, don't poke it.
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com



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Re: [time-nuts] 100 watt higher LED power supply...

[lists]

You really want to drive the LEDs with switcher designs typical in battery 
chargers, basically hysteretic current output. Prior to LIon batteries (which 
are voltage sensitive), the old nicad/NiMH chargers used the hysteretic scheme. 
 

If you want a simpler switcher, you can take the garden variety voltage 
regulated switcher and hack it to be current regulated. LTC and Micrel sell 
chips for exactly that use.

Note that the really bright LEDs are designed for a 10 year life at those power 
levels. (Sadly, true for LED backlit TVs.)

I was at a trade show where CREE had a display. For natural lighthing, they 
mix some red LEDs in with the white LEDs. Uh, the dope growing LED fixtures do 
the same thing. ;-)


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Re: [time-nuts] Hi Power LED Light power supply...

[lists]

If you take your garden variety boost converter and place a resistor as the 
load, the current in the inductor is regulated. (Current is vreference over 
this resistor value.) All these dedicated LED drive chips do is reduce the 
voltage across the resistor to improve efficiency. In addition, they might have 
 an overvoltage protection scheme. If for some reason the load, namely the LED 
string, is removed, the boost converter will self destruct. Unlikely to happen 
if everything is soldered together, but LEDs are external, and possibly 
connection can get loose.
 

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Re: [time-nuts] GPSDO control loops and correcting quantization error

[lists]

The PWM DAC should have perfect differential linearity, which I believe is all 
that matters in this application. (That and no missing codes.) Not so when you 
try to combine two DACs to make one higher resolution DAC. 

-Original Message-
From: Tom Harris celephi...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Sun, 16 Sep 2012 12:00:55 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] GPSDO control loops and correcting quantization
error

Second the comments on implementing a 16 bit DAC. You need separate
analogue/digital grounds, superb voltage references, and lots of attempts
to get a good design that actually uses the L.S. bit (rather than losing it
in the noise).

What you can do is use a second DAC to offset the 16 bit DAC. The offset
DAC need only be 8 bit, as long as it is stable. I used this to autozero
the output of a photomultiplier amplifier, and I needed about 20 bits  to
get the correct resolution. However, it can be tricky to adjust the offset
DAC without jumps in the output.

Incidentally superb experimental design, circuit boards taped to an odd
piece of cardboard, with jumpers leads to tie everything together :). I use
a dab of hot melt glue to do similar, and it can be used to secure wiring
as well.


On 15 September 2012 07:01, Don Latham d...@montana.com wrote:

 Michael: Actually implementing a 16 bit DAC to its 1-bit minimum
 resolution will be headache enough. You will gain a real education in
 good grounding practice, shielding, power supply stability and noise,
 and other Murphy intrusion. A 32 bit DAC IMHO, is impossible, and that's
 the name of that tune.
 Don

 Chris Albertson
  On Fri, Sep 14, 2012 at 11:21 AM, Michael Tharp
  g...@partiallystapled.com wrote:
 
  Finally, do people think a 16 bit DAC is adequate or should I consider
  building a 32-bit one? I looked at a few designs when putting this
  together
  but decided to keep it simple until things were up and running.
 
  Having a 32-bit DAC would give you enough range so that you could drop
  in any OCXO you might have.  But if you can have trimmer resisters to
  selected for your specif OCXO then 16-bits should be enough.   If it
  were me, I'd want the DAC steps to be smaller than what the phase
  detector can measure. Said another way a 32-bit DAC might
  eliminate the need for scale and offset trimmer resistors.
 
  Chris Albertson
  Redondo Beach, California
 
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 --
 Neither the voice of authority nor the weight of reason and argument
 are as significant as experiment, for thence comes quiet to the mind.
 De Erroribus Medicorum, R. Bacon, 13th century.
 If you don't know what it is, don't poke it.
 Ghost in the Shell


 Dr. Don Latham AJ7LL
 Six Mile Systems LLP
 17850 Six Mile Road
 POB 134
 Huson, MT, 59846
 VOX 406-626-4304
 www.lightningforensics.com
 www.sixmilesystems.com



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-- 

Tom Harris celephi...@gmail.com
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Re: [time-nuts] Be aware of test equipment seller orzel-enterprises oneBay

[lists]

Fedex ground is awful. Fedex air is fine. 

I go out of my way not to use Fedex ground. Fedex ground is mostly remnants of 
RPS. Air and ground operate like two different companies, at least in attitude. 
I have no idea if there is a firewall between them.
 
 
-Original Message-
From: Peter Gottlieb n...@verizon.net
Sender: time-nuts-boun...@febo.com
Date: Tue, 11 Sep 2012 11:02:15 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Be aware of test equipment seller
 orzel-enterprises  oneBay

   I've had FedEx destroy packages.  One was so bad the driver told me he
   didn't even want to accept it at loading but thought I should see it
   before sending it back.  The seller told me they gave him a really hard
   time and wanted to deny any responsibility as he had packaged using a
   used box.  Even if a carton is marked re-usable, do not destroy they
   will try using that as an excuse.  I got another unit and never heard
   if he ever collected on the first one.
   Lately I have had better luck with the USPS, but I think it varies by
   location and other factors beyond our control.
   Peter
   Sep 11, 2012 11:38:35 AM, time-nuts@febo.com wrote:

 After experiencing UPS issues, I now specify Fed-X where possible.
 The outside condition of the containers even look better when
 delivered. These people seem to care more about what they are doing.
 I once had a large ~150 lb low-pass RF filter that arrived by Fed-X
 freight that was delivered by two very svelte young blondes. They
 babied that crate every step of the way into the building. Was also
 a pleasure to watch them work!
 If you have a chance, you should visit one of the UPS shipping test
 labs where customers are supposed to take their prototype packaging
 to have it tested to see if it will stand up to the rigors of UPS
 shipping. Your jaw will drop when you see what they put the packages
 through.
 Greg
 On Tue, 11 Sep 2012 04:29:29 -0700, jim s
 the observation about UPS is especially true, they will try and say
 anything to escape paying. Unless they loose the package expect an
 argument on anything, they are thieves. Nothing to do but avoid them
 on
 shipping. Actually freight or Postal is the best choice. For freight
 a
 professional crate is your best protection, and my best luck has
 been
 with postal people who don't really care if they beat a claim if it
 is
 not patently BS. YMMV.
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Re: [time-nuts] Be aware of test equipment seller orzel-enterprises oneBay

[lists]

Ebay fees don't reflect shipping cost, so the seller makes more money by 
inflating the shipping price, even if it reduces the final sales price. 



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Re: [time-nuts] Be aware of test equipment seller orzel-enterprises oneBay

[lists]

Items can swim through peanuts. You can put the peanuts in bags so the items 
in the box don't reach the outside.


-Original Message-
From: Tom Miller tmil...@skylinenet.net
Sender: time-nuts-boun...@febo.com
Date: Mon, 10 Sep 2012 19:18:15 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Tom Miller tmil...@skylinenet.net,
Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Be aware of test equipment seller orzel-enterprises
 oneBay

For me, the link does not work. About a month ago I received a 8566B with 
both the handles broken off. So I feel your pain. It was packed in a box 
filled with foam peanuts.



- Original Message - 
From: David Kirkby david.kir...@onetel.net
To: Discussion of precise time and frequency measurement 
time-nuts@febo.com
Sent: Monday, September 10, 2012 6:16 PM
Subject: [time-nuts] Be aware of test equipment seller orzel-enterprises 
oneBay


I hope the list admin does not mind this email, but I think it will be
useful to any time nut buying test equipment from eBay.

orzel-enterprises sells electronic test equipment on eBay. I would
advise anyone to think twice before purchasing from him. This is how
he shipped a vector network analyzer and S-parameter test set which I
won on an auction for $2750. It was shipped from the USA to the UK.

http://boxen.math.washington.edu/home/kirkby/damaged-VNA-by-inadequate-packaging/badly-shipped-8753A-and-85046A.jpg

Note the box is far too small, and so obviously both units suffered damage.

He takes no reponsibility for this, and originally expected me to ship
it back at my expense, and still pay the shipping charges from the
USA. So I'd pay for two international shipments, as well as customs
duties. After I pointed out Paypal would expect him to pay the
shipping to me, he has agreed to refund the USA - UK shipping
charges,  but he still expects me to pay the UK - USA shipping costs.
I object to this, since it was his total stupidity the thing not
damaged. I don't see why I should pay for someone elses stupidity.

Dave.

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Re: [time-nuts] RE; New Wrist watch

[lists]

I have a Junghans. I can't say it is easy on the batteries. Otherwise they 
work. I regret not getting the glows in the dark version.



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Re: [time-nuts] HP10514B Mixer Terminations

[lists]

What am I missing here? Vce = Vbe, so the diode connected transistor isn't 
saturated.

-Original Message-
From: Bob Camp li...@rtty.us
Sender: time-nuts-boun...@febo.com
Date: Sun, 9 Sep 2012 19:16:22 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] HP10514B Mixer Terminations

Hi

….. and of course, once you go into saturation the mixer doesn't look much like 
50 ohms any more. Sort of gets us back to terminations again.

Bob

On Sep 9, 2012, at 6:21 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote:

 NIST have indicated that mixer PN noise measurements with a non dissipative 
 terminations (even RF) are intended to be made.
 
 Using a discrete mixer using diode connected transistors may also be useful 
 at least for 5MHz and 10MHz input frequencies in that their flicker noise can 
 be significantly lower than for mixers using diodes. NIST used a simple 
 diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst 
 using a reactive termination for the difference frequency.
 With such a termination the minicircuits phase detectors had lower measured 
 PN noise than the 10514.
 
 Another issue to consider is saturated or unsaturated (linear) operation of 
 the mixer.
 Saturated operation, for most mixers, produces lower  noise (flicker and 
 floor) however linear operation can have for some mixers lower phase shift 
 tempco which can be important depending on the environment and required phase 
 shift stability.
 
 Bruce
 
 Bob Camp wrote:
 Hi
 
 In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 
 and 20 MHz). Termination at the IF (in this case audio) frequencies is 
 what turns out to be tricky. Any time you terminate a source in a high 
 impedance, you get a higher output voltage. Reactance rarely adds noise to a 
 termination. With a DMTD, slew rate is the issue, generally mixer noise goes 
 up less than the slew rate increases with a non-50 ohm termination.
 
 Bob
 
 
 
 On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz  
 wrote:
 
   
 David Kirkby wrote:
 
 On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com   wrote:
 
   
 Hello Brian,
  I am a radio amateur and and also in the Time nuts list,  At 
 the moment I am planning to bild a DMTD for experimentation. and as you 
 have a nice experience in this field , for me will be very wellcame your 
 help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 
 100Hz)  ¿what about the amp, limiters and zero crosing detec.)
 
 
 Mixers should be terminated in 50 Ohms - at least at all frequencies
 where there is an output. Someone mentioned minicircuits. They sell
 constant impedance filters, where the impedance in the both the
 passband and stopband are 50 Ohms. Most filters have a impedance far
 away from 50 Ohms in the stopband.
 
 
   
 This is an often repeated fallacy.
 For low IF frequencies such as in a DMTD, a reactive IF termination can 
 have the advantage of lower noise and larger IF signal slew rate.
 The resultant reduction in RF and LO port VSWR is easily corrected (at 
 least for low RF and LO frequencies) with a series resistor and/or 
 resistive pad.
 There are a number of NIST papers on the effect of mixer termination for 
 DMTDs and phase noise measurements.
 The minicircuits phase detectors (actually specialised mixers) are 
 specified for use with 500 ohm IF terminations.
 
 I don't know the details of what you are trying to do, but keep in
 mind what I said.
 
 Dave
 
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Re: [time-nuts] ublox chip sets - what GPS device should I buy?

[lists]

I think 50% is the employee discount, at least back in the day.

I worked at a company that was one of the early users of Silvaco. The founder, 
Ivan Pesic, bought all the gear for his start up at employee discount, then 
started a company competing with HP TECAP.  He got the network analyzer, the 
last bit of gear he needed, then turned in his notice. 

Uh, lawyers were involved eventually. ;-) 

-Original Message-
From: David Kirkby david.kir...@onetel.net
Sender: time-nuts-boun...@febo.com
Date: Sat, 1 Sep 2012 08:09:07 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] ublox chip sets - what GPS device should I buy?

On 1 September 2012 00:00, Kevin Rosenberg ke...@rosenberg.net wrote:
 On Aug 31, 2012, at 4:05 PM, David Kirkby david.kir...@onetel.net wrote:
 I don't have it yet, but bought it on eBay today from the seller
 agilentused which is Agilent, and sells used/ex-demo units which
 have been reconditioned, and have a fully warranty. Since I have not
 [...]

 I bought my MSO7104B oscilloscope from the same seller and was overall very 
 pleased. It did take a long time to get the scope with the software options 
 that I requested (6 weeks). But, they apologized and offered to include 
 another $3K of options of my choice to compensate for the delay. The 3-year 
 Agilent warranty was also important to me.

 Kevin

Hi Kevin,

A friend of mine done really well too when he bought from Agilent via
eBay. He had one of their first items they listed, but they did not
list the options - just the capabilities. As such, they agreed to
provide all the options so it met all the capabilites that were
listed.

Agilent don't make that mistake any more, and make it clear what
options are present. They listed two of the VNAs I bought - one with
just the 6 GHz extension and one with all the options. But the one
with all the options was listed at more than twice the price of the
one with just the 6 GHz extension.

I'd suffer a 6 week delay, if they chucked in the TDR option. The only
two options I did not get is the TDR (which is $3774 ) and the ability
to connect an external USB power meter ($511), for which I personally
have no use for.

Taking prices from the Agilent site, bought new, the VNA I have would
cost $22639, so to get it for $12000, I've saved $10639 and paid
just 53% of the new price. I put saved in quotes, as there is no way
I would have paid over $22k for this!

Dave
Dave

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Re: [time-nuts] 60 Hz line quirks, anybody recognize this stuff?

[lists]

I think monitoring a signal generator was the best idea presented. You always 
need a baseline (sanity) test in any experiment. 


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Re: [time-nuts] ublox chip sets - what GPS device should I buy?

[lists]

Some of those Microsoft hockey pucks used SIRF III chipset. I would check ebay 
for that kind of USB GPS. Streets and Trips, well specifically using a notebook 
for a display, has long been out of favor.

So I'm assuming here ST didn't use NEMA interface format.

-Original Message-
From: David Kirkby david.kir...@onetel.net
Sender: time-nuts-boun...@febo.com
Date: Fri, 31 Aug 2012 22:03:57 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] ublox chip sets - what GPS device should I buy?

On 31 August 2012 20:35,  saidj...@aol.com wrote:
 Dave,

 that depends on which uBlox the unit supports. There are basically three
 different sizes: AMY, LEA, and NEO. They also sell chip-sets, but only to
 very  large volume customers.


It plugs in on USB. Somewhere I read it had to be ublox  compatible,
but having looked in the manual, it says:

-
GPS (Global Positioning System) allows you to ‘stamp’ each data trace
with your physical position in latitude/longitude/elevation format.
This can be useful when making measurements on cell towers or other
antennas at remote locations. NOTE This feature is usable ONLY with
the GPS receiver that is shipped with Microsoft “Streets and Trips”
and “AutoRoute”. The GPS receiver is NOT available from Agilent. Only
the GPS USB receiver is used with the FieldFox. Therefore, it is NOT
necessary to purchase the very latest version of the map software.
-

So it seems I need to purchase Microsoft Streets and Trips with the
optional GPS device, which is only $70 in total.

http://www.microsoft.com/streets/en-us/default.aspx

Does anyone know how good/bad that device is? I'd be using it in the
UK 99% of the time.

Dave

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Re: [time-nuts] ublox chip sets - what GPS device should I buy?

[lists]

These mapping programs tend to fall back to NEMA, but also have proprietary 
formats. (Certainly true of Garmin and Delorme.) Now I wonder if by specifying 
a ST USB GPS they want whatever proprietary format MS used. That is, it would 
have made more sense that if they wanted NEMA, they would specify NEMA.

Those MS hockey pucks were notorious for being mistaken by the OS as a mouse 
out of the blue.  You eould have to boot the notebook. All in all, a technology 
that didn't work well.
 
-Original Message-
From: Don Latham d...@montana.com
Sender: time-nuts-boun...@febo.com
Date: Fri, 31 Aug 2012 17:05:58 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] ublox chip sets - what GPS device should I buy?

I have a gps called ambicom with a usb that works with Msoft streets
directly.
Don

Bob Camp
 Hi

 It's not a great receiver, but it works. Back when it first came out,
 the price was pretty good for what you got. Time marches on and you now
 can get some very good / very cheap stand alone units.

 Bob

 On Aug 31, 2012, at 5:03 PM, David Kirkby david.kir...@onetel.net
 wrote:

 On 31 August 2012 20:35,  saidj...@aol.com wrote:
 Dave,

 that depends on which uBlox the unit supports. There are basically
 three
 different sizes: AMY, LEA, and NEO. They also sell chip-sets, but
 only to
 very  large volume customers.


 It plugs in on USB. Somewhere I read it had to be ublox  compatible,
 but having looked in the manual, it says:

 -
 GPS (Global Positioning System) allows you to ‘stamp’ each data trace
 with your physical position in latitude/longitude/elevation format.
 This can be useful when making measurements on cell towers or other
 antennas at remote locations. NOTE This feature is usable ONLY with
 the GPS receiver that is shipped with Microsoft “Streets and Trips”
 and “AutoRoute”. The GPS receiver is NOT available from Agilent. Only
 the GPS USB receiver is used with the FieldFox. Therefore, it is NOT
 necessary to purchase the very latest version of the map software.
 -

 So it seems I need to purchase Microsoft Streets and Trips with the
 optional GPS device, which is only $70 in total.

 http://www.microsoft.com/streets/en-us/default.aspx

 Does anyone know how good/bad that device is? I'd be using it in the
 UK 99% of the time.

 Dave

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-- 
Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind.
De Erroribus Medicorum, R. Bacon, 13th century.
If you don't know what it is, don't poke it.
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com



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Re: [time-nuts] Modern motherboard with RS232 port

[lists]

Power factor. 

-Original Message-
From: Tom Knox act...@hotmail.com
Sender: time-nuts-boun...@febo.com
Date: Sun, 19 Aug 2012 13:19:20 
To: Time-Nutstime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Modern motherboard with RS232 port


Hi Ed;
I may not have had enough coffee yet, but if Volt X Amps = Watts why would 
there be a difference?
Best Wishes;
Thomas Knox



 Date: Sun, 19 Aug 2012 12:35:51 -0600
 From: ed_pal...@sasktel.net
 To: time-nuts@febo.com
 Subject: Re: [time-nuts] Modern motherboard with RS232 port
 
 It's important to remember that on a computer, the wattage shown has no 
 relationship to the wattage pulled from the socket.  The numbers shown 
 are maximum values.  You have to measure the power draw and you have to 
 measure it in volt-amps, not watts because that's how residential power 
 is measured (at least in North America).  Buy an energy meter that shows 
 volt-amps.  They're relatively cheap - typically less than $50.
 
 Ed
 
 On 8/19/2012 11:06 AM, Chris Albertson wrote:
  This sounds like a newer version of the board I use.   The thing to check
  is if the CPU heat sink has a fan or not.  Having no fan indicates that the
  CPU is not using much power.  It also removes a common failure point.
 
  To reduce power even more.  On an NTP server you can unplug the keyboard,
  mouse and monitor and if you have other servers on the LAN configure one as
  a boot server and have it run TFTP then your NTP server does not need a
  disk drive.  It can run off a RAM disk.  This makes it very fast, even
  faster than a SSD and it saves some cash.  Makes backup easy too as there
  is nothing to backup if there is no local storage.  If you don't have a
  TFTP server use a small notebook size disk drive. Even a 80GB drive is
  overkill.  You can also boot from a USB thumb drive and run a RAM disk.
 
  It is worth it to look at your electric bill to find how much you pay for
  power.  Here I'm at $0.21 per KWH.  A full size PC server can use 250W or
  more.  There are 8760 hours in a year so you get $460 per year to run that
  250W PC.  The little Atom will pay for itself in just a few months.  The
  first time I did that calculation, my power hogs where given away.
 
 
 
 
  On Sun, Aug 19, 2012 at 7:42 AM, Stan, W1LE stanw...@verizon.net wrote:
 
  Hello The Net,
 
  For your consideration:
 
  The INTEL model DN2800mt ITX mother board uses a ATOM CPU and
  draws about 11 watts of AC power when configured as:
  (I have not measured DC power yet.)
 
  30 GB OCZ Nocti mSATA solid state drive,
  WIN7 pro, 64 bit, USB keyboard and mouse
  APEX MI-0008 case.
 
  Also has:
  parallel port available on mother board, you extend to a connector
  RS232 serial port available on mother board, you extend to a connector
  a single DC power supply from 11 to 19 V DC.
  1 each PCIe expansion port, I will use with a premium 4 channel sound card
  SATA ports available for HDD/SDD,
  USB ports are available,
  Motherboard sound, and Gigalan.
 
  I have not played with NTP, (yet), but it sounds like a decent time nut
  technical challenge.
 
  My application is for a remote site with only 13V DC power available from
  PV/batteries.
  Then use fiber ethernet to get off site.
 
  The INTEL website would have further details.
 
  Stan, W1LECape Cod   FN41sr
 
 
 
 
  z
 
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Re: [time-nuts] Modern motherboard with RS232 port

[lists]

If you live near a Fry's, get a basic Kill-A-Watt. About $20. Often less on 
sale. You don't need the fancy version that computes cost versus time of day, 
etc.

-Original Message-
From: Ed Palmer ed_pal...@sasktel.net
Sender: time-nuts-boun...@febo.com
Date: Sun, 19 Aug 2012 12:35:51 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Modern motherboard with RS232 port

It's important to remember that on a computer, the wattage shown has no 
relationship to the wattage pulled from the socket.  The numbers shown 
are maximum values.  You have to measure the power draw and you have to 
measure it in volt-amps, not watts because that's how residential power 
is measured (at least in North America).  Buy an energy meter that shows 
volt-amps.  They're relatively cheap - typically less than $50.

Ed

On 8/19/2012 11:06 AM, Chris Albertson wrote:
 This sounds like a newer version of the board I use.   The thing to check
 is if the CPU heat sink has a fan or not.  Having no fan indicates that the
 CPU is not using much power.  It also removes a common failure point.

 To reduce power even more.  On an NTP server you can unplug the keyboard,
 mouse and monitor and if you have other servers on the LAN configure one as
 a boot server and have it run TFTP then your NTP server does not need a
 disk drive.  It can run off a RAM disk.  This makes it very fast, even
 faster than a SSD and it saves some cash.  Makes backup easy too as there
 is nothing to backup if there is no local storage.  If you don't have a
 TFTP server use a small notebook size disk drive. Even a 80GB drive is
 overkill.  You can also boot from a USB thumb drive and run a RAM disk.

 It is worth it to look at your electric bill to find how much you pay for
 power.  Here I'm at $0.21 per KWH.  A full size PC server can use 250W or
 more.  There are 8760 hours in a year so you get $460 per year to run that
 250W PC.  The little Atom will pay for itself in just a few months.  The
 first time I did that calculation, my power hogs where given away.




 On Sun, Aug 19, 2012 at 7:42 AM, Stan, W1LE stanw...@verizon.net wrote:

 Hello The Net,

 For your consideration:

 The INTEL model DN2800mt ITX mother board uses a ATOM CPU and
 draws about 11 watts of AC power when configured as:
 (I have not measured DC power yet.)

 30 GB OCZ Nocti mSATA solid state drive,
 WIN7 pro, 64 bit, USB keyboard and mouse
 APEX MI-0008 case.

 Also has:
 parallel port available on mother board, you extend to a connector
 RS232 serial port available on mother board, you extend to a connector
 a single DC power supply from 11 to 19 V DC.
 1 each PCIe expansion port, I will use with a premium 4 channel sound card
 SATA ports available for HDD/SDD,
 USB ports are available,
 Motherboard sound, and Gigalan.

 I have not played with NTP, (yet), but it sounds like a decent time nut
 technical challenge.

 My application is for a remote site with only 13V DC power available from
 PV/batteries.
 Then use fiber ethernet to get off site.

 The INTEL website would have further details.

 Stan, W1LECape Cod   FN41sr




 z

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Re: [time-nuts] L1 GPS timing signal(s) into local time on computer(s)

[lists]

If you are using a desktop, I'd suggest putting in a serial card. The Netmos 
chip based cards work on windows and linux, though your should do an internet 
search on the particular card before you buy.

I have the prolific based converter. It didn't work with my Starloc. (The 
netmos worked fine with Lady Heather.) I just got a Gearmo branded FTDI based 
usb to serial. I haven't tried it on the Starloc, but it works well on other 
devices.
 
-Original Message-
From: Sarah White kuze...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Sun, 19 Aug 2012 00:25:51 
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] L1 GPS timing signal(s) into local time on computer(s)

Hi, this is my first post.

First off. Windows 7 USB connection to the GPS (no serial ports / modern
computer) and I'm pretty sure that is my main problem.

Past few months, I've been trying to figure out my timing issues. Lots
of reading  trying to figure out how to best configure everything. I'm
typically still off (randomly) by 20-100 miliseconds. I'd like to at
least get to within 50 microseconds (nanoseconds would be wonderful)

1) I need a computer with a serial port. The curent GPS module I'm using
is INTERNALLY RS232 -- USB converter, and recognized by my windows 7
computer as: Prolific USB-to-Serial Comm Port (COM3) ... the latency
and jitter is horrible, and both are seemingly random.

2) I need to run my stratum 1 clock (connected to the stratum 0 time
source via old-school RS232 serial) on linux or a form of BSD with
support for kernel timestamps, and a version of NTP with a driver to
supports my reference clock... points 1 and 2 seem fine.

3) I'm clueless about mounting an antenna, running cable, grounding /
lightning protection, etc... Really want an easy to install one.

For software, I've used 4.2.6 (stable / production) as well as 4.2.7
(dev version) NTP and haven't been able to tell any difference.
Just using the generic NMEA driver / this is a no-name cheapo SIRF module.

Also, trying to wrap my head around these:

http://linuxpps.org/wiki/index.php/LinuxPPS_installation
http://linuxpps.org/wiki/index.php/LinuxPPS_NTPD_support

And here is where I give up. As the subject line suggests:

HELP!!! I'd like to convert L1 GPS timing signal(s) into local time on
computer(s)

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