Re: [time-nuts] unknown GPSDO

[Volker Esper]

Thanks so far. I will have a look at the docs.

The machine is running well, particularly the OCXO is performing very
good when free running (without GPS signal). It is stable and its ADEV
looks good (2E-10 at 10s). Not so the overall ADEV (when GPS locked)
(1E-5 at 10s). It seems to not having the right filter time constant
what had to be much longer. As I understand the documents, the filter
constant can be programmed and I will experiment whith that this afternoon.

Thank you

Volker

Am 17.07.2017 um 16:36 schrieb EB4APL:
> Hi Volker,
> 
> Browsing on my documentation I found that 402NE wast the last version of
> Brooks Shera's (W5OJM) code for the PIC, made in collaboration with
> Bob Leichner (WO6W). Probably this ham was one of Shera´s friends who
> developed the last version and published the sources.
> 
> I include below the instructions that Shera sent me with version 402NE
> 
> Regards,
> 
> Ignacio, EB4APL
> 
> 
> 
> W5OJM GPS-DISCIPLINED FREQUENCY STANDARD...
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Re: [time-nuts] Question about HP-53132A decimal display

[Volker Esper]

I think he wants to point out, that he doesn't mean the menu option, where you 
swap the american decimal point with the european (German?) decimal comma... 

Am 5. Juli 2017 06:38:36 MESZ schrieb Tom Van Baak :
>Mark,
>
>It should be in the hidden "Utility menu" which you access by holding
>Recall during power-up.
>
>Not sure what you mean by enabling commas vs. swapping commas.
>
>For more details see page 2-57 when you google: 53132a user manual
>or look for hp / Agilent / Keysight document 53131-90055.
>
>/tvb
>
>- Original Message - 
>From: "Mark Sims" 
>To: 
>Sent: Monday, July 03, 2017 10:52 PM
>Subject: [time-nuts] Question about HP-53132A decimal display
>
>
>>I recently got in a 53132A with what I think is fairly early firmware
>(it's tied up doing some measurements right now so I can't check the
>version number).   All the photos of the 53132A that I have seen show
>it with commas separating groups of 3 digits after the decimal point. 
>Mine does not do this.  Is there a menu option for enabling the commas
>(not the option for swapping commas and decimal poimts) or was this
>feature added in a later firmware revision?
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Re: [time-nuts] How good is the left end of your ADEV curve?

[Volker Esper]

What can I do at home, to observe such processes? Or is it way beyond 
any imagination to participate in any such experiments?


Volker


Am 25.01.2017 um 06:15 schrieb Hal Murray:

...

How long will it be before we need a gravity-nuts list?



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Re: [time-nuts] Sad news Ulrich Bangert

[Volker Esper]

I am shocked to hear that.

Urich was a very helpful friend, I've learned a lot from him. I'm so 
sorry to hear that.


Please allow me to say some words in Ulrichs (and my) native language.

Die Nachricht vom Tode Urich's hat mich sehr getroffen. Ich habe ihn als 
einen hilfsbereiten und offenen Menschen kennen gelernt, aber leider nie 
persönlich kennen lernen können. Bitte, lieber Hartmut, falls Du Kontakt 
hast, richte der Familie mein herzliches Beileid aus.


Thank you very much.

Volker - DF9PL


Am 20.06.2014 22:52, schrieb Hartmut Paesler:

Dear group,

unfortunately I have to deliver the sad news that Ulrich Bangert, DF6JB
passed away on 11/06, aged 59.

Best regards,

Hartmut DL1YDD


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Re: [time-nuts] I can't get a nice waveform from my rubidium !

[Volker Esper]

Hi Claude,

Am 17.04.2014 07:32, schrieb Claude Fender:
  connect an output directly to the oscilloscope, the shape is nearly 
 squared and when I use a probe, the shape is nearly sine !

 When I send a 10 MHz signal from a generator, the waveform is a clean sine 
 with or whithout the probe.
I assume you use the same probe for the generator and the rubi.
Was the probe calibrated for square wave? That's important - if you
haven't calibrated it yet, you should do that at first.
Are you using the 1:1 position? What, if you use a 1:10 probe/position?
Is it the original Rigol probe?
What is the output impedance of your generator, 50 ohms?
What is the output impedance of your Rubidium? If you don't know,
attache a trim-pot as load, in parallel to the scope (without probe).
Adjust the pot until the output voltage has dropped to half of the
unloaded voltage. Measure the value of your pot - that's the output
resistance of your Rubidium.

What I imagine: the probe isn't calibrated or has a problem, the
Rubidium output is square wave, but the probe doesn't respond correctly
(to low the upper cut-off frequency). The generator will always look ok
(with or without a defective probe), since it outputs a sine wave anyway.

Cheers

Volker


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Re: [time-nuts] ADEV from phase or frequency measurement

[Volker Esper]

Even if the -3dB were an issue, I'd have much more faith in a clear, passive
resistor network than in a complex amplifier with all it's unknown non linear
characteristics, temperature dependent time delays, noise sources, etc., etc.
This simple home made network is a useful, manageable gadget.
Volker

 Bob Camp li...@rtty.us hat am 10. März 2014 um 01:47 geschrieben:


 Hi

 So far, I have not found the 3db lost in a a passive splitter to be a problem
 with anything I have played with. With proper termination , they seem to be a
 good thing to use.

 Bob

 On Mar 9, 2014, at 7:55 PM, Volker Esper ail...@t-online.de wrote:

  Bob,
 
  I sometimes indeed do arc welding, as well as forging... But that's
  another story.
 
  When waiting for an ADEV measurement I sit still, trying not to move a
  millimeter. Seriously, I try to avoid any rf noise, e.g. ham radio, any
  airflow, any temperature change. I log supply voltages and check, if
  there's anything odd. I avoid any switching supply. I regularely check,
  if any switching voltage regulator (TV, monitors, PC,...) disturbs my rf
  ether...
 
  As the legends of my plots tell, I do use a passive splitter to get two
  similar signals (start and stop) for phase measurement. But I haven't
  used it for splitting the 10MHz for frequency measurement (reference and
  input).
 
  Lower level is a concern, since it increases phase jitter.
 
  Volker
 
 
  Am 09.03.2014 23:32, schrieb Bob Camp:
  Hi
 
  Do you routinely do arc welding while waiting for an ADEV plot to finish
  :)… (I drink beer, but not everybody is into that …)
 
  You might consider trying a passive splitter on one of the outputs of the
  GPSDO. There aren’t many ways they will mess up a signal other than by
  dropping it’s level. If level is a concern then indeed they could be an
  issue.
 
  Bob
 
  On Mar 9, 2014, at 6:17 PM, Magnus Danielson mag...@rubidium.dyndns.org
  wrote:
 
  On 09/03/14 22:36, Volker Esper wrote:
  Am 09.03.2014 19:46, schrieb Magnus Danielson:
  On 04/03/14 01:05, Volker Esper wrote:
  Am 03.03.2014 23:04, schrieb Magnus Danielson:
  Volker,
 
  On 03/03/14 00:50, Volker Esper wrote:
  Sorry for the time delay...
 
  TIC: SR620 with Z3805 as external reference; signal source
  Nortel/Trimble GPSTM (GPSDO) 10MHz output
 
  Enclosed two plots (SW: Plotter):
  - one is sigma(tau) calculated from phase samples (SR620 TIME mode),
  - the other one is sigma(tau) from frequency data (SR620 FREQ mode)
 
  Whole equipment had a power up time of several days/weeks. Room
  temperature was stable over both measurements (within about 2 degrees
  C).
  The SR620 uses a bit different path through the logic when doing TI
  and FREQ measurements. The frequency measurement has a feature that
  means that the time error between start and stop signal needs to be
  calibrated out. This can be done using the calibration routines given
  in the manual. This should not affect the ADEV measure, but as a
  precaution.
 
  Try doing a pair of noise-floor measurements. That is, feed the
  reference 10 MHz to the A input for the frequency noise measurement.
  Then, for the TI noise-floor measurement, put a T on the A input, put
  it in high-Z mode and then use a 1 m cable to put the signal onto the
  B input which is terminating.
 
  You indeed have a higher level. Your initial shape makes me wonder. I
  would really like to get the TimeLab measurement files and eye-ball
  them closer.
 
  If you plot the phase or frequency, it may be easier to spot
  systematic wobbles. TDEV would also help, as it provides a general
  *tau scaling to the ADEV plot.
 
  Cheers,
  Magnus
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  and follow the instructions there.
  I already did these measurements, I stick the plots at this posting.
 
  - The plot with the long file name shows frequency mode measurement:
  10MHz external reference put into channel A.
  - ...Plot2 shows a phase measurement, where I fed the reference
  signal
  via a home made 50 ohms splitter into both input channels. (I prefer
  feeding the channels symmetrically)
  Both plots show linear negative gradients, but the phase plot is
  steeper. The frequency plot transitions into a horizontal at about
  1000s.
  The 1/sqrt(tau) curve is higher than the background noise of the
  counter. That flicker phase noise is more typical of a buffer or
  source than of the counter.
 
  For shorter taus I would expect the white noise to dominate.
 
  I'm just surprised about the level of flicker phase noise. What is the
  source?
 
  Cheers,
  Magnus
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  Source in both cases is an HP Z3805 GPSDO. I didn't insert

Re: [time-nuts] ADEV from phase or frequency measurement

[Volker Esper]

Am 09.03.2014 19:46, schrieb Magnus Danielson:
 On 04/03/14 01:05, Volker Esper wrote:
 Am 03.03.2014 23:04, schrieb Magnus Danielson:
 Volker,

 On 03/03/14 00:50, Volker Esper wrote:
 Sorry for the time delay...

 TIC: SR620 with Z3805 as external reference; signal source
 Nortel/Trimble GPSTM (GPSDO) 10MHz output

 Enclosed two plots (SW: Plotter):
 - one is sigma(tau) calculated from phase samples (SR620 TIME mode),
 - the other one is sigma(tau) from frequency data (SR620 FREQ mode)

 Whole equipment had a power up time of several days/weeks. Room
 temperature was stable over both measurements (within about 2 degrees
 C).

 The SR620 uses a bit different path through the logic when doing TI
 and FREQ measurements. The frequency measurement has a feature that
 means that the time error between start and stop signal needs to be
 calibrated out. This can be done using the calibration routines given
 in the manual. This should not affect the ADEV measure, but as a
 precaution.

 Try doing a pair of noise-floor measurements. That is, feed the
 reference 10 MHz to the A input for the frequency noise measurement.
 Then, for the TI noise-floor measurement, put a T on the A input, put
 it in high-Z mode and then use a 1 m cable to put the signal onto the
 B input which is terminating.

 You indeed have a higher level. Your initial shape makes me wonder. I
 would really like to get the TimeLab measurement files and eye-ball
 them closer.

 If you plot the phase or frequency, it may be easier to spot
 systematic wobbles. TDEV would also help, as it provides a general
 *tau scaling to the ADEV plot.

 Cheers,
 Magnus
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.
 I already did these measurements, I stick the plots at this posting.

 - The plot with the long file name shows frequency mode measurement:
 10MHz external reference put into channel A.
 - ...Plot2 shows a phase measurement, where I fed the reference signal
 via a home made 50 ohms splitter into both input channels. (I prefer
 feeding the channels symmetrically)
 Both plots show linear negative gradients, but the phase plot is
 steeper. The frequency plot transitions into a horizontal at about
 1000s.

 The 1/sqrt(tau) curve is higher than the background noise of the
 counter. That flicker phase noise is more typical of a buffer or
 source than of the counter.

 For shorter taus I would expect the white noise to dominate.

 I'm just surprised about the level of flicker phase noise. What is the
 source?

 Cheers,
 Magnus
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Source in both cases is an HP Z3805 GPSDO. I didn't insert an additional
buffer, however, the Z3805 has two (buffered) outputs. I used one for
counter reference, the other one for counter input.

Volker

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Re: [time-nuts] ADEV from phase or frequency measurement

[Volker Esper]

Bob,

I sometimes indeed do arc welding, as well as forging... But that's
another story.

When waiting for an ADEV measurement I sit still, trying not to move a
millimeter. Seriously, I try to avoid any rf noise, e.g. ham radio, any
airflow, any temperature change. I log supply voltages and check, if
there's anything odd. I avoid any switching supply. I regularely check,
if any switching voltage regulator (TV, monitors, PC,...) disturbs my rf
ether...

As the legends of my plots tell, I do use a passive splitter to get two
similar signals (start and stop) for phase measurement. But I haven't
used it for splitting the 10MHz for frequency measurement (reference and
input).

Lower level is a concern, since it increases phase jitter.

Volker


Am 09.03.2014 23:32, schrieb Bob Camp:
 Hi

 Do you routinely do arc welding while waiting for an ADEV plot to finish :)… 
 (I drink beer, but not everybody is into that …)

 You might consider trying a passive splitter on one of the outputs of the 
 GPSDO. There aren’t many ways they will mess up a signal other than by 
 dropping it’s level. If level is a concern then indeed they could be an issue.

 Bob

 On Mar 9, 2014, at 6:17 PM, Magnus Danielson mag...@rubidium.dyndns.org 
 wrote:

 On 09/03/14 22:36, Volker Esper wrote:
 Am 09.03.2014 19:46, schrieb Magnus Danielson:
 On 04/03/14 01:05, Volker Esper wrote:
 Am 03.03.2014 23:04, schrieb Magnus Danielson:
 Volker,

 On 03/03/14 00:50, Volker Esper wrote:
 Sorry for the time delay...

 TIC: SR620 with Z3805 as external reference; signal source
 Nortel/Trimble GPSTM (GPSDO) 10MHz output

 Enclosed two plots (SW: Plotter):
 - one is sigma(tau) calculated from phase samples (SR620 TIME mode),
 - the other one is sigma(tau) from frequency data (SR620 FREQ mode)

 Whole equipment had a power up time of several days/weeks. Room
 temperature was stable over both measurements (within about 2 degrees
 C).
 The SR620 uses a bit different path through the logic when doing TI
 and FREQ measurements. The frequency measurement has a feature that
 means that the time error between start and stop signal needs to be
 calibrated out. This can be done using the calibration routines given
 in the manual. This should not affect the ADEV measure, but as a
 precaution.

 Try doing a pair of noise-floor measurements. That is, feed the
 reference 10 MHz to the A input for the frequency noise measurement.
 Then, for the TI noise-floor measurement, put a T on the A input, put
 it in high-Z mode and then use a 1 m cable to put the signal onto the
 B input which is terminating.

 You indeed have a higher level. Your initial shape makes me wonder. I
 would really like to get the TimeLab measurement files and eye-ball
 them closer.

 If you plot the phase or frequency, it may be easier to spot
 systematic wobbles. TDEV would also help, as it provides a general
 *tau scaling to the ADEV plot.

 Cheers,
 Magnus
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.
 I already did these measurements, I stick the plots at this posting.

 - The plot with the long file name shows frequency mode measurement:
 10MHz external reference put into channel A.
 - ...Plot2 shows a phase measurement, where I fed the reference signal
 via a home made 50 ohms splitter into both input channels. (I prefer
 feeding the channels symmetrically)
 Both plots show linear negative gradients, but the phase plot is
 steeper. The frequency plot transitions into a horizontal at about
 1000s.
 The 1/sqrt(tau) curve is higher than the background noise of the
 counter. That flicker phase noise is more typical of a buffer or
 source than of the counter.

 For shorter taus I would expect the white noise to dominate.

 I'm just surprised about the level of flicker phase noise. What is the
 source?

 Cheers,
 Magnus
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.
 Source in both cases is an HP Z3805 GPSDO. I didn't insert an additional
 buffer, however, the Z3805 has two (buffered) outputs. I used one for
 counter reference, the other one for counter input.
 Hmm... what is the noise when you measure it on the SR620 itself?

 It seems a little high here.

 Cheers,
 Magnus

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Re: [time-nuts] SR620 binary dump

[Volker Esper]

...I'll try that, too. Tomorrow.
Volker

Am 09.03.2014 00:29, schrieb Tom Van Baak:
 Using XREL exposes an additional digit of resolution. Set XREL to 1E7 and 
 then you get ascii readings like:

1.E-4
-6.E-5
2.E-4
-1.4E-4
.0E-6
-1.9E-4
 I should clarify. Yes, it appears that when using XREL, one can get ~2.7 ps 
 timing resolution/granularity for frequency readings 10 MHz. But when the 
 frequency reading is 10 MHz the timing resolution/granularity is 10 ps.

 For example, here are 1000 measurements using XREL 1E7 (columns are 
 occurrence, value):

   1  999.999480
   1  999.999510
   1  999.999560
   1  999.999590
   4  999.999620
   3  999.999640
   9  999.999670
   6  999.999700
   8  999.999720
  22  999.999750
  24  999.999780
  28  999.999810
  50  999.999830
  71  999.999860
  45  999.999890
  73  999.10
 122  999.40
  54  999.70
 294 1000.00
 152 1000.000100
  28 1000.000200
   2 1000.000300
   1 1000.000500

 Notice how all the readings less than 10 MHz differ by 20 or 30 uHz (mean 
 27), but all the readings greater than 10 MHz differ by 100 MHz. I will 
 continue to look into this, but my hunch is that this is a bug in the SR620 
 firmware; the only solution is using binary mode.

 /tvb

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[time-nuts] ADEV from phase or frequency measurement

[Volker Esper]

Hello dear fellow time-nuts,

I stumbled over a question that may sound stupid to you:

Is the usual ADEV plot the result of a phase or a frequency measurement?

I get totally different results when comparing a phase and a frequency
measurement of the same source. Or am I doing something totally wrong?

Thanks a lot

Volker



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Re: [time-nuts] ADEV from phase or frequency measurement

[Volker Esper]

Thank you, Tom, so far. Yes, I know that I have to use different
formulas, but - of course - I didn't calculate the ADEV curves myself, I
let some software do the job, namely Ulrich's Plotter and TimeLab as
well. Plotter has a menu item, where you have to check if you deal with
phase or frequency data, so I assumed the software would do right.

I am confused. The ADEVs of the phase data are about 10 times better and
have a different shape...

Volker

Am 01.03.2014 12:37, schrieb Tom Van Baak:
 Hi Volker,

 Either phase or frequency raw data can be used to generate an ADEV plot, but 
 you have to use different methods depending on the data type.

 See the two formulas for Allan Variance in: http://www.wriley.com/paper2ht.htm

 Usually we use the x form of the formula, where x is an array of phase 
 samples. But if you have frequency samples then use the y form instead, 
 where y is an array of frequency samples.

 Note you can also convert phase data to frequency data (by differentiating) 
 and use the y form. Or convert frequency data to phase data (by 
 integrating) and use the x form.

 /tvb

 - Original Message - 
 From: Volker Esper ail...@t-online.de
 To: Discussion of precise time and frequency measurement 
 time-nuts@febo.com
 Sent: Saturday, March 01, 2014 3:15 AM
 Subject: [time-nuts] ADEV from phase or frequency measurement


 Hello dear fellow time-nuts,

 I stumbled over a question that may sound stupid to you:

 Is the usual ADEV plot the result of a phase or a frequency measurement?

 I get totally different results when comparing a phase and a frequency
 measurement of the same source. Or am I doing something totally wrong?

 Thanks a lot

 Volker

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Re: [time-nuts] comparing two clocks

[Volker Esper]

Jim,

If I get you right, you want to compare the 10MHz outputs (not the
1PPS). As Jim and Bob told us so far, the thing is to provide, that
input A _always_ starts before input B (or the other way around).

Connect the signals to an oscilloscope, and check, how much the phase
differs - if the rising slopes occur close together, put some
meters/yards of coaxial cable into one of the two signal paths. 1 meter
is roughly worth 5ns - while the period of 10MHz is 100ns, 1m cable will
phase shift about 18 degrees. I didn't verify, if the coax cable (with
it's microphonic effect) affects the ADEV - does anybody have experience
with this? Otherwise I'd have to fire up my counter and have a
measurement on the run...

Of course, inverting one signal will do as well. If you do it with extra
electronics that definitely will affect the ADEV. I find it much easier
to use some meters of cable.

Ok, my counter is heating up by now...

Volker


Am 22.02.2014 14:17, schrieb Jimmy Burrell:
 I need some help with a 'noob' question regarding some practical examples in 
 some of the NIST literature. When attempting to compare two clocks, I'm a bit 
 confused on the subject of exactly how to use my counter to compare a delayed 
 clock relative to another. Or perhaps I should just say 'comparing two 
 clocks'. Let's take some concrete examples. 

 Let's say I want to characterize my Morion MV89 ocxo using my HP5335a. 
 Obviously, I can tune the MV89's 10MHz by +/- 1Hz and feed it to the 
 counter's input 'A'. Obviously, I can feed in a second, external reference 
 clock at 10MHz into input 'B'.  Suppose, however, I didn't have an external 
 reference clock. Can I compare against the counter's internal time base by 
 hooking a line from the rear jack time base output to channel 'B' input? Or 
 am I making it too complicated? Do I simply plug into input 'A' and go?

 In a somewhat related question, in this article 
 (http://www.wriley.com/Examples%20of%201%20PPS%20Clock%20Measuring%20Systems.pdf)
  where two clocks, both divided to 1PPS, were compared, W.Riley makes the 
 following statement, The two 1 PPS outputs were connected to a Racal Dana 
 1992 time internal counter having 1 nanosecond resolution, and the start and 
 stop signals were separated sufficiently in time for the counter to function 
 properly.  I wonder what exactly is meant by separated sufficiently in time 
 for the counter to function properly and how one would go about doing this? 
 For example, is inverting one of the signals sufficient separation? If not, 
 how is this typically done? Delay line?

 Thank you,

 Jim...
 N5SPE
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Re: [time-nuts] GPS W/10KHz

[Volker Esper]

Perry,

you don't need 10kHz to build a GPS disciplined oscillator. GPSDOs are
build with control loop response times in the range of some hours, so
the loop will be absolutely happy with a 1PPS input.

To keep the frequency stable at short times, you need a very stable
quartz oscillator instead, something like a TCXO. There are many aviable
on the surplus market, for example

http://www.ebay.de/itm/Vanguard-TCXO-0-1ppm-25-000MHz-Ultra-precision-Golden-Oscillator-/131020893918?pt=LH_DefaultDomain_0hash=item1e81742ede

or

http://www.ebay.de/itm/HP-10811-60111-10-MHz-Quartz-Crystal-Oscillator-/321311911853?pt=LH_DefaultDomain_0hash=item4acfaeafad

Volker



Am 08.02.2014 05:10, schrieb Perry Sandeen:

 List,

  
 Wrote: where is a good source of GPS receiver modules I need one which has 
 10kHz output to phase lock a quartz oscillator.


 Fluke.1 Motorola ONCORE M12+T timing gps receiver
 1pps 100hz eBay item number:290656401551
  
  
 Also RDR
  
 There is another china seller that has them(10KHz)
 with leads for $90 but is almost impossible to find.  Last time I searched it 
 took me a hour.  But he has a wide assortment. I forgot to bookmark
 his site.
  
 Regards,
  
 Perrier
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Re: [time-nuts] GPS W/10KHz

[Volker Esper]

Thanks, Chris, I didn't gather that from his posting. It'd be up to
Perrier to illuminate that point.

Volker


Am 08.02.2014 18:33, schrieb Chris Albertson:
 On Sat, Feb 8, 2014 at 3:44 AM, Volker Esper ail...@t-online.de wrote:

 you don't need 10kHz to build a GPS disciplined oscillator. GPSDOs are
 build with control loop response times in the range of some hours, so
 the loop will be absolutely happy with a 1PPS input.


 Of course you are correct.  Most GPSDOs are driven with a 1Hz pulse.  But I
 think maybe the OP is not building just any GPSDO but maybe he is looking
 to repair a specific GPSDO that is designed to use the old (and now rare)
 Rockwell GPS.  If that is the case he needs the old Rockwell or needs
 to redesign his system.

 If you are starting from scratch to build a new GPSDO it's easier now.  All
 you need is some kind of a phase detector (74HC4046 ?) and a small uP that
 has a good built-in DAC.  The uP checks the phase once per second and
 adjusts it'sDAC accordingly.

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Re: [time-nuts] housing multiple GPS timing receivers in the same box.

[Volker Esper]

http://www.ebay.de/itm/HP-58516A-GPS-1-4-signal-Distribution-Amplifier-Splitter-N-type-/300997787447?pt=US_Ham_Radio_Receivershash=item4614ddbf37



Am 04.02.2014 14:08, schrieb mike cook:
 Hi,
   Till now I have been putting receivers in individual boxes. So to limit the 
 growing number of boxes, I want to put two Resolution-T SMT receivers in one 
 box, sharing power and antenna inputs. My question is  How best can I share 
 the antenna input, minimizing any interference between the receivers? . Will 
 any interference matter? For example, I can easily connect three bits of 
 shielded coax in a Y , but will probably get reflections from each 
 receiver. As the cables will only be about 15cm long, would it matter? How 
 about the DC antenna supply? The antenna DC will NOT be powering an antenna 
 as it passes through a DC blocked splitter used to share an antenna between 
 most of my receivers. I might be able squeeze a Mini-Circuits splitter in the 
 box and DC-block both outputs but that may be overkill.  What discrete 
 circuitry might be a replacement? Will the Y do it?

 Someone must have already succeeded with this type of config. 

 Thanks in advance  for your input.

 Regards,
 Mike

  
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Re: [time-nuts] Replacement fan in SR620

[Volker Esper]

Magnus,

 Yes, and the EBM-Papst 624 matches it well. The Papst seems to have
 much lower noise from the datasheet.

There's yet another problem: the mechanical construction conducts the
fan noise to the case, so the noise is kind of amplified by the case. I
felt somewhat disappointed after replacing the fan, don't expect too much.

I just read the postings of Charles and I, too, was unhappy with the
startup behaviour. I changed the values of the driver circuit, but kept
the sensor in the tunnel. That helped making the motor speed rising
monotonically.

The air inlets are too small - that's true, if you need so much air
flow. We agree that the fan speed is at it's maximum, not at it's
equilibrium. So I tried to separate the heat sources. At the right (and
left) side of the case various voltage regulators heat the side wall. I
placed a heat sink with vertikal fins from the outside on that wall, the
screws of the regulators screwed into the aluminium. I'll  further place
a wall inside the counter right before those heating parts. The
experiment isn't completed yet, but I'm keen enough to claim that it'll
help to stabilize internal temperature particularly at the sensitive
components.

Volker

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Re: [time-nuts] Replacement fan in SR620

[Volker Esper]

Magnus,

I took an EBMPabst 624. Pabst has a good reputation.
The original fan is a Delta Electronics DFB0624 H, Dimensions are 60mm x
60mm x 25mm, DC24V 0.11A

Volker


Am 01.02.2014 18:56, schrieb Magnus Danielson:
 Fellow time-nuts,

 I heard the fan in one of my SR620s and it didn't really was a nice
 sound. Has someone found a good replacement fan? Quieter would be nice.

 Considering performance checks and calibration this evening.

 Cheers,
 Magnus
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Re: [time-nuts] EFC divider resistors

[Volker Esper]

The ratio tempco is the point! It's hard to design a divider yourself,
since temperature differences between the two divider resistors is the
problem.

Resistor networks with very low ratio tempcos are fairly expensive. I
don't know your budget and how far you want to go. If you want to try it
yourself, use voltage divider resistors of only one value and combine
the required number of resistors. That is to have each resistor at the
same power dissipation (and therefore at the same drift), then put them
together very closely. Isolate them with insultation tape or so.
Example: 10V to 2.5V: use 4 resistors of say 1k and pickup the 2.5 volts
at the resistor next to ground.

By the way: in a temperature sensitive environment where every microvolt
counts I would not recommend using a potentiometer. Use it for
determining the exact values and then replace the pot by the required
number of resistors, see above.

Tell us something about your intended budget.

Volker



Am 31.01.2014 18:40, schrieb Robert LaJeunesse:
 Jellybean resistors can have a tempco in the 100s of PPM per degree C. Some 
 precision resistors are as low as 25 PPM/C while really good resistors can be 
 had at 5 PPM/C. Better yet look for a resistor array where part tracking is 
 called out. Some arrays get below 5 PPM tracking so the division ratio holds 
 much better than the absolute value. (I find the DigiKey part search tool 
 helpful in finding the low PPM parts I want.) 

 Another possibility is an integrated resistive divider like the Maxim MAX549x 
 series. The have pre-trimmed dividers in a number of ratios and values, 
 typically with 35 PPM/C absolute tempcos but ratiotempcos as low as 2 PPM/C.

 Bob LaJeunesse



 
 From: Bob Stewart b...@evoria.net
 To: Discussion of precise time and frequency measurement 
 time-nuts@febo.com 
 Sent: Friday, January 31, 2014 12:01 PM
 Subject: [time-nuts] EFC divider resistors


 I put a divider network in the EFC line of my GPSDO to restrict the OCXO 
 range to 2Hz.  Now I'm seeing heat-related drift that wasn't apparent 
 before.  I put a 20K resistor from the same strip on my 3456A, and the 
 warmth of holding it between fingers moves it by about 50 ohms.  What type 
 of resistors should I put in there?  Or am I chasing a problem that doesn't 
 exist?  Totally out of my league here.

 Bob - AE6RV

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Re: [time-nuts] EFC divider resistors

[Volker Esper]

Here's how to place the divider resistors. The picture is from 1992, I
didn't use SMDs then. But the results are promising at a very low price.


Isolierband = insulation tape
wärmeleit. Kern = thermoconducting core

The picture shows two examples, the left one if you need three
resistors, the right one if you need six. Use metal film types with low
tempco. Keep in mind: it's the fluctuating _difference_ between the
resistor values, that'll kill your stability. So avoid everything, that
leads to different temperatures at the resistors. In particular avoid
placing them into an airstream.

Volker


Am 31.01.2014 20:25, schrieb Volker Esper:
 The ratio tempco is the point! It's hard to design a divider yourself,
 since temperature differences between the two divider resistors is the
 problem.

 Resistor networks with very low ratio tempcos are fairly expensive. I
 don't know your budget and how far you want to go. If you want to try it
 yourself, use voltage divider resistors of only one value and combine
 the required number of resistors. That is to have each resistor at the
 same power dissipation (and therefore at the same drift), then put them
 together very closely. Isolate them with insultation tape or so.
 Example: 10V to 2.5V: use 4 resistors of say 1k and pickup the 2.5 volts
 at the resistor next to ground.

 By the way: in a temperature sensitive environment where every microvolt
 counts I would not recommend using a potentiometer. Use it for
 determining the exact values and then replace the pot by the required
 number of resistors, see above.

 Tell us something about your intended budget.

 Volker



 Am 31.01.2014 18:40, schrieb Robert LaJeunesse:
 Jellybean resistors can have a tempco in the 100s of PPM per degree C. Some 
 precision resistors are as low as 25 PPM/C while really good resistors can 
 be had at 5 PPM/C. Better yet look for a resistor array where part tracking 
 is called out. Some arrays get below 5 PPM tracking so the division ratio 
 holds much better than the absolute value. (I find the DigiKey part search 
 tool helpful in finding the low PPM parts I want.) 

 Another possibility is an integrated resistive divider like the Maxim 
 MAX549x series. The have pre-trimmed dividers in a number of ratios and 
 values, typically with 35 PPM/C absolute tempcos but ratiotempcos as low as 
 2 PPM/C.

 Bob LaJeunesse



 
 From: Bob Stewart b...@evoria.net
 To: Discussion of precise time and frequency measurement 
 time-nuts@febo.com 
 Sent: Friday, January 31, 2014 12:01 PM
 Subject: [time-nuts] EFC divider resistors


 I put a divider network in the EFC line of my GPSDO to restrict the OCXO 
 range to 2Hz.  Now I'm seeing heat-related drift that wasn't apparent 
 before.  I put a 20K resistor from the same strip on my 3456A, and the 
 warmth of holding it between fingers moves it by about 50 ohms.  What type 
 of resistors should I put in there?  Or am I chasing a problem that doesn't 
 exist?  Totally out of my league here.

 Bob - AE6RV

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Re: [time-nuts] EFC divider resistors

[Volker Esper]

Sorry, missing picture...

Am 31.01.2014 20:47, schrieb Volker Esper:
 Here's how to place the divider resistors. The picture is from 1992, I
 didn't use SMDs then. But the results are promising at a very low price.


 Isolierband = insulation tape
 wärmeleit. Kern = thermoconducting core

 The picture shows two examples, the left one if you need three
 resistors, the right one if you need six. Use metal film types with low
 tempco. Keep in mind: it's the fluctuating _difference_ between the
 resistor values, that'll kill your stability. So avoid everything, that
 leads to different temperatures at the resistors. In particular avoid
 placing them into an airstream.

 Volker


 Am 31.01.2014 20:25, schrieb Volker Esper:
 The ratio tempco is the point! It's hard to design a divider yourself,
 since temperature differences between the two divider resistors is the
 problem.

 Resistor networks with very low ratio tempcos are fairly expensive. I
 don't know your budget and how far you want to go. If you want to try it
 yourself, use voltage divider resistors of only one value and combine
 the required number of resistors. That is to have each resistor at the
 same power dissipation (and therefore at the same drift), then put them
 together very closely. Isolate them with insultation tape or so.
 Example: 10V to 2.5V: use 4 resistors of say 1k and pickup the 2.5 volts
 at the resistor next to ground.

 By the way: in a temperature sensitive environment where every microvolt
 counts I would not recommend using a potentiometer. Use it for
 determining the exact values and then replace the pot by the required
 number of resistors, see above.

 Tell us something about your intended budget.

 Volker



 Am 31.01.2014 18:40, schrieb Robert LaJeunesse:
 Jellybean resistors can have a tempco in the 100s of PPM per degree C. Some 
 precision resistors are as low as 25 PPM/C while really good resistors can 
 be had at 5 PPM/C. Better yet look for a resistor array where part tracking 
 is called out. Some arrays get below 5 PPM tracking so the division ratio 
 holds much better than the absolute value. (I find the DigiKey part search 
 tool helpful in finding the low PPM parts I want.) 

 Another possibility is an integrated resistive divider like the Maxim 
 MAX549x series. The have pre-trimmed dividers in a number of ratios and 
 values, typically with 35 PPM/C absolute tempcos but ratiotempcos as low as 
 2 PPM/C.

 Bob LaJeunesse



 
 From: Bob Stewart b...@evoria.net
 To: Discussion of precise time and frequency measurement 
 time-nuts@febo.com 
 Sent: Friday, January 31, 2014 12:01 PM
 Subject: [time-nuts] EFC divider resistors


 I put a divider network in the EFC line of my GPSDO to restrict the OCXO 
 range to 2Hz.  Now I'm seeing heat-related drift that wasn't apparent 
 before.  I put a 20K resistor from the same strip on my 3456A, and the 
 warmth of holding it between fingers moves it by about 50 ohms.  What type 
 of resistors should I put in there?  Or am I chasing a problem that 
 doesn't exist?  Totally out of my league here.

 Bob - AE6RV

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Re: [time-nuts] EFC divider resistors

[Volker Esper]

Don't underestimate the effect of resistors being at different
temperatures. The tempco isn't linear at all, so your drift caused by
ambient temp won't be the same at the different resistors. It is best to
have them at the same value!

I'd been experimenting quite some days to find a reasonable solution
with single resistors. It's essential to have them at the same
temperature and to couple them thermally as good as you can.

Precision resistor dividers do it just the same way: very small resistor
pills very tightly placed on a very good thermally conducting
substrate.  If you find the right value/ratio, and are game for paying
about 30$ you can get a ready-to-use divider from Vishay or so.

Another suggestion: replace the divider R3/4/5 by a precision reference
at the desired voltage. 5V sounds like a TTL supply - that would be no
good idea.

My personal story: When I had my divider placed on the PCB I was
wondering the oscilloscope showing sudden milli volt jumps from time to
time (where I expected a noise of some micro volts...). After hours of
searching I noticed a correlation with the wind blowing outside my
shack. It was a small crack in the window that let a tiny airstream flow
across my PCB, so tiny, I couldn't sense.

Volker


Am 31.01.2014 21:23, schrieb Bob Stewart:
 Hi Volker,

 Thanks for the ideas.  The resistors are all within a short radius of each 
 other.  I hadn't thought about bundling them all together.  I suppose I could 
 epoxy them together as a last resort.  I've got some EPF foam, so I could try 
 putting that on the board right against them.  In fact, I could try that 
 while waiting for the new parts.  I've already used foam to fill most of the 
 space in the box, except for around and above the OCXO.





 
 From: Volker Esper ail...@t-online.de
 To: Robert LaJeunesse lajeune...@mail.com; Discussion of precise time and 
 frequency measurement time-nuts@febo.com 
 Sent: Friday, January 31, 2014 1:51 PM
 Subject: Re: [time-nuts] EFC divider resistors


 Sorry, missing picture...

 Am 31.01.2014 20:47, schrieb Volker Esper:
 Here's how to place the divider resistors. The picture is from 1992, I
 didn't use SMDs then. But the results are promising at a very low price.


 Isolierband = insulation tape
 wärmeleit. Kern = thermoconducting core

 The picture shows two examples, the left one if you need three
 resistors, the right one if you need six. Use metal film types with low
 tempco. Keep in mind: it's the fluctuating _difference_ between the
 resistor values, that'll kill your stability. So avoid everything, that
 leads to different temperatures at the resistors. In particular avoid
 placing them into an airstream.

 Volker

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Re: [time-nuts] Nortel GPSDO osc age alarm

[Volker Esper]

...thanks, Bob, it seems to be the oscillator, that is at it's limit, it
cannot tune to 10 MHz at full EFC voltage, see new thread (started by Mark).

Volker

Am 24.01.2014 01:09, schrieb Bob Camp:
 Hi

 That’s a cell phone base station board. It’s got a bunch of outputs, some of 
 which are related to the cell network it was built for rather than 10MHz. I’d 
 bet your 9.8 MHz output is one of those. They are DDS based so there likely 
 is some range of possible outputs. 

 The age alarm is not unusual on a newly powered up board. It’s moving faster 
 than it should. It may settle down. 

 The DAC at limit is not a real good sign ….

 Bob

 On Jan 23, 2014, at 6:43 PM, Volker Esper ail...@t-online.de wrote:

 Hi!

 I bought a Trimble/Nortel GPSDO

 http://www.ebay.de/itm/300933951405?ssPageName=STRK:MEWNX:IT_trksid=p3984.m1497.l2648

 and Lady Heather's now tells me that everything is alright - except
 - DAC 6.04V
 - OSC BAD
 - osc age alarm

 The rectangle 10MHz output signal (J5) shows a signal at about 9.8MHz
 (a deviation of about 200kHz), wobbling 4Hz up and down. Oddly enough,
 the direct oscillator output (J4) shows a sine wave at a stable
 10.004MHz (a deviation of 0.4Hz).

 It seems to me it's not the oscillator that is bad but the servo loop -
 what can I do?

 Thank you

 Volker
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Re: [time-nuts] Nortel GPSDO osc age alarm

[Volker Esper]

Thanks so much, Nigel, for this very interesting mail.

Yes, the voltages are exactly as my ones. And yes, I've removed the
oscillator, already. I then removed the thermal isolation from the osc,
as well as the label, in slight hope for a hidden tuning screw. Of
course, there isn't any.

I, too, had this idea to level shift the EFC voltage. So I took seat at
my computer to find out, which maximum EFC voltage would be ok. And saw
your mail. Do you have any further information about the osc? The number
on the sign (Trimble *0110-2450-T*  *34310-T*) isn't really informative.
By the way: When removing the big Trimble label I found a smaller one
beneath, reading DOC2127 0101/1940; I think it's a Tekelc osc?

Is there a pull-up resistor behind the EFC input pin so that I could use
two diodes for level shifting? Or how did you?

This part is more thrilling than I expected...

Regards

Volker


Am 24.01.2014 12:08, schrieb gandal...@aol.com:
 Hi Volker
  
 One possibility, as I found with one of these recently, is that your  
 oscillator has aged such that the required EFC voltage for 10MHz output is 
 now  
 outside the range provided by the board.
  
 The EFC behaviour can be tracked if Lady Heather is  enabled from switch on 
 and the DAC voltage monitored.
  
 The EFC voltage should start at 3 volts, in my case reported by LH as  
 3.02 Volts, and will sit at this level until enough satellites are being  
 tracked for the board to decide it can start the conditioning process, at 
 which  point the DAC voltage will ramp upwards over the course of a few 
 seconds 
 until  the point is reached where the oscillator frequency crosses 10MHz and 
 the  control loop takes over.
  
 All standard stuff of course but, as you've discovered, if the  oscillator 
 hasn't reached 10MHz by the time the EFC voltage reaches, in my  case 
 anyway, approximately 5.6 volts the board's OSC report switches to  BAD 
 and 
 Normal OSC age switches to OSC age alarm and LH highlights  both in red.
 The EFC voltage finishes its ramp at 6 Volts, reported as 6.04  Volts, 
 and then just sits there, all exactly as you're seeing.
  
 Having removed my faulty oscillator, something that needs to be  done 
 VERY carefully to avoid damage to the board, I found that it  required an EFC 
 voltage of just under 6.6 Volts for the the output frequency to  reach 10MHz.
  
 The seller, fluke.l, was very helpful as always and offered to  supply a 
 replacement 34310-T oscillator, this one did have it's required  EFC voltage 
 in the correct range and resolved the problem.
  
 However, whilst waiting for the replacement to arrive I left the  original 
 oscillator on test and monitoring it for a  while suggested that the only 
 thing wrong with it was the required EFC  voltage, so I reconnected it to 
 the board using a wired  lash-up on the bench with a simple 2 Volt level 
 shifter inserted into the  control loop and did indeed get a locked condition 
 with Lady H reporting the DAC  voltage from the board as close to 4.5 volts.
  
 This suggests that whilst the board  design requires the oscillator EFC 
 Voltage at 10 MHz  to be between 3 and 6 Volts an oscillator that falls 
 outside 
 this  range shouldn't automaticall be assumed to be faulty in more 
 general terms,  although it's obviously getting a bit long in the tooth and 
 that 
 doesn't  help much if it happens to be soldered into your circuit board !
  
 Whilst it is possible to remove and replace the original  oscillator there 
 is an alternative to physical replacement, one which  I've now implemented, 
 and this uses the mounting positions already  available beneath the 
 oscillator, not usable though until it's  removed, to fit a couple of SMA or 
 SMB 
 connectors.
 These two connectors couple the 10MHz signal from the oscillator into  the 
 board (J9) and the EFC Voltage out to the oscillator (J10).
 Although there is a  regulated supply available from the  oscillator, which 
 might be expected to supply the EFC  circuitry, in practice this connection 
 does not seem to be  required.
 I have not investigated further as yet to determine whether the board  auto 
 senses and uses this supply if it is present, or whether it always just  
 ignores it, but it doesn't seem to be an issue either way and it's 
 interesting 
  to note, at the extremes anyway, that LH does report the DAC voltage to be 
  the same in both instances.
 The oscillator can be powered from the board or given its own supply,  in 
 which case the only required connections between them are the two coax  leads.
  
 Using this arrangement, and some variation of a positive or negative  level 
 shifter if required, it becomes possible to use different  oscillators with 
 the Nortel board and it does become an even  more interesting toy.
  
 One limitation though when using the Nortel boards in this way is  that 
 they don't seem to share the versatility of the Thunderbolt when it comes  to 
 modifying the oscillator 

Re: [time-nuts] Nortel GPSDO osc age alarm

[Volker Esper]

Ignacio,

thanks for your message. Answeres within the text:

 And one word of caution: if you observe the cable that goes from the
 main board to the small interface board, you will see that one of the
 connectors is reversed so be careful if you make a custom one for your
 cabinet, do it in the same fashion.  
Yes, I've seen that by chance, when disconnecting the board to
reassemble the oscillator.
 Using a normal cable produces bizarre results that can actually drive
 you nuts, don't ask how I know.
It's a wonder you didn't kill the beast...
 ...the 9.8304 frequency has mislead some users to think that it was
 the 10 MHz output, not your case.
Me, too, at the beginning
 The seller (Bob Mokia , fluke.l) is well known to the Time Nuts
Yeah, of course, I know. The thing is, usually people are cautious
naming sellers. Time Nuts' point of view isn't quite that narrow. Ok,
yes, I admit, it's Bob ;-)
 1pps on the back d sub connector 
I read that, too, but like you I only found the even PPS.
 I have to put a scope on the DSR pin because it is the only connected
 to the main board other than TxD and RxD.  Could you verify this on
 your unit when you change the OCXO and get it running?
That's no problem, the GPS stuff works well on my item. I'll post a message.

Regards

Volker
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Re: [time-nuts] Nortel GPSDO osc age alarm

[Volker Esper]

Nice! I didn't know that. But what a number, 300... Why such a
digital-hostile factor? Why not 256 or 512?

Volker


Am 24.01.2014 20:51, schrieb tmil...@skylinenet.net:
 9.8304 MHz divided by 300 is 32,768 Hz.
 Feed that to an electronic clock and you will have an atomic clock of sorts.

 Regards




 Thomas Miller,
 Director of Wireless Services
 Skyline Network Engineering, LLC
 443-250-6381
 
 From: time-nuts-boun...@febo.com time-nuts-boun...@febo.com on behalf of 
 EB4APL eb4...@cembreros.jazztel.es
 Sent: Friday, January 24, 2014 2:27 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Nortel GPSDO osc age alarm

 Volker,

 I have also a Trimble Nortel NTG550AA and fortunately it works very well
 from the beginning.  I have a downloaded manual and some other info that
 I can send you if interested.
 And one word of caution: if you observe the cable that goes from the
 main board to the small interface board, you will see that one of the
 connectors is reversed so be careful if you make a custom one for your
 cabinet, do it in the same fashion.  Using a normal cable produces
 bizarre results that can actually drive you nuts, don't ask how I know.
 The coax connector, J5 is a 9.8304 MHz output, an odd frequency used by
 the cell tower equipment, J4 carries 1/2 PPS (even seconds), the next
 one (J1) is the for the antenna and J4 is the 10 MHz output. You already
 know that but I want to note that the 9.8304 frequency has mislead some
 users to think that it was the 10 MHz output, not your case.

 The seller (Bob Mokia , fluke.l) is well known to the Time Nuts, he has
 a technical background and normally known quite well what he sells and
 is very positive about solving the problems that may arise, his only
 problem is that his English is worse than mine .  I think that he
 regularly monitors this list.

 I have observed a strange thing on this offering, at the end of the page
 he says:

 power on it ...

 after 30 minutes/it will locked/10mhz come on the SMB connector

 1pps on the back d sub connector 

 I never heard of a 1PPS signal on these units, only 1/2 PPS on the J4
 coax and I had asked on this list if anybody had found how to extract 1
 PPS from the unit.   I have to put a scope on the DSR pin because it is
 the only connected to the main board other than TxD and RxD.  Could you
 verify this on your unit when you change the OCXO and get it running?

 Best regards,
 Ignacio EB4APL


 On 24/01/2014 16:23, Volker Esper wrote:
 ...thanks, Bob, it seems to be the oscillator, that is at it's limit, it
 cannot tune to 10 MHz at full EFC voltage, see new thread (started by Mark).

 Volker

 Am 24.01.2014 01:09, schrieb Bob Camp:
 Hi

 That’s a cell phone base station board. It’s got a bunch of outputs, some 
 of which are related to the cell network it was built for rather than 
 10MHz. I’d bet your 9.8 MHz output is one of those. They are DDS based so 
 there likely is some range of possible outputs.

 The age alarm is not unusual on a newly powered up board. It’s moving 
 faster than it should. It may settle down.

 The DAC at limit is not a real good sign ….

 Bob

 On Jan 23, 2014, at 6:43 PM, Volker Esper ail...@t-online.de wrote:

 Hi!

 I bought a Trimble/Nortel GPSDO

 http://www.ebay.de/itm/300933951405?ssPageName=STRK:MEWNX:IT_trksid=p3984.m1497.l2648

 and Lady Heather's now tells me that everything is alright - except
 - DAC 6.04V
 - OSC BAD
 - osc age alarm

 The rectangle 10MHz output signal (J5) shows a signal at about 9.8MHz
 (a deviation of about 200kHz), wobbling 4Hz up and down. Oddly enough,
 the direct oscillator output (J4) shows a sine wave at a stable
 10.004MHz (a deviation of 0.4Hz).

 It seems to me it's not the oscillator that is bad but the servo loop -
 what can I do?

 Thank you

 Volker
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Re: [time-nuts] Nortel GPSDO osc age alarm

[Volker Esper]

Oukaay - I should've known... Thanks, Jim!


Am 24.01.2014 21:12, schrieb Jim Lux:
 On 1/24/14 11:57 AM, Volker Esper wrote:
 Nice! I didn't know that. But what a number, 300... Why such a
 digital-hostile factor? Why not 256 or 512?

 Volker


 Am 24.01.2014 20:51, schrieb tmil...@skylinenet.net:
 9.8304 MHz divided by 300 is 32,768 Hz.
 Feed that to an electronic clock and you will have an atomic clock
 of sorts.

 Regards


 9.8304 is 300 baud * 32768.  So you can generate all the conventional
 digital data rates (1200,2400,.., 38.4k with powers of two). 
 Typically, a UART wants to see a clock that is 16x or 8x bit time, so
 you need something a bit higher.


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[time-nuts] Nortel GPSDO osc age alarm

[Volker Esper]

Hi!

I bought a Trimble/Nortel GPSDO

http://www.ebay.de/itm/300933951405?ssPageName=STRK:MEWNX:IT_trksid=p3984.m1497.l2648

and Lady Heather's now tells me that everything is alright - except
- DAC 6.04V
- OSC BAD
- osc age alarm

The rectangle 10MHz output signal (J5) shows a signal at about 9.8MHz
(a deviation of about 200kHz), wobbling 4Hz up and down. Oddly enough,
the direct oscillator output (J4) shows a sine wave at a stable
10.004MHz (a deviation of 0.4Hz).

It seems to me it's not the oscillator that is bad but the servo loop -
what can I do?

Thank you

Volker
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Re: [time-nuts] 32.768Khz Crystal/Resonator suggestions.

[Volker Esper]

Hi Dan,

I beg your pardon for being so curious, but where do you have to put
electronics in a thousand G's at 100Hz?

Thank you

Volker



Am 01.11.2013 17:30, schrieb Dan Kemppainen:
 Hi all,

 I've got a project upcoming that will require a frequency of 32.768 Khz
 in a harsh environment (Imagine a thousand G's at 100Hz with 150 Deg C
 temperatures). Also, this thing needs to be small, 2mmx1.5x1.5mm or so.
 It also has to be low power. Frequency stability is probably less of a
 concern than just surviving (some frequency error vs. temp can be
 trimmed out with other smarts in the design.


 In the past, crystals just haven't liked surviving due to the
 construction. Have had good luck with ceramic resonators at higher
 frequencies (50Mhz and up). I've also looked at silicon oscillators,
 which will work in the application, however with the chip and associated
 resistors/caps they get a little bigger that what I was hoping for.

 Is anyone aware of a frequency source (crystal/resonator or other) in a
 small package that is robustly mounted?

 Or are there any ceramic resonators available that are in small packages
 in those low frequencies? I checked the big distributors, and did not
 have any luck.


 Dan


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Re: [time-nuts] exponential+linear fit

[Volker Esper]

very cool

Am 07.10.2013 09:46, schrieb Ulrich Bangert:
 Jim,

 most if not all fitting strategies make use of an assumption concerning the
 underlying model.

 For those who are not sure what the underlying model is this one

 http://creativemachines.cornell.edu/eureqa

 is the hottest tool that I have ever seen. Give it a try.

 Best regards

 Ulrich

 -Ursprungliche Nachricht-
 Von: time-nuts-boun...@febo.com 
 [mailto:time-nuts-boun...@febo.com] Im Auftrag von Jim Lux
 Gesendet: Freitag, 4. Oktober 2013 19:38
 An: Discussion of precise time and frequency measurement
 Betreff: [time-nuts] exponential+linear fit


 I'm trying to find a good way to do a combination 
 exponential/linear fit 
 (for baseline removal).  It's modeling phase for a moving 
 source plus a 
 thermal transient, so the underlying physics is the linear term (the 
 phase varies linearly with time, since the velocity is constant) plus 
 the temperature effect.

 the general equation is y(t) = k1 + k2*t + k3*exp(k4*t)

 Working in matlab/octave, but that's just the tool, I'm 
 looking for some 
 numerical analysis insight.

 I could do it in steps.. do a straight line to get k1 and k2, 
 then fit 
 k3 k4 to the residual; or fit the exponential first, then do the 
 straight line., but I'm not sure that will minimize the 
 error, or if it 
 matches the underlying model (a combination of a linear trend and 
 thermal effects) as well.

 I suppose I could do something like do the fit on the 
 derivative, which 
 would be

 y'(t) = k2 + k3*k4*exp(k4*t)

 Then solve for the the k1.  In reality, I don't think I care as much 
 what the numbers are (particularly the k1 DC offset) so  
 could probably 
 just integrate (numerically)

 y'()-k2-k3*k4*exp(k4*t) and get my sequence with the DC term, linear 
 drift, and exponential component removed.


 The fear I have is that differentiating emphasizes noise. 
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Re: [time-nuts] 82357B GPIB USB from China

[Volker Esper]

I bought one about a year ago but couldn't get it running under Win XP.
There were a dozen well-meant advices on the forums that told me to read
the firmware and flash the beast with a better one. However, I
couldn't keep my nerve, so I purchased a Prologix adapter - which worked
instantly.

Volker


Am 10.09.2013 16:07, schrieb Bob Smither:
 My apologies if this is in the archives.  I could not find any discussion 
 about it.

 A seller on Ebay is offering a USB-GPIB interface equivalent to the Agilent 
 82357B:

  
 http://www.ebay.com/itm/82357B-GPIB-USB-Interface-Compatible-with-AGILENT-82357B-/261270515849?pt=LH_DefaultDomain_0hash=item3cd4efb089

 or

   http://tinyurl.com/qbsjjmr

 Has anyone here tried this?  In particular, can it be made to work under 
 Linux?

 I have the Prologix unit which works great with simple PERL scripts under 
 Linux,
 but always looking for a bargain!

 Thanks,



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Re: [time-nuts] My GPSDO project: OCXO Thermal Oscillation?

[Volker Esper]

Hi Bob,

treat your GPSDO like a closed loop control system. If  you could 
optimize the process itself, e.g. make it's behaviour linear or 
eliminate environmental inluences, you should. Then you have to know the 
characteristics of your process (the transfer coefficients of the 
controlled system). You can test it with a test pulse (e.g. put a 
voltage jump at the process input (EFC) and observe the process output 
(frequency)). You then can calculate the controller parameters and wich 
type of controller you want to use (P, PID,...). In the case of a 
precision system you shouldn't handle it straight intuitivly, rather use 
a little bit of control theory.


Volker




Am 16.08.2013 17:09, schrieb Bob Stewart:

I'm converting the code for the VE2ZAZ FLL to a PLL.  I'm seeing the phase correction 
change the EFC up and down about .02V to .03V over a period of 5 minutes or so (it 
varies).  The full range on the OCXO is about +/- 4Hz varied by 0 to +6V, so at least 
this is a tiny value.  I feel pretty confident with my code at this point.  I'm using a 
Trimble 34310-T OCXO for which I've been able to find almost no information.  Could this 
oscillating phase correction be some sort of thermal oscillation?  I've tried two 
separate 34310s and both act more or less the same.  My GPS device is normally a UT+, but 
I just now swapped in an Adafruit Ultimate GPS Breakout to the same effect.  
Is this good, bad, or indifferent for a GPSDO?  I started this project not knowing what 
to expect, and I still don't.  Experienced help, speculation, or even just kind words at 
this point would be appreciated!  =)  I don't have a known good/stable reference to 
compare this
  to.

Bob - AE6RV
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Re: [time-nuts] Rb video

[Volker Esper]

The number on the front panel shows 53 on the current picture...
That gives hope to those who still think about it... :-)

Volker



Am 08.08.2013 16:05, schrieb Dr. David Kirkby:

On 8 August 2013 14:49, mc235960mc235...@gmail.com  wrote:
   

None left from that batch.  Hope you got yours.
 

I suspect he has a lot. He originally listed 10, and all them have
gone, so he has listed another 10

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItemitem=161082475549

Dave
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Re: [time-nuts] How dangerous if Rb lamp broken?

[Volker Esper]

Thanks, Robert, for this detailed information.
Volker

Am 10.07.2013 21:01, schrieb Robert Atkinson:

Hi Hui,
This is a little off-topic for time nuts, but here goes. the
Becquerel is a measurement of radioactivity, 1Bq being one decay per
second. Bg/gm is specific activity so if you have 1g of material with a
specific activity of 200Bq/g you will have 200 decays per second. We
need to use this as not all the Rb in a lamp is Rb 87 and the weight
quoted includes it all. The Sievert is a measurement of effective dose.
It depends on time, quantity of radioactive material, type and energy of
  radiation emitted, distance and the organ exposed. It is not a simple
calculation or conversion. As Rb87 is a beta emitter with a maximum
energy of 272 keV, it will only produce localised effects. externally it
  will only cause skin exposure and you would need megabecquerels in
direct contact to cause something like a sunburn. Anything else
  would need internal exposure.
Rb87 is of so little concern that the
standard dose rate calculation program I use does not even list it.
Chemically Rb is similar to potassium, K, which is essential to humans. 
  Natural K contains 0.0117% of the radioactive isotope K40. A typical

70kg human male is 0.2%K so has more than 3000Bq of K40.  So if you
swallowed 2mg of the Rb from a bulb AND the body absorbed ALL of it, the
  total additional dose would be less than 0.1% of that you are getting
from the natural K in your body. In practice it would be even less
because your body would not absorb it all and that it did absorb would
probably displace some K. Intact Rb cells cells have on detectable
external radiation. My half gram estimate came from a web search of peer
  reviewed articles.
The US occupational ingestion limit is 1mCi or
37000Bq per year. Inhallation is twice that. US labs can discharge water
  to the sewer with 370Bq/liter of Rb87 
Rb cells are perfectly safe for all practical purposes. An injury from the broken glass is probably much more of a risk!



HTH,Robert G8RPI.



  From: Hui Zhangba...@163.com
To: Robert Atkinsonrobert8...@yahoo.co.uk; Discussion of precise time and frequency 
measurementtime-nuts@febo.com
Sent: Wednesday, 10 July 2013, 14:53
Subject: Re:Re: [time-nuts] How dangerous if Rb lamp broken?



Hello Robert:
I am a little confuse how exactly much Rb87 in a bulb? Some people say
that it's couple millgram,  but you tell
me it's half a millgram, which is ture?
You message is good new to me, it let me relax, but I don’t
understand Bq/gram unit, would you please convert it to mSV unit, I can know
the how many mSV of human is safety by search by internet. I mean in extreme
situration, if all Rb87 of buld sprinkled in my table, how many exposure value
will I accepet in 24 Hour?
I found some people (other electronics fan) wrote a formula about
Rb87 radioactivity calculation, that is:
1mg Rubidium * 27.835 * 0.27835 * 6.02 *10^23 /
87/4.88/10^10/2/365/24/3600*1=625.
So, decay energy=0.283MeV, about 600 electron per second, Is this calculation
correct?
  
27.835=Percent of Rb87

6.02*10^23 = Avogadro's constant
87= Atomic weight
4.88*10^10== Half time of Rb87 (Year)
2 = Rb87 decay to half
365 = day of year
24 = hour of day
3600 = second of hour
  
   I

am very glad to read many relay of my email, I want say thanks for everyone. As
you said why people be afraid of Rb87 but not other things, I think maybe
because we don’t understand it. Such as, I don’t afraid of RF exposure, because
I know it, I am a HAM and learned many RF exposure knowledge, but of atom and
radioactivity, I have only poor knowledge.
  
  
Thanks everyone again, this is amazing mail-list. Say sorry for my poor English.
  
Hui



At 2013-07-09 19:40:50,Robert Atkinsonrobert8...@yahoo.co.uk  wrote:
   

Hi Hui,
Most bulbs use a mix of Rb87 and Rb85 with an activity of around 1500 Bq/gram 
with less than half a millgram in a typical bulb, that's less than a Bq per 
bulb (about 20 picocuries). You will get more ardiation from using low sodium 
salt (potassium chloride) on your food. Potasium is essential for life and Rb 
is chemically similar.
In short don't worry.
Robert G8RPI (also a geiger nut and collector of radioactive material)



From: Hui Zhangba...@163.com
To: Discussion of precise time and frequency measurementtime-nuts@febo.com  
Sent: Tuesday, 9 July 2013, 5:07

Subject: [time-nuts] How dangerous if Rb lamp broken?


Dear Group:
 I have four compact Rb Stanard, but I am worried about what if my Rb lamp 
broken in accident someday? How dangerous of this situration? Is Rb87 came out 
from Rb lamp will be a disaster? You know I haven't any beta rays detect 
instrument.


Hui
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Re: [time-nuts] How dangerous if Rb lamp broken?

[Volker Esper]

Hi,

Toxicity is not the problem. Radioactivity was my biggest concern, when 
I ordered my first Rb-clock.The manufacturer told me, there's no 
radioactivity, that you have to fear. When the package came I used a 
Geiger tube to calm myself down - there was no measurable activity at all.


If the clock doesn't work anymore, be careful when opening it, the bulb 
could be broken (though impropable). I don't know how the Rubidium will 
react in such a case, but it can react with the air and start to burn 
(but remember, it's a very small amount) and you could get some mg of a 
strong base, which is corrosive/caustic.


To come to the point: You won't be able to wreak havoc with a Rb-lamp...

Volker


Am 09.07.2013 11:40, schrieb Attila Kinali:

On Tue, 09 Jul 2013 11:24:27 +0200
Magnus Danielsonmag...@rubidium.dyndns.org  wrote:

   

On 07/09/2013 06:07 AM, Hui Zhang wrote:
 

Dear Group:
  I have four compact Rb Stanard, but I am worried about what if my Rb lamp 
broken in accident someday? How dangerous of this situration? Is Rb87 came out 
from Rb lamp will be a disaster? You know I haven't any beta rays detect 
instrument.
   

Considering that you have 48,8 milliard years in half-time, you are
pretty safe. The problem is rather that it reacts to water and becomes a
strong base, so you want to keep it dry and well protected. Keeping it
in a clock chassi is good enough.
 

IIRC Rb is hygroscopic, ie keeping dry wont help, it will react with
the air humidity as well. But then, you have only a couple mg of Rb
in the cell. And the whole thing is enclosed. So you wont get much
exposure anyways. As for toxidity, AFAIK Rb by itself is not toxic.
Rb solution is, as Magnus said, a strong base, but you will get very little
of it and and i am not aware of any toxidity beside being a stron base.
So don't let it get into your eyes and you will be fine :-)

For comparison: Natrium hydroxide is sold in tablet form as un-clogging agent.
It is, for it being a strong base, rated with a high toxidity/danger class,
(about the same as hydrochloric acid) but is not toxic in it self.
Handling it is safe, unless you throw a lot of it into water.
In dry form, the most danger it poses is making soap out of the fat
in your skin :-)

Attila Kinali

   



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Re: [time-nuts] How dangerous if Rb lamp broken?

[Volker Esper]

Am 09.07.2013 14:16, schrieb Attila Kinali:

If radioactivity is a concern, you should stop eating bananas and
do not go down to your cellar. And for gods sake, stop flying! ;-)
   

...yes, and don't use mobiles and so on.

Radioactivity is a concern, because I don't have any serious experience 
with it. And I guess, many of us don't. And I totally lack a sense of 
the amounts of radioactive radiation. I know well, what a Volt is or an 
Amp and I know, where I have to put my fingers and where not on my lab 
desk. Going down to my cellar may expose myself to some radiation, but I 
don't work there for hours. Sitting at my lab bench for hours, daily, is 
another thing, if there is a radioactive contamination of an unknown 
radiation dose. Now, that we know, the amount is very little or zero, 
we're all happy. That's all, not more, not less. I only wanted to be 
cautious, and I guess, Hui, too.

The amount of Rb in a vapor cell is very little. You take in more radiocative
material by eating a banana. For the Rb to cause serious damage by burning, you 
need to drop a couple
of gramms into water. Anything else will not cause a fast enough reaction.
   

Interesting.

Beside, you have only a couple of milligram, not enough to cause anythingm
major.  Also, if the cell is broken it is most likely that the Rb is already
highly oxidized by the time you open it (and thus mostly harmless, beside
it's basic behaviour).

Yes. Broken glass is sharp and will cause serious cuts if not handled
carefully.
   
I think so. I only wanted to be careful with my advice, since I'm not a 
physicist or a chemist. By the way: I don't eat bananas, but for some 
other reason...


Volker



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Re: [time-nuts] How dangerous if Rb lamp broken?

[Volker Esper]

Am 09.07.2013 13:49, schrieb Robert Atkinson:

Why are so many people radiophobic?
In my opinion, the answere isn't hard to find. Those people don't have 
any experience with it and don't know, which information is correct. 
Radiation can be dangerous, there's no doubt about it, is it? The 
question is: is this paticular situation dangerous. So there's no sense 
in mocking someone or making fun of him. We just need enough information 
to estimate the risk. It would be better to inform someone who's scared 
with precise information.

Rant off,
   
Since I'm no native speaker, I'm not sure, what exactly you are meaning 
- declamatory, elevated, fray, excited?


Thanks

Volker

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Re: [time-nuts] Question about effect of sample interval on ADEV

[Volker Esper]

Bob,

Sorry, I'm not sure, if I've understood the issue - what exactly did you 
wrong?


Thank you

Volker


Am 08.07.2013 14:48, schrieb Robert Darby:

John,

After a night's sleep and a rereading of  your post I finally realized 
what I was doing wrong.  I did not understand the the role of the 
sampling interval setting and the display rate setting on the 5370.  
When I follow the process below the results are totally consistent.


Sorry to taken your time and thanks all for your help.  Now to find 
the original issue.


Bob Darby

On 7/7/2013 8:57 PM, John Miles wrote:
So the only difference between the test setups is the setting of the 
Display Rate control on the 5370, correct? You're allowing TimeLab to 
estimate the sample rate automatically, and giving it enough time to 
converge on a stable reading before hitting 'Start Measurement'? 
You're correct in that changing the real-world sample rate should 
yield results that are identical (or at least very similar) to 
resampling the phase data after the fact. In frequency mode, dead 
time between readings would make that an iffy proposition, but for 
data taken in TI mode the outcomes should be close. -- john, KE5FX 
Miles Design LLC 


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Re: [time-nuts] New to list and GPSDO questions

[Volker Esper]

...but remember, you don't need 10kHz to get the control loop working. 
Since you need a time constant of some hours, the PPS output will do. 
Even more important is to use a good OCXO.


By the way: welcome to the list :-)

Volker


Am 13.06.2013 12:20, schrieb cfo:

On Wed, 12 Jun 2013 20:29:26 -0700, Bob Stewart wrote:

   

I saw on K3PGP's site a mention that the UT-41 GPS
receiver had a 10KHz signal on-board so I decided, why not build a GPSDO
for my new HP 5334B?  Unfortunately the one I bought doesn't have a
10KHz point, and the board doesn't even pull out the 1PPS signal from
the chip.
 

As a backup plan have a look at this one *Bay 290860812674
It has 10Khz, afaik it's the one mentioned for the Miller GPSDO.

Make sure also to get the Antenna cable that belongs to it.

CFO
Denmark

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Re: [time-nuts] Ground loops in measurements?

[Volker Esper]

Moin Attila,

yes ground loops can cause serious measurement problems. And solving 
those could fill a hole book. Here's what I do in practical:

1.) avoid the loop
2.) if you can't, try harder to avoid it
- depending on the problem: break up the dc loop by using capacitors 
(most often you only need to kill 50/60 Hz so you can possibly insert a 
C in the shield)
- if you need dc current or extremly low frequencies flowing in the 
shield, use inductors in the shield to get rid of 50/60 Hz
- if you have to transfer low frequency rectangular pulses, you have to 
decide or even to try, what will be the better choice
- but that induces new problems if you have to be synchronous to within 
some ns...
- on the lab bench - if you can't avoid loops - make the area of the 
loop as small as you can to reduce the inducing field - keep shields 
together
- use a well grounded!! metal plate (use iron, if you can) under your 
experiment and lay the coax cables flat down on it

- as far as you can connect all case grounds at one point only
- if you are experimenting with low frequency on your bench you can try 
to not connect the shield on one side of the cable - be aware, that the 
current now takes another way, so that is practicable in only few 
situations (and if you fumble around it will change measurement conditions)
- use floating power supplies - but remember, they can be coupled to 
earth or the power line over the stray capacitance of the transformer 
(rather a problem for higher frequencies than 50/60 Hz)



Volker


Am 20.05.2013 14:08, schrieb Attila Kinali:

Moin,

A couple of weeks ago, there was a short discussion on bad connectors
and cables and the coupled in noise of those. Summarized it said that
measurements in the time-nuts scale are very sensitive to even the lowest
noise levels and coupled in signals.

But, all the measurements we do are done using some sort of coax which
have their shield connected to the case of the devices. As the invovled
devices in a measurement are also grounded over their power supply
this will lead to ground loops and thus a 50/60Hz noise. Also, because
loops are good magnetic antennas, a lot of other noise floating around
in the ether is coupled in (eg a nearby radio station).

How do you handle this kind of problems?

Attila Kinali

   



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Re: [time-nuts] Cesium wrist-watch-lite

[Volker Esper]

...if I understand what the article says, the watch won't be the demo 
board. So it has to be the price for thhe sheet cube itself.



Am 02.05.2013 01:31, schrieb Bob Camp:

Hi

Rummor has it that the single piece price in the US is $1475 for just the CSAC. 
Weather that's with or without the demo board ….

Bob

On May 1, 2013, at 11:45 AM, Volker Esperail...@t-online.de  wrote:

   

Cool. Is the Symmetricom CSAC SA.45s available to mere mortals? Which price 
could we expect?

Volker


Am 01.05.2013 14:57, schrieb Poul-Henning Kamp:
 

Looks a fair bit more comfortable than the one Tom's brother showed.

http://www.theregister.co.uk/2013/05/01/hoptroff_shows_first_atomic_watch_movement/


   


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Re: [time-nuts] Cesium wrist-watch-lite

[Volker Esper]

Cool. Is the Symmetricom CSAC SA.45s available to mere mortals? Which 
price could we expect?


Volker


Am 01.05.2013 14:57, schrieb Poul-Henning Kamp:

Looks a fair bit more comfortable than the one Tom's brother showed.

http://www.theregister.co.uk/2013/05/01/hoptroff_shows_first_atomic_watch_movement/

   



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Re: [time-nuts] Z38XX

[Volker Esper]

How do I recognize a wear out? Does the receiver send an error message 
every time I try to change the NVRAM or do I have to ask it?

Volker

Am 24.04.2013 00:08, schrieb Mark C. Stephens:

Thanks Ulrich, Much Appreciated, prefer to use your software.

Thanks Again,
mark

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf 
Of Ulrich Bangert
Sent: Tuesday, 23 April 2013 5:36 PM
To: Time nuts
Subject: [time-nuts] Z38XX

Gentlemen,

due to the discussion that evolved concerning Z38XX i looked up the sources and 
found that indeed every time the current time is read using a

:PTIM:TCOD?

a

:PTIM:TCOD:FORM F2

is sent in advance to make the receiver answer in the format that Z38XX needs. 
I have not been aware that this could lead to NVRAM wear out but have been 
thinking this simply sets the format of the next output. I have changed the 
software so that the FORM F2 command is now only written once after program 
start. The software can be downloaded from the usual place but I have currently 
no time to test it.

My own experiences with NV memory that can only be written for a limited number 
of times  (EEPROM on ATMEL processors) indicates that a clever made NV writing 
routine would first compare the NV contents to what shall be written on a byte 
by byte base and write only changed bytes.

Best regards

Ulrich Bangert
www.ulrich-bangert.de
Ortholzer Weg 1
27243 Gross Ippener

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Re: [time-nuts] Z38XX

[Volker Esper]

thanks

Am 24.04.2013 13:22, schrieb Bob Camp:

Hi

At least on the 53131, the first sign of wear out was an error message. I 
believe it was a self test message (checksum error). I could easily be wrong 
about that. We blew them out within 9 months of when they were first 
introduced. That was a long time ago.

Bob

On Apr 24, 2013, at 3:43 AM, Volker Esperail...@t-online.de  wrote:

   

How do I recognize a wear out? Does the receiver send an error message every 
time I try to change the NVRAM or do I have to ask it?
Volker

Am 24.04.2013 00:08, schrieb Mark C. Stephens:
 

Thanks Ulrich, Much Appreciated, prefer to use your software.

Thanks Again,
mark

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf 
Of Ulrich Bangert
Sent: Tuesday, 23 April 2013 5:36 PM
To: Time nuts
Subject: [time-nuts] Z38XX

Gentlemen,

due to the discussion that evolved concerning Z38XX i looked up the sources and 
found that indeed every time the current time is read using a

:PTIM:TCOD?

a

:PTIM:TCOD:FORM F2

is sent in advance to make the receiver answer in the format that Z38XX needs. 
I have not been aware that this could lead to NVRAM wear out but have been 
thinking this simply sets the format of the next output. I have changed the 
software so that the FORM F2 command is now only written once after program 
start. The software can be downloaded from the usual place but I have currently 
no time to test it.

My own experiences with NV memory that can only be written for a limited number 
of times  (EEPROM on ATMEL processors) indicates that a clever made NV writing 
routine would first compare the NV contents to what shall be written on a byte 
by byte base and write only changed bytes.

Best regards

Ulrich Bangert
www.ulrich-bangert.de
Ortholzer Weg 1
27243 Gross Ippener

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Re: [time-nuts] Z3805A OCXO p/n 3505A09422?

[Volker Esper]

Yes, indeed, I've got one with a 10811 and one with a symmetricom 5 MHz 
oscillator with doubler.

Volker

Am 19.04.2013 01:15, schrieb Charles P. Steinmetz:
Check the output on a spectrum analyzer for 5 MHz content.  I've seen 
several internet-sourced Z3805As that were explicitly claimed to have 
HP 10811-60165 oscillators, but actually contained unlabeled 
oscillators that look like this one and appear to be 5 MHz oscillators 
with doublers (the output contains 5 MHz at ~ -50 dBc).  I have heard 
that Symmetricom may have made oscillators fitting this description, 
but have no further knowledge.

...

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Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver

[Volker Esper]

Am 17.04.2013 15:23, schrieb David:

...
I have been looking into low jitter triggers for sampling systems
recently and will probably end up using a discrete differential
amplifier driving ECL logic.
   

Why discrete?

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Re: [time-nuts] Low-pass Filter for 5 and 10 MHz

[Volker Esper]

...but what about the phase jitter of the filter itself? While absolute 
phase shift may not (or may?) be an issue I guess that passive filters 
do have a phase jitter, too, due to mechanical vibration, tempco, and 
what else.


Particularly at frequencies where the filter response has sharp slopes 
(resonance or corner frequency) the phase variation (d phi / d f) is 
quite big. Thus small frequency changes lead to considerable phase shift 
variation what in turn should lead to phase jitter added to our holy 
signal - what about overall ADEV?


Wouldn't it be better to not filter the 10 MHz signal when used solely 
as a frequency standard?


I understand, that a high Q filter in a PLL reduces the phase noise of 
that oscillator - until the jitter of the filter becomes important. Am I 
wrong?


Volker


Am 12.04.2013 02:31, schrieb Richard (Rick) Karlquist:

Actually, the opposite is true.  Notches have the least phase
shift at the frequency being passed, which is what matters.
It is true that the phase shift at the notch frequency is
uncontrolled, but that is not important.  The HP8662A
had an interesting PLL synthesizer where they had 10 notch
filters for the first 10 harmonics of the sampling frequencies.
This minimized phase shift within the loop bandwidth that
detracted from phase margin.  I designers of the 8662
definitely know what they were doing.

Rick Karlquist N6RK

On 4/11/2013 5:02 PM, Alan Melia wrote:

Maybe a silly question but isnt the phase response of the filter
important in this application ?? notches have fairly vicious phase 
shifts.


Alan
G3NYK
- Original Message - From: Luciano Paramithiotti
timeok...@gmail.com
To: time-nuts@febo.com
Sent: Thursday, April 11, 2013 5:42 PM
Subject: [time-nuts] Low-pass Filter for 5 and 10 MHz


A simple low pass filter to cut second and third harmonics from a 5 
or 10

MHZ signal.
See the paper:
http://www.timeok.it/files/5_and_10mhz_low_pass_notch_filter.pdf

Luciano Timeok
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Re: [time-nuts] Connectors

[Volker Esper]

Yes, I use those compression types, too, for example

http://www.reichelt.de/F-Anschluss/IK-FKPS-49/3/index.html?;ACTION=3;LA=446;ARTICLE=87371;GROUPID=3538;artnr=IK+FKPS+49

Of course, everything has to match, the cable, the connector, the 
pliers. Be careful with the inner conductor. It's good up to 2 GHz, I 
didn't measure it above that frequency.


Volker


Am 11.04.2013 22:21, schrieb Gordon Batey:

Greetings,

I have used the longitudinal compression F connectors for some time now with
several GPS units and RG-6 cable.  They certainly appear to be waterproof
and quite sturdy.  Not inexpensive but very serviceable.  I found a kit with
the installation tool and connectors and separate connectors at LOWES that
does a nice job.  I also found one for BNC that use the same principle but
have not used it yet.  Gordon WA4FJC

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Re: [time-nuts] Low-pass Filter for 5 and 10 MHz

[Volker Esper]

Am 12.04.2013 18:24, schrieb Bob Camp:

A simple way to look at filter stability is to first look at group delay at
10 MHz...

That's what I meant (d phi / d f), I just wrote it in a roundabout way...

The higher the group delay,
the more likely you are to get into the sort of trouble you thinking about.
   

Yep, my apprehension...

Unless you are playing with 1x10^-15 at tau=1 sec sort of signals, or really
crazy environments (missile launch), you can get away with some filtering on
the signal. It's likely that the harmonics you remove would have caused you
as much grief as the stability you compromise with the filter.
   
I haven't launched missiles, yet :-), but am playing with GPSDO signals, 
and planning to build a distribution amp - so I am a bit afraid about 
using filters, at least high Q ones.


Thank you, Bob, for your comment.


-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Volker Esper
Sent: Friday, April 12, 2013 10:59 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Low-pass Filter for 5 and 10 MHz


...but what about the phase jitter of the filter itself? While absolute
phase shift may not (or may?) be an issue I guess that passive filters
do have a phase jitter, too, due to mechanical vibration, tempco, and
what else.

Particularly at frequencies where the filter response has sharp slopes
(resonance or corner frequency) the phase variation (d phi / d f) is
quite big. Thus small frequency changes lead to considerable phase shift
variation what in turn should lead to phase jitter added to our holy
signal - what about overall ADEV?

Wouldn't it be better to not filter the 10 MHz signal when used solely
as a frequency standard?

I understand, that a high Q filter in a PLL reduces the phase noise of
that oscillator - until the jitter of the filter becomes important. Am I
wrong?

Volker


Am 12.04.2013 02:31, schrieb Richard (Rick) Karlquist:
   

Actually, the opposite is true.  Notches have the least phase
shift at the frequency being passed, which is what matters.
It is true that the phase shift at the notch frequency is
uncontrolled, but that is not important.  The HP8662A
had an interesting PLL synthesizer where they had 10 notch
filters for the first 10 harmonics of the sampling frequencies.
This minimized phase shift within the loop bandwidth that
detracted from phase margin.  I designers of the 8662
definitely know what they were doing.

Rick Karlquist N6RK

On 4/11/2013 5:02 PM, Alan Melia wrote:
 

Maybe a silly question but isnt the phase response of the filter
important in this application ?? notches have fairly vicious phase
shifts.

Alan
G3NYK
- Original Message - From: Luciano Paramithiotti
timeok...@gmail.com
To:time-nuts@febo.com
Sent: Thursday, April 11, 2013 5:42 PM
Subject: [time-nuts] Low-pass Filter for 5 and 10 MHz


   

A simple low pass filter to cut second and third harmonics from a 5
or 10
MHZ signal.
See the paper:
http://www.timeok.it/files/5_and_10mhz_low_pass_notch_filter.pdf

Luciano Timeok
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Re: [time-nuts] FE-5680 frequency jump

[Volker Esper]

Thank you for this information, Bob! I have to reconsider the frequency 
jumps of my GPSDOs...

Volker

Am 05.04.2013 20:59, schrieb Bob Quenelle:
I found the cause of the 4 mHz  frequency jump.  I have an LPRO-101, 
an FE-5680, power supplies and a Motorola M12T GPS board in a surplus 
case. When I put the case away to work on another project I piled the 
hockey puck antenna and lead in the case and it happened to land on 
the FE-5680.  I noticed the antenna stuck firmly to the FE-5680 case 
when I got the project back out.  I found I could get a 6 mHz (0.6 
ppb) shift comparing the frequency with residual magnetism from the 
magnet stuck on the FE-5680 case to the frequency after demagnetizing 
the FE-5680 case.  Unintentional C field adjustment.  Dope slap, live 
and learn.

Bob

-Original Message- From: Magnus Danielson
Sent: Monday, April 01, 2013 5:13 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] FE-5680 frequency jump

On 04/02/2013 01:12 AM, Attila Kinali wrote:

On Mon, 01 Apr 2013 23:57:48 +0200
Magnus Danielsonmag...@rubidium.dyndns.org  wrote:


On 04/01/2013 10:06 PM, Bob Quenelle wrote:
I’ve been running an FE-5680 for maybe a total of 50 hours over the 
last
several months.  I found that an offset setting of 180 made it 
track GPS and
(previously-set) LPRO-101 10 MHz signals.  Even with power cycling, 
after
about 1/2 hour, with an offset setting of 180 the FE-5680 was 
stable. The
last time I turned on the FE-5680, it drifted with a setting of 180 
and
needed a new setting of –415 to track the other signals.  That’s a 
change of
595 counts and with a resolution of 6.8 uHz per count, a frequency 
change of
4 mHz (0.004 Hz) and 0.4 ppb.   Operation at the new setting is 
stable for
now.  The lock signal indicates lock and the power supply voltage 
is still

15V.  I haven’t checked lamp voltage or VCXO voltage as that requires
  opening the case.


How long have it been turned on since last power-up?

Let it sit for a day at least.

I've found that it is easy to be in too much hurry to judge the
situation and trim things efter power-up. The crystal oscillator just
doesn't get the time to settle in.


That might be indeed the case. Figure 3 in [1] gives quite high
frequency aging differences after switch on and long run time.



Attila Kinali

[1] 
http://www.pi5.uni-stuttgart.de/common/show_file.php/lectures/100/blaetter/The%20Rubidium%20Clock%20and%20Basic%20Research.pdf 





You are confusing the VCXOs frequency drift with that of the rubidiums
(which is the result of the FLL locking of the VCXO to the rubidium
resonance).

If the VCXO still has a fair distance to drift, then false locking can
occur while compating the initially quite vigorous drift rate. The only
real way to handle that is to sit and wait for it to settle down. Only
after that may trimming of the oscillator be done to zeroize the
integrator state.

A small commercial rubidium doesn't need very long to get a feel if it
is in good condition or not, but sitting on your hands and let it warm
up gives you a fair idea of just how skewed situation it is. That's also
true for caesium clocks.

So, sit on your hands and let it settle. Better yet, leave on while you
do other things. Just recall to put enought cooling on it!

Cheers,
Magnus
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[time-nuts] SR620: cal error 23

[Volker Esper]

Hi all,

While auto calibrating the SR620 I get the message cal error 23 - the 
manual isn't that specific about this message, it only states, that 
error numbers 19 to 23 are caused by Stop TAC problems. However, the 
counter counts, but I can't do automatic calibration any more.


Anyone having experience with that?

Thanks a lot

Volker

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Re: [time-nuts] SR620: cal error 23

[Volker Esper]

Am 18.03.2013 18:00, schrieb Herbert Poetzl:

The manual also states that error codes 19-23 are the
same as the start values (n - 16), so 23 minus 16 should
be the same as '7' i.e. 'stop linearity byte out of range'
   

Where do you read that, I can't find it :-/

Volker

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Re: [time-nuts] SR620: cal error 23

[Volker Esper]

Am 18.03.2013 19:53, schrieb Herbert Poetzl:

page 40, search for 'stop tac'
   
Herbert, you are the best :-) I didn't expect the error codes in the 
programming commands section.


I'm afraid it could be a hardware failure.

Thanks Volker



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Re: [time-nuts] SR620: cal error 23

[Volker Esper]

Running Auto Cal a few seconds after switching the counter on, the 
calibration succeeds, though with values different from the warm ones 
(who'd have thunk). After warming up, error 23 wins. I have to open it 
and do the old school trouble shooting with coolant spray...


However, any advice, tip, hint would be appreciated.

Thank you

Volker


Am 18.03.2013 20:33, schrieb Volker Esper:


Am 18.03.2013 19:53, schrieb Herbert Poetzl:

page 40, search for 'stop tac'
Herbert, you are the best :-) I didn't expect the error codes in the 
programming commands section.


I'm afraid it could be a hardware failure.

Thanks Volker



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Re: [time-nuts] HP53132A vs SR625

[Volker Esper]

Hi,

I just powered on my SR and looked for the offset, when the 10 MHz 
reference is connected to the input (at a gate time of 1s without 
further averaging). It shows an offset of 0 to 400uHz which should 
represent a mean error of 2E-11, while the manual predicts an error of 
about 1E-10 (as Said told us, and as my manual tells me). That's within 
the spec.


Unfortunately I don't have a 53132, but the manual of the HP predicts an 
error of E-10 - just the same value as with the SR.


If I was a manufacturer of such a counter, I wouldn't show the digits 
beneath the predicted error, but SR does: it shows 13 digits. How many 
digits does the HP show? Could it be, that the HP shows one or two 
digits less at this measurement? With only 11 digits displayed, the SR 
wouldn't show any offset, too.


By the way, HP's 100ps isn't the worst case value - that is 500ps.

So, what's the big difference beetween them?
- the predicted error is the same for both (or am I wrong?).
- my SR is within it's specification at 10 MHz (I did the calibration 
myself).
- the uncertain digits (below 1mHz, in this case) are within the error 
spec, and I guess they are uncertain because they come from an analog 
circuitry (namely the interpolation circuitry). The statement, that a 
counter only has to count zero crossings and nothing else, isn't right 
at that point, and that's the case for both,

- and they both have to deal with the analog stuff, such as noise and so on

Again, since I don't have a 53132 I can't compare the counters directly, 
I was just a little concerned about a discussion - no offense! - that 
compares apples and oranges.


Thank you for a still inspiring discussion!

Volker





Am 17.03.2013 20:05, schrieb saidj...@aol.com:

Ed,

the calculation is the same, however the numbers are 100ps for 53132A
versus 350ps, and I have not seen an average systemic offset being displayed on
any of the 3x 53132A units I use, and I see one on the SR-620. That's  why
I sent it into SRS for calibration, paid the $$$ and got it back with the
same exact offset and a statement that it is operating within specifications
so  no adjustment is necessary.

HP manages to show zero error on average, with the digits bouncing back and
  forth. The SRS unit manages to show a hard frequency offset. If I remember
  correctly the SR-620 even shows this offset with it's own reference
connected to  the inputs, the HP does not.

bye,
Said


In a message dated 3/17/2013 11:26:16 Pacific Daylight Time,
ed_pal...@sasktel.net writes:

Hi  Said,

That equation looks similar in form to the specs for any counter.  What
are the comparable equations for the  53132A or the 5370(A or  B)?

Ed

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Re: [time-nuts] HP53132A vs SR625

[Volker Esper]

What small error are we speaking about? The statement that SRS users 
have to tolerates a small error while HP users don't seems a little to 
general to me. IMHO we might be a bit more precise. Anyone who's already 
done an error analysis for - say - a 10MHz count and a comparison of the 
counters?


In real life every type of equipment has it's domain, where it has it's 
specific advantage. Could it be, that's the case for these counters, too?


Cheers

Volker


Am 16.03.2013 19:57, schrieb Rick Karlquist:

1) I paid quite a bit of money and I had it calibrated and fixed by
SRS,
and it still exhibits a significant frequency offset with a perfect
reference  and perfect DUT!!!
   
 

SRS says a small frequency error is normal, well that prevents me from
using the unit as a frequency counter, for me it's only useful as a
relative
display frequency counter. HP doesn't have such a frequency error, so no
worries there.
   

I worked with the guy who designed the HP53132A.  He would
never tolerate as normal a so-called small error.  The term
frequency counter brings to mind something that digitally counts
zero crossings and should never have an error.  First of all, even
if that is all you do, it is still possible to screw it up.
Secondly, counters have relied on analog interpolation even going
back to the HP524 circa 1950.  There is no theoretical basis of having zero
error in this case, but the idea is that you display the number of
digits that are commensurate with the worst case accuracy of your
interpolator.  Again, my colleague who designed the interpolator
did very high quality work.  I am pleased to learn that our stuff
is better than the stuff from the company up the road.

Rick Karlquist N6RK
HP Santa Clara Division 1979-1998
(still working for Agilent!)

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Re: [time-nuts] Distribution amplifier phase noise

[Volker Esper]

Am 14.03.2013 19:02, schrieb Bruce Griffiths:


This paper is very sloppily written. e.g.:


Yes, actually.


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Re: [time-nuts] Thunderbolt antenna

[Volker Esper]

Hi Peter,

Why not. The antenna is optimized for that purpose (receiving GPS L1), 
omnidirectional and tuned to the GPS frequency, snow skids down, birds 
can't land on it. As N0UU affirms, there's nothing further sensational 
inside.


I don't know, how proficient you are with radio frequency stuff, but a 
gain of 35dB does not guarantee a good reception. You primarily need 
gain to compensate (cable) losses. The noise figure (NF), for example, 
can get much more important.


What antenna do you use at the time? If you are using a magnetic car 
roof antenna a Trimble Bullet surely will be a better choice...


There are lots of GPS antennas on ebay for even less than 30 Dollars. I 
run four different antennas, which I purchased from ebay and none of 
them has failed so far.


Volker






Am 10.03.2013 06:07, schrieb Peter Gottlieb:

I'd like to get a better antenna for my Thunderbolt.

I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, 
specs look to be 5 volt 35 dB gain.


Would something like this be a good choice?

Peter



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Re: [time-nuts] Thunderbolt antenna

[Volker Esper]

To me, that seems to be a much more important issue than suggestions 
about the right cable.

Volker

Am 10.03.2013 21:48, schrieb Bob Camp:

Hi

You do need to be a little careful with gain. Past a certain point, you do no 
more good for the noise figure of the system , but you do degrade the overload 
performance.

Bob

On Mar 10, 2013, at 3:40 PM, Chuck Forsberg WA7KGX N2469Rc...@omen.com  wrote:

   

I bought one of the 40 db gain GPS antennas that were on Ebay
some time ago.  I had been using a mushroom style antenna with
an rg-59 lead that came with one of the Thunderbolts.  I have
maybe 75 feet of rg-6 lead in.

Rg-6 sold for satellite dishes or cable companies should do just fine
without requiring a second mortgage on one's house.  Try to liberate
some from your cable guy or order some from pchcables.com.

--
 Chuck Forsberg WA7KGX   c...@omen.com   www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
  Omen Technology Inc  The High Reliability Software
10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430

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

[Volker Esper]

Yes, we all have to learn that lesson...

At the time I use bedea RG-223 and Belden H155 with soldered and crimped 
Telegaertner BNC connectors as general purpose cable (up to 2 GHz). 
Above that frequency I wouldn't use BNC. If you simply connect your 
tracking generator with the spectrum analyzer by using such a BNC cable 
there's not one that is absolutely stable when stressing the connector. 
I tried several manufacturers, HP, Suhner, Radiall, Rosenberger, it's 
always the same.


To make precise measurements I prefer screwed connectors like N or SMA.

Volker


Am 03.03.2013 17:30, schrieb Jim Lux:

On 3/3/13 8:00 AM, Kevin Rosenberg wrote:

On Mar 3, 2013, at 7:59 AM, John Ackermann j...@febo.com wrote:
Lesson learned -- use only double-shielded cable in the oscillator 
rack (and in any RF measurement path) from now on.


I've learned that lesson as well. John Miles said that RG-58 is 
occasionally referred to as 'soaker hose'.


RG-58 (which by the way, is a spec that officially no longer exists as 
part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military 
apparently doesn't use PVC insulated wire any more.) comes in myriad 
forms all of which bear a passing resemblance to each other.  (leaving 
aside the RG-58A, RG-58, RG-58C differences).


The term seems to be used for any 50 ohm single shield coax that's 
about 0.20 inch in diameter with solid polyethylene insulation. You 
really need to look at the specific model number to know what the 
shielding looks like. It could be anything from a  very loose weave of 
thin copper strands to something nice and dense.






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

[Volker Esper]

RG-223 fits with Telegaertner J01000B0608 (Solder), Buerklin 78F201
or Rosenberger 51S107-108N4 (Crimp)
(straight plugs BNC)
H155 fits with Telegaertner T00100B3300 N Crimp)
...



Am 03.03.2013 19:50, schrieb Henk ten Pierick:

Hi,

The use of double shielded cables does raise the question to what type of 
connectors to use?

Regards,

Henk

Op 3 mrt. 2013 om 17:30 heeft Jim Luxjim...@earthlink.net  het volgende 
geschreven:

   

On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
 

On Mar 3, 2013, at 7:59 AM, John Ackermannj...@febo.com  wrote:
   

Lesson learned -- use only double-shielded cable in the oscillator rack (and in 
any RF measurement path) from now on.
 

I've learned that lesson as well. John Miles said that RG-58 is occasionally 
referred to as 'soaker hose'.
   

RG-58 (which by the way, is a spec that officially no longer exists as part of 
MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use 
PVC insulated wire any more.) comes in myriad forms all of which bear a passing 
resemblance to each other.  (leaving aside the RG-58A, RG-58, RG-58C 
differences).

The term seems to be used for any 50 ohm single shield coax that's about 0.20 
inch in diameter with solid polyethylene insulation. You really need to look at 
the specific model number to know what the shielding looks like. It could be 
anything from a  very loose weave of thin copper strands to something nice and 
dense.





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Re: [time-nuts] Z3805A/58503A time receiver : 2 questions

[Volker Esper]

Claude,

I see a jump even smaller than the first one and as I calculated before 
(in an answere to Said's mail) this latest jump is much less than the 
first one of 550 microHz. I agree with Said that this could be a crystal 
jump.


If you want to check the GPSDO's absolute frequency you'd need a second 
GPSDO... If you want to check it's stability - how do you know that it's 
the GPSDO that jumps? Ok, you see a synchonous jump on the EFC voltage, 
that's a good evidence.


If you want to compare the frequency of your 5334B (nice thing, by the 
way), the accuracy of your locked GPSDO should be sufficient - the 
uncertainty of your locked GPSDO might be in the range of several uHz...


Since GPSDOs make use of highly stable OCXOs to maintain short time 
stability (and improve side band noise) it depends on your oscillators, 
which one has better stability, the 5334B built-in osc, or the GPSDO 
osc. On the picture on ebay I recognize an HP type (most likely 10811) 
which is known for it's very good stability performance. I guess it's 
not easy to find an oscillator that can beat the 10811.


I use my GPSDOs as external references for my counters and all that 
stuff (amateur radio equipment, spectrum analyzer,...) and I'd recommend 
that.


...The receiver is a 6 channels and it outputs two 10 MHz and one PPS.

I think my statement about the osc frequency was a bit unclear. All the 
Z38xx have 10 MHz outputs (as far as I know). But the OCXOs inside the 
units are different - there are 10 MHz types (HP 10811) (like yours, as 
it seems) and 5 MHz types (Symmetricom), which have a doubler to achieve 
the 10 MHz.


To cut a long story short, I think, your GPSDO is working fine. With an 
antenna seeing some more of the hemisphere it would be working even 
better, I think... :-)


Volker


Am 02.03.2013 13:15, schrieb Claude Fender:

Thanks you both for your answers.

I had another jump (positive this time, 24h after the first one) and the efc 
curve came back to its previous state, see : 
http://uppix.net/f/4/d/c5a277798ca58bb04b41481ece6e7.png.

The receiver is a 6 channels and it outputs two 10 MHz and one PPS.
The antenna has noname and it is installed on a balcony, that's why it has a 
poor reception. Sure this is not perfect and I have to improve that.
The log is running every 5 minutes and I didn't notice a holdover mode of the 
oscillator.

(I've bought this GPSO to check the frequency of my 5334B for gates times of 
60s and 100s. I know I can use the 10MHz of the GPSDO as Frequency Reference 
for the 5534B but I wanted to check its frequency first !)



  De : Volker Esperail...@t-online.de
À : time-nuts@febo.com
Envoyé le : Jeudi 28 février 2013 2h12
Objet : Re: [time-nuts] Z3805A/58503A time receiver : 2 questions


If your unit is exactly like that on ebay 251226027893, it has a 10 MHz HP 
oscillator in a double oven, and it's absolutely sure that it's got a 6 channel 
receiver.

I should have read before, sorry.

I'm still not sure about your antenna, is it a Garmin? Well, it's most likely 
an active type, so what gain does it have? If you installed it on a roof top, 
it should see sufficient field strength.
Then do that simple test: disconnect your antenna from the receiver unit and 
measure with a multimeter the voltage at the center pin of your N connecter 
antenna plug. It has to show 5 Volts, otherwise your antenna can't be working 
well.

Volker


Am 28.02.2013 01:26, schrieb Volker Esper:
   

Hi Claude!

Said says, you should see 6+ sats, I guess he means _at_least_ six. I'm almost 
sure, you've got a 6 channel receiver, so you naturally cant't get more than 6 
sats at a time.

There are some different models of the Z3805A out there, though they're all 
named the same. I've got two units, one with an 8 channel and one with a 16 
channel receiver. My 8channel unit never receives more than 6 sats at a time, 
never. So I'm shure, it's a 6 channel type...

Maybe I should improve my antenna. But the same antenna provides enough voltage 
to receive 12 to 14 sats at once with the 16 channel unit. On the other hand, 
my 6/8 channel gizmo very rarely shows less than 6 sats, so, like Said, I too 
think, that there is some space for improving your antenna. What antenna do you 
have?

One day, while using the 16 channel unit, I experienced the same hops as you 
did. All time nuts told me that it had to be a crystal jump. I read about such 
phenomenons and all I found was, that the jump in my receiver was too big to 
fit to the idea of a crystal jump. Unfortunately my receiver gained fun in 
jumping. Now I'm absolutely not sure what it is. Maybe it's a faulty 
oscillator. Which one do you have built in? A 5 or a 10 MHz type? I've got a 10 
MHz HP and a 5 MHz Symmetricom oscillator.

Cheers

Volker



Am 28.02.2013 00:17, schrieb Claude Fender:
 

Hello,

This is my first message here although I read this list for a few weeks.

I bought a Z3805A/58503A frequency

Re: [time-nuts] Z3805A/58503A time receiver : 2 questions

[Volker Esper]

Hi Claude!

Said says, you should see 6+ sats, I guess he means _at_least_ six. I'm 
almost sure, you've got a 6 channel receiver, so you naturally cant't 
get more than 6 sats at a time.


There are some different models of the Z3805A out there, though they're 
all named the same. I've got two units, one with an 8 channel and one 
with a 16 channel receiver. My 8channel unit never receives more than 6 
sats at a time, never. So I'm shure, it's a 6 channel type...


Maybe I should improve my antenna. But the same antenna provides enough 
voltage to receive 12 to 14 sats at once with the 16 channel unit. On 
the other hand, my 6/8 channel gizmo very rarely shows less than 6 sats, 
so, like Said, I too think, that there is some space for improving your 
antenna. What antenna do you have?


One day, while using the 16 channel unit, I experienced the same hops as 
you did. All time nuts told me that it had to be a crystal jump. I read 
about such phenomenons and all I found was, that the jump in my receiver 
was too big to fit to the idea of a crystal jump. Unfortunately my 
receiver gained fun in jumping. Now I'm absolutely not sure what it is. 
Maybe it's a faulty oscillator. Which one do you have built in? A 5 or a 
10 MHz type? I've got a 10 MHz HP and a 5 MHz Symmetricom oscillator.


Cheers

Volker



Am 28.02.2013 00:17, schrieb Claude Fender:

Hello,

This is my first message here although I read this list for a few weeks.

  I bought a Z3805A/58503A frequency receiver  and I didn't notice on the 
pictures that the model number was not  written on the front panel. It's not 
important but is there a reason for that, if you know ?
The item : http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItemitem=251226027893


I log some parameters of the receiver and today I notice a gap in the 
frequency.

Picture : http://uppix.net/e/2/4/cf39ac772e5a69fc616f5cf30f208.png

I have a Rubidium and I measure it's frequency with a 5334B counter locked to the GPS, 
and I can see the gap too :
http://uppix.net/f/b/a/d86c2737ad135264e4a2b78e503d5.png
measurements are with Gate Time of 10s, 60s and 100s,


Do you know why this happens and how to prevent this behaviour ?

Thanks for yours advices


Claude
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Re: [time-nuts] Z3805A/58503A time receiver : 2 questions

[Volker Esper]

I just calculated the frequency offset. I count 5 crosses, while jumping 
down to 200 ns, I guess, 1 cross equals 10 min? So let's say the jump 
lasts 60 min (= T jump). When we want to calculate the frequency offset 
out of a phase jump, we have to differentiate the phase and we should 
achieve


delta f = delta phase / delta T
delta f = (delta t / T period) / T jump
delta f = (200ns / 100ns) / 60 min
delta f = 0,55 mHz (milli, not Mega!)

What precision / stability do you demand?

Volker


Am 28.02.2013 00:47, schrieb saidj...@aol.com:

Hello Claude,

that gap is a classic crystal jump. It could be caused by the crystal
changing frequency by itself, or by being hit with e.g. gamma particles etc.
Could also have been instigated by vibration or shock to the unit.

You should be seeing 6+ sats at all times though, your plot shows you
sometimes seem to see 2 or 3 sats only? Maybe a better antenna position would
help the stability of that unit.

Nothing to worry about if it doesn't happen regularly. Enjoy,

bye,
Said


In a message dated 2/27/2013 15:18:51 Pacific Standard Time,
lab...@yahoo.fr writes:

Hello,

This is my first message here although I read this  list for a few weeks.

I bought a Z3805A/58503A frequency  receiver  and I didn't notice on the
pictures that the model number was  not  written on the front panel. It's not
important but is there a reason  for that, if you know ?
The item :  http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItemitem=251226027893


I log some parameters of the receiver and today I notice a gap  in the
frequency.

Picture :  http://uppix.net/e/2/4/cf39ac772e5a69fc616f5cf30f208.png

I have a  Rubidium and I measure it's frequency with a 5334B counter locked
to the GPS,  and I can see the gap too  :
http://uppix.net/f/b/a/d86c2737ad135264e4a2b78e503d5.png
measurements  are with Gate Time of 10s, 60s and 100s,


Do you know why this  happens and how to prevent this behaviour ?

Thanks for yours advices


Claude

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Re: [time-nuts] Z3805A/58503A time receiver : 2 questions

[Volker Esper]

If your unit is exactly like that on ebay 251226027893, it has a 10 MHz 
HP oscillator in a double oven, and it's absolutely sure that it's got a 
6 channel receiver.


I should have read before, sorry.

I'm still not sure about your antenna, is it a Garmin? Well, it's most 
likely an active type, so what gain does it have? If you installed it on 
a roof top, it should see sufficient field strength.
Then do that simple test: disconnect your antenna from the receiver unit 
and measure with a multimeter the voltage at the center pin of your N 
connecter antenna plug. It has to show 5 Volts, otherwise your antenna 
can't be working well.


Volker


Am 28.02.2013 01:26, schrieb Volker Esper:


Hi Claude!

Said says, you should see 6+ sats, I guess he means _at_least_ six. 
I'm almost sure, you've got a 6 channel receiver, so you naturally 
cant't get more than 6 sats at a time.


There are some different models of the Z3805A out there, though 
they're all named the same. I've got two units, one with an 8 channel 
and one with a 16 channel receiver. My 8channel unit never receives 
more than 6 sats at a time, never. So I'm shure, it's a 6 channel type...


Maybe I should improve my antenna. But the same antenna provides 
enough voltage to receive 12 to 14 sats at once with the 16 channel 
unit. On the other hand, my 6/8 channel gizmo very rarely shows less 
than 6 sats, so, like Said, I too think, that there is some space for 
improving your antenna. What antenna do you have?


One day, while using the 16 channel unit, I experienced the same hops 
as you did. All time nuts told me that it had to be a crystal jump. I 
read about such phenomenons and all I found was, that the jump in my 
receiver was too big to fit to the idea of a crystal jump. 
Unfortunately my receiver gained fun in jumping. Now I'm absolutely 
not sure what it is. Maybe it's a faulty oscillator. Which one do you 
have built in? A 5 or a 10 MHz type? I've got a 10 MHz HP and a 5 MHz 
Symmetricom oscillator.


Cheers

Volker



Am 28.02.2013 00:17, schrieb Claude Fender:

Hello,

This is my first message here although I read this list for a few weeks.

  I bought a Z3805A/58503A frequency receiver  and I didn't notice on 
the pictures that the model number was not  written on the front 
panel. It's not important but is there a reason for that, if you know ?
The item : 
http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItemitem=251226027893



I log some parameters of the receiver and today I notice a gap in 
the frequency.


Picture : http://uppix.net/e/2/4/cf39ac772e5a69fc616f5cf30f208.png

I have a Rubidium and I measure it's frequency with a 5334B counter 
locked to the GPS, and I can see the gap too :

http://uppix.net/f/b/a/d86c2737ad135264e4a2b78e503d5.png
measurements are with Gate Time of 10s, 60s and 100s,


Do you know why this happens and how to prevent this behaviour ?

Thanks for yours advices


Claude
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Re: [time-nuts] Looking for Z3801

[Volker Esper]

...3805... better receiver...
Bear in mind, there are several versions out there with very different 
receivers and oscillators. I've got one with an 8-channel- and one with 
a 16-channel receiver.


Volker


Am 14.02.2013 22:12, schrieb Rex:

Here is a Z3816a -- 271152849045
I don't know the seller but has lots of sales.

3816 requires no serial configuration (like 3801) and has two 10 MHz 
out standard. Several years back I came up with a mod to convert the 4 
19...MHz outputs to additional 10 MHz square outputs. -- 
http://www.xertech.net/Projects/Z3816/3816_mod.html


If the picture matches the unit, this one needs +20 to 72 V. I run 
mine on +28V.


3805 is also good (better receiver) but I haven't looked for listings 
today.




On 2/14/2013 6:14 AM, Greg Broburg wrote:

Hello

I am looking for a working Z3801 for a shop bench reference.

Located in Minneapolis.

I see that there is essentially nothing on eBay.

Considering T-Bolt or Z3805 also.

Greg



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Re: [time-nuts] switchers

[Volker Esper]

No shipment to Europe...

Am 13.02.2013 21:51, schrieb Don Latham:

lot of 4 16 in 12 out, 251144853198
Don



   



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Re: [time-nuts] Nifty MINI TIC for DMTD

[Volker Esper]

I bought a stereo microscope some days before and I agree with Bob. I 
keep building non-RF projects the classical way (through hole) but if it 
comes to radio frequency I prefer SMD since high frequency is easier to 
handle. Can you tinker with the idea of buying a stereo microscope? It's 
absolute fun to easily solder those miniature parts!


Volker - DF9PL


Am 08.02.2013 01:15, schrieb Robert Darlington:

On Thu, Feb 7, 2013 at 4:02 PM, Don Lathamd...@montana.com  wrote:

   

through hole forever :-)
Don of the old hands and blurred vision :-)

ewkehren
 



I grew out of thru-hole about 10 years ago.  My nearly 40 year old eyes
have trouble reading the numbers on 0603 parts for the past few years, but
it's amazingly easy under a stereo microscope.  Much faster to stuff boards
with surface mount parts since I don't need to keep flipping them over and
cutting leads.  Even folks with very shaky hands can solder up tiny surface
mount parts.  The brain is an amazing PID controller.  Using a microscope
at 30x means your hands shake at about 1/30th of what they did before.

-Bob
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Re: [time-nuts] HP53132A vs SR625

[Volker Esper]

If the SR is in good shape I would prefer the SR. I love my one not only 
for it's technical data but also for the way of operation. Less menues, 
more controls, logically arranged.


Volker


Am 07.02.2013 17:53, schrieb Azelio Boriani:

The SR625 at the same price of the HP53132A: either the HP is overvalued or
the SR625 is a real bargain...

On Thu, Feb 7, 2013 at 5:36 PM, Bob Campli...@rtty.us  wrote:

   

Hi

The SR625 is a SR620 with a rubidium time base. If the Rb is in good shape,
and you don't have a house standard, then that's a significant plus.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Hui Zhang
Sent: Thursday, February 07, 2013 9:43 AM
To: time-nuts@febo.com
Subject: [time-nuts] HP53132A vs SR625

Dear Group:


 I am intend to buy a second-hand counter, I have not decided yet
between
SR625 and HP53132A, they have very close price in surplus market of here,
so, which is better choice? Any suggestion will be appreciated.


Best Regards!


Hui Zhang
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Re: [time-nuts] ***SPAM*** Brad Parkinson: GPS for Humanity

[Volker Esper]

oh, well, very interesting and delighting
Thanks, Hal!


Am 02.02.2013 09:51, schrieb Hal Murray:

Stanford has an Engineering Heroes program.
   http://engineering.stanford.edu/about/heroes
Brad Parkinson was elected last year.  This is the video of his talk last May.

In case you don't recognize the name, he's the Father of GPS.  No surprise,
but he's a very good speaker.

Bradford Parkinson GPS for Humanity - Stanford Engineering Hero Lecture
   http://www.youtube.com/watch?v=d6I6wFf-X_c

His PhD is from Stanford and he is now Professor Emeritus.  In between, he
was in the Air Force managing the GPS program and teaching at Stanford.

It's a high level talk, far from focused on geeky technical details.  Several
times his slides said GP(t)S to remind people about time.  He mentioned
jammers and LightSquared and common view.


   



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Re: [time-nuts] How far can I push a crystal?

[Volker Esper]

My friend Karl-Heinz DJ7NN has dragged/jerked/teared/wrenched crystals 
even more (what is the most nasty description of pulling a quartz 
crystal?) - if need be, he opens it and strikes a brush over it to 
carefully grind some material, what makes it oscillating a little 
faster. If you've ground too much, make a stroke with a pencil on it and 
it will oscillate slower. But the aging...


Ok, the drawback is, you won't get a very clean signal...

In my humble opinion, as Ed told before: forget about it.

Volker




Am 18.01.2013 00:59, schrieb Rick Karlquist:

Ed Breya wrote:

I've got to make a very clean 10.0594... MHz VCXO for a redo of one
of my old circuits. I previously used a 10 MHz ceramic resonator, which


Forget about it.  This is well beyond even the lunatic fringe of pulling.

Rick


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Re: [time-nuts] How far can I push a crystal?

[Volker Esper]

If you need a very clean signal - what would mean, stable (and 
accurate) you'll have to purchase one. There are manufacturers that do 
the job for, say, 30 Dollars? if it is a normal cut. If you like to get 
a crystal for a specific temperature to build your own oven (to achieve 
a very stable frequency) you can use an SC-cut - what is propably much 
more expensive.


Volker



Am 18.01.2013 01:16, schrieb Hal Murray:

Forget about it.  This is well beyond even the lunatic fringe of pulling.


So how far can I pull a crystal?

Does it depend upon the cut or anything that turns into price?






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Re: [time-nuts] How far can I push a crystal?

[Volker Esper]

Here an example manufactorer in my country:
http://www.quarztechnik.com/eng/hochfrequentequarze.html

or
http://www.icmfg.com/


Am 18.01.2013 01:31, schrieb Volker Esper:


If you need a very clean signal - what would mean, stable (and
accurate) you'll have to purchase one. There are manufacturers that do
the job for, say, 30 Dollars? if it is a normal cut. If you like to get
a crystal for a specific temperature to build your own oven (to achieve
a very stable frequency) you can use an SC-cut - what is propably much
more expensive.

Volker



Am 18.01.2013 01:16, schrieb Hal Murray:

Forget about it. This is well beyond even the lunatic fringe of pulling.


So how far can I pull a crystal?

Does it depend upon the cut or anything that turns into price?






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Re: [time-nuts] 1970's flashback

[Volker Esper]

Thanks, Joe. Though I don't have such time equipment, the pictures are 
fascinating me and make me recall the days when the name HP stood for 
High Precision (or High Price) rather than for cheap printers.

Those days are gone...

Volker


Am 13.01.2013 12:27, schrieb Dave Brown:

Thanks for these, Joe.
The photo with the sign 'set your watch' is especially interesting for
me as it shows a pair of old clock displays the same as one I have here.
These are the two digital displays that are showing the same digits.
There's part of a third one the same on the extreme left but the display
on that one is not visible in the photo. My clock has a different
mechanical dial on the ten turn pot at the extreme right of the front
panel- otherwise the unit I have here looks identical to those in the
photograph.
I have never been able to track down any info on this unit. Mine came
from a US military installation here in NZ (Black Birch) that has long
since been shut down. It's certainly old technology- RCA 'numitron'
displays and mostly TTL circuitry. I've had it running here continuously
now for about six years driven from an HP 5245M timebase - the clock has
never missed a beat. (recent quakes excepted ) Also. one of the
newspaper cuttings in that collection you posted mentions the flying
clock being down here in NZ to visit Mount John, a magnificent
observatory site in South Canterbury. These days it's a well known
astronomical observatory run as part of Canterbury University Physics
Department.
Dave Brown
Christchurch, NZ


- Original Message - From: Joseph Gray jg...@zianet.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Sunday, January 13, 2013 10:10 PM
Subject: [time-nuts] 1970's flashback



Some time ago, a local Amateur gave me a CD with some radio related
information. Also on the CD was some information from when he was in
the Air Force. As it is Time Nuts related, some of you might find this
of interest. I have posted the images in my Dropbox and will leave
them there for a few days before removing them. Several images are
large.

https://www.dropbox.com/sh/ri8md891qne99vn/fuSDWspqWD

Joe Gray
W5JG

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Re: [time-nuts] Z3805A cooling requirements?

[Volker Esper]

 I wonder if the forced convection is to strong. You don't want to
 hit the limits of the oven control-range. Wonder if this is a
 long-term effect and if even small adjustment to the setup can
 remove the bursts of noise you are seeing.

Now, some hours after switching off the fan, I'm discovering such noise 
bursts even without ventilation :-( That means, I can't be sure, that 
the change in deviation for small tau is caused by the ventilation. May 
be it's just within the natural variation.


I have to state, that this experiment can't proof the assumtion that a 
constant air flow affects the deviation curves of an HP 10811 
significantly. Except for the humps in the greater tau ranges - what 
averages out. In fact, if there is any effect, the effect is small.


What could be worked on further: Not comparing the OCXO with the 
internal GPS signal (which is quite noisy in short term) but with an 
external oscillator. I've got an HP 10544 (similar to the 10811), which 
could be the reference for external time interval measurement.


I'll need some more days...

Volker





Am 22.12.2012 19:14, schrieb Magnus Danielson:

On 12/22/2012 06:44 PM, Volker Esper wrote:

Thank you for your statement, I have to think about it.

It seems to be clear, that ADEV/MDEV aren't the convenient tools for
characterizing such an event. My goal was to answere the question asked
in the beginning of this thread: Does a constant ventilation of the OCXO
affect the deviation curves and if so in what manner? More precisely: do
I have worse deviation due to ventilation?


Well, the deviation curves was only meant to separate various
phase-noise forms, not systematic effects, even if they may be
illustrated to some degree using the tool. However, since noise(s) and
systematic effects have completely different properties in how
confidence intervals builds, so they are better measured and treated
separately before being put back together again. For longer taus the
systematic effects dominates, so drift, temperature, supply voltage and
pressure kicks in.


 ... phase/frequency/drift plots and FT of them might be more
 useful.

So let's have a look at the time domain. The picture shows the PPS-TI of
the Z3805 (blue: time difference between OCXO and GPS; red: EFC).

In the middle of the diagram we recognize the reaction to the
ventilation. Before that happens, the curve has a somewhat stable high
frequency noise. After starting the ventilation this noise is extremely
varying in amplitude. IMHO that might mean, that Allan deviation will be
affected at the short term values of tau. This seems to coincide with
the MDEV vs time curves of my diagrams.

Agree?


Agree. I wonder if the forced convection is to strong. You don't want to
hit the limits of the oven control-range. Wonder if this is a long-term
effect and if even small adjustment to the setup can remove the bursts
of noise you are seeing.

Cheers,
Magnus

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Re: [time-nuts] time-nuts Digest, Vol 101, Issue 152

[Volker Esper]

greater. That should

have a significant impact on the ADEV.

I don't put the ADEV curves here, I make up for it

when the EFC

compensation is completely out of the scope, that

will be in about 12

hours. I don't have the ADEV at 1 s, but the ADEV

at 10 s has been

almost constant. The ADEV at about 1000 s has a

nasty bump now.


IMHO that fits to the physical facts: the airflow

will surely not affect

the 10 s ADEV since the OCXO tries its best to

isolate the oscillator

from short time temperature influences. However,

the turbulent air flow

that I applied will influence the longer time

ADEV.


Have a nice solstice

Volker




Am 21.12.2012 12:44, schrieb Volker Esper:


Yes, I made such a setup, it's now running 22

hours. I'll post the

results in two hours or so (if nothing evil

happens to the earth,

meanwhile).

Volker


Am 21.12.2012 03:35, schrieb saidj...@aol.com:

Wish I had more time to play with this

setup.


How about fellow time nuts spend some time

and present similar test

data on
their OCXO's to compare?

I was interested in the 1s to 100s ADEV,

and my runs were from 8

minutes to
20 minutes, certainly enough time to

capture data for 1s to 100s ADEV

measurements..

bye,
Said


In a message dated 12/20/2012 14:17:59

Pacific Standard Time,

mag...@rubidium.dyndns.org

writes:


On 12/20/2012 01:34 PM, Bob Camp wrote:

Hi

Temperature transients are not a good

thing for an OCXO. If you

deliberately use the fan to create a

transient, then yes the OCXO will

not be
happy. The question it - what happens after

the transient has settled

out? The
plot you have still looks a lot like a step

function.


I agree. Temperature steps stresses the

OCXO oven loop and easily

creates a gradient over the crystal. As the

oven loop tracks in, the

frequency returns to around normal. The

trouble with forced air over a

crystal is that the metal shield couples

very well and acts like a heat

sink. A think plastic cover over it and

forced convection doesn't have

the same effect. There is even being used

by at least one vendor. Works

very well for the extra cents of

manufacturing cost.


The HP10811 is recommended to be put in a

airflow-quiet corner of the

world. Look at it's mounting in the

HP5370A/B for instance.


Cheers,
Magnus

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DSCF1758_bb.jpg
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--

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End of time-nuts Digest, Vol 101, Issue 152
***

MV89A Fan turned on at 460 seconds v2.png
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1_DF9PL_GPSDO_1_sigma(tau)_alle_MDEV_b.jpg
2_DF9PL_GPSDO_1_sigma(tau)(t)_alle_MDEV_b.jpg
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Re: [time-nuts] time-nuts Digest, Vol 101, Issue 152

[Volker Esper]

Thank you very much for the advice, I didn't know that at all...
Volker


Am 22.12.2012 22:26, schrieb Alan Melia:

Volker.look at the subject line, the posting is in your hands, you
dont need to just use the reply button, as somone did with a digest
which forked the thread.. This means all the posing under Digest
are hidden from view and searching. You can edit the subject line but
this does not always return to the old thread if you use he reply
button. I think it depends on the mail client.
Alan
G3NYK
- Original Message - From: Volker Esper ail...@t-online.de
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Saturday, December 22, 2012 8:44 PM
Subject: Re: [time-nuts] time-nuts Digest, Vol 101, Issue 152




Plot 1: MDEV of the time interval reported by GPSDO
Yes, Said, that are important issues.

By the way: I'm now writing in two threads, I don't know, why the
original thread (Z3805A cooling requirements?) was splitted... Can
we please move to the original thread?

I am sure, that the noise of the GPSDO PPS-TI data is much to high to
recognize the effects. I'm going to make a new setup, where I'll
compare the GPSDO PPS with an external oscilator, e.g. an HP 10544 or
the high stability reference within my SMX signal generator.

Volker


Am 22.12.2012 05:07, schrieb Said Jackson:

Hi Volker,

What is being plotted here? Efc? Time interval as reported by the
GPSDO? External counter versus a stable reference?

It looks like the resolution is approaching 10ns/s (1E-08 at 1s), and
that the short term effects may be hidden in this noise?

The effects are clearly visible in your first GPSCon plot, not sure
if we can see the short term noise in these plots..

The 10811 I had tested went from ~3E-012 at 100s to ~2E-011 when the
fan was on, I think both values are quite a bit below the noise floor
of your plot so probably hard to measure.

Bye,
Said

Sent from my iPad

On Dec 21, 2012, at 6:47 PM, Volker Esperail...@t-online.de wrote:


Said,

Unfortunately I don't have the equipment to measure the phase noise
of an HP 10811 (yet).

But I did some work on evaluating the results of my fan experiment.
Within this posting you'll find two diagrams. The first (named
1_DF9PL...) shows five MDEV curves (Modified Allan Deviation),
each of them measured at different times. Total time span is 30.5
hours.

At small tau values (up to 1000 s) only a slight increase of sigma
over time can be noticed. However, at a tau of 5000 s or greater you
can watch sigma making a big bump. Ok, that's what we expected before.

In diagram no. 1 it's somewhat fussy to recognize the change of a
particular sigma(tau). Now, that we've got curious, we want to see,
how the sigma(tau) changes over time. So I've been providing a
second diagram (2_...), where sigma(tau) is a function of the time.

You can see, for example, the curve of tau=20480s developing a big
hump, and falling back to a proper value after about 1800 minutes.
All curves at a tau greater or equal 2560 do so.

At smaller values the curves are esentially less affected, but -
they are not back at their starting value after 1800 minutes (30
hours)! You could guess, that the hump moves up to longer times with
increasing sigma - but it doesn't. There is something significantly
different below tau=2560s.

1 hour ago, I switched off the fan and laid back the aluminium
cover. We wait and see.

And now, dear time nuts, it's time to go to bed.

Volker




Am 21.12.2012 18:53, schrieb Said Jackson:

Mark,

Your plot still shows excursions of +/-1E-010, about 100x higher
base noise than the Z3801A/Z3805A are capable of achieving. Wonder
where that noise is coming from? This noise is probably much higher
than the thermal effects.

The original post was the question does my Z380xA have reduced
stability if I add a fan or similar, I think the answer is shown
to be yes.

Volker, I wonder if you also see fan-induced spurs in the phase
noise from 1Hz to 100Hz. I would not be surprised if the fan
vibration adds significant spurs to the 10811A crystal.

Bye,
Said

Sent from my iPad

On Dec 21, 2012, at 9:42 AM, Mark Spencermspencer12...@yahoo.ca
wrote:


This plot should show the frequency change more clearly. (Same
data just presented differently.)

It seems to me that the noise goes may be going down a bit for a
minute or so just after the fan is turned on but I don't believe
these plots provide conclusive evidence of this.


Regards
Mark Spencer

Message: 7
Date: Fri, 21 Dec 2012 09:27:29 -0800
From: Said Jacksonsaidj...@aol.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Cc: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Z3805A cooling requirements?
Message-ID:83ce0384-2996-4155-b51b-9d79910b2...@aol.com
Content-Type: text/plain;
charset=us-ascii

Great plots guys!

Looking at these results I think my original claim still
holds: ADEV goes up when a fan is involved

Re: [time-nuts] Z3805A cooling requirements?

[Volker Esper]

Yes, I made such a setup, it's now running 22 hours. I'll post the 
results in two hours or so (if nothing evil happens to the earth, 
meanwhile).


Volker


Am 21.12.2012 03:35, schrieb saidj...@aol.com:

Wish I had more time to play with this setup.

How about fellow time nuts spend some time and present similar test data on
  their OCXO's to compare?

I was interested in the 1s to 100s ADEV, and my runs were from 8 minutes to
  20 minutes, certainly enough time to capture data for 1s to 100s ADEV
measurements..

bye,
Said


In a message dated 12/20/2012 14:17:59 Pacific Standard Time,
mag...@rubidium.dyndns.org writes:

On  12/20/2012 01:34 PM, Bob Camp wrote:

Hi

Temperature  transients are not a good thing for an OCXO. If you

deliberately use the fan  to create a transient, then yes the OCXO will not be
happy. The question it -  what happens after the transient has settled out? The
plot you have still  looks a lot like a step function.

I agree. Temperature steps stresses  the OCXO oven loop and easily
creates a gradient over the crystal. As the  oven loop tracks in, the
frequency returns to around normal. The trouble  with forced air over a
crystal is that the metal shield couples very well  and acts like a heat
sink. A think plastic cover over it and forced  convection doesn't have
the same effect. There is even being used by at  least one vendor. Works
very well for the extra cents of manufacturing  cost.

The HP10811 is recommended to be put in a airflow-quiet corner of  the
world. Look at it's mounting in the HP5370A/B for  instance.

Cheers,
Magnus


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Re: [time-nuts] Grounding

[Volker Esper]

Simon,

Welcome to the list!

Since I'm working on grounding problems for some 20 years I can confirm 
this an important issue. Many of my engineer colleagues do not have a 
clue about it. The article you recommended describes the thing very 
clearly. I will recommend it my colleagues and use it to teach my students.


Thank you

Volker


Am 21.12.2012 13:28, schrieb M. Simon:

I'm new to the list so this may have been mentioned before. An excellent series 
on grounding devoted to mainly PCB issues but the thinking is universal:

http://www.edn.com/design/analog/4394761/Successful-PCB-grounding-with-mixed-signal-chips---Part-1--Principles-of-current-flow


There are 3 parts to the article - links are available at the end of every 
section to the next section.

Simon

Engineering is the art of making what you want from what you can get at a 
profit.
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Re: [time-nuts] Z3805A cooling requirements?

[Volker Esper]

...and we do not know how much air flow and how turbulent each of us 
applied. We can only give an _idea_ of what happens and in which order 
of magnitude it could be.


When Stu started the thread (elderly time nuts can surely recall) his 
question was about cooling a Z38xx unit. I recommended building a wind 
shield between the oven and the power supply bricks and cool the bricks 
with a fan. When my current test is completed, I'll try that, too.


The power supply most often seems to be the weak spot, so some 
additional cooling wouldn't be wrong (apart from acoustic noise).


Yes, I bear in mind the warnings about a non ventilated seperate oven 
chamber and the hints about maximum temperature vs oven temperature. So 
I measured the temperature in the closed original aluminium case (which 
however has some ventilation slots). It was about 45°C=113°F, at a room 
temeprature of 21°C=70°F. With an oven temp of about 80°C=176°F I don't 
expect problems, even if the oven chamber temp will increase some degrees.


Till then...

Volker





Am 21.12.2012 18:27, schrieb Said Jackson:

Great plots guys!

Looking at these results I think my original claim still holds: ADEV goes up 
when a fan is involved versus no fan, even on a double oven 10811..

Clearly visible on the 10811, maybe not so much on the MV89 but that unit seems 
to have frequency moves into the xE-010 region on Marks plot so maybe the 
effect is just a bit hidden?

Bye,
Said

Sent from my iPad

On Dec 21, 2012, at 5:44 AM, Volker Esperail...@t-online.de  wrote:


...and the picture of the experiment...



The picture enclosed can give you a first impression. What we see is
the difference time between the GPS signal and the OCXO (blue)
(PPS-TI), which is an HP 10811. In red we can see the EFC. The total
span is 24 h.

Before I applied the fan, the noise was at a maximum of about +/- 20 ns.
Some hours after starting the fan the noise is much greater. That should
have a significant impact on the ADEV.

I don't put the ADEV curves here, I make up for it when the EFC
compensation is completely out of the scope, that will be in about 12
hours. I don't have the ADEV at 1 s, but the ADEV at 10 s has been
almost constant. The ADEV at about 1000 s has a nasty bump now.

IMHO that fits to the physical facts: the airflow will surely not affect
the 10 s ADEV since the OCXO tries its best to isolate the oscillator
from short time temperature influences. However, the turbulent air flow
that I applied will influence the longer time ADEV.

Have a nice solstice

Volker




Am 21.12.2012 12:44, schrieb Volker Esper:


Yes, I made such a setup, it's now running 22 hours. I'll post the
results in two hours or so (if nothing evil happens to the earth,
meanwhile).

Volker


Am 21.12.2012 03:35, schrieb saidj...@aol.com:

Wish I had more time to play with this setup.

How about fellow time nuts spend some time and present similar test
data on
their OCXO's to compare?

I was interested in the 1s to 100s ADEV, and my runs were from 8
minutes to
20 minutes, certainly enough time to capture data for 1s to 100s ADEV
measurements..

bye,
Said


In a message dated 12/20/2012 14:17:59 Pacific Standard Time,
mag...@rubidium.dyndns.org writes:

On 12/20/2012 01:34 PM, Bob Camp wrote:

Hi

Temperature transients are not a good thing for an OCXO. If you

deliberately use the fan to create a transient, then yes the OCXO will
not be
happy. The question it - what happens after the transient has settled
out? The
plot you have still looks a lot like a step function.

I agree. Temperature steps stresses the OCXO oven loop and easily
creates a gradient over the crystal. As the oven loop tracks in, the
frequency returns to around normal. The trouble with forced air over a
crystal is that the metal shield couples very well and acts like a heat
sink. A think plastic cover over it and forced convection doesn't have
the same effect. There is even being used by at least one vendor. Works
very well for the extra cents of manufacturing cost.

The HP10811 is recommended to be put in a airflow-quiet corner of the
world. Look at it's mounting in the HP5370A/B for instance.

Cheers,
Magnus


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DSCF1758_bb.jpg
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Re: [time-nuts] time-nuts Digest, Vol 101, Issue 152

[Volker Esper]

Vibration: interesting consideration. In my experiment the fan is very 
softly coupled to the case (since it is lying on some soft cables), 
furthermore the power supply is a different one - not the one that 
powers the Z3805. I've tried to avoid those effects. I send some ADEV 
plots in an hour.


Volker

Am 21.12.2012 18:53, schrieb Said Jackson:

Mark,

Your plot still shows excursions of +/-1E-010, about 100x higher base noise 
than the Z3801A/Z3805A are capable of achieving. Wonder where that noise is 
coming from? This noise is probably much higher than the thermal effects.

The original post was the question does my Z380xA have reduced stability if I add a fan 
or similar, I think the answer is shown to be yes.

Volker, I wonder if you also see fan-induced spurs in the phase noise from 1Hz 
to 100Hz. I would not be surprised if the fan vibration adds significant spurs 
to the 10811A crystal.

Bye,
Said

Sent from my iPad

On Dec 21, 2012, at 9:42 AM, Mark Spencermspencer12...@yahoo.ca  wrote:


This plot should show the frequency change more clearly.   (Same data just 
presented differently.)

It seems to me that the noise goes may be going down a bit for a minute or so 
just after the fan is turned on but I don't believe these plots provide 
conclusive evidence of this.


Regards
Mark Spencer

Message: 7
Date: Fri, 21 Dec 2012 09:27:29 -0800
From: Said Jacksonsaidj...@aol.com
To: Discussion of precise time and frequency measurement
 time-nuts@febo.com
Cc: Discussion of precise time and frequency measurement
 time-nuts@febo.com
Subject: Re: [time-nuts] Z3805A cooling requirements?
Message-ID:83ce0384-2996-4155-b51b-9d79910b2...@aol.com
Content-Type: text/plain;
charset=us-ascii

Great plots guys!

Looking at these results I think my original claim still
holds: ADEV goes up when a fan is involved versus no fan,
even on a double oven 10811..

Clearly visible on the 10811, maybe not so much on the MV89
but that unit seems to have frequency moves into the xE-010
region on Marks plot so maybe the effect is just a bit
hidden?

Bye,
Said

Sent from my iPad

On Dec 21, 2012, at 5:44 AM, Volker Esperail...@t-online.de
wrote:


...and the picture of the experiment...



The picture enclosed can give you a first

impression. What we see is

the difference time between the GPS signal and the

OCXO (blue)

(PPS-TI), which is an HP 10811. In red we can see

the EFC. The total

span is 24 h.

Before I applied the fan, the noise was at a

maximum of about +/- 20 ns.

Some hours after starting the fan the noise is much

greater. That should

have a significant impact on the ADEV.

I don't put the ADEV curves here, I make up for it

when the EFC

compensation is completely out of the scope, that

will be in about 12

hours. I don't have the ADEV at 1 s, but the ADEV

at 10 s has been

almost constant. The ADEV at about 1000 s has a

nasty bump now.


IMHO that fits to the physical facts: the airflow

will surely not affect

the 10 s ADEV since the OCXO tries its best to

isolate the oscillator

from short time temperature influences. However,

the turbulent air flow

that I applied will influence the longer time

ADEV.


Have a nice solstice

Volker




Am 21.12.2012 12:44, schrieb Volker Esper:


Yes, I made such a setup, it's now running 22

hours. I'll post the

results in two hours or so (if nothing evil

happens to the earth,

meanwhile).

Volker


Am 21.12.2012 03:35, schrieb saidj...@aol.com:

Wish I had more time to play with this

setup.


How about fellow time nuts spend some time

and present similar test

data on
their OCXO's to compare?

I was interested in the 1s to 100s ADEV,

and my runs were from 8

minutes to
20 minutes, certainly enough time to

capture data for 1s to 100s ADEV

measurements..

bye,
Said


In a message dated 12/20/2012 14:17:59

Pacific Standard Time,

mag...@rubidium.dyndns.org

writes:


On 12/20/2012 01:34 PM, Bob Camp wrote:

Hi

Temperature transients are not a good

thing for an OCXO. If you

deliberately use the fan to create a

transient, then yes the OCXO will

not be
happy. The question it - what happens after

the transient has settled

out? The
plot you have still looks a lot like a step

function.


I agree. Temperature steps stresses the

OCXO oven loop and easily

creates a gradient over the crystal. As the

oven loop tracks in, the

frequency returns to around normal. The

trouble with forced air over a

crystal is that the metal shield couples

very well and acts like a heat

sink. A think plastic cover over it and

forced convection doesn't have

the same effect. There is even being used

by at least one vendor. Works

very well for the extra cents of

manufacturing cost.


The HP10811 is recommended to be put in a

airflow-quiet corner of the

world. Look at it's mounting in the

HP5370A/B for instance.


Cheers,
Magnus

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Re: [time-nuts] time-nuts Digest, Vol 101, Issue 154

[Volker Esper]

Mark,
Could you please post a photograph of your experiment?
Thanks
Volker


Am 21.12.2012 20:05, schrieb Mark Spencer:

Said, not sure where the noise is coming from but I suspect it's from the MV89 
OCXO itself which was only powered up for 10 hours when the data was collected. 
  The  BVA reference and the counter (an HP5370B) have performed  significantly 
better on other occasions.  When I have some time over the holidays I'll take 
another look at this and confirm that the BVA and HP5370B are working as they 
should. I'll likely compare the BVA to another OCXO using another HP5370B at 
the same time I'm comparing the BVA to the MV89, then swap the two counters and 
repeat the measurements, but I  didn't have time for that this am (:

I saw your request for data re OCXO's and fans and this gave me the incentive 
to spend a few minutes to power up one of my MV89's, then blow some air over it 
and collect a bit of data the next morning (:

As a side note I've got two Z3805's in service and yes they are great 
performers over short time intervals (one of them seems to match the short term 
performance of my BVA on many occasions.)  I need to save my pennies for better 
counter / analyzer  as well as the HP5370B is of little use at tau's of less 
than 100 seconds or so (:

Regards Mark S

--- On Fri, 12/21/12, time-nuts-requ...@febo.comtime-nuts-requ...@febo.com  
wrote:


From: time-nuts-requ...@febo.comtime-nuts-requ...@febo.com
Subject: time-nuts Digest, Vol 101, Issue 154
To: time-nuts@febo.com
Received: Friday, December 21, 2012, 10:23 AM
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Today's Topics:

1. Re: time-nuts Digest, Vol 101, Issue
152 (Said Jackson)
2. Re: Brooks Shera (Chris Albertson)
3. Re: Z3805A cooling requirements?
(Volker Esper)
4. Re: A Day in the Life of Five PPS
Sources.. (Tom Miller)
5. Re: time-nuts Digest, Vol 101, Issue
152 (Volker Esper)


--

Message: 1
Date: Fri, 21 Dec 2012 09:53:51 -0800
From: Said Jacksonsaidj...@aol.com
To: Discussion of precise time and frequency measurement
 time-nuts@febo.com
Cc: time-nuts@febo.com
time-nuts@febo.com
Subject: Re: [time-nuts] time-nuts Digest, Vol 101, Issue
152
Message-ID:6e6305fd-df54-44d5-9ceb-5d4aeb5ae...@aol.com
Content-Type: text/plain;
charset=us-ascii

Mark,

Your plot still shows excursions of +/-1E-010, about 100x
higher base noise than the Z3801A/Z3805A are capable of
achieving. Wonder where that noise is coming from? This
noise is probably much higher than the thermal effects.

The original post was the question does my Z380xA have
reduced stability if I add a fan or similar, I think the
answer is shown to be yes.

Volker, I wonder if you also see fan-induced spurs in the
phase noise from 1Hz to 100Hz. I would not be surprised if
the fan vibration adds significant spurs to the 10811A
crystal.

Bye,
Said

Sent from my iPad

On Dec 21, 2012, at 9:42 AM, Mark Spencermspencer12...@yahoo.ca
wrote:


This plot should show the frequency change more

clearly.   (Same data just presented
differently.)


It seems to me that the noise goes may be going down a

bit for a minute or so just after the fan is turned on but I
don't believe these plots provide conclusive evidence of
this.



Regards
Mark Spencer

Message: 7
Date: Fri, 21 Dec 2012 09:27:29 -0800
From: Said Jacksonsaidj...@aol.com
To: Discussion of precise time and frequency

measurement

  time-nuts@febo.com
Cc: Discussion of precise time and frequency

measurement

  time-nuts@febo.com
Subject: Re: [time-nuts] Z3805A cooling

requirements?

Message-ID:83ce0384-2996-4155-b51b-9d79910b2...@aol.com
Content-Type: text/plain;
charset=us-ascii

Great plots guys!

Looking at these results I think my original claim

still

holds: ADEV goes up when a fan is involved versus

no fan,

even on a double oven 10811..

Clearly visible on the 10811, maybe not so much on

the MV89

but that unit seems to have frequency moves into

the xE-010

region on Marks plot so maybe the effect is just a

bit

hidden?

Bye,
Said

Sent from my iPad

On Dec 21, 2012, at 5:44 AM, Volker Esperail...@t-online.de
wrote:


...and the picture of the experiment...



The picture enclosed can give you a first

impression. What we see is

the difference time between the GPS signal

and the

OCXO (blue)

(PPS-TI), which is an HP 10811. In red we

can see

the EFC. The total

span is 24 h.

Before I applied the fan, the noise was at

a

maximum of about +/- 20 ns.

Some hours after starting the fan

Re: [time-nuts] Z3805A cooling requirements?

[Volker Esper]

Diagram 2 shows the MDEV values of my GPSDO varying over the time, due 
to blowing air at the OCXO - not the frequency of an OCXO. I'm still 
hoping, that my MDEVs do not age :-)



Am 22.12.2012 04:00, schrieb Bob Camp:

Hi

In most cases, when you see an OCXO (or TCXO) begin to rise past a few thousand 
seconds, you are either looking at aging or the room temperature.

Bob
...



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Re: [time-nuts] Z3805A cooling requirements?

[Volker Esper]

Although I am dog-tired it gives me no peace...

I come to the following conclusion:
- The long term Allan deviation gets worse, as long, as the effect of 
EFC compensating is in the range of tau

- But: It gets back to its normal value after that
- The short term deviation, however,  increases slowly, but it doesn't 
settle. It's increasing more and more.


So it is the short term stability, that is affected, rather than the 
long term stability.


Am I right or wrong?

Perhaps I'm to tired to decide.

Volker



Am 22.12.2012 03:54, schrieb Volker Esper:

Here come the curves...

You'll find two diagrams. The first (named 1_DF9PL...) shows five MDEV
curves (Modified Allan Deviation), each of them measured at different
times. Total time span is 30.5 hours.

At small tau values (up to 1000 s) only a slight increase of sigma over
time can be noticed. However, at a tau of 5000 s or greater you can
watch sigma making a big bump. Ok, that's what we expected before.

In diagram no. 1 it's somewhat fussy to recognize the change of a
particular sigma(tau). Now, that we've got curious, we want to see, how
the sigma(tau) changes over time. So I've been providing a second
diagram (2_...), where sigma(tau) is a function of the time.

You can see, for example, the curve of tau=20480s developing a big hump,
and falling back to a proper value after about 1800 minutes. All curves
at a tau greater or equal 2560 do so.

At smaller values the curves are esentially less affected, but - they
are not back at their starting value after 1800 minutes (30 hours)! You
could guess, that the hump moves up to longer times with increasing
sigma - but it doesn't. There is something significantly different below
tau=2560s.

What is it?

Volker



Am 21.12.2012 14:42, schrieb Volker Esper:

(oh, I've got to split the posting)


The picture enclosed can give you a first impression. What we see is
the difference time between the GPS signal and the OCXO (blue)
(PPS-TI), which is an HP 10811. In red we can see the EFC. The total
span is 24 h.

Before I applied the fan, the noise was at a maximum of about +/- 20 ns.
Some hours after starting the fan the noise is much greater. That should
have a significant impact on the ADEV.

I don't put the ADEV curves here, I make up for it when the EFC
compensation is completely out of the scope, that will be in about 12
hours. I don't have the ADEV at 1 s, but the ADEV at 10 s has been
almost constant. The ADEV at about 1000 s has a nasty bump now.

IMHO that fits to the physical facts: the airflow will surely not affect
the 10 s ADEV since the OCXO tries its best to isolate the oscillator
from short time temperature influences. However, the turbulent air flow
that I applied will influence the longer time ADEV.

Have a nice solstice

Volker




Am 21.12.2012 12:44, schrieb Volker Esper:


Yes, I made such a setup, it's now running 22 hours. I'll post the
results in two hours or so (if nothing evil happens to the earth,
meanwhile).

Volker


Am 21.12.2012 03:35, schrieb saidj...@aol.com:

Wish I had more time to play with this setup.

How about fellow time nuts spend some time and present similar test
data on
their OCXO's to compare?

I was interested in the 1s to 100s ADEV, and my runs were from 8
minutes to
20 minutes, certainly enough time to capture data for 1s to 100s ADEV
measurements..

bye,
Said


In a message dated 12/20/2012 14:17:59 Pacific Standard Time,
mag...@rubidium.dyndns.org writes:

On 12/20/2012 01:34 PM, Bob Camp wrote:

Hi

Temperature transients are not a good thing for an OCXO. If you

deliberately use the fan to create a transient, then yes the OCXO will
not be
happy. The question it - what happens after the transient has settled
out? The
plot you have still looks a lot like a step function.

I agree. Temperature steps stresses the OCXO oven loop and easily
creates a gradient over the crystal. As the oven loop tracks in, the
frequency returns to around normal. The trouble with forced air over a
crystal is that the metal shield couples very well and acts like a
heat
sink. A think plastic cover over it and forced convection doesn't have
the same effect. There is even being used by at least one vendor.
Works
very well for the extra cents of manufacturing cost.

The HP10811 is recommended to be put in a airflow-quiet corner of the
world. Look at it's mounting in the HP5370A/B for instance.

Cheers,
Magnus


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Re: [time-nuts] Considerations When Using The SR620

[Volker Esper]

I'm curious, which way you went and which accuracy you achieved... :-)
Can you tell us?
Volker


Am 06.12.2012 19:10, schrieb Paul DeStefano:

On Tuesday, 4 December 2012, Tom Van Baak wrote:

We are using the SR620 to measure the interval between 1PPS signals from
two clocks. One is the Septentrio PolaRx4 GPS receiver and the other
is a
Rubidium clock.

Many Thanks,
Paul

1) If you are making frequency measurements, the warm-up of the
internal oscillator is the major factor limiting accuracy. ...
Plotting digits of precision as a function of warm-up time would make
a very educational graph you could tape to the top of your SR620.

2) If you are making time interval measurements and using an external
standard, the warm-up time will also affect the accuracy of your TI
measurements, but to a far lesser degree. Here are informal results
for TI (time interval) mode after a 5 minute power-down (see also
attached plots):

- if you need 1 ns accuracy, you can use the SR620 immediately after
power-up
- if you need 100 ps accuracy, wait 2+ minutes
- if you need 10 ps accuracy, wait 15+ minutes
- if you need 1 ps accuracy, you need a seriously stable lab
environment or a different counter.

Given that you plan to use the SR620 with high-end GPS gear I would
suggest you try this quick experiment for yourself to see what *your*
SR620 does, with *your* inputs, in *your* environment. Your numbers
will come out different than mine; but the methodology is the same.
Your procedures can then be based on measurement and confidence
instead of guesswork and folklore.


Tom  Co.,

Thank you! These plots are excellent and will be very helpful. You are
quite right; we should do the test ourselves. We will definitely do
that. Obviously, there is not need to worry, as we can characterize the
instrument behavior ourselves, which is probably necessary anyway if
we're going to publish these measurements with error values.

Many Thanks,
Paul





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Re: [time-nuts] Z3805A cooling requirements?

[Volker Esper]

Steward,

What is the intended and what is the actual supply voltage? Which 
current is the unit consuming?
When we know that, we can compare the power consumption with our units. 
If it is in the same range, it should - with a little luck - be working 
properly.


My two units are intended to be supplied by 19.5 to 30 V. I use 24 V and 
the Z3805s draw 0.9 A each. If I increase voltage the current decreases 
(typical for the switching supplies inside the Z3805).


I don't cool the units, they just lie on an old electronics magazine 
(for not to scratch the case of my signal generator, lying below the 
magazine), so they can freely convect their heat.


Cheers

Volker



Am 12.12.2012 01:21, schrieb Stewart Cobb:

This may be a newbie question, but I'm a newbie, so:

Do the HP telecom GPSDOs (Z38xx) require external airflow for cooling?
They don't have built-in fans, but they sorta look like they depend on a
rack-level cooling fan, which a telecom rack would almost certainly have.

I ask because I bought a Z3816 awhile back which worked for about a week
and then failed. I traced the failure to an internal power supply brick,
which had a big finned heat-sink attached but nevertheless smelled
overheated and was shorted internally.

I never found a replacement power brick, and I don't have time to mess with
it right now, so I recently bought a Z3805A. It, too, looks like it's
working, but it started to feel awfully warm after a few hours, so I
unplugged it for now.

It probably wouldn't take much of a fan to bring the internal temperature
down close to ambient, and the fan could be powered easily enough from the
supply rails. But that might create a temperature gradient where the
designers didn't intend one. Or it might cause problems I don't even know
about yet.

At the moment, the Z3805A is in a fan-less 19-inch rack with a bunch of
other equipment, in a lab environment. Should it have its own fan?

Cheers!
--Stu
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Re: [time-nuts] Z3805A cooling requirements?

[Volker Esper]

It's the same as with the SR620 TIC. As long as you have only one common 
chamber for all parts, you have to make tradeoffs for everyone:
the power supply needs cooling (as much as it can get), the control loop 
of the oven is not designed for additional cooling, and comparators and 
further electronics don't need extremely low but stable temperatures, 
that means no air flow.


If you are ready for a change of your mechanical design, (e.g. placing a 
fan at/in the case), place a(n) (isolating) sheet between oven and 
switching supply, then cool the supply bricks abundantly. Make sure that 
the air flow of your fan does not penetrate the seperate oven chamber.


Arranging for a seperate chamber for your oven keeps the natural air 
flow due to convection undisturbed.


I guess, placing the additional sheet shouln't be too much of work.

Volker


Am 12.12.2012 02:20, schrieb saidj...@aol.com:

Stu,

a fan is about the worst thing you can do for your Z3805 it will
significantly worsen the stability of the output frequency. The oven inside 
does  get
warm, that's why it is an oven :)

The power consumption will go down once it heats itself up, the unit is
designed to work without a fan sitting on a desk etc. Just make sure the vent
holes are not clogged.

Sounds like your Z3816 had a failure that caused the units power  supply to
overheat.

bye,
Said


In a message dated 12/11/2012 16:22:10 Pacific Standard Time,
stewart.c...@gmail.com writes:

This may  be a newbie question, but I'm a newbie, so:

Do the HP telecom GPSDOs  (Z38xx) require external airflow for cooling?
They don't have built-in  fans, but they sorta look like they depend on a
rack-level cooling fan,  which a telecom rack would almost certainly have.

I ask because I  bought a Z3816 awhile back which worked for about a week
and then failed. I  traced the failure to an internal power supply brick,
which had a big  finned heat-sink attached but nevertheless smelled
overheated and was  shorted internally.

I never found a replacement power brick, and I  don't have time to mess with
it right now, so I recently bought a Z3805A.  It, too, looks like it's
working, but it started to feel awfully warm after  a few hours, so I
unplugged it for now.

It probably wouldn't take  much of a fan to bring the internal temperature
down close to ambient, and  the fan could be powered easily enough from the
supply rails. But that  might create a temperature gradient where the
designers didn't intend one.  Or it might cause problems I don't even know
about yet.

At the  moment, the Z3805A is in a fan-less 19-inch rack with a bunch of
other  equipment, in a lab environment. Should it have its own  fan?

Cheers!
--Stu

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Re: [time-nuts] Z3805A cooling requirements?

[Volker Esper]

Indeed? I didn't expect that. There are people who say, that the control 
loop of OCXOs is optimized for still air and no additional cooling at all.


Said told us, that...

...a fan is about the worst thing you can do for your Z3805 it will
significantly worsen the stability of the output frequency...

Since the main task of the OCXO-oven is to stabilize the internal 
temperature, I can't imagine, that it get's into trouble when not 
externally cooled!?


If I'd ventilate the air around the OCXO case the heater had to work 
more and the power dissipation would be greater.


Am I wrong with taht?

Volker



Am 16.12.2012 15:35, schrieb Bob Camp:

Hi

By far the most common way to test and certify OCXO's is in moving air. It's 
rare to see one get in trouble from to much ventilation. The more common 
problem is thermal runaway due to inadequate ventilation.

Bob

On Dec 16, 2012, at 7:57 AM, Volker Esperail...@t-online.de  wrote:



Steward,

What is the intended and what is the actual supply voltage? Which current is 
the unit consuming?
When we know that, we can compare the power consumption with our units. If it 
is in the same range, it should - with a little luck - be working properly.

My two units are intended to be supplied by 19.5 to 30 V. I use 24 V and the 
Z3805s draw 0.9 A each. If I increase voltage the current decreases (typical 
for the switching supplies inside the Z3805).

I don't cool the units, they just lie on an old electronics magazine (for not 
to scratch the case of my signal generator, lying below the magazine), so they 
can freely convect their heat.

Cheers

Volker



Am 12.12.2012 01:21, schrieb Stewart Cobb:

This may be a newbie question, but I'm a newbie, so:

Do the HP telecom GPSDOs (Z38xx) require external airflow for cooling?
They don't have built-in fans, but they sorta look like they depend on a
rack-level cooling fan, which a telecom rack would almost certainly have.

I ask because I bought a Z3816 awhile back which worked for about a week
and then failed. I traced the failure to an internal power supply brick,
which had a big finned heat-sink attached but nevertheless smelled
overheated and was shorted internally.

I never found a replacement power brick, and I don't have time to mess with
it right now, so I recently bought a Z3805A. It, too, looks like it's
working, but it started to feel awfully warm after a few hours, so I
unplugged it for now.

It probably wouldn't take much of a fan to bring the internal temperature
down close to ambient, and the fan could be powered easily enough from the
supply rails. But that might create a temperature gradient where the
designers didn't intend one. Or it might cause problems I don't even know
about yet.

At the moment, the Z3805A is in a fan-less 19-inch rack with a bunch of
other equipment, in a lab environment. Should it have its own fan?

Cheers!
--Stu
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Re: [time-nuts] GPSDO Alternatives

[Volker Esper]

Am 05.12.2012 18:31, schrieb Bob Camp:

Hi

If the intent is to come up with something in the same league as the TBolt
there are a few other things you will need:

1) Something to compare the two pps signals to within 0.1 ns


Following Ulrich Bangerts suggestions, that a loop time constant should 
be at about 3 hours (GPS disciplining an OCXO), do I really need that 
resolution? Ok, the more accurate, the better. But the question is: can 
I reduce this requirement when using long time constants (1s)? The 
ratio then is 10E14...


Volker


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Re: [time-nuts] Considerations When Using The SR620

[Volker Esper]

Tom,

I agree. Since Paul want's to use an SR620 I presume he needs precision. 
Otherwise almost any TIC with a fairly stable osc would do, for example 
one with a battery backup. So I further presume that he needs nearly the 
full accuracy / stability. But that's just speculation, surely Paul can 
answere this question?


Volker


Am 04.12.2012 14:11, schrieb Tom Van Baak:

We are using the SR620 to measure the interval between 1PPS signals from
two clocks.  One is the Septentrio PolaRx4 GPS receiver and the other is a
Rubidium clock.

Many Thanks,
Paul


Hi Paul,

1) If you are making frequency measurements, the warm-up of the internal 
oscillator is the major factor limiting accuracy. This doesn't mean you have 
wait 12 hours. For example, if all you need is 6 digits of precision, a 
one-minute warm-up may be sufficient. For each further digit of precision you 
wait longer. You can probably get 9 digits with 1/2 hour of warm-up. It depends 
on the oscillator. Plotting digits of precision as a function of warm-up time 
would make a very educational graph you could tape to the top of your SR620.

2) If you are making time interval measurements and using an external standard, 
the warm-up time will also affect the accuracy of your TI measurements, but to 
a far lesser degree. Here are informal results for TI (time interval) mode 
after a 5 minute power-down (see also attached plots):

- if you need 1 ns accuracy, you can use the SR620 immediately after power-up
- if you need 100 ps accuracy, wait 2+ minutes
- if you need 10 ps accuracy, wait 15+ minutes
- if you need 1 ps accuracy, you need a seriously stable lab environment or a 
different counter.

Given that you plan to use the SR620 with high-end GPS gear I would suggest you 
try this quick experiment for yourself to see what *your* SR620 does, with 
*your* inputs, in *your* environment. Your numbers will come out different than 
mine; but the methodology is the same. Your procedures can then be based on 
measurement and confidence instead of guesswork and folklore.

Note also if your data collection is automated, there's really no reason to 
wait after power-up at all. Just collect data as soon as you can and skip the 
predetermined number of samples. I can send you the SR620 GPIB scripts I used 
for my test. This way you have a record of the warm-up settling time itself, 
which further gives you confidence in the data that follows.

/tvb



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Re: [time-nuts] Introducing myself

[Volker Esper]

Welcome, Erich!
(By the way, are you from Germany?)
Volker



Am 02.12.2012 21:06, schrieb Erich Heine:

Hi everyone.

I just wanted to introduce myself to the list. My name is Erich Heine, I'm
a researcher at the University of Illinois. I am a programmer attached to a
couple of projects, but the one relevant here is called TCIP (Trustworthy
Cyber-Infrastructure for the Power Grid - url: tcipg.org).

Our group does computer security research relevant the the US power grid
infrastructure (and when relevant to all power delivery :) ). Recently
we've had researchers looking at GPS spoofing, and are beginning to examine
secure time synchronization more broadly. It's fascinating to discover just
how much havoc can be caused by assuming the time signal is good enough
when it may not be. (This seems to be the way of computer security - assume
something is good or good enough, then someone comes along an breaks
everything because the assumption was bad. Then everyone scrambles to get
better solutions, and other areas become assumed good enough. Repeat
ad-nauseam).

I was pointed here by Magnus a month or two ago, after a fascinating
discussion of just how deep this time and timing rabbit-hole goes. I'm
quite impressed with this community - both in terms of deep knowledge and
overall friendliness. It's been a pleasure just lurking and soaking up some
knowledge since then.

Anyway, I just wanted to say Hi all before I start posting questions,
comments, etc. :)

Regards,
Erich
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Re: [time-nuts] Termination talk

[Volker Esper]

...yeah - it's better not to know those people ;-) ...

Am 29.11.2012 08:28, schrieb Ulrich Bangert:

Simon,

...which prefers to remain anonymous...

sounds as if it were a group of criminals or so.

Best regards

Ulrich Bangert


-Ursprüngliche Nachricht-
Von: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] Im Auftrag von M. Simon
Gesendet: Mittwoch, 28. November 2012 23:53
An: time-nuts@febo.com
Betreff: [time-nuts] Termination talk


I was going to post an anecdote about termination to the list
and then thought that the piece would make a great column. It
did. My magazine featured it in one of its daily mailings.

If you want to check it out:
http://www.ecnmag.com/blogs/2012/11/long-lines-pcb

Simon


Engineering is the art of making what you want from what you
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Re: [time-nuts] Z3805 incident

[Volker Esper]

Sorry, Ulli, if I'm not quite with it, today...

Which one is the bad guy now, the oven or the RX? We can't decide that, 
can we? IMHO does neither the EFC nor the PPS TI response tell us, 
whether the RX or the Crystal caused this peak, what we see is just the 
difference time between them.


Or does the time constant reveal more?

Thank you

Volker



Am 29.11.2012 08:28, schrieb Ulrich Bangert:

Volker,

please note that much of the clear text in the status information is
generated by Z38XX itself to make it easier to read.


2012-11-28 10:01:40: The last Smartclock Status is undefined
2012-11-28 10:01:40: Starting with status LOCK


for example means that Z38XX is unaware of the receiver status and assumes
that the status is locked.

73s de Ulli, DF6JB


-Ursprüngliche Nachricht-
Von: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] Im Auftrag von Volker Esper
Gesendet: Mittwoch, 28. November 2012 22:24
An: Discussion of precise time and frequency measurement
Betreff: [time-nuts] Z3805 incident


When looking at the PPS TI vs. time curve today I felt kind
of appalled
- a big incident peak (not an outlier) on the curve! See picture.

What happened to my Z3805? Any idea?

No entry in the error log, the staus log says

2012-11-28 10:01:30: The Smartclock Status has changed to LOC
2012-11-28 10:01:40: The last Smartclock Status is undefined
2012-11-28 10:01:40: Starting with status LOCK

Thanks

Volker




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Re: [time-nuts] Z3805 incident

[Volker Esper]

...and I should see the loop time constant in the ADEV, too - if that is 
the case, the time constant should be about 2000 s, shouldn't it? (see 
picture)


Volker


Am 29.11.2012 05:35, schrieb Said Jackson:

Volker,

This is a classic crystal jump. The crystal changed its frequency magically 
from one second to the next and the software compensated for it

You can nicely see the time constant of the loop..

Bye
Said

Sent From iPhone

On Nov 28, 2012, at 13:24, Volker Esperail...@t-online.de  wrote:


When looking at the PPS TI vs. time curve today I felt kind of appalled - a big 
incident peak (not an outlier) on the curve! See picture.

What happened to my Z3805? Any idea?

No entry in the error log, the staus log says

2012-11-28 10:01:30: The Smartclock Status has changed to LOC
2012-11-28 10:01:40: The last Smartclock Status is undefined
2012-11-28 10:01:40: Starting with status LOCK

Thanks

Volker
DF9PL_GPSDO_2_20121128_2108_PPS-TI_b.jpg
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attachment: DF9PL_GPSDO_1_20121128_2109_sigma(tau)_b.jpg___
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Re: [time-nuts] Z3805 two frequency maxima

[Volker Esper]

I agree. Please, Paul, start a new thread, and we'll be there.

Volker

Am 28.11.2012 08:10, schrieb Hal Murray:


You might get better answers by starting a new thread rather than hiding your
question in an existing thread.  (Use your New message button rather than
Reply, and cut-paste the To address from an old message, then type in the new
Subject.)

Using a useful Subject also helps people find things in the archives.


paul.destef...@willamettealumni.com said:

We have an application in which we plan to travel 7 hours with an SR620
turned off, then turn it on for 1 hour and take measurements we expect to
be accurate to less than 1ns.  I would appreciate more information about
how to get reliable data out of this instrument.


What do you mean by accurate to less than 1ns?  What are you trying to 
measure?

The internal clock in the SR620 may be off a bit.  The specs should be in the 
users manual.  In general, you have to wait a while for it to warm up and it 
will depend on which options you have.  (Some units have good crystals.  Some 
have low cost crystals to save $$ if they will normally run off an in-house 
reference clock.)

Suppose it's worst case 1 part in 1E9, just to pick a handy number to work with.

If you measure the width of a 1 microsecond pulse, the error from the clock 
will be 1E-15 seconds or 1E-6 ns.

If you measure the time between 2 consecutive PPS pulses, the error from the 
clock will be 1E-9 seconds or 1 ns.







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Re: [time-nuts] Z3805 two frequency maxima

[Volker Esper]

...and I found a very interesting article on that topic:

http://www.micrel.com/_PDF/App-Notes/clk/PAN1202291%20-%20AFM%20Period%20Jitter.pdf

It's written by Eddy van Keulen (Micrel): Relation between Harmonics and 
Deterministic Jitter. His approach is the assumption, that frequency 
modulationt causes a spectrum with 10MHz and 5MHz (and of course 15MHz). 
Using the FM thesis and formulas give us a very graphic description of 
the observed two-maxima-histograms (a.k.a. bimodal or double peak).


I'll do more experiments and calculations at the weekend.

Volker



Am 28.11.2012 01:36, schrieb Volker Esper:


Now, that you ask: the measurements are in that range, yes, though it's
not exactly the values.

time shift 12ns - spacing 10ns
28ns 35ns
66ns 55ns
0ns 8ns

and yes, the peaks get closer while reducing the amplitude of the 5MHz,
it's almost exactly linear:

With the 10MHz at 200mV and a time shift of 66ns, I measured the
following spacings:

5MHz voltage in mV spacing in ns
200 55
100 27.5
50 13.0
25 6.5
12.5 3.3
6.3 1.6
3.2 0.86
1.6 0.44
0.8 0,24

The functional relation of voltage ratio and spacing is quite obvious.

I have to admit, that my counter is not at it's optimal calibration. I
will adjust it first before I can tell you more.

To be precise: all these findings were made while trying to adjust the
trigger circuits of the counter. To do that I needed a well designed 180
degrees power splitter - but I didn't have one at the time. I've
received a Mini Circuits ZSCJ-2-2 recently, now I can go on with my
adjustments.

Though the SR620 TIC is a great instrument when hunting the pico seconds
we have to realize, that it's a thermal design desaster (I have to
apologize to all sr620 friends). I have to run it for at least 12 hours
if not 24 to be shure, that every single part is at a more or less
stationary thermal state. Some (NERC) say ...never switch it off.

I can't do that during the week, we have to wait till weekend.

Thanks for your response

Volker


Am 28.11.2012 00:25, schrieb Azelio Boriani:

Very interesting indeed. Two questions: after adding the 66nS phase
shift,
were the two peaks at 66nS when at the same amplitude? Then, while
reducing
the amplitude of the 5MHz, were they getting closer (until the 240pS)?

On Tue, Nov 27, 2012 at 9:21 PM, Bob Campli...@rtty.us wrote:


Hi

Phase does indeed matter, it just messes up the math. Most multiplier /
filter combinations have significant phase shift between the
sub-harmonic
and the carrier. You rarely know what the phase shift is, but you can
read
the sub-harmonic. The simple db to jitter ratio gets you close enough to
make rational decisions on how much filtering you need. You could
play with
filter phase but I've never seen that done in practice.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Volker Esper
Sent: Tuesday, November 27, 2012 2:34 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Z3805 two frequency maxima


I followed your argument and tried to synthesize such a signal. I built
a simple power combiner (3 times 18 ohms resistors) and combined the 10
MHz reference output of my signal generator with a 5 MHz signal from the
same generators regular output at the same amplitude. My oscilloscope
showed the locked phase of the two signals.

I applied this combo signal to the SR620 and observed a wonderful
two-maxima histogram. When reducing the amplitude of the 5 MHz signal
(while keeping the 10 MHz amplitude) the peaks distance decreased
linearly with the voltage reduction, until the peaks melted togehter at
about -20dBc.

On the one hand it was a success, but why only 20dBc? My experiences
with the Z3805 showed a 5 MHz subharmonic at 62dBc and the peaks spaced
at 60 ps.

So I startet to add phase delay to the 5 MHz signal by looping-in some
meters of coax cable.

When coming to a delay time of 66 ns I could distinguish the two peaks
at a spacing of 240 ps down to an amplitude ratio of about 1000, that
is, 60dB.

Volker





Am 18.11.2012 03:36, schrieb Bob Camp:

Hi

Just good old Fourier series.

Bob

On Nov 17, 2012, at 9:12 PM, Volker Esperail...@t-online.de wrote:



I'm impressed - but what law is behind this?


Am 17.11.2012 21:26, schrieb Bob Camp:

Hi

60 db isn't to bad a number. More or less:

100 ns - 100 ps is 1000:1. 20 log of that is 60 db. 100 ps to 60 ps

is about 4.4 db. That would sum up to -64.4 dbc. The main gotcha is that
you
*might* also have some 15 MHz (and higher) energy in the signal as well.
Also phase gets into the calculation. Still, pretty close.


Bob

On Nov 17, 2012, at 12:50 PM, Volker Esperail...@t-online.de

wrote:




So let's have a look into the machine... and what do we see?
There's a

nice little Symmetrcom oven, with the sign reading 5.000 MHz - bingo!


May be there's a time saving way to determine the energie of the sub

harmonic: using my spectrum analyzer. It tells me, that there's

[time-nuts] Z3805 incident

[Volker Esper]

When looking at the PPS TI vs. time curve today I felt kind of appalled 
- a big incident peak (not an outlier) on the curve! See picture.


What happened to my Z3805? Any idea?

No entry in the error log, the staus log says

2012-11-28 10:01:30: The Smartclock Status has changed to LOC
2012-11-28 10:01:40: The last Smartclock Status is undefined
2012-11-28 10:01:40: Starting with status LOCK

Thanks

Volker
attachment: DF9PL_GPSDO_2_20121128_2108_PPS-TI_b.jpg___
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Re: [time-nuts] Z3805 incident

[Volker Esper]

Not Rb but OCXO vs GPS...

Am 28.11.2012 22:47, schrieb Azelio Boriani:

Ops, I missed the EFC value...

On Wed, Nov 28, 2012 at 10:43 PM, Azelio Boriani
azelio.bori...@screen.itwrote:


The reference is still the Rb? Then how you can tell which of the two is
doing that...

On Wed, Nov 28, 2012 at 10:24 PM, Volker Esperail...@t-online.de  wrote:


When looking at the PPS TI vs. time curve today I felt kind of appalled -
a big incident peak (not an outlier) on the curve! See picture.

What happened to my Z3805? Any idea?

No entry in the error log, the staus log says

2012-11-28 10:01:30: The Smartclock Status has changed to LOC
2012-11-28 10:01:40: The last Smartclock Status is undefined
2012-11-28 10:01:40: Starting with status LOCK

Thanks

Volker

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Re: [time-nuts] Z3805 two frequency maxima

[Volker Esper]

I followed your argument and tried to synthesize such a signal. I built 
a simple power combiner (3 times 18 ohms resistors) and combined the 10 
MHz reference output of my signal generator with a 5 MHz signal from the 
same generators regular output at the same amplitude. My oscilloscope 
showed the locked phase of the two signals.


I applied this combo signal to the SR620 and observed a wonderful 
two-maxima histogram. When reducing the amplitude of the 5 MHz signal 
(while keeping the 10 MHz amplitude) the peaks distance decreased 
linearly with the voltage reduction, until the peaks melted togehter at 
about -20dBc.


On the one hand it was a success, but why only 20dBc? My experiences 
with the Z3805 showed a 5 MHz subharmonic at 62dBc and the peaks spaced 
at 60 ps.


So I startet to add phase delay to the 5 MHz signal by looping-in some 
meters of coax cable.


When coming to a delay time of 66 ns I could distinguish the two peaks 
at a spacing of 240 ps down to an amplitude ratio of about 1000, that 
is, 60dB.


Volker





Am 18.11.2012 03:36, schrieb Bob Camp:

Hi

Just good old Fourier series.

Bob

On Nov 17, 2012, at 9:12 PM, Volker Esperail...@t-online.de  wrote:



I'm impressed - but what law is behind this?


Am 17.11.2012 21:26, schrieb Bob Camp:

Hi

60 db isn't to bad a number. More or less:

100 ns -   100 ps is 1000:1. 20 log of that is 60 db. 100 ps to 60 ps is about 
4.4 db. That would sum up to -64.4 dbc. The main gotcha is that you *might* also 
have some 15 MHz (and higher) energy in the signal as well. Also phase gets into 
the calculation.  Still, pretty close.

Bob

On Nov 17, 2012, at 12:50 PM, Volker Esperail...@t-online.de   wrote:



So let's have a look into the machine... and what do we see? There's a nice little 
Symmetrcom oven, with the sign reading 5.000 MHz - bingo!

May be there's a time saving way to determine the energie of the sub harmonic: 
using my spectrum analyzer. It tells me, that there's a 5 MHz subharmonic at 
the level of -62dBc.

How would you have calculated the energy? What would be your ansatz?

Thanks so far

Volker


Am 17.11.2012 17:55, schrieb Bob Camp:

Hi

That's what you get if you have sub harmonic energy in the output of your 
OCXO. I'd bet you a warm glass of beer that you have a 5 MHz / doubled to 10 MHz MTI OCXO 
in your Z3805.  If you have a lot of time on your hands, you can calculate the likely 
level of the energy from the amount of jitter (spacing between the two peaks) you get.

Bob

On Nov 17, 2012, at 11:41 AM, Volker Esperail...@t-online.dewrote:


Hi,

while playing with my recently aquired TIC (SR620) and measuring the period 
time of some oscillators I discovered something I hadn't expect at all:

The output of my GPSDO (Z3805) writes two maxima in the period histogram (at a 
spacing of 60ps).

I didn't believe that result and assumed an inherent error in my measuring 
setup or the counter itself.

So I plugged another oscillator, the reference TCXO of my signal generator (RS 
SMX), and that result made me happy and uneasy at once: The TCXO hat only one 
maximum.

I havn't calculated the ADEV curve, yet.

See pictures.

Why does my GPSDO produce such a weird result?

Cheers

Volker - DF9PL
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Re: [time-nuts] Z3805 two frequency maxima

[Volker Esper]

Now, that you ask: the measurements are in that range, yes, though it's 
not exactly the values.


time shift 12ns - spacing 10ns
   28ns35ns
   66ns55ns
0ns 8ns

and yes, the peaks get closer while reducing the amplitude of the 5MHz, 
it's almost exactly linear:


With the 10MHz at 200mV and a time shift of 66ns, I measured the 
following spacings:


5MHz voltage in mV spacing in ns
20055
10027.5
 5013.0
 25 6.5
 12.5   3.3
  6.3   1.6
  3.2   0.86
  1.6   0.44
  0.8   0,24

The functional relation of voltage ratio and spacing is quite obvious.

I have to admit, that my counter is not at it's optimal calibration. I 
will adjust it first before I can tell you more.


To be precise: all these findings were made while trying to adjust the 
trigger circuits of the counter. To do that I needed a well designed 180 
degrees power splitter - but I didn't have one at the time. I've 
received a Mini Circuits ZSCJ-2-2 recently, now I can go on with my 
adjustments.


Though the SR620 TIC is a great instrument when hunting the pico seconds 
we have to realize, that it's a thermal design desaster (I have to 
apologize to all sr620 friends). I have to run it for at least 12 hours 
if not 24 to be shure, that every single part is at a more or less 
stationary thermal state. Some (NERC) say ...never switch it off.


I can't do that during the week, we have to wait till weekend.

Thanks for your response

Volker


Am 28.11.2012 00:25, schrieb Azelio Boriani:

Very interesting indeed. Two questions: after adding the 66nS phase shift,
were the two peaks at 66nS when at the same amplitude? Then, while reducing
the amplitude of the 5MHz, were they getting closer (until the 240pS)?

On Tue, Nov 27, 2012 at 9:21 PM, Bob Campli...@rtty.us  wrote:


Hi

Phase does indeed matter, it just messes up the math. Most multiplier /
filter combinations have significant phase shift between the sub-harmonic
and the carrier. You rarely know what the phase shift is, but you can read
the sub-harmonic. The simple db to jitter ratio gets you close enough to
make rational decisions on how much filtering you need. You could play with
filter phase but I've never seen that done in practice.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Volker Esper
Sent: Tuesday, November 27, 2012 2:34 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Z3805 two frequency maxima


I followed your argument and tried to synthesize such a signal. I built
a simple power combiner (3 times 18 ohms resistors) and combined the 10
MHz reference output of my signal generator with a 5 MHz signal from the
same generators regular output at the same amplitude. My oscilloscope
showed the locked phase of the two signals.

I applied this combo signal to the SR620 and observed a wonderful
two-maxima histogram. When reducing the amplitude of the 5 MHz signal
(while keeping the 10 MHz amplitude) the peaks distance decreased
linearly with the voltage reduction, until the peaks melted togehter at
about -20dBc.

On the one hand it was a success, but why only 20dBc? My experiences
with the Z3805 showed a 5 MHz subharmonic at 62dBc and the peaks spaced
at 60 ps.

So I startet to add phase delay to the 5 MHz signal by looping-in some
meters of coax cable.

When coming to a delay time of 66 ns I could distinguish the two peaks
at a spacing of 240 ps down to an amplitude ratio of about 1000, that
is, 60dB.

Volker





Am 18.11.2012 03:36, schrieb Bob Camp:

Hi

Just good old Fourier series.

Bob

On Nov 17, 2012, at 9:12 PM, Volker Esperail...@t-online.de   wrote:



I'm impressed - but what law is behind this?


Am 17.11.2012 21:26, schrieb Bob Camp:

Hi

60 db isn't to bad a number. More or less:

100 ns -100 ps is 1000:1. 20 log of that is 60 db. 100 ps to 60 ps

is about 4.4 db. That would sum up to -64.4 dbc. The main gotcha is that
you
*might* also have some 15 MHz (and higher) energy in the signal as well.
Also phase gets into the calculation.  Still, pretty close.


Bob

On Nov 17, 2012, at 12:50 PM, Volker Esperail...@t-online.de

wrote:




So let's have a look into the machine... and what do we see? There's a

nice little Symmetrcom oven, with the sign reading 5.000 MHz - bingo!


May be there's a time saving way to determine the energie of the sub

harmonic: using my spectrum analyzer. It tells me, that there's a 5 MHz
subharmonic at the level of -62dBc.


How would you have calculated the energy? What would be your ansatz?

Thanks so far

Volker


Am 17.11.2012 17:55, schrieb Bob Camp:

Hi

That's what you get if you have sub harmonic energy in the output

of
your OCXO. I'd bet you a warm glass of beer that you have a 5 MHz / doubled
to 10 MHz MTI

Re: [time-nuts] Surge Arresters

[Volker Esper]

There's not much in this world that is able to reliably protect a radios 
input from a direct lightning hit (maybe a block of copper instead of 
the antenna...). But a surge protector (sometimes called EMP protector 
or surge arrester) can increase the probability that a nearby lightning 
strike won't induce to high a voltage surge on your receivers input. 
Since the input itself may have protection diodes the surge arrester has 
to eliminate the part of energy, that would blow the diodes.


If you have a look here
http://precision.hubersuhner.com/co-rub/mozilla/products/hs-p-rf/hs-rf-lightning-protectors/hs-p-rf-lp-pg/hs-p-rf-lp-pg-fp.htm

you'll find types, that are able to handle up to 30kA.

If you could get a GPS receiver protector for, say, 15 or 20 Dollars, I 
would apply it. It should be designed to particularly protect receivers, 
since transmitter protectors have higher ignition voltages.

Cheers

Volker - DF9PL




Am 26.11.2012 19:18, schrieb Mark Spencer:

I don't use one on my gpsdo feed line.   The shield of the feed line is 
grounded prior to it entering the house and I don't live in a lightning prone 
area.  The gps antenna I use apparently has diode protection to provide some 
immunity to near by lightning strikes.  Most of my radio antennas are dc 
grounded.  I also had a dedicated roof top ground system installed during some 
prior home renovations that the coax shields of my roof top antenna(s) are 
connected to.   This ground system is in turn connected to the electrical 
service ground out side of the house.  I'm hopeful the roof top ground will be 
a more attractive path to ground for lightning than the shields of the feed 
lines that run into the house that are connected to gpsdo's and radios that are 
in turn grounded via the electrical system in the house.

If I see a surge suppressor for a decent price on eBay I might re consider 
getting one, but I'm unsure if it would make much difference in my 
circumstances in the event of a direct hit.   I'm primarily interested in 
protecting the house and it's occupants.   The survival of the radios is a 
fairly low priority to me.

I hope I never get to find out what happens if my roof top antennas get hit by 
lightning.

Regards


Mark Spencer








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