date:20141020

Hi

Yes, but there’s this large object in the sky that modifies the ionosphere as 
it travels in a “about one a day” track. It appears to be coming up just about 
now, but I do need more coffee to be sure …

The combination of the constellation and the ionosphere are what I believe give 
you the once a day (rather than once per 12 hours) bump. 

Bob

 On Oct 20, 2014, at 3:43 AM, Magnus Danielson mag...@rubidium.dyndns.org 
 wrote:
 
 Bob,
 
 Since the satellite orbit the earth with a period of 11 hours and 58 minutes, 
 it is actually twice a day.
 
 Cheers,
 Magnus
 
 On 10/20/2014 03:50 AM, Bob Camp wrote:
 Hi
 
 The GPS constellation repeats roughly once a day. It is not at all uncommon 
 to have a “worst case” sattelite  geometry for a given antenna location. If 
 you have one, it will repeat once a day and show up as a bump in the timing 
 out of your GPS module. If you track long term data, it will / may / can 
 keep you from getting to the sort of stability you would expect in the 
 100,000 second range. It’s one of the main reasons that things like 
 GPSD-Rb’s lock up with time constants much longer than 100K seconds. Yes 
 having a Cs or something similar helps a lot looking for this sort of thing.
 
 Bob
 
 On Oct 19, 2014, at 9:26 PM, Bob Stewart b...@evoria.net wrote:
 
 Hi Bob Camp,
 
 
 In your response to Chris, you said: Once you have it “right” you really 
 need to check it over a month or two to watch for GPS “once a day” issues. 
 
 Could I ask you what you meant by these once a day issues?  Was this a 
 general comment, or was it about something specific?  As you know I'm 
 working on a GPSDO and am doing a lot of testing, so if there's something 
 else I should be looking for, please let me know.
 
 
 Bob - AE6RV
 
 
 
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Re: [time-nuts] GPS once a day issues ?

2014-10-20 Thread John C. Westmoreland, P.E.

Bob,

You mean the Sun, correct?

Regards,
John
 On Oct 20, 2014 4:16 AM, Bob Camp kb...@n1k.org wrote:

 Hi

 Yes, but there’s this large object in the sky that modifies the ionosphere
 as it travels in a “about one a day” track. It appears to be coming up just
 about now, but I do need more coffee to be sure …

 The combination of the constellation and the ionosphere are what I believe
 give you the once a day (rather than once per 12 hours) bump.

 Bob

  On Oct 20, 2014, at 3:43 AM, Magnus Danielson 
 mag...@rubidium.dyndns.org wrote:
 
  Bob,
 
  Since the satellite orbit the earth with a period of 11 hours and 58
 minutes, it is actually twice a day.
 
  Cheers,
  Magnus
 
  On 10/20/2014 03:50 AM, Bob Camp wrote:
  Hi
 
  The GPS constellation repeats roughly once a day. It is not at all
 uncommon to have a “worst case” sattelite  geometry for a given antenna
 location. If you have one, it will repeat once a day and show up as a bump
 in the timing out of your GPS module. If you track long term data, it will
 / may / can keep you from getting to the sort of stability you would expect
 in the 100,000 second range. It’s one of the main reasons that things like
 GPSD-Rb’s lock up with time constants much longer than 100K seconds. Yes
 having a Cs or something similar helps a lot looking for this sort of thing.
 
  Bob
 
  On Oct 19, 2014, at 9:26 PM, Bob Stewart b...@evoria.net wrote:
 
  Hi Bob Camp,
 
 
  In your response to Chris, you said: Once you have it “right” you
 really need to check it over a month or two to watch for GPS “once a day”
 issues. 
 
  Could I ask you what you meant by these once a day issues?  Was this
 a general comment, or was it about something specific?  As you know I'm
 working on a GPSDO and am doing a lot of testing, so if there's something
 else I should be looking for, please let me know.
 
 
  Bob - AE6RV
 
 
  
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Re: [time-nuts] GPS once a day issues ?

Hi

Gee, now after a few cups of coffee … yes that does appear to be the sun.



The GPS system does it’s best to model the ionosphere and transmit that data. 
Unfortunately the model / model resolution is not as good as it could be. That 
lets the ionosphere creep into the solution more than it might with a perfect 
model. My *guess* (as in I have no data) is that constellations with a 
significant number of low(er) angle sats *and* a sun rise / sun set over one 
end of the constellation are the worst ones. That could easily be pure bunk.

Bob

 On Oct 20, 2014, at 7:31 AM, John C. Westmoreland, P.E. 
 j...@westmorelandengineering.com wrote:
 
 Bob,
 
 You mean the Sun, correct?
 
 Regards,
 John
 On Oct 20, 2014 4:16 AM, Bob Camp kb...@n1k.org wrote:
 
 Hi
 
 Yes, but there’s this large object in the sky that modifies the ionosphere
 as it travels in a “about one a day” track. It appears to be coming up just
 about now, but I do need more coffee to be sure …
 
 The combination of the constellation and the ionosphere are what I believe
 give you the once a day (rather than once per 12 hours) bump.
 
 Bob
 
 On Oct 20, 2014, at 3:43 AM, Magnus Danielson 
 mag...@rubidium.dyndns.org wrote:
 
 Bob,
 
 Since the satellite orbit the earth with a period of 11 hours and 58
 minutes, it is actually twice a day.
 
 Cheers,
 Magnus
 
 On 10/20/2014 03:50 AM, Bob Camp wrote:
 Hi
 
 The GPS constellation repeats roughly once a day. It is not at all
 uncommon to have a “worst case” sattelite  geometry for a given antenna
 location. If you have one, it will repeat once a day and show up as a bump
 in the timing out of your GPS module. If you track long term data, it will
 / may / can keep you from getting to the sort of stability you would expect
 in the 100,000 second range. It’s one of the main reasons that things like
 GPSD-Rb’s lock up with time constants much longer than 100K seconds. Yes
 having a Cs or something similar helps a lot looking for this sort of thing.
 
 Bob
 
 On Oct 19, 2014, at 9:26 PM, Bob Stewart b...@evoria.net wrote:
 
 Hi Bob Camp,
 
 
 In your response to Chris, you said: Once you have it “right” you
 really need to check it over a month or two to watch for GPS “once a day”
 issues. 
 
 Could I ask you what you meant by these once a day issues?  Was this
 a general comment, or was it about something specific?  As you know I'm
 working on a GPSDO and am doing a lot of testing, so if there's something
 else I should be looking for, please let me know.
 
 
 Bob - AE6RV
 
 
 
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Re: [time-nuts] LTE-Lite module

Hi

We tend to focus on this or that enhanced feature in a piece of code. It’s fun 
to talk about. That’s not what keeps most designs from doing what they should. 
By focusing on this rather than the testing required, we set people up to fail. 
If you start off the project believing you mostly need fancy code when you 
mostly need long term testing instead, you hit a wall pretty fast. Setting up 
for one is not at all the same as setting up for the other. 

Bob

 On Oct 20, 2014, at 5:51 AM, Charles Steinmetz csteinm...@yandex.com wrote:
 
 Poul-Henning wrote:
 
 PLLs are really not that hard  [context: we have been discussing all-digital 
 PLLs (ADPLLs)]
 
 Yes, I know -- I have designed more than a few.  I have also reviewed more 
 than a dozen hobbyist designs and modeled some of them, and found that few 
 hobbyists seem to have mastered the art.  Judging also by on-list responses 
 over the years, it does not appear that many time nuts are interested in 
 designing and building their own ADPLLs.  So, I conclude that disciplining a 
 good OCXO with GPS and getting the best stability the OCXO can deliver is not 
 practicable for most hobbyists.
 
 The OP in this sub-thread indicated that he was considering using an LTE-Lite 
 to discipline a really good 10811, and it appeared that his expectation was 
 to end up with a GPSDO more or less as good as his 10811.  My point was 
 simply to put realistic bounds on the expectation.
 
 Said posted that a quick lash-up with an OCXO produced stability about 10x 
 better than with the on-board TCXO.  That is a useful improvement, but a good 
 OCXO (certainly, a really good 10811) will have stability about 3 orders of 
 magnitude better than a TCXO (1000x), so two decades of possible improvement 
 were not realized.
 
 Said's experiment was a proof-of-concept exercise and not a careful 
 optimization, so it is almost certain one could do better than 10x with some 
 further work.  But I very much doubt that optimization can gain the entire 
 two decades of potential improvement (short of designing a full ADPLL, in 
 which case you don't need the LTE-Lite at all -- all you need is a source of 
 PPS), and I doubt it is possible to gain even one whole decade.
 
 So, I am inclined to think that there are better (and easier) ways to 
 discipline a 10811 to reach its ful potential, that's all.
 
 Best regards,
 
 Charles
 
 
 
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Re: [time-nuts] GPS once a day issues ?

2014-10-20 Thread Tim Shoppa

having kept watch over oscillators for about half a century now... My first
assumption would be that a once-a-day bump in time offset or tuning word,
is due to earthside changes especially temperature of the earthside
oscillator environment.


Tim N3QE



On Sunday, October 19, 2014, Bob Stewart b...@evoria.net wrote:

 Hi Bob Camp,


 In your response to Chris, you said: Once you have it “right” you really
 need to check it over a month or two to watch for GPS “once a day” issues. 

 Could I ask you what you meant by these once a day issues?  Was this a
 general comment, or was it about something specific?  As you know I'm
 working on a GPSDO and am doing a lot of testing, so if there's something
 else I should be looking for, please let me know.


 Bob - AE6RV


 
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[time-nuts] Femtosecond Systems FSS 600 phase noise detector

2014-10-20 Thread Timestep

From:  Dave Cawley
Dartmouth  United Kingdom


Femtosecond Systems FSS 600 phase noise detector

Guys

Just won this on eBay.  Try as I might,  I can't find any details especially a 
circuit/schematic diagram.  Can anyone help please ?

Thanks

Dave

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Re: [time-nuts] GPS once a day issues ?

2014-10-20 Thread Brian Lloyd

On Mon, Oct 20, 2014 at 2:43 AM, Magnus Danielson 
mag...@rubidium.dyndns.org wrote:

 Bob,

 Since the satellite orbit the earth with a period of 11 hours and 58
 minutes, it is actually twice a day.


But then your house has only completed half an orbit.

-- 
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
br...@lloyd.aero
+1.210.802-8FLY (1.210.802-8359)
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Re: [time-nuts] GPS once a day issues ?

The GPS satellites are at an altitude that gives them an orbit of 12* hours. 
But during that time the earth has made half a rotation. Thus it takes -two- SV 
orbits and -one- earth rotation to get back to the same geometry. It is this 
24* hour ground-track repeat time that is of interest in high-precision work.

That's why you often see GPS time-transfer data based on days*, rather than 
just a few thousand seconds or 12 hours. This is not likely to affect any of 
you working on home GPSDO projects. But it is a concern for the folks that do 
positioning at mm levels.

* Fun facts:
1) Right, it's not actually 24 hours (solar day); instead it's closer to 23h 
56m (sidereal day).
2) However, if you look closely you find it's not precisely a sidereal day 
(86164 s) either; instead the repeat time is closer to 86155 s, due to 
gravitational effects (inclined orbits, non-spherical earth).
3) If you look even closer you find each SV has its own repeat time; 86155 is 
merely the constellation average.
4) Also the per-SV repeat times are not constant; they slowly drift by about 10 
seconds a year. As the orbit decays and the repeat time gets out of spec, an 
orbital maneuver puts the SV back.

For a nice description of this effect, here's a short 2-page summary:
http://www.insidegnss.com/pdf/ig0806_gnss-solutions.pdf

For deeper technical details, start with these papers:
http://spot.colorado.edu/~kristine/gpsrep.pdf
http://www.isprs.org/proceedings/XXXVII/congress/4_pdf/162.pdf
http://web.gps.caltech.edu/classes/ge167/file/Ragheb2007.pdf

And finally, to see the effect on a GPSDO, I have some ADEV plots at:
http://leapsecond.com/pages/sidereal/
http://leapsecond.com/pages/sidereal/14years.htm

/tvb
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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread Charles Steinmetz


Bob wrote:

We tend to focus on this or that enhanced feature in a piece of 
code. It's fun to talk about. That's not what keeps most designs 
from doing what they should. By focusing on this rather than the 
testing required, we set people up to fail. If you start off the 
project believing you mostly need fancy code when you mostly need 
long term testing instead, you hit a wall pretty fast. Setting up 
for one is not at all the same as setting up for the other.


Not really sure what this has to do with my post to which you 
replied??  I assure you, I do not find code to be a fun, or even very 
interesting, topic of conversation, and I did not mention it at all 
in that post.  Really, the only thing I've said about code is that 
I've found it takes more than 100 lines to do a proper ADPLL.  When I 
have some time, I have to sit down and study Poul-Henning's code to 
see what I can learn from it about parsimony.


Best regards,

Charles



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Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

2014-10-20 Thread Dave M

Stu,
Many thanks for the heads-up on htese units. Great deals.

Can you advise the size of these units? Are they full-size 19 rack mount
or the half-size units like the Z3801A?
Can the REF-1 unit (the one with the GPS receiver) be operated separately
from the REF-0 unit?

There is a mod on Didier's site to add the 10 MHz output to the RFTGm unit
at
http://www.ko4bb.com/manuals/download.php?file=05)_GPS_Timing/Lucent_RFTGm_RFTGm-II-XO_GPSDO_modification_to_add_10MHz.pdf.
I don't know if the mod will apply to the units on Ebay right now, but it's
quite possible that it does.

Cheers,
Dave M

Stewart Cobb wrote:

Fellow time-nuts,

This (long) post is a review of the HP/Symmetricom Z3810A (or Z3810AS)
GPSDO system built for Lucent circa 2000. I wrote it because I looked
for more information before I bought one, and couldn't find much.
It's relevant because (as of this writing), you can buy a full system
on the usual auction site for about $150 plus shipping. For those of
you lamenting the dearth of cheap Thunderbolts, this looks like one of
the best deals going. The description of these objects does not
include GPSDO, so time-nuts may have missed it. Search for one of
the part numbers in the subject line and you should find it.

So what is it? It's a dual GPSDO built by HP as a reference
(Redundant Frequency and Time Generator, or RFTG) for a Lucent
cell-phone base station, built to Lucent's spec KS-24361. Internally,
it's a close cousin of a later-model Z3805A. Externally, it looks to
be almost a drop-in replacement for the earlier RFTG system built to
Lucent's spec KS-24019. That was a redundant system containing one
rubidium (LPRO, in the one I have) and one OCXO in two
almost-identical boxes. That spec went through several revisions with
slightly different nameplates and presumably slightly different
internals. You can generally find one or two examples on the auction
site (search for RFTG or KS-24019).

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Re: [time-nuts] LTE-Lite module

 http://phk.freebsd.dk/time/20141018.html

PHK,

This is the best news I've heard in a long time; an overhaul of NTP!

One suggestion I'd like to make. You've seen the GPSDO simulator code I started:
http://leapsecond.com/tools/gpsim1.c
And you've seen the growing collection of GPS receiver and OCXO oscillator raw 
data:
http://leapsecond.com/pages/gpsdo-sim/

Instead of tweaking GPSDO algorithms or tuning parameters and having to wait 
days to see if it works or not, the idea was to replay pre-recorded 1PPS data 
and pre-recorded oscillator data into the PLL. This means one can test any new 
design change in a GPSDO in a matter of seconds instead of days.

So the question is -- could you do the same for NTP? On your own, or with 
world-wide contributions, you could collect long data sets (phase or frequency) 
of free-running PC clock oscillators, every shape and size and environment. And 
then also collect high-precision real-life NTP packet timings, warts and all 
(especially outlier examples).

Then instead of testing iterations of your new code on live NTP servers you 
merely apply previously collected packet data and previously collected clock 
data. With a little scripting you'd get performance plots within seconds 
instead of waiting hours or days. Moreover, the plots you generate would cover 
tens or hundreds of historical scenarios instead of just the few you could find 
in real time.

/tvb

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Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

2014-10-20 Thread Glen Hoag

Dave,
The seller is offering the REF-0 and REF-1 units at $75 each plus
shipping. When I searched for Lucent KS-24361, I found the
original item with both, as well as the individual units.

--Glen Hoag
h...@hiwaay.net

At 10:22 AM 10/20/2014, you wrote:

Stu,
Many thanks for the heads-up on htese units. Great deals.

Can you advise the size of these units? Are they full-size 19 rack
mount or the half-size units like the Z3801A?
Can the REF-1 unit (the one with the GPS receiver) be operated
separately from the REF-0 unit?

There is a mod on Didier's site to add the 10 MHz output to the
RFTGm unit at
http://www.ko4bb.com/manuals/download.php?file=05)_GPS_Timing/Lucent_RFTGm_RFTGm-II-XO_GPSDO_modification_to_add_10MHz.pdf.
I don't know if the mod will apply to the units on Ebay right now,
but it's quite possible that it does.

Cheers,
Dave M

Stewart Cobb wrote:

Fellow time-nuts,

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Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

2014-10-20 Thread Anthony Roby

In the link below there's a photo of one of the units with a ruler against it - 
11 wide.

Anthony

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave M
Sent: Monday, October 20, 2014 10:22 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, 
Z3811A, Z3812A GPSDO system

Stu,
Many thanks for the heads-up on htese units.  Great deals.

Can you advise the size of these units?  Are they full-size 19 rack mount or 
the half-size units like the Z3801A?
Can the REF-1 unit (the one with the GPS receiver) be operated separately from 
the REF-0 unit?

There is a mod on Didier's site to add the 10 MHz output to the RFTGm unit at 
http://www.ko4bb.com/manuals/download.php?file=05)_GPS_Timing/Lucent_RFTGm_RFTGm-II-XO_GPSDO_modification_to_add_10MHz.pdf.

I don't know if the mod will apply to the units on Ebay right now, but it's 
quite possible that it does.

Cheers,
Dave M

Stewart Cobb wrote:
 Fellow time-nuts,

 This (long) post is a review of the HP/Symmetricom Z3810A (or Z3810AS) 
 GPSDO system built for Lucent circa 2000.  I wrote it because I looked 
 for more information before I bought one, and couldn't find much.
 It's relevant because (as of this writing), you can buy a full system 
 on the usual auction site for about $150 plus shipping.  For those of 
 you lamenting the dearth of cheap Thunderbolts, this looks like one of 
 the best deals going.  The description of these objects does not 
 include GPSDO, so time-nuts may have missed it.  Search for one of 
 the part numbers in the subject line and you should find it.

 So what is it?  It's a dual GPSDO built by HP as a reference 
 (Redundant Frequency and Time Generator, or RFTG) for a Lucent 
 cell-phone base station, built to Lucent's spec KS-24361. Internally, 
 it's a close cousin of a later-model Z3805A.  Externally, it looks to 
 be almost a drop-in replacement for the earlier RFTG system built to 
 Lucent's spec KS-24019.  That was a redundant system containing one 
 rubidium (LPRO, in the one I have) and one OCXO in two 
 almost-identical boxes.  That spec went through several revisions with 
 slightly different nameplates and presumably slightly different 
 internals.  You can generally find one or two examples on the auction 
 site (search for RFTG or KS-24019).

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Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

Hi Glen,

I'm looking at this unit, but I have to say that I can't make any sense from 
the listing.  I don't know what the REF-0 and REF-1 units do, and I don't know 
whether they need to be connected to a Z3810AS, which I don't have.  Could you 
or someone elaborate on exactly what these are?

Bob - AE6RV




 From: Glen Hoag h...@hiwaay.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com 
Sent: Monday, October 20, 2014 11:04 AM
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, 
Z3811A, Z3812A GPSDO system
 

Dave,
The seller is offering the REF-0 and REF-1 units at $75 each plus 
shipping.  When I searched for Lucent KS-24361, I found the 
original item with both, as well as the individual units.

--Glen Hoag
  h...@hiwaay.net
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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread Brian Lloyd

On Mon, Oct 20, 2014 at 6:48 AM, Bob Camp kb...@n1k.org wrote:

 Hi

 We tend to focus on this or that enhanced feature in a piece of code. It’s
 fun to talk about. That’s not what keeps most designs from doing what they
 should. By focusing on this rather than the testing required, we set people
 up to fail. If you start off the project believing you mostly need fancy
 code when you mostly need long term testing instead, you hit a wall pretty
 fast. Setting up for one is not at all the same as setting up for the other.


Sounds to me like the hardware and code are pretty straight-forward. The
difference comes from the terms and coefficients in the PLL loop filter and
those need to be optimized for each OCXO. There appear to be here a handful
of people who have a pretty good idea of what those coefficients should be
for various well-known OCXOs out there.

So why not do the GPSD hardware, software, and then provide the
coefficients that will get a handful of the more popular OCXOs available
out there to within a decade of optimum, certainly closer than what one
would be talking about by just bolting x-random OCXO onto an LTE-lite? I
suspect there would be a market in the time-nut world for such a critter.

-- 
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
br...@lloyd.aero
+1.210.802-8FLY (1.210.802-8359)
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Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

Oh, duh.  Sorry.  I missed the relevant post.  Never mind.  Now I'll go feel 
embarrassed for awhile.


Bob




 From: Bob Stewart b...@evoria.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com 
Sent: Monday, October 20, 2014 11:59 AM
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,
Z3811A, Z3812A GPSDO system
 

Hi Glen,

I'm looking at this unit, but I have to say that I can't make any sense from 
the listing.  I don't know what the REF-0 and REF-1 units do, and I don't know 
whether they need to be connected to a Z3810AS, which I don't have.  Could you 
or someone elaborate on exactly what these are?

Bob - AE6RV







From: Glen Hoag h...@hiwaay.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com 
Sent: Monday, October 20, 2014 11:04 AM
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, 
Z3811A, Z3812A GPSDO system


Dave,
The seller is offering the REF-0 and REF-1 units at $75 each plus 
shipping.  When I searched for Lucent KS-24361, I found the 
original item with both, as well as the individual units.

--Glen Hoag
  h...@hiwaay.net
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Re: [time-nuts] GPS once a day issues ?

2014-10-20 Thread Hal Murray


kb...@n1k.org said:
 The combination of the constellation and the ionosphere are what I believe
 give you the once a day (rather than once per 12 hours) bump.  

There is another layer.  In addition to the normal once-a-day type 
differences, the pattern of satellites drifts slowly from day to day.  So 
there is another pattern with a period of something like a month.  If you 
have a marginal setup, for example an indoor antenna, you can see things like 
the holdover times drifting both in time-of-day when they happen and in 
length of holdover as the satellite pattern at dawn/dusk changes.

Of course, at that level of detail, there are lots of other contributions 
like rain that will also show up and may be more important.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] WTB: GPS Antenna Splitter

2014-10-20 Thread Peter Loron

Well, may memory was somewhat faulty. The units I have are
3ZN2PD-1910-1. There is a seller on ebay with the same thing:

http://www.ebay.com/itm/Mini-Circuits-3ZN2PD-1910-1-RF-Power-Splitter-LUCENT-COMCODE-408781904-/131191412618

If anybody is interested, I'll let mine go for $20 shipped in USA each.

-Pete

On 2014-10-15 16:43, Dave M wrote:

Pete, I see a ZAPD-30 on the miniCircuits web site. Might those be
the models that you have?
If so, (and assuming that you can find them), how much for a couple?

Thanks,
Dave M

Peter Loron wrote:

Dave, I think I have a MiniCircuits ZAPD-3(?) splitter or two kicking
around. I'll try to get a look in the stash this weekend.

-Pete

On 2014-10-06 13:01, Dave M wrote:

Does anyone in the group have, or can point me to, a low-cost (but
not cheap) 2-port splitter for a GPS antenna? Those on Ebay are
rather expensive.

I have two GPSDO units, and have both an older timing antenna and a
new choke ring antenna (Thanks, Pete L). I already have one 2-port
splitter
(working well), but my intent is to connect both antennas through the
splitters and a couple coaxial relays so that I can, with the twist
of a
switch, allow me to run each GPS from a different antenna, or both
from the
same antenna. I would like to gather some data as to the differences
between the two antennas. I know I could switch the connections
manually,
but I like the idea of a switch to sort of automate the connections,
and I'd
need another splitter anyway.

Before I go to the trouble and expense of building upon this idea,
are there
any comments as to the value of the project?
Some questions come to mind:
I'm thinking about mounting both antennas on the same mast, at the
same elevation, just separated by a couple feet. Any problems that
I should be
aware of by putting both antennas so close together? Will that small
distance have a noticeable effect when switching a receiver from one
antenna
to the other? Will the GPS notice the difference and want to do
another
survey?

Thanks for your comments.
Dave M

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Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

Stu said:

Power is applied to the connector labeled +24VDC and P1, in exactly the 
same way as the earlier RFTG units. Apply +24V to pin 1 and the other side of 
the power supply (GND or RTN) to pin 2.  In these units, that power supply goes 
directly to an isolated Lucent DC/DC converter brick labeled IN: DC 18-36, 
1.9A.  Presumably you can run both units with a 4-amp supply.

Hi Stu,

I decided to get a set of these as a reference for my own GPSDO development 
efforts.  Now to power it.  From your description, it looks like a pair of 
laptop supply bricks might fit the bill.  I'm looking at one here that says DC 
22.5-18V 2.0-2.5A.  Does that sound reasonable or should I get something a bit 
better?


Bob




 From: Stewart Cobb stewart.c...@gmail.com
To: time-nuts@febo.com 
Sent: Sunday, October 19, 2014 11:53 PM
Subject: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A,
Z3812A GPSDO system
 

Fellow time-nuts,

This (long) post is a review of the HP/Symmetricom Z3810A (or Z3810AS)
GPSDO system built for Lucent circa 2000.  I wrote it because I looked
for more information before I bought one, and couldn't find much.
It's relevant because (as of this writing), you can buy a full system
on the usual auction site for about $150 plus shipping.  For those of
you lamenting the dearth of cheap Thunderbolts, this looks like one of
the best deals going.  The description of these objects does not
include GPSDO, so time-nuts may have missed it.  Search for one of
the part numbers in the subject line and you should find it.

big snip
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Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

2014-10-20 Thread Dave M

Arg!  I read the whole article on the mod but just didn't see the ruler. 
Oops!


Thanks for the alert,
Dave M


Anthony Roby wrote:

In the link below there's a photo of one of the units with a ruler
against it - 11 wide.

Anthony

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave
M
Sent: Monday, October 20, 2014 10:22 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A,
Z3810A, Z3811A, Z3812A GPSDO system

Stu,
Many thanks for the heads-up on htese units.  Great deals.

Can you advise the size of these units?  Are they full-size 19 rack
mount or the half-size units like the Z3801A?
Can the REF-1 unit (the one with the GPS receiver) be operated
separately from the REF-0 unit?

There is a mod on Didier's site to add the 10 MHz output to the RFTGm
unit at
http://www.ko4bb.com/manuals/download.php?file=05)_GPS_Timing/Lucent_RFTGm_RFTGm-II-XO_GPSDO_modification_to_add_10MHz.pdf.
I don't know if the mod will apply to the units on Ebay right now,
but it's quite possible that it does.

Cheers,
Dave M


Stewart Cobb wrote:

Fellow time-nuts,

This (long) post is a review of the HP/Symmetricom Z3810A (or
Z3810AS) GPSDO system built for Lucent circa 2000.  I wrote it
because I looked for more information before I bought one, and
couldn't find much. It's relevant because (as of this writing), you
can buy a full system on the usual auction site for about $150 plus
shipping.  For those of you lamenting the dearth of cheap
Thunderbolts, this looks like one of the best deals going.  The
description of these objects does not include GPSDO, so time-nuts
may have missed it.  Search for one of the part numbers in the
subject line and you should find it.

So what is it?  It's a dual GPSDO built by HP as a reference
(Redundant Frequency and Time Generator, or RFTG) for a Lucent
cell-phone base station, built to Lucent's spec KS-24361. Internally,
it's a close cousin of a later-model Z3805A.  Externally, it looks to
be almost a drop-in replacement for the earlier RFTG system built to
Lucent's spec KS-24019.  That was a redundant system containing one
rubidium (LPRO, in the one I have) and one OCXO in two
almost-identical boxes.  That spec went through several revisions
with slightly different nameplates and presumably slightly different
internals.  You can generally find one or two examples on the auction
site (search for RFTG or KS-24019).





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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread Poul-Henning Kamp


In message 60CC0E034928B664249EAC88407F@pc52, Tom Van Baak writes:
 http://phk.freebsd.dk/time/20141018.html

PHK,

This is the best news I've heard in a long time; an overhaul of NTP!

Indeed :-)

Instead of tweaking GPSDO algorithms or tuning parameters and
having to wait days to see if it works or not, the idea was to
replay pre-recorded 1PPS data and pre-recorded oscillator data
into the PLL. This means one can test any new design change in a
GPSDO in a matter of seconds instead of days.

So the question is -- could you do the same for NTP?

Well, first of all it's not days any longer.  My proto-PLL wrangles
the clock phase in a matter of seconds and frequency in a few
minutes.  Some of the (really) old NTP assumptions and metrics no
longer hold, revisiting them opens up a lot of parameter space.

Second, I'm already doing such simulations, and the ability to
do that is part of the design basis of what I'm doing.

I spent a month of my NTP-time trying to resurrect the SIM code in
ntpd, in order to get some kind of reproducible test-bench going and
in the end I concluded that 100k lines of code is not the way forward.

My current plan is to release a brand new client-only NTP daemon
with a decent PLL and high attack resistance before X-mas and then
work from there to one or two other programs: NTP-slave server (ie:
stratum 2..14) and a NTP-master/stratum 1 server.

All along the way, the intent is to try to pull PTP into this also,
since there is no material (ie: only protocol) difference between
a NTP and PTP timekeeping program, and the user shouldn't need to
notice the difference.

More as it happens.

The mini-blog entries I've started will happen every so often
when there is some progress to report or interesting data to
present.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread Poul-Henning Kamp


In message CAGVVbuGv_-cFDAA=T6hGE1ey32=omxxcg-cxub5scusao_t...@mail.gmail.com
, Brian Lloyd writes:

So why not do the GPSD hardware, software, [...]

It would be a really worthwhile project in general, and it could be
made very general with very little trouble.

I would find a cheap ARM board (Olimex ?) that can support ChibiOS:

http://www.chibios.org/dokuwiki/doku.php?id=news

and add a cape PCB with a high resolution DAC for EFC control
and two phase detectors, one for 100kHz-20MHz frequencies and one
for 1-100Hz frequencies.  (The latter could have a TVB PIC divider
as an option on the reference input).

Maybe add a couple of isolated distribution amp outputs also ?

That would make for a really experimenter-friendly computer PLL
platform.

People who want to code can do so, people less ambitious could
tweak PLL params in the default firmware using the ChibiOS command
line interface...

Count me in...


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread S. Jackson via time-nuts

Hi Brian, Bob, Charles, et. al.
 
Bob has a great point about the difference between a one-off in a basement  
lab, and a commercial product that has to work under any circumstances, 
wether  flying at 50,000 feet at -56C, or in an urban canyon, or under whatever 
other  stress could be thrown at it. In fact the testing and fine tuning 
does take  90% of a product design cycle.
 
That said here is the ADEV plot from my overnight test with the DOCXO. No  
comments.
 
This was done without any loop adjustment whatsoever, same board and  
software that drives the on-board TCXO. I will let the result speak for  
itself, 
save to say the loop, the DAC, the DAC reference, and the GPS with a  proper 
OCXO can achieve performance at a level approaching two orders of  
magnitude better than our spec which is 1ppb for this  particular product.
 
PLEASE(!) do not send me emails once you get your board and plug in your  
own OCXO and don't see similar performance for whatever reasons. There is not 
 much we can do about that, other than say our product meets 
specifications. On  the other hand if you connect a really good OCXO you may 
even get 
better  performance than I got, but who knows.

Thanks,
Said
 
 
 
 
In a message dated 10/20/2014 10:21:15 Pacific Daylight Time,  
br...@lloyd.aero writes:

On Mon,  Oct 20, 2014 at 6:48 AM, Bob Camp kb...@n1k.org wrote:

  Hi

 We tend to focus on this or that enhanced feature in a  piece of code. It’
s
 fun to talk about. That’s not what keeps most  designs from doing what 
they
 should. By focusing on this rather than  the testing required, we set 
people
 up to fail. If you start off the  project believing you mostly need fancy
 code when you mostly need long  term testing instead, you hit a wall 
pretty
 fast. Setting up for one  is not at all the same as setting up for the 
other.


Sounds to  me like the hardware and code are pretty straight-forward. The
difference  comes from the terms and coefficients in the PLL loop filter and
those need  to be optimized for each OCXO. There appear to be here a handful
of people  who have a pretty good idea of what those coefficients should be
for  various well-known OCXOs out there.

So why not do the GPSD hardware,  software, and then provide the
coefficients that will get a handful of the  more popular OCXOs available
out there to within a decade of optimum,  certainly closer than what one
would be talking about by just bolting  x-random OCXO onto an LTE-lite? I
suspect there would be a market in the  time-nut world for such a critter.

-- 
Brian Lloyd
Lloyd  Aviation
706 Flightline Drive
Spring Branch, TX  78070
br...@lloyd.aero
+1.210.802-8FLY  (1.210.802-8359)
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lte-lite_DOCXO_adev.png
Description: Binary data
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[time-nuts] Antenna spacing - non scientific

2014-10-20 Thread Pete Lancashire

This weekend I walked over the the park next to where I live. In that park
is a water tower/tank with its safety railing covered in cell transceivers.
Looks like there are 3 providers, based on the number of power company
watthour meters I can see.

Each has their own GPS antennas, two of which are about 10 feet apart and
the same height.

The third, one weekend changed from a A/C'ed building to a medium size NEMA
box. Its GPS antenna is now about 15 feet from the others and about 3 feet
lower.

Totally non scientific

-pete
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[time-nuts] LTE-Lite order question

2014-10-20 Thread paul swed

Said
Having some fun reading your posts on time-nuts.

I placed an order last Friday or Saturday for one 20 Mhz unit. But a couple
of funny things seemed to happen like ebay saying 2 units ordered I
corrected that.
But today I received an email reminding me to pay you for the unit.
I have the paypal email saying I had.
Lastly the ship date was late November??
Would appreciate any help you could give me insuring you have a proper
order and what the ship date may be.
Thank you in advance for your time.
Paul Swedberg
WB8TSL
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Re: [time-nuts] LTE-Lite module

Hi

PHK has a roughly 6 line code snippet that does a basic PLL. Add two more lines 
to check / clamp the integrator if you wish. That’s 8 lines. If you want a D 
term (to give it an FLL component) add 2 more lines. We’re up to 10 lines. 

It’s just a control loop, not a full GPSDO. There’s not a lot to it.

The code and some magic hardware to run it on is not the key to all this. 
Setting up and spending the time testing and optimizing is.

Bob

 On Oct 20, 2014, at 8:54 AM, Charles Steinmetz csteinm...@yandex.com wrote:
 
 Bob wrote:
 
 We tend to focus on this or that enhanced feature in a piece of code. It's 
 fun to talk about. That's not what keeps most designs from doing what they 
 should. By focusing on this rather than the testing required, we set people 
 up to fail. If you start off the project believing you mostly need fancy 
 code when you mostly need long term testing instead, you hit a wall pretty 
 fast. Setting up for one is not at all the same as setting up for the other.
 
 Not really sure what this has to do with my post to which you replied??  I 
 assure you, I do not find code to be a fun, or even very interesting, topic 
 of conversation, and I did not mention it at all in that post.  Really, the 
 only thing I've said about code is that I've found it takes more than 100 
 lines to do a proper ADPLL.  When I have some time, I have to sit down and 
 study Poul-Henning's code to see what I can learn from it about parsimony.
 
 Best regards,
 
 Charles
 
 
 
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Re: [time-nuts] LTE-Lite module

Hi

The problem is that there are no “magic coefficients”. What you run depends 
very much on the exact OCXO you have, the environment you run it in, and the 
result you are after. 

For instance, Bert is after frequency stability. Tom is after the right time. 
Each of them will have very different coefficients for the same oscillator. 

My Morion OCXO has a floor of 2x10^-12, Bert has some that are 10X better than 
that (maybe). His coefficients and mine will be very different. 

I had an antenna outdoors. It got many sat’s all the time. Now I have one 
indoors. It’s not getting lots of sats all the time. My old coefficients are 
not going to be my new coefficients. 

No magic bullet, you have to do the work. 

Bob

 On Oct 20, 2014, at 1:20 PM, Brian Lloyd br...@lloyd.aero wrote:
 
 On Mon, Oct 20, 2014 at 6:48 AM, Bob Camp kb...@n1k.org wrote:
 
 Hi
 
 We tend to focus on this or that enhanced feature in a piece of code. It’s
 fun to talk about. That’s not what keeps most designs from doing what they
 should. By focusing on this rather than the testing required, we set people
 up to fail. If you start off the project believing you mostly need fancy
 code when you mostly need long term testing instead, you hit a wall pretty
 fast. Setting up for one is not at all the same as setting up for the other.
 
 
 Sounds to me like the hardware and code are pretty straight-forward. The
 difference comes from the terms and coefficients in the PLL loop filter and
 those need to be optimized for each OCXO. There appear to be here a handful
 of people who have a pretty good idea of what those coefficients should be
 for various well-known OCXOs out there.
 
 So why not do the GPSD hardware, software, and then provide the
 coefficients that will get a handful of the more popular OCXOs available
 out there to within a decade of optimum, certainly closer than what one
 would be talking about by just bolting x-random OCXO onto an LTE-lite? I
 suspect there would be a market in the time-nut world for such a critter.
 
 -- 
 Brian Lloyd
 Lloyd Aviation
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.aero
 +1.210.802-8FLY (1.210.802-8359)
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Re: [time-nuts] LTE-Lite module

Hi

The top of my list for “new NTP” would be to bring the 1588 hardware packet 
time tagging into the NTP code base. There’s a pretty good base of hardware out 
there that tags. It should help things on a loaded system.

Bob

 On Oct 20, 2014, at 3:41 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
 
 
 In message 60CC0E034928B664249EAC88407F@pc52, Tom Van Baak writes:
 http://phk.freebsd.dk/time/20141018.html
 
 PHK,
 
 This is the best news I've heard in a long time; an overhaul of NTP!
 
 Indeed :-)
 
 Instead of tweaking GPSDO algorithms or tuning parameters and
 having to wait days to see if it works or not, the idea was to
 replay pre-recorded 1PPS data and pre-recorded oscillator data
 into the PLL. This means one can test any new design change in a
 GPSDO in a matter of seconds instead of days.
 
 So the question is -- could you do the same for NTP?
 
 Well, first of all it's not days any longer.  My proto-PLL wrangles
 the clock phase in a matter of seconds and frequency in a few
 minutes.  Some of the (really) old NTP assumptions and metrics no
 longer hold, revisiting them opens up a lot of parameter space.
 
 Second, I'm already doing such simulations, and the ability to
 do that is part of the design basis of what I'm doing.
 
 I spent a month of my NTP-time trying to resurrect the SIM code in
 ntpd, in order to get some kind of reproducible test-bench going and
 in the end I concluded that 100k lines of code is not the way forward.
 
 My current plan is to release a brand new client-only NTP daemon
 with a decent PLL and high attack resistance before X-mas and then
 work from there to one or two other programs: NTP-slave server (ie:
 stratum 2..14) and a NTP-master/stratum 1 server.
 
 All along the way, the intent is to try to pull PTP into this also,
 since there is no material (ie: only protocol) difference between
 a NTP and PTP timekeeping program, and the user shouldn't need to
 notice the difference.
 
 More as it happens.
 
 The mini-blog entries I've started will happen every so often
 when there is some progress to report or interesting data to
 present.
 
 
 -- 
 Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
 p...@freebsd.org | TCP/IP since RFC 956
 FreeBSD committer   | BSD since 4.3-tahoe
 Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] LTE-Lite order question

2014-10-20 Thread Said Jackson via time-nuts

Paul,

I will answer you offline.

Guys please don't post items like this that aren't really of interest to all 
the others on the list.

Thanks,
Said

Sent From iPhone

 On Oct 20, 2014, at 13:41, paul swed paulsw...@gmail.com wrote:
 
 Said
 Having some fun reading your posts on time-nuts.
 
 I placed an order last Friday or Saturday for one 20 Mhz unit. But a couple
 of funny things seemed to happen like ebay saying 2 units ordered I
 corrected that.
 But today I received an email reminding me to pay you for the unit.
 I have the paypal email saying I had.
 Lastly the ship date was late November??
 Would appreciate any help you could give me insuring you have a proper
 order and what the ship date may be.
 Thank you in advance for your time.
 Paul Swedberg
 WB8TSL
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[time-nuts] LTE-Lite ? to SAID very sorry I emailed time-nuts

2014-10-20 Thread paul swed

I absolutely did not intend to email time-nuts with my question on the
order.
I am embarrassed that happened and sorry everyone for the noise.
Regards
Paul
WB8TSL
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[time-nuts] LTE-Lite 20MHz module

2014-10-20 Thread S. Jackson via time-nuts

 
Hello Jean-Louis, 
unfortunately the 20MHz kits sold-out already so Ebay  took down the page. 
We only had 50pcs with 20MHz TCXOs. We are  contacting the factory now to 
see if we can get more on a quick  turn. 
Looks like instead of getting 50x 19.2MHz units we should  have gotten more 
20MHz crystals. Since not many want the 19.2MHz, we could  re-task those 
boards to 20MHz if we can locate TCXOs. We will put up more on Ebay as soon as 
we can locate  those TCXOs, but right now those are quoted as 8 weeks lead 
time.. We will  do our best. 
Thanks everyone for your support, 
bye,
Said 
Hello Said, 
I'm unable to find the 20 MHz version of the LTE Lite  evaluation kit on 
eBay.  It seems that there are problems from abroad (I'm  in France). Even 
using the direct links seems to work only for the 10 MHz and  19.2 MHz: the 20 
MHz terminated. I wasn't able to connect this weekend, would  that means 
that they are all gone already? 
If that's the case, do you have any time frame for the  next batch?  
Thanks again for your  help,  
Jean-Louis Oneto 
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[time-nuts] cheap low power digital compensated XO

2014-10-20 Thread Jim Lux


http://www.petermann-technik.com/products/rtc/ptrtc1010/

http://www.edn.com/electronics-products/other/4435988/Low-cost-real-time-clock-IC-offers-precise-timing

...Temperature stability is ±5 ppm within the -40°C to +85°C range, 
which enables a highly accurate absolute time offset of 15 seconds over 
the temperature range


I don't know that 5ppm is all that wonderful, considering I can get a 
TCXO that is that good fairly easily, but it's much lower power..


They claim 6 microwatts to generate a 1pps.

I don't know how much they cost, but I suspect they're pretty inexpensive

The apnote at Petermann's website gives a fair number of specs (more 
like a datasheet), but no timing performance.


They also don't say much about the DTCXO or how it works.

They're SW of Munich a bit past DLR Oberpfaffenhofen on the way to the 
Boden See.

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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread Bert Kehren via time-nuts

Allow me to clarify.
I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3  
month +  burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. 
 Only two have been tested for ADEV and are close to 1 E-12,  2X not 10  X.
Bert Kehren
 
 
In a message dated 10/20/2014 5:58:37 P.M. Eastern Daylight Time,  
kb...@n1k.org writes:

Hi

The  problem is that there are no “magic coefficients”. What you run 
depends very  much on the exact OCXO you have, the environment you run it in, 
and 
the result  you are after. 

For instance, Bert is after frequency stability. Tom is  after the right 
time. Each of them will have very different coefficients for  the same 
oscillator. 

My Morion OCXO has a floor of 2x10^-12, Bert has  some that are 10X better 
than that (maybe). His coefficients and mine will be  very different. 

I had an antenna outdoors. It got many sat’s all the  time. Now I have one 
indoors. It’s not getting lots of sats all the time. My  old coefficients 
are not going to be my new coefficients. 

No magic  bullet, you have to do the work. 

Bob

 On Oct 20, 2014, at  1:20 PM, Brian Lloyd br...@lloyd.aero wrote:
 
 On Mon,  Oct 20, 2014 at 6:48 AM, Bob Camp kb...@n1k.org wrote:
  
 Hi
 
 We tend to focus on this or that  enhanced feature in a piece of code. It
’s
 fun to talk about.  That’s not what keeps most designs from doing what 
they
 should. By  focusing on this rather than the testing required, we set 
people
  up to fail. If you start off the project believing you mostly need  
fancy
 code when you mostly need long term testing instead, you hit  a wall 
pretty
 fast. Setting up for one is not at all the same as  setting up for the 
other.
 
 
 Sounds to me like the  hardware and code are pretty straight-forward. The
 difference comes  from the terms and coefficients in the PLL loop filter 
and
 those need  to be optimized for each OCXO. There appear to be here a 
handful
 of  people who have a pretty good idea of what those coefficients should  
be
 for various well-known OCXOs out there.
 
 So why not  do the GPSD hardware, software, and then provide the
 coefficients that  will get a handful of the more popular OCXOs available
 out there to  within a decade of optimum, certainly closer than what one
 would be  talking about by just bolting x-random OCXO onto an LTE-lite? I
  suspect there would be a market in the time-nut world for such a  
critter.
 
 -- 
 Brian Lloyd
 Lloyd  Aviation
 706 Flightline Drive
 Spring Branch, TX 78070
  br...@lloyd.aero
 +1.210.802-8FLY (1.210.802-8359)
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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread S. Jackson via time-nuts

Thanks much Charles,
 
just to remind everyone that the main idea of making the boards  available 
was to get folks a good disciplined TCXO, not to work as a  development 
platform to discipline external OCXOs.. Also as mentioned in the  FAQ, the 
typical performance plots I have been sending and are also in the  user-manual 
are gathered under optimal conditions of course: a roof-top antenna,  units 
shielded from airflow, and units running for a couple of days before  testing.
 
Please also note that I tried an OCXO with only +/-2Hz EFC range and  it 
did not lock due to the ~10Ks resulting time-constant and the loop being way  
to slow to capture the OCXO..
 
External oscillators should have between 9Hz per Volt to 100Hz+ per  Volt 
EFC sensitivity from what I can tell, otherwise an OPAMP circuit would be  
needed to bring the EFC into that range. Sorry, I cannot propose such a 
circuit,  but such a circuit had been sent as a schematic to the time nuts some 
 
years ago by someone if I remember correctly.
 
Bye,
Said
 
 
In a message dated 10/20/2014 15:55:45 Pacific Daylight Time,  
csteinm...@yandex.com writes:


here is the ADEV plot from my overnight test with the  DOCXO.  *  *  *

This was done without any loop  adjustment whatsoever, same board and
software that drives the on-board  TCXO. I will let the result speak 
for  itself,
save to say  the loop, the DAC, the DAC reference, and the GPS with a   
proper
OCXO can achieve performance at a level approaching two orders  of
magnitude better than our spec which is 1ppb for this   particular product.

Thanks for the ADEV plot, Said -- more pertinent  for most time nuts 
purposes than PN.  Of course, the typical  performance of the LTE-Lite 
with the TCXO is significantly better than the  spec (according to the 
user manual, about 5e-11 at 1 second and 1e-10 at  10 seconds, already 
1 to 1.5 OOM better than spec), so the typical  improvement with the 
OCXO wouldn't be a full two orders of  magnitude.  Still, very 
noteworthy performance that *surely*  justifies time nuts in buying 
one of the good, cheap OCXOs flooding the  surplus market to go along 
with their LTE-Lite.  Good  show.

Best  regards,

Charles



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Re: [time-nuts] LTE-Lite ? to SAID very sorry I emailed time-nuts


No worries, Paul. This was minor.

Actually, there have been quite a few postings in the past month that I suspect 
went to the entire list instead of one recipient. It may have to do with the 
recent changes to the mail list server (e.g., to accommodate AOL domains)? I'm 
not really sure. It's not the end of the world, but it has the potential to be 
very embarrassing to someone, someday. Remember also that time-nuts is, beyond 
our control, cloned in real time and archived in several places on the web.

In any event, everyone please be mindful of the To or Cc address in your reply 
before you hit send.

Thanks,
/tvb
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Re: [time-nuts] LTE-Lite module

To add to Bert's note...

Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent, 
almost by definition. What matters is phase noise and short-term stability, 
neither of which you can possibly fix with disciplining against GPS. GPS takes 
care of the rest.

Long-term stability can be critical for non-GPS applications, which is why 
oscillators with daily aging rates in the -11's and -12's are so amazing.

Consider this: if you want to run your bench with a clean 10 MHz source, stable 
to 11 or 12 digits and accurate to 9 digits -- you may be much better off with 
a free-running, stand-alone OCXO with an aging rate down at 1e-11/day than 
using a GPSDO/TCXO. To maintain accuracy of your OCXO just re-tune your OCXO 
*once a year*. Aside from ADEV plots, this is another way to appreciate how 
amazing some OCXO are, any why many of us still troll eBay for high-stability, 
low-noise, low-drift quartz oscillators.

/tvb

- Original Message - 
From: Bert Kehren via time-nuts time-nuts@febo.com
To: time-nuts@febo.com
Sent: Monday, October 20, 2014 4:01 PM
Subject: Re: [time-nuts] LTE-Lite module


Allow me to clarify.
I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3  
month +  burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. 
 Only two have been tested for ADEV and are close to 1 E-12,  2X not 10  X.
Bert Kehren
 

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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread Charles Steinmetz




here is the ADEV plot from my overnight test with the DOCXO.  *  *  *

This was done without any loop adjustment whatsoever, same board and
software that drives the on-board TCXO. I will let the result speak 
for  itself,

save to say the loop, the DAC, the DAC reference, and the GPS with a  proper
OCXO can achieve performance at a level approaching two orders of
magnitude better than our spec which is 1ppb for this  particular product.


Thanks for the ADEV plot, Said -- more pertinent for most time nuts 
purposes than PN.  Of course, the typical performance of the LTE-Lite 
with the TCXO is significantly better than the spec (according to the 
user manual, about 5e-11 at 1 second and 1e-10 at 10 seconds, already 
1 to 1.5 OOM better than spec), so the typical improvement with the 
OCXO wouldn't be a full two orders of magnitude.  Still, very 
noteworthy performance that *surely* justifies time nuts in buying 
one of the good, cheap OCXOs flooding the surplus market to go along 
with their LTE-Lite.  Good show.


Best regards,

Charles



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Re: [time-nuts] LTE-Lite module

Hi Tom,

One of the biggest problems I've unwittingly faces is that of retrace.  I had 
seen the term used several times, but hadn't looked it up until last night.  As 
you can imagine, with a GPSDO under development I've had to remove power more 
than a few times to make hardware changes.  I think the next time power is down 
I'm going to try to rearrange things so that the OCXO is permanently powered 
and just the board gets switched.  But then again would big jumps in the EFC 
cause other problems that are almost as bad?  


There is just so much to learn to get this going; especially without either an 
engineering degree or experience in this field.  Bob Camp is definitely right 
that you have to put your time in - lots of it.


Bob - AE6RV



 From: Tom Van Baak t...@leapsecond.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com 
Sent: Monday, October 20, 2014 6:42 PM
Subject: Re: [time-nuts] LTE-Lite module
 

To add to Bert's note...

Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent, 
almost by definition. What matters is phase noise and short-term stability, 
neither of which you can possibly fix with disciplining against GPS. GPS takes 
care of the rest.

Long-term stability can be critical for non-GPS applications, which is why 
oscillators with daily aging rates in the -11's and -12's are so amazing.

Consider this: if you want to run your bench with a clean 10 MHz source, stable 
to 11 or 12 digits and accurate to 9 digits -- you may be much better off with 
a free-running, stand-alone OCXO with an aging rate down at 1e-11/day than 
using a GPSDO/TCXO. To maintain accuracy of your OCXO just re-tune your OCXO 
*once a year*. Aside from ADEV plots, this is another way to appreciate how 
amazing some OCXO are, any why many of us still troll eBay for high-stability, 
low-noise, low-drift quartz oscillators.

/tvb

- Original Message - 
From: Bert Kehren via time-nuts time-nuts@febo.com
To: time-nuts@febo.com
Sent: Monday, October 20, 2014 4:01 PM
Subject: Re: [time-nuts] LTE-Lite module


Allow me to clarify.
I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3  
month +  burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. 
Only two have been tested for ADEV and are close to 1 E-12,  2X not 10  X.
Bert Kehren


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Re: [time-nuts] LTE-Lite module

OK, Yahoo has done it to me again.  Sent to Tom direct and not to the list.  
So, repeated here:

Hi Tom,

One of the biggest problems I've unwittingly faces is that of retrace.  I 
had seen the term used several times, but hadn't looked it up until last night. 
 As you can imagine, with a GPSDO under development I've had to 
remove power more than a few times to make hardware changes.  I think 
the next time power is down I'm going to try to rearrange things so that the 
OCXO is permanently powered and just the board gets switched.  But 
then again would big jumps in the EFC cause other problems that are 
almost as bad?  


There is just so much to learn to get this going; especially without either 
an engineering degree or experience in this field.  Bob Camp is 
definitely right that you have to put your time in - lots of it.

Bob - AE6RV



 From: Tom Van Baak t...@leapsecond.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com 
Sent: Monday, October 20, 2014 6:42 PM
Subject: Re: [time-nuts] LTE-Lite module
 

To add to Bert's note...

Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent, 
almost by definition. What matters is phase noise and short-term stability, 
neither of which you can possibly fix with disciplining against GPS. GPS takes 
care of the rest.

Long-term stability can be critical for non-GPS applications, which is why 
oscillators with daily aging rates in the -11's and -12's are so amazing.

Consider this: if you want to run your bench with a clean 10 MHz source, stable 
to 11 or 12 digits and accurate to 9 digits -- you may be much better off with 
a free-running, stand-alone OCXO with an aging rate down at 1e-11/day than 
using a GPSDO/TCXO. To maintain accuracy of your OCXO just re-tune your OCXO 
*once a year*. Aside from ADEV plots, this is another way to appreciate how 
amazing some OCXO are, any why many of us still troll eBay for high-stability, 
low-noise, low-drift quartz oscillators.

/tvb

- Original Message - 
From: Bert Kehren via time-nuts time-nuts@febo.com
To: time-nuts@febo.com
Sent: Monday, October 20, 2014 4:01 PM
Subject: Re: [time-nuts] LTE-Lite module


Allow me to clarify.
I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3  
month +  burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. 
Only two have been tested for ADEV and are close to 1 E-12,  2X not 10  X.
Bert Kehren


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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread Said Jackson via time-nuts

Bob,

You are on the right track!

Large changes in EFC can cause hysteresis, meaning you go back to an initial 
voltage but the crystal does not return to the exact initial frequency. It can 
also create dead bands in the efc vs frequency curve.

Hysteresis can cause integrator wind up as the loop is chasing an ever changing 
OCXO..

Retrace and hysteresis are two major issues for any disciplined oscillator.

Bye,
Said

Sent From iPhone

 On Oct 20, 2014, at 17:03, Bob Stewart b...@evoria.net wrote:
 
 OK, Yahoo has done it to me again.  Sent to Tom direct and not to the list.  
 So, repeated here:
 
 Hi Tom,
 
 One of the biggest problems I've unwittingly faces is that of retrace.  I 
 had seen the term used several times, but hadn't looked it up until last 
 night.  As you can imagine, with a GPSDO under development I've had to 
 remove power more than a few times to make hardware changes.  I think 
 the next time power is down I'm going to try to rearrange things so that the 
 OCXO is permanently powered and just the board gets switched.  But 
 then again would big jumps in the EFC cause other problems that are 
 almost as bad?  
 
 
 There is just so much to learn to get this going; especially without either 
 an engineering degree or experience in this field.  Bob Camp is 
 definitely right that you have to put your time in - lots of it.
 
 Bob - AE6RV
 
 
 
 From: Tom Van Baak t...@leapsecond.com
 To: Discussion of precise time and frequency measurement time-nuts@febo.com 
 Sent: Monday, October 20, 2014 6:42 PM
 Subject: Re: [time-nuts] LTE-Lite module
 
 
 To add to Bert's note...
 
 Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent, 
 almost by definition. What matters is phase noise and short-term stability, 
 neither of which you can possibly fix with disciplining against GPS. GPS 
 takes care of the rest.
 
 Long-term stability can be critical for non-GPS applications, which is why 
 oscillators with daily aging rates in the -11's and -12's are so amazing.
 
 Consider this: if you want to run your bench with a clean 10 MHz source, 
 stable to 11 or 12 digits and accurate to 9 digits -- you may be much better 
 off with a free-running, stand-alone OCXO with an aging rate down at 
 1e-11/day than using a GPSDO/TCXO. To maintain accuracy of your OCXO just 
 re-tune your OCXO *once a year*. Aside from ADEV plots, this is another way 
 to appreciate how amazing some OCXO are, any why many of us still troll eBay 
 for high-stability, low-noise, low-drift quartz oscillators.
 
 /tvb
 
 - Original Message - 
 From: Bert Kehren via time-nuts time-nuts@febo.com
 To: time-nuts@febo.com
 Sent: Monday, October 20, 2014 4:01 PM
 Subject: Re: [time-nuts] LTE-Lite module
 
 
 Allow me to clarify.
 I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3  
 month +  burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. 
 Only two have been tested for ADEV and are close to 1 E-12,  2X not 10  X.
 Bert Kehren
 
 
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Re: [time-nuts] LTE-Lite module

Hi Said,

OK, I hadn't understood the full consequences of hysteresis, but yes, I've seen 
it.  For an hour the DAC ratchets up a step every few minutes and the phase 
stubbornly stays put.  And then, the bottom falls out and it suddenly pushes 
way past where you want it.  Well, at least I have a better understanding of it 
now.  I'll try to avoid any hardware changes for the next few weeks.  I may 
even make changes that will keep the DAC stable when loading new code.

Thanks!


Bob




 From: Said Jackson saidj...@aol.com
To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency 
measurement time-nuts@febo.com 
Sent: Monday, October 20, 2014 7:21 PM
Subject: Re: [time-nuts] LTE-Lite module
 

Bob,

You are on the right track!

Large changes in EFC can cause hysteresis, meaning you go back to an initial 
voltage but the crystal does not return to the exact initial frequency. It can 
also create dead bands in the efc vs frequency curve.

Hysteresis can cause integrator wind up as the loop is chasing an ever changing 
OCXO..

Retrace and hysteresis are two major issues for any disciplined oscillator.

Bye,
Said

Sent From iPhone




 On Oct 20, 2014, at 17:03, Bob Stewart b...@evoria.net wrote:
 
 OK, Yahoo has done it to me again.  Sent to Tom direct and not to the list.  
 So, repeated here:
 
 Hi Tom,
 
 One of the biggest problems I've unwittingly faces is that of retrace.  I 
 had seen the term used several times, but hadn't looked it up until last 
 night.  As you can imagine, with a GPSDO under development I've had to 
 remove power more than a few times to make hardware changes.  I think 
 the next time power is down I'm going to try to rearrange things so that the 
 OCXO is permanently powered and just the board gets switched.  But 
 then again would big jumps in the EFC cause other problems that are 
 almost as bad?  
 
 
 There is just so much to learn to get this going; especially without either 
 an engineering degree or experience in this field.  Bob Camp is 
 definitely right that you have to put your time in - lots of it.
 
 Bob - AE6RV
 
 
 
 From: Tom Van Baak t...@leapsecond.com
 To: Discussion of precise time and frequency measurement time-nuts@febo.com 
 Sent: Monday, October 20, 2014 6:42 PM
 Subject: Re: [time-nuts] LTE-Lite module
 
 
 To add to Bert's note...
 
 Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent, 
 almost by definition. What matters is phase noise and short-term stability, 
 neither of which you can possibly fix with disciplining against GPS. GPS 
 takes care of the rest.
 
 Long-term stability can be critical for non-GPS applications, which is why 
 oscillators with daily aging rates in the -11's and -12's are so amazing.
 
 Consider this: if you want to run your bench with a clean 10 MHz source, 
 stable to 11 or 12 digits and accurate to 9 digits -- you may be much better 
 off with a free-running, stand-alone OCXO with an aging rate down at 
 1e-11/day than using a GPSDO/TCXO. To maintain accuracy of your OCXO just 
 re-tune your OCXO *once a year*. Aside from ADEV plots, this is another way 
 to appreciate how amazing some OCXO are, any why many of us still troll eBay 
 for high-stability, low-noise, low-drift quartz oscillators.
 
 /tvb
 
 - Original Message - 
 From: Bert Kehren via time-nuts time-nuts@febo.com
 To: time-nuts@febo.com
 Sent: Monday, October 20, 2014 4:01 PM
 Subject: Re: [time-nuts] LTE-Lite module
 
 
 Allow me to clarify.
 I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3  
 month +  burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. 
 Only two have been tested for ADEV and are close to 1 E-12,  2X not 10  X.
 Bert Kehren
 
 
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Re: [time-nuts] LTE-Lite module

2014-10-20 Thread Said Jackson via time-nuts

Thats exactly right Bob.

By the time your ocxo jumps to catch up to the efc voltage, you have 
oversteered,  then the process starts in reverse and the ocxo jumps in the 
opposite direction.

The result is a phase jumping up and down.

You want a crystal that reacts to xE-012 changes in EFC voltage or even 
better.. We may be talking only 100s of nanovolts per LSB.

Bye,
Said

Sent From iPhone

 On Oct 20, 2014, at 17:30, Bob Stewart b...@evoria.net wrote:
 
 Hi Said,
 
 OK, I hadn't understood the full consequences of hysteresis, but yes, I've 
 seen it.  For an hour the DAC ratchets up a step every few minutes and the 
 phase stubbornly stays put.  And then, the bottom falls out and it suddenly 
 pushes way past where you want it.  Well, at least I have a better 
 understanding of it now.  I'll try to avoid any hardware changes for the next 
 few weeks.  I may even make changes that will keep the DAC stable when 
 loading new code.
 
 Thanks!
 
 Bob
 
 From: Said Jackson saidj...@aol.com
 To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency 
 measurement time-nuts@febo.com 
 Sent: Monday, October 20, 2014 7:21 PM
 Subject: Re: [time-nuts] LTE-Lite module
 
 Bob,
 
 You are on the right track!
 
 Large changes in EFC can cause hysteresis, meaning you go back to an initial 
 voltage but the crystal does not return to the exact initial frequency. It 
 can also create dead bands in the efc vs frequency curve.
 
 Hysteresis can cause integrator wind up as the loop is chasing an ever 
 changing OCXO..
 
 Retrace and hysteresis are two major issues for any disciplined oscillator.
 
 Bye,
 Said
 
 Sent From iPhone
 
 
 
  On Oct 20, 2014, at 17:03, Bob Stewart b...@evoria.net wrote:
  
  OK, Yahoo has done it to me again.  Sent to Tom direct and not to the list. 
   So, repeated here:
  
  Hi Tom,
  
  One of the biggest problems I've unwittingly faces is that of retrace.  I 
  had seen the term used several times, but hadn't looked it up until last 
  night.  As you can imagine, with a GPSDO under development I've had to 
  remove power more than a few times to make hardware changes.  I think 
  the next time power is down I'm going to try to rearrange things so that 
  the OCXO is permanently powered and just the board gets switched.  But 
  then again would big jumps in the EFC cause other problems that are 
  almost as bad?  
  
  
  There is just so much to learn to get this going; especially without either 
  an engineering degree or experience in this field.  Bob Camp is 
  definitely right that you have to put your time in - lots of it.
  
  Bob - AE6RV
  
  
  
  From: Tom Van Baak t...@leapsecond.com
  To: Discussion of precise time and frequency measurement 
  time-nuts@febo.com 
  Sent: Monday, October 20, 2014 6:42 PM
  Subject: Re: [time-nuts] LTE-Lite module
  
  
  To add to Bert's note...
  
  Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent, 
  almost by definition. What matters is phase noise and short-term stability, 
  neither of which you can possibly fix with disciplining against GPS. GPS 
  takes care of the rest.
  
  Long-term stability can be critical for non-GPS applications, which is why 
  oscillators with daily aging rates in the -11's and -12's are so amazing.
  
  Consider this: if you want to run your bench with a clean 10 MHz source, 
  stable to 11 or 12 digits and accurate to 9 digits -- you may be much 
  better off with a free-running, stand-alone OCXO with an aging rate down at 
  1e-11/day than using a GPSDO/TCXO. To maintain accuracy of your OCXO just 
  re-tune your OCXO *once a year*. Aside from ADEV plots, this is another way 
  to appreciate how amazing some OCXO are, any why many of us still troll 
  eBay for high-stability, low-noise, low-drift quartz oscillators.
  
  /tvb
  
  - Original Message - 
  From: Bert Kehren via time-nuts time-nuts@febo.com
  To: time-nuts@febo.com
  Sent: Monday, October 20, 2014 4:01 PM
  Subject: Re: [time-nuts] LTE-Lite module
  
  
  Allow me to clarify.
  I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3  
  month +  burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. 
  Only two have been tested for ADEV and are close to 1 E-12,  2X not 10  X.
  Bert Kehren
  
  
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[time-nuts] FE5680A Corrupted EEPROM

2014-10-20 Thread Tom Wimmenhove

Skip Withrow contacted me and explained that apparently the FE5650 has a
tendency to get it's internal EEPROM corrupted when sending commands to it
right after power up. This confirms my suspicion that the EEPROM of my
FE5680A unit suffered the same fate.
He offered me to reprogram the unit as he has an ST programmer but I would
need a donor unit. He would also make the files publicly available.
Is there anyone out there that would let me or Skip borrow their FE5680A
unit for a short amount of time to read it out? This would be greatly
appreciated!

Regards,
 Tom
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[time-nuts] GPS for ntp

2014-10-20 Thread Joseph Gray

What does everyone think of this GPS module for ntp use? According to the
specsheet, it uses a Ublox Neo-7N.

http://www.ebay.com/itm/RY725AI-10Hz-UART-USB-interface-GPS-Glonass-QZSS-antenna-module-flash-memory-/181562403752

I'm thinking about using it for a Beaglebone ntp server. I know there was
some discussion about Beaglebones a while back. Has anyone gotten ntpd with
PPS and time stamping running on a Beaglebone yet (like on the Soekris
Net4501)?

Does anyone want to take a wild guess as to the best/worst case UTC offset
I might get with such a setup? I realize that I'd have to try it to really
find out, but guesses and advice from those more knowledgeable is always
appreciated.

What I'm really after is to eventually have several Beaglebones scattered
around the area as part of a TDOA DF network. I have spare radios to
dedicate to the task. Each fixed node will timestamp incoming transmissions
and then relay that information to a central location. The central system
will use the data to calculate the location of the transmitter.

Does anyone here have any experience with this sort of thing? Would you
recommend a better way of accurately timing the transmissions vs using ntp
on each Beaglebone?

I know that TDOA is used by the cellular companies. Is anyone aware of some
user level projects or source code for this? I've Googled a bit, but
haven't turned up much. There was one thesis about an Amateur doing part of
this, but he didn't have much detail on the satellite nodes and didn't
describe anything about the centralized processing part.

I have one Beaglebone White that I got cheap, so I have something to get
started with. Later, as I figure out things, I'll buy a few Beaglebone
Blacks.

Joe Gray
W5JG
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Re: [time-nuts] FE5680A Corrupted EEPROM

Hi

Unless we are talking about flash rather than EEPROM, an image may not do you 
much good. 

Firmware normally gets stored in flash. That code is at least similar from unit 
to unit. 

Calibration data normally gets stored in EEPROM. On a modern Rb there are a lot 
of things that are “tweaked” by EEPROM settings rather than fiddling pots and 
jumpers. Each EEPROM is unique to a unit. The settings in one may not be very 
healthy for another one.

Again, ignore all this if the objective is a flash re-load.

Bob


 On Oct 20, 2014, at 6:08 PM, Tom Wimmenhove tom.wimmenh...@gmail.com wrote:
 
 Skip Withrow contacted me and explained that apparently the FE5650 has a
 tendency to get it's internal EEPROM corrupted when sending commands to it
 right after power up. This confirms my suspicion that the EEPROM of my
 FE5680A unit suffered the same fate.
 He offered me to reprogram the unit as he has an ST programmer but I would
 need a donor unit. He would also make the files publicly available.
 Is there anyone out there that would let me or Skip borrow their FE5680A
 unit for a short amount of time to read it out? This would be greatly
 appreciated!
 
 Regards,
 Tom
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Re: [time-nuts] GPS for ntp