Re: [time-nuts] 10 mhz accuracy for a satellite system

[Bob kb8tq]

Hi

That’s an odd one. It is very unclear *where* that OCXO came from. 

Bob

> On Feb 5, 2019, at 7:16 PM, Richard Solomon  wrote:
> 
> Here's a shot of what's inside those T-Bolts I bought.
> (thanks to tvb for reducing the size of my original).
> 
> Comments solicited ...
> 
> 73, Dick, W1KSZ
> 
> Sent from Outlook
> 
> From: time-nuts  on behalf of Bob kb8tq 
> 
> Sent: Tuesday, February 5, 2019 12:11 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
> 
> Hi
> 
> If the sticker on the OCXO (not the label on the outside of the box) has a 
> date code
> in 2006, that should be fine. I’ve seen cases on … errr … various sites … 
> errr …
> where the stuff inside the box did not match up very well with the labels on 
> the outside
> of the box. No idea why ….
> 
> Bob
> 
>> On Feb 5, 2019, at 12:26 PM, Richard Solomon  wrote:
>> 
>> The two I have are Trimbles with Red & Black Labels with White letters.
>> It's marked D/C 0635, which if I assume is the Date Code puts them in
>> 2006.
>> 
>> 73, Dick, W1KSZ
>> 
>> Sent from Outlook
>> 
>> From: time-nuts  on behalf of Bob kb8tq 
>> 
>> Sent: Tuesday, February 5, 2019 8:32 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>> 
>> Hi
>> 
>> The parts we typically call TBolt’s  were produced from about 1997 through 
>> about 2006.
>> The date codes on the parts are one way to work out how far along the uint 
>> you have is
>> in that sequence. There are other parts that Trimble produced (produces) 
>> under the same
>> Thunderbolt brand. Those can be quite different beasts depending on which 
>> one you
>> happen to be looking at.
>> 
>> The early parts had OCXO’s labeled “PIEZO” on them. The later parts had a 
>> generic
>> “TRIMBLE” label on them. The PIEZO labels have a date code stamped on them 
>> sort
>> of randomly. The TRIMBLE labels have a field marked “date code”. In all 
>> cases I have seen
>> it’s a two digit year followed by a two digit week.
>> 
>> Anything with a PIEZO label is “early”. Anything from about 2003 on should 
>> be a pretty good
>> OCXO.  There are no guarantees, but that’s a pretty good guess.
>> 
>> There are also changes in the temperature sensor IC and mods to the firmware 
>> along the
>> way. The novel approach to a precision DAC and the resulting “noticeable” 
>> temperature
>> coefficient seems to have been a constant through the entire production run. 
>> They also
>> have various little spurs and noise bumps that some people get into cleaning 
>> up.
>> 
>> The good news is that they all (from the first unit to the very last) run 
>> very well with LH.
>> *That* more than any other factor makes them a really good choice. When 
>> tuned up,
>> set up, and monitored with LH, they do much better than they would just 
>> running on their own.
>> 
>> Bob
>> 
>>> On Feb 5, 2019, at 9:23 AM, Richard Solomon  wrote:
>>> 
>>> How does one tell the difference between "early" and "later" ?
>>> 
>>> S/N, Rev # ??
>>> 
>>> 73, Dick, W1KSZ
>>> 
>>> Sent from Outlook
>>> 
>>> From: time-nuts  on behalf of Bob kb8tq 
>>> 
>>> Sent: Monday, February 4, 2019 7:23 PM
>>> To: Discussion of precise time and frequency measurement
>>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>>> 
>>> Hi
>>> 
>>> One thing to watch on the TBolts - the ocxo’s used in them got better as the
>>> years went by. An early one likely will not do quite as well as a later 
>>> one. They
>>> also updated the firmware as time went by, same basic issue - later is 
>>> probably
>>> better ….
>>> 
>>> Bob
>>> 
 On Feb 4, 2019, at 8:51 PM, Richard Solomon  wrote:
 
 There have been some Trimble Thunderbolts over on that auction site
 that were being sold for $80 each (not surplus Telcom ones).
 I grabbed two and they work.
 
 My antenna was a "hockey puck" style antenna sitting on the window
 sash, facing South.
 
 73, Dick, W1KSZ
 
 Sent from Outlook
 
 From: time-nuts  on behalf of Grant 
 Hodgson 
 Sent: Monday, February 4, 2019 11:15 AM
 To: time-nuts@lists.febo.com
 Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
 
 Paul
 
 The keyword is GPSDO - GPS disciplined oscillator.  The vast majority of
 these will give a 10MHz output.  The long term accuracy is the same as
 the GPS navigation system, which for most purposes is similar to that of
 national standards.  GPSDOs are more stable than most rubidium standards
 in the long term, and GPSDOs are extremely common in most laboratories.
 
 The Trimble Thunderbolt is very common and available on 

Re: [time-nuts] 10 mhz accuracy for a satellite system

[Paul Bicknell]

Hi All 

I have just pulled out of redundant stock a Trimble 2102 Plus satellite
navigation unit for an aircraft can this be used as a frequency standard at
such as  1/5/10 Mhz

Paul B

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Bob
kb8tq
Sent: 05 February 2019 19:12
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system

Hi

If the sticker on the OCXO (not the label on the outside of the box) has a
date code 
in 2006, that should be fine. I've seen cases on . errr . various sites .
errr .
where the stuff inside the box did not match up very well with the labels on
the outside
of the box. No idea why ..

Bob

> On Feb 5, 2019, at 12:26 PM, Richard Solomon  wrote:
> 
> The two I have are Trimbles with Red & Black Labels with White letters.
> It's marked D/C 0635, which if I assume is the Date Code puts them in
> 2006.
> 
> 73, Dick, W1KSZ
> 
> Sent from Outlook
> 
> From: time-nuts  on behalf of Bob kb8tq

> Sent: Tuesday, February 5, 2019 8:32 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
> 
> Hi
> 
> The parts we typically call TBolt's  were produced from about 1997 through
about 2006.
> The date codes on the parts are one way to work out how far along the uint
you have is
> in that sequence. There are other parts that Trimble produced (produces)
under the same
> Thunderbolt brand. Those can be quite different beasts depending on which
one you
> happen to be looking at.
> 
> The early parts had OCXO's labeled "PIEZO" on them. The later parts had a 
> generic "TRIMBLE" label on them. The PIEZO labels have a date code stamped

> on them sort of randomly. The TRIMBLE labels have a field marked "date 
> code". In all cases I have seen it's a two digit year followed by a two 
> 
> digit week. Anything with a PIEZO label is "early". Anything from about
2003 on should be a pretty good
> OCXO.  There are no guarantees, but that's a pretty good guess.
> 
> There are also changes in the temperature sensor IC and mods to the 
> firmware along the way. The novel approach to a precision DAC and the 
> resulting "noticeable" temperature coefficient seems to have been a 
> constant through the entire production run. They also have various little.
> spurs and noise bumps that some people get into cleaning up
> The good news is that they all (from the first unit to the very last) run.
> very well with LH *That* more than any other factor makes them a really 
> good choice. When tuned up,set up, and monitored with LH, they do much
better than they would just running on their own.
> 
> Bob
> 
>> On Feb 5, 2019, at 9:23 AM, Richard Solomon  wrote:
>> 
>> How does one tell the difference between "early" and "later" ?
>> 
>> S/N, Rev # ??
>> 
>> 73, Dick, W1KSZ
>> 
>> Sent from Outlook
>> 
>> From: time-nuts  on behalf of Bob kb8tq

>> Sent: Monday, February 4, 2019 7:23 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>> 
>> Hi
>> 
>> One thing to watch on the TBolts - the ocxo's used in them got better as 
>> the years went by. An early one likely will not do quite as well as a 
>> later one. They also updated the firmware as time went by, same basic 
>> issue - later is probably better ..
>> 
>> Bob
>> 
>>> On Feb 4, 2019, at 8:51 PM, Richard Solomon  wrote:
>>> 
>>> There have been some Trimble Thunderbolts over on that auction site
>>> that were being sold for $80 each (not surplus Telcom ones).
>>> I grabbed two and they work.
>>> 
>>> My antenna was a "hockey puck" style antenna sitting on the window
>>> sash, facing South.
>>> 
>>> 73, Dick, W1KSZ
>>> 
>>> Sent from Outlook
>>> 
>>> From: time-nuts  on behalf of Grant
Hodgson 
>>> Sent: Monday, February 4, 2019 11:15 AM
>>> To: time-nuts@lists.febo.com
>>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>>> 
>>> Paul
>>> 
>>> The keyword is GPSDO - GPS disciplined oscillator.  The vast majority of
>>> these will give a 10MHz output.  The long term accuracy is the same as
>>> the GPS navigation system, which for most purposes is similar to that of
>>> national standards.  GPSDOs are more stable than most rubidium standards
>>> in the long term, and GPSDOs are extremely common in most laboratories.
>>> 
>>> The Trimble Thunderbolt is very common and available on the surplus
>>> market, as is the HP Z3801A.  James Miller (G3RUH) used to sell an
>>> excellent GPSDO.  There are other home-brew designs available if you
>>> want to build.   These have all been extensively characterised if you
>>> want the details.
>>> 
>>> If you want to buy new, then there are products such as the Fury and
>>> Firefly from 

Re: [time-nuts] GPS Weekly Rollover Fail

[Bob kb8tq]

Hi

From what I can see, you can send it a command that puts a new “oldest date”
number into flash. Since it also tracks Glonass and Galileo, that will stretch 
out the
time before you *need* to do something (like into the next century). They also 
have 
the “no dates before the firmware was issued” check.  There may be other date 
checks in there. Those are just what I’ve found so far.

It also is likely that the “new” GPS sats will be flying within 19 years. That 
will add 
more bits to the GPS time fields. Who knows if the “modern” modules already 
handle 
those bits or not ….

Bob

> On Feb 5, 2019, at 5:23 PM, Hal Murray  wrote:
> 
> 
> kb...@n1k.org said:
>> The F9P has multiple cross checks, traps, and even a user configurable
>> “oldest  possible date” entry.  
> 
> Neat/thanks.
> 
> Is that stored in flash, or lost on power cycle?
> 
> If it's in flash, I can "fix" things for another 20 years by extracting the 
> device from its box, taking it to a bench setup, running a flash-update 
> program, then reassembling things.  As ugly as that is, it may be simpler 
> than 
> updating the firmware in the box.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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[time-nuts] HP Stories: The life and times of the 5060A/5061A Harmonic Generators. In memory of Vic Olson.

[Rice, Hugh (IPH Writing Systems)]

A quick intro for those who haven't seen past "HP Stories":  I work for Hewlett 
Packard, and my first job at HP in 1984 was working on the HP 5061B Cesium Beam 
Frequency Standard.   I was part of the two man team that did the 5061A to 
5061B development, and then I was the "production engineer" on the 5061B for a 
few years. I have been writing a series of stories from the old days for 
the entertainment of the time-nuts mailing list.



The 5061A "A4 Harmonic Generator", at first glance, appears to be an odd 
mechanical device attached to the top of the Cesium Beam Tube in the 5061A.   I 
have faint memories of technicians using it as a carrying handle for the CBT, 
when removing it from the instrument. But it has that suspicious shape of a 
microwave wave guide, where it attaches to the CBT, that tips off trained eyes 
that this is much more than an oddly shaped carrying handle.

As my knowledge of the 5061B system grew (under the tutelage of Chuck Little, 
Lou Mueller and Robert Montesi), the Harmonic Generator innocence transformed 
into an intimidating presence.A quick read of the theory of operation from 
the service manual seems simple enough.

"The phase modulated 5MHz signal is multiplied by 18 in the A3 Multiplier, and 
then multiplied by 102 in the A4 Harmonic Generator Assembly."   No big deal.   
Easy math. "Just" multiply the 5MHz signal a couple times.

But later in the details of the Harmonic Generator:
"The A4 Harmonic Generator generates a microwave signal of 9192.63... MHz 
(phase-modulated microwave by 137 Hz) to be applied to the cesium beam tube.  
A4 receives a phase-modulated 90 MHz signal from the A3 Multiplier and a 
12.63... MHz signal from the A1 Synthesizer.  Step-recover diode CR2 is the 
heart of the harmonic generator.  The conductivity of the p-n junction diode 
during reverse recovery is nearly a step function.  The transition from reverse 
conduction to cutoff occurs in about 0.1 nanoseconds.  This produces high-order 
harmonics with greater efficiency than conventional non-linear harmonic 
generators." It continues on for three more paragraphs in more obscure RF 
circuit nomenclature detail.

The old guys, when talking about the harmonic generator and frightening me 
about the black magic it contained, often concluded with:  "But it works really 
well, so just don't touch it."

Rick Karlquist in a recent posting talked about the RF design work he did on 
the 5071A, replacing the A2 Synthesizer, A3 Multiplier, and A4 Harmonic 
generator with modern (1990) techniques to generate the 9,192,631,772.5 magic 
Cesium frequency, without the use of wave-guides and step recovery diodes.   
Rick mentioned the Korean visiting professor who invented the A4 in about 1964. 
  Lou Mueller once told me a story about this same professor (who I will call 
Professor K), when he was working at HP back then:

Professor K had an elaborate microwave test bench, full of wave guides, 
attenuators, tuning circuits and RF instrumentation that he used in development 
of the A4.  One day someone thought it would be fun to play a joke on him, and 
put a honey-bee inside the wave guide in his test setup.   Professor K returns 
from lunch, and starts noticing anomalies in his measurements.   He carefully 
measures and calculates, scratching his head to figure out what was wrong.   
After a bit of analysis, he finally unbolts on section of the wave guide, which 
according to his calculations was the problem.  And sure enough, that was were 
the bee was. Looking back, the A4 was an brilliant design.  It was in 
production from 1965 to 1990, 25 years, essentially untouched and working 
flawlessly the whole time.

As you can see from the attached picture, there are a number of adjustments 
that can be made to the A4, which leads to Vic Olsen.Vic was in his early 
60's when I met him, and the epitome of a curmudgeonly old school tech.A 
bit course around the edges, wore the same sloppy jeans and simple plaid shirt 
to work every day, but knew how to do his job, and begrudgingly endured 
ignorant young engineers like me.   Vic was one of the two technicians that 
worked on the 5061A in production, and was the one who did the adjustments on 
the A4 as it was assembled into a complete instrument.   I have faint memories 
of the ancient test setup he used to "tune" the A4 before attaching it to the 
CBT.   There was some sort of oscilloscope like instrument with a small round 
CRT, with a few wave guide like things.   I'm sure they all dated back to the 
original 5060A setup from 1965.   Vic would fiddle with all the adjustments on 
the A4 for a few minutes, in a seemingly random manner, and then declare it 
done.He then would really crank down on all the lock nuts for each tuning 
element, and the attachment for the step-recovery-diode.   "Gotta make these 
things tight, or the tuning will drift off"This concluded with him bashing 
the A4 on all 

Re: [time-nuts] GPS Weekly Rollover Fail

[Hal Murray]

kb...@n1k.org said:
> The F9P has multiple cross checks, traps, and even a user configurable
> “oldest  possible date” entry.  

Neat/thanks.

Is that stored in flash, or lost on power cycle?

If it's in flash, I can "fix" things for another 20 years by extracting the 
device from its box, taking it to a bench setup, running a flash-update 
program, then reassembling things.  As ugly as that is, it may be simpler than 
updating the firmware in the box.


-- 
These are my opinions.  I hate spam.




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Re: [time-nuts] LN RB

[John Miles]

> http://www.ke5fx.com/lnrb_18hrs_phase.png
> 
> No excursions beyond +/- 10 ns so far, we'll see how it does over the next
> few days.

Something else I should note is that the 'house clock' GPSDO in the magenta
trace (a) is very well-shielded from airflow in an unventilated rack
enclosure; (b) has been painstakingly optimized for that very environment;
and (c) has been running almost uninterrupted for about 10 years.  

The LN Rb unit in comparison is unenclosed and strapped to a rack rail with
a cable tie.  It's a preproduction unit that was GPS-locked at this location
for only about eight hours before I started the test.  So I'm actually
pretty happy with its response to normal room temperature variations, given
the handicaps I'm imposing on it.

-- john, KE5FX
Miles Design LLC 



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Re: [time-nuts] GPS Weekly Rollover Fail

[Steve Allen]

On Tue 2019-02-05T13:02:47-0800 Tom Van Baak hath writ:
> GPS time began Jan-1980 and the first rollover occurred in Aug-1999.
> The next one is April-2019 and Nov-2038 after that.

> We time nuts will be on full alert Saturday evening April 6 to
> Sunday morning April 7 to find and record any anomalies.

The actual GPS 1023 to 0 is not the only date when these events happen.
About a dozen buses in the county fleet are currently displaying dates
in mid 1999 presumably because their GPS firmware adds some constant
to the GPS week number.  Previous rollovers happened last year and
have been fixed; new rollovers happened around the beginning of this
year.

--
Steve Allen  WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
1156 High Street   Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064   https://www.ucolick.org/~sla/  Hgt +250 m

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Re: [time-nuts] LN RB

[John Miles]

To some extent, since JLT doesn't make the rubidium MAC module itself, they
are subject to whatever performance limitations are inherited from the OEM.
Holdover specifications don't involve thermal shocks, and the telecoms
rarely want to pay extra for performance beyond the requirements.  I agree
that this is probably not the best possible solution for environments where
significant temperature fluctuations are anticipated.  

That said, there are some pretty drastic excursions on your plot, no
question about that.  It's possible that your unit has an issue which should
be ruled out before concluding that the product as a whole is falling short
of expectations.  

As a disclaimer, I work with JLT on other products, but am not involved with
this particular one.  We used a preproduction unit to demonstrate another
product at PTTI last week, and I was actually so impressed with how well it
performed that I asked to bring it back with me for further testing.  So
while I don't mean to get in the middle of this issue, I'd suggest working
with Said offline to figure out what's really going on, for the benefit of
all concerned.  I see he's gotten back in touch with you now, so I'll bow
out of that conversation. 

Right now, the unit I brought back from PTTI is coming up on 18 hours in a
3-way test with an HP 5065A and a highly-optimized custom GPSDO, with no
signs of the misbehavior that appeared in your data.  Temperature has
fluctuated a couple of degrees under normal HVAC cycling.  I'm not making a
special effort to stabilize it, but I'm also not throwing blankets on it or
blowing air on it during this particular run. :)  Just for the record,
here's how the unit has been performing:

http://www.ke5fx.com/lnrb_18hrs_phase.png

No excursions beyond +/- 10 ns so far, we'll see how it does over the next
few days.

-- john, KE5FX
Miles Design LLC 

> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of
> AC0XU (Jim)
> Sent: Monday, February 04, 2019 7:31 PM
> To: time-nuts@lists.febo.com
> Subject: [time-nuts] LN RB
> 
> John-
> 
> The LNRB had been powered on continously for several weeks prior to my
> tests. Also, the same antenna/LNA is feeding multiple GPSDOs (4 others)
> with Lady Heather connected and running continuously, and none of them
> exhibited any kind of strange behavior at the times of the anomalies in
the
> LN RB timing.
> 
> It certainly appears that Jackson Labs did not design the LN RB to be
stable in
> the presence of external temperature fluctuations. To be useful, this
seems
> to imply that it needs an external environmental temperature control.
> Furthermore, it doesn't seem to be stable near the top end of its
supported
> temperature range even when the external temperature is constant, so the
> external temperature needs to be fairly low (probably under 40C or so).
One
> application I was interested in is a low SWaP timing reference for
smallsats.
> Its sensitivity to temperature seems to make that application unlikely,
> because adding external temperature control would make the electrical
> power prohibitive, even if size and weight can be kept under control. As a
> lab reference, I expect I can implement an external temperature control
and
> it may work well enough. Overall, I am very disappointed with the product.
I
> have written to Jackson Labs about my concerns but I have not heard back
> from them.
> 
> Jim


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Re: [time-nuts] GPS Weekly Rollover Fail

[Bob kb8tq]

Hi

If you take a look at some of the modules that have come out in the last few 
years, 
they now have much better protection for rollover issues than the older parts 
did.
The F9P has multiple cross checks, traps, and even a user configurable “oldest 
possible date” entry. 

Bob

> On Feb 5, 2019, at 4:02 PM, Tom Van Baak  wrote:
>  
> Bob,
> 
>> is this just a known routine bug
> 
> Yes, known. Yes, routine. No, not a bug.
> 
> GPS system time is kept as a 10-bit week number and 20-bit second number. The 
> seconds count from 0 to 604799 and the week counts from 0 to 1023. What this 
> means is that every 1024 weeks (approx 19.62 years) there is a rollover. [1]
> 
> GPS time began Jan-1980 and the first rollover occurred in Aug-1999. The next 
> one is April-2019 and Nov-2038 after that.
> 
> These rollovers tend to have zero impact on position and navigation, but it 
> can affect the calculated UTC time in some receivers. This is not due to a 
> flaw in GPS but a lack of rigorous design and testing by the authors of the 
> receiver firmware. Even with simulation it's hard to fully test something 
> that occurs only once every 20 years under all conditions.
> 
> We time nuts will be on full alert Saturday evening April 6 to Sunday morning 
> April 7 to find and record any anomalies.
> 
> /tvb
> 
> [1] https://www.gps.gov/cgsic/meetings/2017/powers.pdf
> 
> 
> - Original Message - 
> From: "Bob Betts" 
> To: 
> Sent: Tuesday, February 05, 2019 10:11 AM
> Subject: [time-nuts] GPS Weekly Rollover Fail
> 
> 
>> Hello All:
>> Just curious, but is this just a known routine bug that is methodically 
>> dealt with or is there a more serious problem in the system(s)? 
>> 
>> Here's the quote from a notice at www.gps.gov
>> 
>> Thanks,
>> Bob, N1KPR
>> 
>> 
>> --
>> 
>> Failure: April 6/7, 2019
>> 
>> •UTC timing displayed and/or time tags of receiver data containing PNT 
>> information could jump by 19.7 years, resulting in system failures
>> •Any month/year conversion could also fail•Navigation solution should be OK 
>> since GPS time is internally self consistent, but associated time tags could 
>> be incorrect thus corrupting navigation data at the system level•And the 
>> failure is not limited to April 6/7 2019
>> •A common fix for week number ambiguity was to hard code new pivot date, 
>> which shifts event to unknown date/time in future.
>> 
>> –December 2014, older legacy USNO monitor receiver failed
>> –Feb 14, 2016 Endruntechnology receivers using a Trimble GPS engine failed
>> –Aug 14, 2016 Motorola OncoreUT+ older firmware failed
>> –July 22, 2017 older Novatel GPS engine failed, notice was posted in Spring 
>> 2017 to upgrade firmware, but many did not check
>> 
>> 
>> 
>> 
>> NOTE Pls add backup address to your phone book: rwbe...@yahoo.com
>> 
>> http://www.bobsamerica.com http://www.youtube.com/n1kpr 
>> 
>> Engineering: Where Enigma meets Paradox
>> 
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>> 
> 
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Re: [time-nuts] GPS Weekly Rollover Fail

[Tom Van Baak]

Bob,

> is this just a known routine bug

Yes, known. Yes, routine. No, not a bug.

GPS system time is kept as a 10-bit week number and 20-bit second number. The 
seconds count from 0 to 604799 and the week counts from 0 to 1023. What this 
means is that every 1024 weeks (approx 19.62 years) there is a rollover. [1]

GPS time began Jan-1980 and the first rollover occurred in Aug-1999. The next 
one is April-2019 and Nov-2038 after that.

These rollovers tend to have zero impact on position and navigation, but it can 
affect the calculated UTC time in some receivers. This is not due to a flaw in 
GPS but a lack of rigorous design and testing by the authors of the receiver 
firmware. Even with simulation it's hard to fully test something that occurs 
only once every 20 years under all conditions.

We time nuts will be on full alert Saturday evening April 6 to Sunday morning 
April 7 to find and record any anomalies.

/tvb

[1] https://www.gps.gov/cgsic/meetings/2017/powers.pdf


- Original Message - 
From: "Bob Betts" 
To: 
Sent: Tuesday, February 05, 2019 10:11 AM
Subject: [time-nuts] GPS Weekly Rollover Fail


> Hello All:
> Just curious, but is this just a known routine bug that is methodically dealt 
> with or is there a more serious problem in the system(s)? 
> 
> Here's the quote from a notice at www.gps.gov
> 
> Thanks,
> Bob, N1KPR
> 
> 
> --
> 
> Failure: April 6/7, 2019
> 
> •UTC timing displayed and/or time tags of receiver data containing PNT 
> information could jump by 19.7 years, resulting in system failures
> •Any month/year conversion could also fail•Navigation solution should be OK 
> since GPS time is internally self consistent, but associated time tags could 
> be incorrect thus corrupting navigation data at the system level•And the 
> failure is not limited to April 6/7 2019
> •A common fix for week number ambiguity was to hard code new pivot date, 
> which shifts event to unknown date/time in future.
> 
> –December 2014, older legacy USNO monitor receiver failed
> –Feb 14, 2016 Endruntechnology receivers using a Trimble GPS engine failed
> –Aug 14, 2016 Motorola OncoreUT+ older firmware failed
> –July 22, 2017 older Novatel GPS engine failed, notice was posted in Spring 
> 2017 to upgrade firmware, but many did not check
> 
> 
> 
> 
> NOTE Pls add backup address to your phone book: rwbe...@yahoo.com
> 
> http://www.bobsamerica.com http://www.youtube.com/n1kpr 
> 
> Engineering: Where Enigma meets Paradox
> 
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Re: [time-nuts] Auto-fail-over switch

[John Ackermann N8UR]

There is a plug-in circuit built for the HPSDR radios that detects 
presence of an external 10 MHz and when it's present shuts off power to 
the onboard oscillator.  It would probably be easy to adapt to other 
environments.  It's at http://www.k9ivb.net/Hermes/index.htm


John


On 2/5/19 2:09 PM, Bob kb8tq wrote:

Hi



On Feb 5, 2019, at 11:59 AM, Mark Goldberg  wrote:

On Tue, Feb 5, 2019, 8:00 AM Bob kb8tq 
Regardless of how you do it, isolation is an issue. Having a 10 MHz
standard line with a very
close in spur is not a real good thing. It can mess up a lot of stuff and
it passes through the
cleanup loops in most gear. Is 120 db far enough down? I’ve certainly seen
problems from
stuff at that level at a small offset …. Simply having a switch with this
or that db isolation is
just a starting point. Grounding and shielding are very much on the “to
do” list as well.



I was going to mention that. I modified my Perseus SDR to use an external
oscillator and just removing some SMT resistors to disconnect the original
oscillator output was insufficient. Still coupled in a spur from the
original oscillator and bad close in phase noise. I had to disable the
original oscillator by removing power. I didn't spend the time to try to do
that automatically. Maintaining phase continuity in the changeover would
also be hard.

Do you have any examples of something small that does this well?


Nothing that I have seen on the surplus market. Some of the things companies 
I’ve worked for over the
years did a pretty good job ( at least to the specs the customer requested …).

Bob



Regards,

Mark





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Re: [time-nuts] Auto-fail-over switch

[Bob kb8tq]

Hi


> On Feb 5, 2019, at 11:59 AM, Mark Goldberg  wrote:
> 
> On Tue, Feb 5, 2019, 8:00 AM Bob kb8tq  
>> Regardless of how you do it, isolation is an issue. Having a 10 MHz
>> standard line with a very
>> close in spur is not a real good thing. It can mess up a lot of stuff and
>> it passes through the
>> cleanup loops in most gear. Is 120 db far enough down? I’ve certainly seen
>> problems from
>> stuff at that level at a small offset …. Simply having a switch with this
>> or that db isolation is
>> just a starting point. Grounding and shielding are very much on the “to
>> do” list as well.
>> 
> 
> I was going to mention that. I modified my Perseus SDR to use an external
> oscillator and just removing some SMT resistors to disconnect the original
> oscillator output was insufficient. Still coupled in a spur from the
> original oscillator and bad close in phase noise. I had to disable the
> original oscillator by removing power. I didn't spend the time to try to do
> that automatically. Maintaining phase continuity in the changeover would
> also be hard.
> 
> Do you have any examples of something small that does this well?

Nothing that I have seen on the surplus market. Some of the things companies 
I’ve worked for over the
years did a pretty good job ( at least to the specs the customer requested …). 

Bob

> 
> Regards,
> 
> Mark
> 
> 
>> 
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Re: [time-nuts] 10 mhz accuracy for a satellite system

[Bob kb8tq]

Hi

If the sticker on the OCXO (not the label on the outside of the box) has a date 
code 
in 2006, that should be fine. I’ve seen cases on … errr … various sites … errr …
where the stuff inside the box did not match up very well with the labels on 
the outside
of the box. No idea why ….

Bob

> On Feb 5, 2019, at 12:26 PM, Richard Solomon  wrote:
> 
> The two I have are Trimbles with Red & Black Labels with White letters.
> It's marked D/C 0635, which if I assume is the Date Code puts them in
> 2006.
> 
> 73, Dick, W1KSZ
> 
> Sent from Outlook
> 
> From: time-nuts  on behalf of Bob kb8tq 
> 
> Sent: Tuesday, February 5, 2019 8:32 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
> 
> Hi
> 
> The parts we typically call TBolt’s  were produced from about 1997 through 
> about 2006.
> The date codes on the parts are one way to work out how far along the uint 
> you have is
> in that sequence. There are other parts that Trimble produced (produces) 
> under the same
> Thunderbolt brand. Those can be quite different beasts depending on which one 
> you
> happen to be looking at.
> 
> The early parts had OCXO’s labeled “PIEZO” on them. The later parts had a 
> generic
> “TRIMBLE” label on them. The PIEZO labels have a date code stamped on them 
> sort
> of randomly. The TRIMBLE labels have a field marked “date code”. In all cases 
> I have seen
> it’s a two digit year followed by a two digit week.
> 
> Anything with a PIEZO label is “early”. Anything from about 2003 on should be 
> a pretty good
> OCXO.  There are no guarantees, but that’s a pretty good guess.
> 
> There are also changes in the temperature sensor IC and mods to the firmware 
> along the
> way. The novel approach to a precision DAC and the resulting “noticeable” 
> temperature
> coefficient seems to have been a constant through the entire production run. 
> They also
> have various little spurs and noise bumps that some people get into cleaning 
> up.
> 
> The good news is that they all (from the first unit to the very last) run 
> very well with LH.
> *That* more than any other factor makes them a really good choice. When tuned 
> up,
> set up, and monitored with LH, they do much better than they would just 
> running on their own.
> 
> Bob
> 
>> On Feb 5, 2019, at 9:23 AM, Richard Solomon  wrote:
>> 
>> How does one tell the difference between "early" and "later" ?
>> 
>> S/N, Rev # ??
>> 
>> 73, Dick, W1KSZ
>> 
>> Sent from Outlook
>> 
>> From: time-nuts  on behalf of Bob kb8tq 
>> 
>> Sent: Monday, February 4, 2019 7:23 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>> 
>> Hi
>> 
>> One thing to watch on the TBolts - the ocxo’s used in them got better as the
>> years went by. An early one likely will not do quite as well as a later one. 
>> They
>> also updated the firmware as time went by, same basic issue - later is 
>> probably
>> better ….
>> 
>> Bob
>> 
>>> On Feb 4, 2019, at 8:51 PM, Richard Solomon  wrote:
>>> 
>>> There have been some Trimble Thunderbolts over on that auction site
>>> that were being sold for $80 each (not surplus Telcom ones).
>>> I grabbed two and they work.
>>> 
>>> My antenna was a "hockey puck" style antenna sitting on the window
>>> sash, facing South.
>>> 
>>> 73, Dick, W1KSZ
>>> 
>>> Sent from Outlook
>>> 
>>> From: time-nuts  on behalf of Grant 
>>> Hodgson 
>>> Sent: Monday, February 4, 2019 11:15 AM
>>> To: time-nuts@lists.febo.com
>>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>>> 
>>> Paul
>>> 
>>> The keyword is GPSDO - GPS disciplined oscillator.  The vast majority of
>>> these will give a 10MHz output.  The long term accuracy is the same as
>>> the GPS navigation system, which for most purposes is similar to that of
>>> national standards.  GPSDOs are more stable than most rubidium standards
>>> in the long term, and GPSDOs are extremely common in most laboratories.
>>> 
>>> The Trimble Thunderbolt is very common and available on the surplus
>>> market, as is the HP Z3801A.  James Miller (G3RUH) used to sell an
>>> excellent GPSDO.  There are other home-brew designs available if you
>>> want to build.   These have all been extensively characterised if you
>>> want the details.
>>> 
>>> If you want to buy new, then there are products such as the Fury and
>>> Firefly from Jackson Labs; , U-Blox have many offerings (not sure if
>>> they do a GPSDO though).
>>> 
>>> Google GPSDO or GPS frequency standard, or check the leapsecond.com
>>> website for more information - there's loads out there, it's just a case
>>> of using the right term in the search engine.
>>> 
>>> regards
>>> Grant
>>> 
 Date: Sun, 3 Feb 2019 23:43:10 -
 From: "Paul Bicknell" 

Re: [time-nuts] 10 mhz accuracy for a satellite system

[Richard Solomon]

The two I have are Trimbles with Red & Black Labels with White letters.
It's marked D/C 0635, which if I assume is the Date Code puts them in
2006.

73, Dick, W1KSZ

Sent from Outlook

From: time-nuts  on behalf of Bob kb8tq 

Sent: Tuesday, February 5, 2019 8:32 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system

Hi

The parts we typically call TBolt’s  were produced from about 1997 through 
about 2006.
The date codes on the parts are one way to work out how far along the uint you 
have is
in that sequence. There are other parts that Trimble produced (produces) under 
the same
Thunderbolt brand. Those can be quite different beasts depending on which one 
you
happen to be looking at.

The early parts had OCXO’s labeled “PIEZO” on them. The later parts had a 
generic
“TRIMBLE” label on them. The PIEZO labels have a date code stamped on them sort
of randomly. The TRIMBLE labels have a field marked “date code”. In all cases I 
have seen
it’s a two digit year followed by a two digit week.

Anything with a PIEZO label is “early”. Anything from about 2003 on should be a 
pretty good
OCXO.  There are no guarantees, but that’s a pretty good guess.

There are also changes in the temperature sensor IC and mods to the firmware 
along the
way. The novel approach to a precision DAC and the resulting “noticeable” 
temperature
coefficient seems to have been a constant through the entire production run. 
They also
have various little spurs and noise bumps that some people get into cleaning up.

The good news is that they all (from the first unit to the very last) run very 
well with LH.
*That* more than any other factor makes them a really good choice. When tuned 
up,
set up, and monitored with LH, they do much better than they would just running 
on their own.

Bob

> On Feb 5, 2019, at 9:23 AM, Richard Solomon  wrote:
>
> How does one tell the difference between "early" and "later" ?
>
> S/N, Rev # ??
>
> 73, Dick, W1KSZ
>
> Sent from Outlook
> 
> From: time-nuts  on behalf of Bob kb8tq 
> 
> Sent: Monday, February 4, 2019 7:23 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>
> Hi
>
> One thing to watch on the TBolts - the ocxo’s used in them got better as the
> years went by. An early one likely will not do quite as well as a later one. 
> They
> also updated the firmware as time went by, same basic issue - later is 
> probably
> better ….
>
> Bob
>
>> On Feb 4, 2019, at 8:51 PM, Richard Solomon  wrote:
>>
>> There have been some Trimble Thunderbolts over on that auction site
>> that were being sold for $80 each (not surplus Telcom ones).
>> I grabbed two and they work.
>>
>> My antenna was a "hockey puck" style antenna sitting on the window
>> sash, facing South.
>>
>> 73, Dick, W1KSZ
>>
>> Sent from Outlook
>> 
>> From: time-nuts  on behalf of Grant 
>> Hodgson 
>> Sent: Monday, February 4, 2019 11:15 AM
>> To: time-nuts@lists.febo.com
>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>>
>> Paul
>>
>> The keyword is GPSDO - GPS disciplined oscillator.  The vast majority of
>> these will give a 10MHz output.  The long term accuracy is the same as
>> the GPS navigation system, which for most purposes is similar to that of
>> national standards.  GPSDOs are more stable than most rubidium standards
>> in the long term, and GPSDOs are extremely common in most laboratories.
>>
>> The Trimble Thunderbolt is very common and available on the surplus
>> market, as is the HP Z3801A.  James Miller (G3RUH) used to sell an
>> excellent GPSDO.  There are other home-brew designs available if you
>> want to build.   These have all been extensively characterised if you
>> want the details.
>>
>> If you want to buy new, then there are products such as the Fury and
>> Firefly from Jackson Labs; , U-Blox have many offerings (not sure if
>> they do a GPSDO though).
>>
>> Google GPSDO or GPS frequency standard, or check the leapsecond.com
>> website for more information - there's loads out there, it's just a case
>> of using the right term in the search engine.
>>
>> regards
>> Grant
>>
>>> Date: Sun, 3 Feb 2019 23:43:10 -
>>> From: "Paul Bicknell" 
>>> To: "'Discussion of precise time and frequency measurement'"
>>>  
>>> Subject: [time-nuts] 10 mhz accuracy for a satellite system
>>> Message-ID: 
>>> Content-Type: text/plain; charset="iso-8859-1"
>>>
>>>
>>> Dear all
>>> I currently use a 198 Khz off air standard but I can no longer use  600 khz
>>> since it moved from Rugby
>>> I have herd a lot about varies frequency references that use satellites
>>> This technology has improved immensely & become more affordable over the
>>> past 5 years
>>>
>>> So can a standard locked to a 

Re: [time-nuts] 10 mhz accuracy for a satellite system

[Bob kb8tq]

Hi

The parts we typically call TBolt’s  were produced from about 1997 through 
about 2006. 
The date codes on the parts are one way to work out how far along the uint you 
have is 
in that sequence. There are other parts that Trimble produced (produces) under 
the same
Thunderbolt brand. Those can be quite different beasts depending on which one 
you 
happen to be looking at. 

The early parts had OCXO’s labeled “PIEZO” on them. The later parts had a 
generic 
“TRIMBLE” label on them. The PIEZO labels have a date code stamped on them sort 
of randomly. The TRIMBLE labels have a field marked “date code”. In all cases I 
have seen
it’s a two digit year followed by a two digit week.

Anything with a PIEZO label is “early”. Anything from about 2003 on should be a 
pretty good
OCXO.  There are no guarantees, but that’s a pretty good guess. 

There are also changes in the temperature sensor IC and mods to the firmware 
along the
way. The novel approach to a precision DAC and the resulting “noticeable” 
temperature 
coefficient seems to have been a constant through the entire production run. 
They also 
have various little spurs and noise bumps that some people get into cleaning 
up. 

The good news is that they all (from the first unit to the very last) run very 
well with LH. 
*That* more than any other factor makes them a really good choice. When tuned 
up,
set up, and monitored with LH, they do much better than they would just running 
on their own. 

Bob

> On Feb 5, 2019, at 9:23 AM, Richard Solomon  wrote:
> 
> How does one tell the difference between "early" and "later" ?
> 
> S/N, Rev # ??
> 
> 73, Dick, W1KSZ
> 
> Sent from Outlook
> 
> From: time-nuts  on behalf of Bob kb8tq 
> 
> Sent: Monday, February 4, 2019 7:23 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
> 
> Hi
> 
> One thing to watch on the TBolts - the ocxo’s used in them got better as the
> years went by. An early one likely will not do quite as well as a later one. 
> They
> also updated the firmware as time went by, same basic issue - later is 
> probably
> better ….
> 
> Bob
> 
>> On Feb 4, 2019, at 8:51 PM, Richard Solomon  wrote:
>> 
>> There have been some Trimble Thunderbolts over on that auction site
>> that were being sold for $80 each (not surplus Telcom ones).
>> I grabbed two and they work.
>> 
>> My antenna was a "hockey puck" style antenna sitting on the window
>> sash, facing South.
>> 
>> 73, Dick, W1KSZ
>> 
>> Sent from Outlook
>> 
>> From: time-nuts  on behalf of Grant 
>> Hodgson 
>> Sent: Monday, February 4, 2019 11:15 AM
>> To: time-nuts@lists.febo.com
>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>> 
>> Paul
>> 
>> The keyword is GPSDO - GPS disciplined oscillator.  The vast majority of
>> these will give a 10MHz output.  The long term accuracy is the same as
>> the GPS navigation system, which for most purposes is similar to that of
>> national standards.  GPSDOs are more stable than most rubidium standards
>> in the long term, and GPSDOs are extremely common in most laboratories.
>> 
>> The Trimble Thunderbolt is very common and available on the surplus
>> market, as is the HP Z3801A.  James Miller (G3RUH) used to sell an
>> excellent GPSDO.  There are other home-brew designs available if you
>> want to build.   These have all been extensively characterised if you
>> want the details.
>> 
>> If you want to buy new, then there are products such as the Fury and
>> Firefly from Jackson Labs; , U-Blox have many offerings (not sure if
>> they do a GPSDO though).
>> 
>> Google GPSDO or GPS frequency standard, or check the leapsecond.com
>> website for more information - there's loads out there, it's just a case
>> of using the right term in the search engine.
>> 
>> regards
>> Grant
>> 
>>> Date: Sun, 3 Feb 2019 23:43:10 -
>>> From: "Paul Bicknell" 
>>> To: "'Discussion of precise time and frequency measurement'"
>>>  
>>> Subject: [time-nuts] 10 mhz accuracy for a satellite system
>>> Message-ID: 
>>> Content-Type: text/plain; charset="iso-8859-1"
>>> 
>>> 
>>> Dear all
>>> I currently use a 198 Khz off air standard but I can no longer use  600 khz
>>> since it moved from Rugby
>>> I have herd a lot about varies frequency references that use satellites
>>> This technology has improved immensely & become more affordable over the
>>> past 5 years
>>> 
>>> So can a standard locked to a satellite be as good as a Rubidium ?
>>> 
>>> What accuracy can I achieve for a satellite system below ?800 as I am not
>>> familiar with the latest that are on offer?
>>> 
>>> Regards Paul Bicknell  South Coast UK
>>> 
>>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe, go to 
>> 

Re: [time-nuts] 10 mhz accuracy for a satellite system

[Richard Solomon]

How does one tell the difference between "early" and "later" ?

S/N, Rev # ??

73, Dick, W1KSZ

Sent from Outlook

From: time-nuts  on behalf of Bob kb8tq 

Sent: Monday, February 4, 2019 7:23 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system

Hi

One thing to watch on the TBolts - the ocxo’s used in them got better as the
years went by. An early one likely will not do quite as well as a later one. 
They
also updated the firmware as time went by, same basic issue - later is probably
better ….

Bob

> On Feb 4, 2019, at 8:51 PM, Richard Solomon  wrote:
>
> There have been some Trimble Thunderbolts over on that auction site
> that were being sold for $80 each (not surplus Telcom ones).
> I grabbed two and they work.
>
> My antenna was a "hockey puck" style antenna sitting on the window
> sash, facing South.
>
> 73, Dick, W1KSZ
>
> Sent from Outlook
> 
> From: time-nuts  on behalf of Grant Hodgson 
> 
> Sent: Monday, February 4, 2019 11:15 AM
> To: time-nuts@lists.febo.com
> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>
> Paul
>
> The keyword is GPSDO - GPS disciplined oscillator.  The vast majority of
> these will give a 10MHz output.  The long term accuracy is the same as
> the GPS navigation system, which for most purposes is similar to that of
> national standards.  GPSDOs are more stable than most rubidium standards
> in the long term, and GPSDOs are extremely common in most laboratories.
>
> The Trimble Thunderbolt is very common and available on the surplus
> market, as is the HP Z3801A.  James Miller (G3RUH) used to sell an
> excellent GPSDO.  There are other home-brew designs available if you
> want to build.   These have all been extensively characterised if you
> want the details.
>
> If you want to buy new, then there are products such as the Fury and
> Firefly from Jackson Labs; , U-Blox have many offerings (not sure if
> they do a GPSDO though).
>
> Google GPSDO or GPS frequency standard, or check the leapsecond.com
> website for more information - there's loads out there, it's just a case
> of using the right term in the search engine.
>
> regards
> Grant
>
>> Date: Sun, 3 Feb 2019 23:43:10 -
>> From: "Paul Bicknell" 
>> To: "'Discussion of precise time and frequency measurement'"
>>   
>> Subject: [time-nuts] 10 mhz accuracy for a satellite system
>> Message-ID: 
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>>
>> Dear all
>> I currently use a 198 Khz off air standard but I can no longer use  600 khz
>> since it moved from Rugby
>> I have herd a lot about varies frequency references that use satellites
>> This technology has improved immensely & become more affordable over the
>> past 5 years
>>
>> So can a standard locked to a satellite be as good as a Rubidium ?
>>
>> What accuracy can I achieve for a satellite system below ?800 as I am not
>> familiar with the latest that are on offer?
>>
>> Regards Paul Bicknell  South Coast UK
>>
>>
>
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> To unsubscribe, go to 
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Re: [time-nuts] Auto-fail-over switch

[Bob kb8tq]

Hi

The thing you will (rarely) find out there are devices that act like a GPSDO 
only the input is
10 MHz, or 1 pps or something else entirely (T1 , E1 …). They watch a set of 
inputs and 
(based on a list of rules) decide what is the best source to use. The output 10 
MHz gets
locked to that until something better comes along or it goes away. 

If all your “stuff” needs a continuous 10 MHz, this is the sort of box you 
would want to have. 
It keeps your radio on the air, your frequency counter counting, and all those 
breadboards 
doing whatever it is they do. 

Since they aren’t real common, finding one is a bit of a chore. Finding one 
with inputs 
(and outputs) that are useful to you is a bit harder still. Figuring out the 
programming interface
to set up rules that make sense to you ….usually not very easy at all. 

Regardless of how you do it, isolation is an issue. Having a 10 MHz standard 
line with a very
close in spur is not a real good thing. It can mess up a lot of stuff and it 
passes through the 
cleanup loops in most gear. Is 120 db far enough down? I’ve certainly seen 
problems from
stuff at that level at a small offset …. Simply having a switch with this or 
that db isolation is
just a starting point. Grounding and shielding are very much on the “to do” 
list as well. 

Lots of fun !!!

Bob

> On Feb 4, 2019, at 9:26 PM, Jeff Blaine  wrote:
> 
> Wondered if anyone had seen some sort of gadget that would look to see if 
> there was a 10 Mhz signal and switch a relay (or provide some other output) 
> in the absence?  I would like to cook up some sort of fail over switch 
> without having to do much actual work. :)
> 
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
> 
> 
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Re: [time-nuts] Auto-fail-over switch

[Tim Shoppa]

Do you have any phase continuity requirements?  Do you need to failover if the 
input is 9MHz or 9.99MHz instead of 10MHz? If not then any carrier-operated 
relay will do it.

Tim N3QE

> On Feb 4, 2019, at 9:26 PM, Jeff Blaine  wrote:
> 
> Wondered if anyone had seen some sort of gadget that would look to see if 
> there was a 10 Mhz signal and switch a relay (or provide some other output) 
> in the absence?  I would like to cook up some sort of fail over switch 
> without having to do much actual work. :)
> 
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
> 
> 
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Re: [time-nuts] Auto-fail-over switch

[Glenn Little WB4UIV]

source --- amplifier --- relay coil.

When source is present the amplified is detected and drives a relay coil 
to keep it energized.

When source fails, relay opens switching to backup source.
When source is again active, relay closes reverting back to primary source.
A 10 MHz xtal or other 10 MHz filter in series with amplifier input will 
ensure that amplifier will respond to source going off frequency.


Glenn

On 2/4/2019 9:26 PM, Jeff Blaine wrote:
Wondered if anyone had seen some sort of gadget that would look to see 
if there was a 10 Mhz signal and switch a relay (or provide some other 
output) in the absence?  I would like to cook up some sort of fail 
over switch without having to do much actual work. :)


73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


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--
---
Glenn LittleARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIVwb4...@arrl.netAMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"


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[time-nuts] Refreshing the HP 3048A (DOS)

[Leon Pavlovic]

Dear Time Nuts,

this is my first post to the group, hello! I've been reading the group for
some time already, but now I've decided to contribute.

Since I am a phase noise enthusiast, I've assembled in the past few months
a 3048A system. With a little difference. The relatively old 3048A system
provides a limited selection of RF analyzers, which nowadays are hard to
get (working at least) for a budget price. So I've acquired a newer
spectrum analyzer HP 8594E (which is again old, but available on ebay), and
of course it is not supported by the 3048A software.

By poking around the DOS application, the 8594E is now happily working with
the system. And yes, I actually like the fast DOS interface.

Anybody interested in the patched app, let me know off the list.

Here are two screenshots from my system:

http://lea.hamradio.si/~s56jlp/tnuts/Setup_HP8594E.png ... Instrument setup
http://lea.hamradio.si/~s56jlp/tnuts/X_03-10H.png ... PN measurement of two
AT-cut crystal oscillators at 100MHz by my own R

Regards,
Leon
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[time-nuts] LN RB

[AC0XU (Jim)]

John-

The LNRB had been powered on continously for several weeks prior to my tests. 
Also, the same antenna/LNA is feeding multiple GPSDOs (4 others) with Lady 
Heather connected and running continuously, and none of them exhibited any kind 
of strange behavior at the times of the anomalies in the LN RB timing.

It certainly appears that Jackson Labs did not design the LN RB to be stable in 
the presence of external temperature fluctuations. To be useful, this seems to 
imply that it needs an external environmental temperature control. Furthermore, 
it doesn't seem to be stable near the top end of its supported temperature 
range even when the external temperature is constant, so the external 
temperature needs to be fairly low (probably under 40C or so). One application 
I was interested in is a low SWaP timing reference for smallsats. Its 
sensitivity to temperature seems to make that application unlikely, because 
adding external temperature control would make the electrical power 
prohibitive, even if size and weight can be kept under control. As a lab 
reference, I expect I can implement an external temperature control and it may 
work well enough. Overall, I am very disappointed with the product. I have 
written to Jackson Labs about my concerns but I have not heard back from them.

Jim


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