Re: [time-nuts] HP 59309A Clock runs, sets via GPIB, but no GPIB output?

On 2016-10-06 4:56 PM, Bob wrote: I'd like to ask the HP 59309A owners on time-nuts if the following symptoms sound familiar, and if so, what would the fix be? o New-to-me HP 59309A clock. o Late build, 1985 date code on many parts. o I replaced the big 1900 uF electrolytic before plugging it

Re: [time-nuts] Measure GPSDO stability with minimum resources?

Hi, On 10/06/2016 08:38 PM, Bob Camp wrote: Hi One very simple experiment: Take a HP that has been off power for a year or so. Fire it up and watch it’s predictions of holdover accuracy. Many of them will go through a “zero” time estimate at one or two days. At three or four days they are

Re: [time-nuts] Need Time Help

On 10/6/2016 8:10 PM, Wes wrote: Although I personally ceased pursuing this activity many years ago, there remain some of us, who are not Luddites, but still believe that "Deep Search Decoding" is a questionable practice, no matter how it is rationalized. "Deep Search Decoding" of the JT

[time-nuts] HP 59309A Clock runs, sets via GPIB, but no GPIB output?

I'd like to ask the HP 59309A owners on time-nuts if the following symptoms sound familiar, and if so, what would the fix be? o New-to-me HP 59309A clock. o Late build, 1985 date code on many parts. o I replaced the big 1900 uF electrolytic before plugging it in. o Visual inspection very clean,

Re: [time-nuts] GPSDO Sigma Tau at large observation times

>> See also the examples here: http://leapsecond.com/pages/gpsdo/ > > Hi Tom, quick question: I've seen these plots before and they are very > useful to know what to aim at for GPSDO performance. Am I right in > thinking these were measured against a master - the page says " a very > stable 10

Re: [time-nuts] Measure GPSDO stability with minimum resources?

On 10/6/16 10:11 AM, Chris Albertson wrote: Wouldn't "aging" be the change in the temperature v. frequncy graph over time? It is hard to hold temperture constant so maybe record the function at several different times. This is one big advantage of using a microprocessor inside the GPSDO,

Re: [time-nuts] Need Time Help

On 10/6/16 11:15 AM, William H. Fite wrote: Indeed, Nick. And more than a little (usually) courteous one upmanship couched in terms of being helpful by correcting all previous posters. This gentlemanly "mine is bigger than yours" phenomenon is part of what makes this group fun to read. Except

Re: [time-nuts] Need Time Help

Very true, Tom! I stand corrected. On Thu, Oct 6, 2016 at 2:50 PM, Tom Van Baak wrote: > Bill, > > Some of the key topics of this hobby are -- what did it cost, absolute > time error, relative frequency instability, and phase noise. In these cases > the goal of time nuts is

Re: [time-nuts] Measure GPSDO stability with minimum resources?

> I think it's worse than that. You have to hold the temperature constant, and Hi Hal, I concur. Here is a nice example for all of you: http://leapsecond.com/pages/tbolt/TBolt-20a-043.gif The image shows 20 new Trimble Thunderbolt's being tested for aging in my house. The daily temperature

Re: [time-nuts] Need Time Help

Bill, Some of the key topics of this hobby are -- what did it cost, absolute time error, relative frequency instability, and phase noise. In these cases the goal of time nuts is always "mine is smaller than yours". /tvb - Original Message - From: "William H. Fite"

Re: [time-nuts] Need Time Help

Hi Often the dive into the fine details is all that is left without guidance from the OP. After a few days (here or elsewhere) it can get pretty deep …. Bob > On Oct 6, 2016, at 2:03 PM, Nick Sayer via time-nuts > wrote: > > To be fair, this is at least partly because

Re: [time-nuts] Measure GPSDO stability with minimum resources?

Hi One very simple experiment: Take a HP that has been off power for a year or so. Fire it up and watch it’s predictions of holdover accuracy. Many of them will go through a “zero” time estimate at one or two days. At three or four days they are struggling to hit spec (10us). The reason is

Re: [time-nuts] Need Time Help

Indeed, Nick. And more than a little (usually) courteous one upmanship couched in terms of being helpful by correcting all previous posters. This gentlemanly "mine is bigger than yours" phenomenon is part of what makes this group fun to read. On Thu, Oct 6, 2016 at 2:03 PM, Nick Sayer via

Re: [time-nuts] Need Time Help

On 10/5/2016 7:40 PM, Chris Albertson wrote: There was a time when HAMs where the ones pushing radio technology forward. Maybe these guys are doing that and building a digital EME network on VHF? We don't know. Actually, we do know. Regarding my earlier comments, I believe at the time

Re: [time-nuts] Need Time Help

To be fair, this is at least partly because asking a relatively simple question here routinely turns into a dissertation defense. > On Oct 6, 2016, at 3:45 AM, Bob Camp wrote: > > Hi > > That’s very typical in a lot of forums. The OP tosses up a question and then > pretty much

Re: [time-nuts] Measure GPSDO stability with minimum resources?

Hi Tim, Thanks for the document.  I have been doing some 12 hour holdover tests.  But as I mentioned, the HP quick projections had fooled me into thinking there was some trick to this other than actually capturing the DAC over multiple days to get a real projection. Bob  

Re: [time-nuts] Measure GPSDO stability with minimum resources?

said: "The somewhat amazing holdover estimates on the HP units are one example of this problem. It does not take much testing to quickly realize that they are far more often wrong than right on a unit that has been on power for less than a few weeks." Thank you Bob.  These two sentences clear

Re: [time-nuts] Measure GPSDO stability with minimum resources?

The HP Smartclock app note will help you a lot: http://leapsecond.com/hpan/an1279.pdf There are lots of Z3801A EFC curves on the web for you to see what typical range of unit-to-unit variation is. Of course to actually test holdover, you do that by opening the PLL loop (unhook GPS antenna) and

Re: [time-nuts] Measure GPSDO stability with minimum resources?

Hi As normally used, the term “aging” means the long term drift in the frequency of an OCXO. It is independent of the temperature effects and things like retrace, warmup, and voltage stability. It is rare that there is any impact on the aging of a properly designed OCXO from drift of the

Re: [time-nuts] ntp and asymmetric delays

Hi NTP can *not* detect “common mode” asymmetric delay. Having a local GPS does not count in this respect. What does count is an NTP client / server sitting in your home trying to figure out what time it is only by hooking to the internet. To do this it must do a few things: 1) Get a signal

Re: [time-nuts] Measure GPSDO stability with minimum resources?

Wouldn't "aging" be the change in the temperature v. frequncy graph over time? It is hard to hold temperture constant so maybe record the function at several different times. This is one big advantage of using a microprocessor inside the GPSDO, It can log internal data to either a SD card or

Re: [time-nuts] ntp and asymmetric delays

I still think NTP can detect asymmetric delays. Only it can't know that is what it is detecting. What else generate those offset numbers? Yes it could very well be that MRS is running slow but I doubt that is the case. And I really doubt your GPS' PPS is off by even one microsecond.A

Re: [time-nuts] Need Time Help

Hi That’s very typical in a lot of forums. The OP tosses up a question and then pretty much vanishes. My observation is that roughly 80% of the “I have a question” threads work that way. I’ve never been able to figure out if it is an expectation that all answers will arrive in an hour or two

Re: [time-nuts] Need Time Help

Given the number of replies to the OP, most pointed but others drifting OT, it is remarkable that there has been no comment or feedback from Larry. He has slung his bottle and gone away it seems. > Le 5 oct. 2016 à 23:58, Bob Camp a écrit : > > Hi > > Given that this is for

Re: [time-nuts] ADC sample voting algorithm?

Hi, You may have already done this, but if you log the same pulses with a counter or actual TDC IC you can view it and see how they compare with your measurements. Then you can look at how to get them closer - or find that it's actually correct and that's just where the pulse is at the time.

Re: [time-nuts] ADC sample voting algorithm?

In message <59ab451c-ca1b-4824-a953-4f0f28b66...@kfu.com>, Nick Sayer via time-nuts writes: >My theory at the moment is that sampling the ADC multiple times in a row might >help, but then what’s the best way to (quickly) pick which sample to use? If you are sampling for noise: Always

Re: [time-nuts] Need Time Help

albertson.ch...@gmail.com said: > The problem is harder then most people think. To avoid jumps in time either > forward or backwards the software must be something that runs continuously > and monitors your clock vs. one or more reference clocks. Logically there > is no other way. I think it