[time-nuts] Z3801A / Z3812A leapsecond funkiness

As discussed earlier there is a bug in the firmware of these devices where they report the wrong date of a leapsecond if it is announced more than three months in advance. Mine were reporting leapseconds will occur on 30 Sep 2016. Well, the event passed and the devices reset their

[time-nuts] Caroliine .. I need to move on

going to the emergency place ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

Re: [time-nuts] Measuring phase with an HP 3456A?

On 10/1/2016 6:54 PM, Bob Stewart wrote: OK, I give up. My participation in this thread is over. Bob - Why? You asked some questions and several people have tried to help you. I think one issue is that you mention measuring

Re: [time-nuts] Measuring phase with an HP 3456A?

Hi DMTD = dual mixer time difference, a system publicized in a paper by NIST in the late 1970’s. You mix two “same frequency” DUT’s with an offset oscillator. The beat notes out of the mixers are measured (often with a “computing counter) to get high resolution measurements. Basically an

Re: [time-nuts] Measuring phase with an HP 3456A?

OK, I give up.  My participation in this thread is over. Bob  - AE6RV.com GFS GPSDO list: groups.yahoo.com/neo/groups/GFS-GPSDOs/info From: Wes To: time-nuts@febo.com Sent: Saturday, October 1, 2016 8:33

Re: [time-nuts] Measuring phase with an HP 3456A?

On 10/1/2016 5:13 PM, Bob Stewart wrote: Hi Bob Albert, Completely eliminate the use of the term "DMTD". I didn't post that. Actually you did in your first post. "I've been spending a small amount of my time looking into making a sort of hybrid DMTD with a pair of DBMs"

[time-nuts] FS: Starbox

AllStar DGPS base station. Uses a 10 MHz internal reference. I have lots of docs that I downloaded some time ago. Make me an offer. https://www.dropbox.com/s/jc4t1959l3bpf2v/Starbox.jpg?dl=01 Joe Gray W5JG ___ time-nuts mailing list --

Re: [time-nuts] Measuring phase with an HP 3456A?

You are firing those acronyms at me too quickly.  I don't know what most of them signify. If you have two oscillators, I assume that somehow you lock them to the same frequency; otherwise the phase difference will be changing.  Which one is the reference, and why? If you want to measure phase

Re: [time-nuts] Measuring phase with an HP 3456A?

Hi > On Oct 1, 2016, at 8:13 PM, Bob Stewart wrote: > > Hi Bob Albert, > > I'm having trouble following it, as well, and I started it. So, let's back > up. Completely eliminate the use of the term "DMTD". I didn't post that. (see way below for why we are confused) >

Re: [time-nuts] Measuring phase with an HP 3456A?

Hi Bob Albert, I'm having trouble following it, as well, and I started it.  So, let's back up.  Completely eliminate the use of the term "DMTD".  I didn't post that.  I'm only interested in measuring phase with the 3456A, which is a voltmeter. So, I have two disciplined OCXOs, a DBM, an LPF,

Re: [time-nuts] Measuring phase with an HP 3456A?

Hi If you have two inputs into the mixer, one comes from one OCXO and the other comes from another OCXO. If you set the EFC voltage on one or the other OCXO so the output of the mixer is zero, the inputs are 90 degrees apart. At that point the mixer has a maximum phase sensitivity and the

Re: [time-nuts] Measuring phase with an HP 3456A?

I am having trouble following this thread.  I assume we are trying to measure phase noise, but of course the result includes the noise of the local oscillator(s).  Isn't the 3456A a voltmeter?  I have one of those.  In AC mode it has a bandwidth of more than 100 kHz and measures true rms.

Re: [time-nuts] Measuring phase with an HP 3456A?

Hi Bob,Can you tell me what you mean by "just put the two inputs in quadrature, attach to a sound card and you have all you need for phase noise."?  What inputs do you assume I have?  I don't think I can attach two 10MHz inputs to a soundcard and expect anything useful. Bob From: Bob

Re: [time-nuts] Normal operating specs of a Morion MV89?

I think you have mistaken the tilde symbol as a negative sign. Tim's 11 dBm is into the pad. 7 dBm +- 2 dB into 50 ohms is the spec for the mv89 no? On Saturday, 1 October 2016, Bob Camp wrote: > HI > > > On Oct 1, 2016, at 4:08 PM, Scott Stobbe

Re: [time-nuts] Measuring phase with an HP 3456A?

HI DMTD = Dual Mixer Time Difference Single Mixer = what is commonly used for most things. If you have a single mixer setup, just put the two inputs in quadrature, attach to a sound card and you have all you need for phase noise. Bob > On Oct 1, 2016, at 4:30 PM, Bob Stewart

Re: [time-nuts] Measuring phase with an HP 3456A?

Hi Bob, I don't have a DMTD breadboarded up for testing.  This was just a test of the new LPF using only a single Mini Circuits ZLW-1H DBM, and things kind of progressed from looking at the output of the LPF on the scope to "I wonder what I would see on the 3456A?" sort of thing.  I'm running a

Re: [time-nuts] Normal operating specs of a Morion MV89?

HI > On Oct 1, 2016, at 4:08 PM, Scott Stobbe wrote: > > If you used a 6db pad in conjunction with a 50 ohm termination you are spot > on. If you used a 6dB pad as a 50 ohm load, the effective load will be a > bit higher than 50 and the attenuation less than 6 dB.

Re: [time-nuts] Measuring phase with an HP 3456A?

Hi What is the beat note coming out of the DMTD? Put another way: DMTD involves three oscillators. Two are on roughly the same frequency and the third is offset from the other two. The difference frequency is typically something like 10 Hz. It does not *have* to be 10 Hz, but that is one

Re: [time-nuts] Normal operating specs of a Morion MV89?

If you used a 6db pad in conjunction with a 50 ohm termination you are spot on. If you used a 6dB pad as a 50 ohm load, the effective load will be a bit higher than 50 and the attenuation less than 6 dB. Either way sounds like the output stage of your OCXO is in spec for 7 dBm into 50 ohms. On

Re: [time-nuts] Measuring phase with an HP 3456A?

Bob, Just try it. Compare it and see how the initial noise slope behaves and compare it to other measurements. Similar phase-measurement setups have been used in historic context. What ends up being the best method for you is a combination of what tools you have available and dare to bring

[time-nuts] Measuring phase with an HP 3456A?

I've been spending a small amount of my time looking into making a sort of hybrid DMTD with a pair of DBMs up front feeding the stereo input to a sound card.  So, I got the 100KHz LPF back from Oshpark and hooked it up to my scope for verification - an obvious step.  Then I hooked it up to my