Re: [time-nuts] Segal law: freq difference for GPSDO

I tried to see the 1PPS on my oscilloscope. Here is the series of screenshots from that experiment: https://www.patoka.ca/OCXO/TBvsSL/ I also tried to catch something using HP5386A. However I was not able to measure the pulse. Regards, Vlad On 2016-03-29 18:53, Henry Hallam wrote: If

Re: [time-nuts] Segal law: freq difference for GPSDO

> May be somebody could recognize, what 10.014 Mhz could be used for ? It sort of looks more like an unlocked OCXO than a magic frequency. Measure phase instead of frequency; see how the phase drifts over time. Also check if the magic frequency varies or drifts over time. See if the offset is

Re: [time-nuts] Trimble Thunderbolt GPSDO Troubleshooting

Hi Charles (et al), So, I did see that post, but I'm not entirely sure how it works. If I understand, the FPGA is generating the 9.7khz clock (which I can see on the test pad he indicated), running it through some logic to square it up, then a low pass filter, then into the op-amp similar to

Re: [time-nuts] high rev isolation amps

With most of these old circuits reducing the LF noise contribution to the emitter/collector current by the biasing circuit by utilising lower noise power supplies and/or using improved biasing methods can improve the clse in PN significantly. The PZT3904 and PZT3906 are still available. Bruce

Re: [time-nuts] Phase noise test set reference articles

I dont believe that the LF IF port output resistance of the minicircuits phase detectors is 500 ohm.Its just that this IF port load provides aa reasonable 50 ohm match at the RF/LO ports. The IF port LF output impedance is likely to be 100 ohms or less some of which will be intrinsic (having a

Re: [time-nuts] Phase noise test set reference articles

Hello Gerhard look that: http://cp.literature.agilent.com/litweb/pdf/5989-8999EN.pdf http://rfic.eecs.berkeley.edu/~niknejad/ee242/pdf/ee242_mixer_noise_design.pdf and also STEPHEN MAAS has very good book on mixers... Microwaves101 | Mixers www.microwaves101.com/encyclopedias/mixers Mixers.

Re: [time-nuts] Phase noise test set reference articles

and here is with very good literature: https://www.google.com/search?q=Haas+Mixer+noise=utf-8=utf-8#q=Maas+Mixer+noise On 3/29/2016 3:28 PM, Gerhard Hoffmann wrote: Am 29.03.2016 um 16:53 schrieb Charles Steinmetz: (10) Phase_detector_with_low_flicker_noise_BARNES_etal_NIST_2011: Describes

Re: [time-nuts] Phase noise test set reference articles

You should add some of the NIST writings on cross-correlation, both traditional and newer. In particular, the more recent papers describe the newly discovered danger of cross-correlation which currently is an open research field. Cross-correlation can give over-optimistic values. Never the

Re: [time-nuts] Phase noise test set reference articles

On 03/30/2016 12:28 AM, Gerhard Hoffmann wrote: Am 29.03.2016 um 16:53 schrieb Charles Steinmetz: (10) Phase_detector_with_low_flicker_noise_BARNES_etal_NIST_2011: Describes a DIY double-balanced mixer phase detector using diode-connected 2N transistors. [Note that only the flicker

Re: [time-nuts] high rev isolation amps

Hi There were (and maybe still are) SOT-89 versions of the 2N3804 and 3906. They will handle more power than most of the other versions. That gives you better Vce on the string. They also have less package inductance which helps tie the base to ground. If you are building some of those

Re: [time-nuts] Segal law: freq difference for GPSDO

> I have no third GPSDO (or equivalent) to compare. There is the crystal in your 5386A. Can you use that to measure the time between PPS pulses? (Some counters/timers don't go over a second and if the crystal is fast, the PPS will look slightly longer than a second.) If both GPSDOs agree,

Re: [time-nuts] Segal law: freq difference for GPSDO

If you put the PPS outputs of the two GPSDOs into an oscilloscope and trigger on the leading edge of one of them, what does the other look like? Henry On Tue, Mar 29, 2016 at 12:56 PM, Vlad wrote: > > > Hello, > > I am looking for for the advise regarding some strange

Re: [time-nuts] Phase noise test set reference articles

Am 29.03.2016 um 16:53 schrieb Charles Steinmetz: (10) Phase_detector_with_low_flicker_noise_BARNES_etal_NIST_2011: Describes a DIY double-balanced mixer phase detector using diode-connected 2N transistors. [Note that only the flicker noise is improved -- the white noise floor is

[time-nuts] Segal law: freq difference for GPSDO

Hello, I am looking for for the advise regarding some strange difference in frequency between of two GPSDO: Trimble Thunderbolt and Datum Starloc II Measuring by HP 5386A counter it shows something around 0.014 delta. If I connect TB as REF source then I am getting numbers like this:

Re: [time-nuts] Timelab bug (was: Framework for simulation of oscillators)

> Here it takes slightly less 3 minutes, but stops at 10M samples. > Memory consumption of Timelab stays below 350MB the whole time > and drops to 98MB after it finished. > > OS is windows XP pro > > How many samples did you get? It should have been 14926518 (ie slightly > less than 15M)

[time-nuts] Phase noise test set reference articles

Since there seems to be some interest in DIY phase noise test sets, I put together the following list of references relevant to such a project, with some comments. I have a ZIP file of these items (about 35MB), but so far have been unsuccessful in uploading it to Didier's site. If anyone has

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

Hi Oleg Le 29/03/2016 07:18, Oleg Skydan a écrit : I also tried DL4YHF Spectrum Lab - it works, but lacks of logarithmic frequency scale (or I just did not find how to enable it). Just right-click on the frequency scale, then click on "more ...", and then tick on "logarithmic" in the

Re: [time-nuts] high rev isolation amps

See below for schematics of the NIST isolation amplifiers from 1990 and 1997. NIST reported the isolation as >120dB. I built isolation amplifiers similar to these (with lower-noise power supplies and biasing tinkered slightly for better dynamic range), and with careful construction achieved

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

NIST indicate in several early papers that using 50 ohm in series with a capacitor increases the noise over that achieved by capacitively terminating the IF port at the sum frequency (LO + RF) as you have done. NB the RF and LO port match will be improved somewhat with suitable low value series

Re: [time-nuts] Meaning of MTBF (was: Reliability of atomic clocks)

On 28 March 2016 at 00:32, Attila Kinali wrote: > > Yes, the MTBF is a very simplicistic measure and there are a couple > of assumptions in its calculation which do not hold generally (or > rather, it's rather seldom that they hold). It get's "interesting" when you look at

Re: [time-nuts] Trimble Thunderbolt GPSDO Troubleshooting

> Stewart Cobb described the operation of the DAC > (actually, PWM) in a post on Nov 2, 2013 > ("Subject: [time-nuts] Thunderbolt tuning DAC > theory of operation"). Check the list archive. https://www.febo.com/pipermail/time-nuts/2013-November/081058.html /tvb

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

Hi Magnus, Would not GNUradio be a good platform to encode the calibration stuff a little more gift-wrapped? I never used the GNUradio. Basically you can use any SA software/hardware which has the necessary capabilities. What spectrum-analyzer software do you use? (Just curious) It is an

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

Hi, Bruce, Thank you for the comments and useful link. Probably you did not understand the goal and positioning of this "project" and I did not tell the history of how it was build :) So, the solely goal of making this "test set" was to assist with the design of the synthesizer unit for my

Re: [time-nuts] Trimble Thunderbolt GPSDO Troubleshooting

Ryan wrote: Also confusing is the quad op-amp seems to be saturated at the negative rail. I can see this Opamp feeds the adjust pin on the OCXO, but I’m not sure what feeds it. Guessing the FPGA? I still can’t find the DAC… all I see are these pictures [ ] but the pictures aren’t of the

Re: [time-nuts] Trimble Thunderbolt GPSDO Troubleshooting

There aren't enough resistors for a high resolution R-2R DAC so its likely to be something like 4 (or more) x 4 bit (R, 2R, 4R, 8R) sub dacs with weighted resistive summing of the sub DAC outputs. Bruce On Tuesday, 29 March 2016 6:09 PM, Ryan Stasel wrote: All,

[time-nuts] Trimble Thunderbolt GPSDO Troubleshooting

Well, if you think the 5V ref is bad, you could pull the ref chip and jumper the logic 5V to its output pad (through a resistor... maybe 1K) to do a quick and dirty test. If the resistor output is dragged down, you know something is loading down the ref voltage.

Re: [time-nuts] Trimble Thunderbolt GPSDO Troubleshooting

Looking at the sample I prepared earlier, except for a single 120 ohm resistors all the blue resistors are 10 kohms. On Tuesday, 29 March 2016 7:27 PM, Bruce Griffiths wrote: There aren't enough resistors for a high resolution R-2R DAC so its likely to be