Re: [time-nuts] Thunderbolt Rollover Testing

On Sat, 4 Mar 2017 20:39:45 -0800, you wrote: >Matthias Jelen did a test on the Trimble Thunderbolt here: > >https://www.febo.com/pipermail/time-nuts/2014-September/086664.html >https://www.febo.com/pipermail/time-nuts/2015-May/091805.html

Re: [time-nuts] Thunderbolt Rollover Testing

> I didn't see any reports of anyone (successfully) implementing a test for it. ... > I obtained all of the receivers the driver currently supports, along with a > Spirent GSS6100 simulator. ... Hi Trevor, Matthias Jelen did a test on the Trimble Thunderbolt here:

Re: [time-nuts] Cs standard stability

Bruce, For the moment, let's forget about the Timepod plot and just concentrate on the screenshot of the two Timelab runs on the 5370: one on GPSDO Unit 2, and one on the Cs.  Given that the test conditions were identical, down to the the clock source for the 5370, how can the phase noise on

[time-nuts] HP 5061 oven temp Tcouple

Working with Frankenstein and those C fumes are getting mighty rare. That said wanted to see what temp the ovens running at. As suggested here there is a direct reading Tcouple in the C tube. Looking at the raw wire colors from the tube best guess is a T type because the actual wire color is

Re: [time-nuts] Cs standard stability

OK, but how does the phase noise of the GPSDO make the ADEV for the Cs worse than that for the GPSDO?  I find it hard to believe that the phase noise from two separate units would cancel out for two GPSDOs but add for the Cs. Bob  From: Bruce Griffiths To:

Re: [time-nuts] Cs standard stability

Bob You should to use the same measurement bandwidth when comparing ADEV measures. The measurement bandwidth of a Timepod is usually less than 1kHz whereas the 5370A has a trigger system bandwidth of 100MHz or so. If the high phase noise of your GPDSO isnt attenuated by a filter it may cause

Re: [time-nuts] Cs standard stability

Bruce, Are we getting a bit off track?  The question I asked is in regards to the Cs, not the purity of the output of the GPSDO.  The two ADEVs were done under the same conditions, yet the ADEV of the Cs is obviously not as good as that of the GPSDO.  Also, the ADEV of the GPSDO pretty much

Re: [time-nuts] Cs standard stability

Bob We are certainly not off track. The phase noise of the GPSDO affects the trigger jitter of both the 5370A and the jitter of the GPSDO PPS output and consequently the ADEV measured by your setup. NB ADEV depends on the measurement bandwidth which is relatively small when using a Timepod.

Re: [time-nuts] Cs standard stability

Hi Bruce, To me, it seems that the reasoning must be circular.  If I measure three units against each other with one piece of test equipment, then the one that has the best noise performance is the one that is not being measured when the ADEV plot is the worst.  At least that's the way I see

Re: [time-nuts] Cs standard stability

Bob The Phase noise of that GPDSO seems quite high and some form of filtering (bandpass or low pass) of its output may be necessary to reduce the resultant jitter when connected to the 5370A input. There are commercial TDCs that claim that sort of performance (~10ps) but a comprehensive test

Re: [time-nuts] Cs standard stability

Bob Your reasoning appears somewhat circular. A typical 5370A may have around 35ps or so rms noise when measuring short time intervals. This translates to an equivalent ADEV of around 4.3E-11 for Tau = 1s due to the 5370A noise alone. The 5370A in particular may have issues with DNL errors of

Re: [time-nuts] HP 5061 oven temp Tcouple

Ran the calculations and the offset is 3% high. The ovens running at 89 degrees C. Regards Paul WB8TSL On Sat, Mar 4, 2017 at 4:56 PM, paul swed wrote: > Working with Frankenstein and those C fumes are getting mighty rare. > That said wanted to see what temp the ovens

Re: [time-nuts] Cs standard stability

Hi Bruce, I'm aware that the GPSDO is better at low tau than the 5370.  This is born out by its low tau ADEV being right at the specs for the 5370, as well as by measurements done some time ago on a Timepod.  Unfortunately, I don't have a Timepod, so I have to make some guesses based on what I

[time-nuts] New project: Raspberry Pi Zero W NTP clock

I’ve made a variation on my GPS clock that uses the new Pi Zero W (in truth, it could use an ordinary Pi Zero with some other network connectivity. The W’s built-in WiFi just simplifies things a bit) to drive the same LED display. The local time would ostensibly be synced by NTP in the usual

Re: [time-nuts] Cs standard stability

Bob That doesn't seem inconsistent with the specs given the contribution of the 5370A to the measured ADEV is likely to be of the same order as the PRS45A spec. The ADEV of the GPSDO also needs to be taken into account. The contribution of the 5370A to ADEV will gradually become insignificant

[time-nuts] Cs standard stability

I hooked up my PRS-45A yesterday, just to do some ADEV comparisons with my GPSDO.  Unfortunately, the GPSDO seems to be better by almost two points at all tau as measured on my HP 5370A and plotted by Timelab.  So, can I infer from that that the OCXO in the PRS has a problem, or could it be