[time-nuts] Re: Misbehaving FTS1050A

[Bob Camp]

Hi

Rather than looking at frequency, it can be better to look at phase. You should not
need a day’s worth of data. It appears that a few hours are enough to show the problem.

Why look at phase? As your plots show, instantaneous frequency can be a very noisy
sort of measure. Phase often is a much easier plot to look at. Since phase is what drives
your ADEV or MDEV measure, it also can link better to what you see on the high level
graphs. 

Bob

> On Apr 30, 2023, at 12:51 PM, Jim Schatzman <james.schatzman at futurelabusa.com> wrote:
> 
> Michael and Bob-
> 
> I thank you guys for your suggestions. I think that I have confused matters by not providing all the data to back up my assertions. In hopes that it will help, here is a bit more....
> 
> I have attached a couple more plots. These are instantaneous frequency measurements, made for the same pair of FTS1050A oscillators (including the notable #7), made with the same TSC5110A  DMTD instrument, made about a week apart.
> 
> You can see a number of small frequency jumps in the B plot.The MADEV for the "B" data is about twice that of the "A" data over much of the tau range. 
> 
> I have performed around 15 tests with #7. What I observe is that the behavior varies from test to test. I see this quirky behavior with #7 and with none of the other 16 FTS1050A and two FTS1150A oscillators in my lab. I haven't shown you all of the data so I can understand some skepticism. I hope that this pair of measurements will be more convincing. Same oscillator pair. Same measurement device. One week apart.
> 
> To be fair, I have in the past had trouble with a TSC5110A  DMTD. Its  internal 32 MHz  oscillator occasionally went dramatically off-frequency, messing up the measurements.These measurements were made with a different TSC5110A unit. I have also observed the bad behavior of #7 using a TSC5120A., which uses a different design.  So... I don't think we can ascribe the results to the instrument.
> 
> Jim
> 
> 
> 
> <3_vs_7_freqA.png><3_vs_7_freqB.png>