[time-nuts] Re: What phase variations to expect in a DMTD due to temperature fluctuations?

[Lux, Jim]

On 10/24/22 1:33 AM, Tom Van Baak via time-nuts wrote:
> > Are these levels to be expected?
>
> I'd say 1 ps / C is fine, but the 10 ps number seems high so you may 
> want to identify the source of that. For some context look at the 
> specs of a metrology grade distribution amp:
>
> https://spectradynamics.com/products/hpda-15rmi-high-performance-distribution-amplifier-1-50mhz/ 
>
>
> Its tempco spec is 1.5 ps/C, which sounds good enough for a 
> professional timing lab to me. Even if you had 3 C modulation of 
> temperature that's under 5e-15 @1000 s so it would be in the noise. 
> And if better performance was required you can simply keep the room to 
> 0.3 C instead of 3 C. That way everything in your lab -- cables, 
> connectors, power supplies, oscillator references, measurement 
> instruments -- improves accordingly.
>
> Another example is John Miles' TimePod [1] and PhaseStation [2]. Note 
> these are not spec'd explicitly in ps/C but rather ps/hour. I had not 
> seen that before.
>
> /tvb
>
> [1] https://www.miles.io/TimePod_5330A_user_manual.pdf
>
> [2] 
> http://ww1.microchip.com/downloads/en/AppNotes/AN3526-Dual-Reference-Noise-and-Stability-Measurements-with-the-53100A-PNA-DS00003526A.pdf



for what it's worth, we've just measured a bunch of GNSS band pass 
filter/LNA combinations and they run about 30-40 picoseconds/C delay tempco