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

[Javier Herrero]

Hello,

PTFE cables have quite a phase variation vs temperature, with the worse 
slope just around 20ºC. Better alternatives are the Huber+Suhner CT 
cables. The catalog shows some nice curves on phase variation vs 
temperature: 
https://literature.hubersuhner.com/Technologies/Radiofrequency/ct-product-family-en/?page=1

Best regards,

Javier

On 10/23/22 22:15, Erik Kaashoek via time-nuts wrote:
> The down converted input signals are converted to digital using an ADC. The
> rest is DSP. No digital circuit triggering timers. Can the clock of the MCU
> still have an impact? For sure the clock of the ADC can have an impact.
>
> The mechanics are very nasty. No touching of the table with the DMTD on it.
> Worst are the coax cables. BNC connectors are terribly unstable.
>
> Is 1 to 10 ps to be expected in the electronics? Or should I invest in semi
> rigid coax?
> Erik
>
> On Sun, Oct 23, 2022, 21:58 Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
>
>> --------
>> Erik Kaashoek via time-nuts writes:
>>
>>> The rest is digital and not expected to be temperature sensitive.
>> At a 1ps level of interest, that is not a well-founded expectation.
>>
>> In particular look out for power-supply variations, which will transpose
>> the trigger point for your "digital" clock-signals.
>>
>> PS: Do not ignore mechanics either: At the speed of light 1ps takes you
>> only 0.3mm.
>>
>> --
>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>> FreeBSD committer       | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by incompetence.
>>
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