[time-nuts] Counter Internal Oscillator Importance with External Reference?

Magnus Danielson magnus at rubidium.dyndns.org
Tue May 9 06:16:43 EDT 2017


Hi,

On 05/09/2017 09:05 AM, Poul-Henning Kamp wrote:
> --------
> In message <bad861e5-00a6-5ffc-e031-be6372a1306f at rubidium.dyndns.org>, Magnus Danielson writes:
>
>> Also, there is a reason that you can buy different internal oscillators,
>> this is one of them. For labs with their frequency distribution there is
>> no need to waste money on stand-alone performance.
>
> Please don't forget that running the counter of the same signal as
> the circuits being measured runs the risk of masking noise processes.

Indeed. On the other hand some measurements is hard not to do that way.
One should think about how isolation is created if needed, and this 
includes AC and DC, common mode and differential mode. Isolation 
amplifier should be part of the arsenal.

> I'm sure that modern counters like 53230 are better at this than
> the 5370, but you should always sanity-check your measurements
> using the counters internal, undisturbed timebase.

Indeed. When you think you have a risc of disturbance, please do 
measurements to verify the setup.

Cheers,
Magnus


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