[time-nuts] The difficulty of low noise measurements

[Poul-Henning Kamp]

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In message <643136da-9599-18ca-be85-ffa62ab04aea at rubidium.se>, Magnus Danielson writes:

>> I have on my ever-growing TODO list to test if serial-BLE adapters
>> are any good.  Has anybody tried that yet ?

>My recommendation is to build on the ESP32, then you can get serial port
>to WiFi directly and the entry level price is small enough and there
>exist a community of things. It is competent enough that you may let it
>do some of the processing for you.

The reason I noted "BLE" and not "WIFI" is the lower power:  Less RF
can never be a bad thing in these circumstances.

>The EFOS10 maser has UPS and batteries, sure they are not prime but I
>can for shorter measurements just go and unplugg power if needed.

Have you tried it ?

How is the electrical grid configured on your rocks with respect to PEN ?

Do you have a ground electrode at each house or does the utility
provide the PEN potential via their cable ?

In the former case:  How old are the one at your house ?  If more
than few decades old, it may not provide good contact any more.

In the latter case, your PEN will be very noisy, and if you think
you can hammer a 2.5m hard copper "electrode" into some kind of wet
underground, a galvanic trafo on the mains might be relevant.

>I have a ham friend that is fairly well into batteries as he needs to
>for his telecom installations.

LVDC people are much better at this than UPS people, the latter often
think that batteries only need to last "until the diesel kicks in"
and that is a very different application.

-- 
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