[time-nuts] Old xtal filter

Magnus Danielson magnus at rubidium.dyndns.org
Sun Mar 6 20:15:24 EST 2016


Hi,

On 03/07/2016 12:42 AM, Poul-Henning Kamp wrote:
> --------
> In message <CAF7oPz0SrwdMed1av2M_tkYw6K+EsR+akKa+kN623_Lf8KVf4g at mail.gmail.com>
> , Joseph Gray writes:
>
>> Assuming I made the pictures small enough, attached are two images of
>> an very old crystal filter that a friend found. The strange thing
>> about it is the bandwidth - 100 Hz. What could this have been used
>> for, with such a narrow bandwidth?
>
> The 100kHz center frequency pretty much rules out that it comes
> from carrier telephony.
>

It does not match any of the FDM pilot tone systems that I've seen.
It also does not match the TDM system rates, and this device seems old 
enough to almost precursor them.

Cheers,
Magnus


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