[time-nuts] OT: xtal osc PN

Bob Camp lists at rtty.us
Sun Sep 19 18:15:07 UTC 2010


Maybe narrow band stuff like low data rate PSK


On Sep 19, 2010, at 1:59 PM, jimlux wrote:

> francesco messineo wrote:
>>>> It's hard to explain why to ones not familiar with weak signal
>>>> operation between broadcasting signals, but really the noise floor
>>>> raise a lot when you have some 5 or 6 broadcasts signals in 500 KHz of
>>>> band (all with power levels of at least 10 dB more than the levels
>>>> used in amateur radio, often +20 dB more)
>>> I would need some more fundamental understanding of the system and needs
>>> to be able to understand how you come up with the above noise level at
>>> 100 Hz.
>> as I said, if it's not possible or not practical, of course I'll take
>> what I can get. The receiver will be limited by its phase noise and
>> not for example by its IMD3.
>> I think already -110 dBc/Hz at 100 Hz is better than any LO in
>> commercial receivers (for ham radio at least).
> But why at 100 Hz offset.  Are you looking for weak signals 100 Hz away from the strong interferer? (and are worried about reciprocal mixing from the LO)  That would imply that the interferer has equally good phase noise, and that's not particularly likely?
> If you want to be a good spectrum citizen and have a real clean transmitter...  (or you're doing some experiment where you are doing some sort of radio science, and need a clean, clean tx)
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