[time-nuts] OT: xtal osc PN

jimlux jimlux at earthlink.net
Sun Sep 19 17:59:04 UTC 2010

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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