[time-nuts] OT: xtal osc PN

[francesco messineo]

On 9/19/10, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
> Frank,
>
> On 09/19/2010 09:35 AM, francesco messineo wrote:
>> Hi
>>
>> On 9/19/10, Bob Camp<lists at rtty.us>  wrote:
>>> Hi
>>>
>>> Is -195 dbc/Hz floor good enough or is it overkill?
>>
>> I'd say this is obviously overkill, -160 dBc/Hz could be a good
>> compromise.
>>
>>>
>>> Is -155 dbc/Hz at 100 Hz offset a requirement or is -40 dbc ok?
>>
>> -40 dBc/Hz at 100 Hz is about useless, -150 dBc/Hz at 100 Hz is again
>> a good compromise, the lower (practically) the better.
>
> Do you *really* need -150 dBc/Hz? That is a hard requirement!
>
>> 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).

Best regards
Frank