[time-nuts] OT: xtal osc PN
lists at rtty.us
Sun Sep 19 16:35:31 UTC 2010
If it's a "reasonably priced" synthesized radio, -90 is probably better than anything you will find on VHF at 100 Hz offset. A lot of stuff out there is closer to -60 than it is to -100. 100 Hz doesn't mess up the adjacent channel rejection, so they don't worry a lot about it.
On Sep 19, 2010, at 12:04 PM, francesco messineo wrote:
> On 9/19/10, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
>> On 09/19/2010 09:35 AM, francesco messineo wrote:
>>> On 9/19/10, Bob Camp<lists at rtty.us> wrote:
>>>> 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
>>>> 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).
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