[time-nuts] OT: xtal osc PN

Mike Feher mfeher at eozinc.com
Sun Sep 19 16:18:25 UTC 2010

Frank -

Did you ever mention at what center frequency you would like to achieve the
PN at your stated offset? Regards - Mike

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of francesco messineo
Sent: Sunday, September 19, 2010 12:04 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT: xtal osc PN

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

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