[time-nuts] OT: xtal osc PN

francesco messineo francesco.messineo at gmail.com
Sun Sep 19 16:37:18 UTC 2010


Hi Mike,

as I said, current plans are for a few frequencies in the 20-50 MHz
range. The current project needs 20, 22 and 42 MHz oscillators.

Best regards
Frank

On 9/19/10, Mike Feher <mfeher at eozinc.com> wrote:
> 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
> 732-886-5960
>
>
>
> -----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
> Frank
>
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