Hi The key point being that a fixed oscillator will have *much* better close in phase noise than your typical synthesized radio.
Bob On Sep 19, 2010, at 12:41 PM, francesco messineo wrote: > Hi Bob, > > sine oscillators like the AXLE184 series (which is one of my candidate > solutions so far) has around -110 dBc/h...@100 Hz offset and -160 dBc/Hz > at 100 KHz. > In the application I'm talking about, the use of 500 - 250 Hz crystal > filters at the IF is normal practice. > > Best regards > Frank > > On 9/19/10, Bob Camp <[email protected]> wrote: >> Hi >> >> 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. >> >> Bob >> >> >> On Sep 19, 2010, at 12:04 PM, francesco messineo wrote: >> >>> On 9/19/10, Magnus Danielson <[email protected]> wrote: >>>> Frank, >>>> >>>> On 09/19/2010 09:35 AM, francesco messineo wrote: >>>>> Hi >>>>> >>>>> On 9/19/10, Bob Camp<[email protected]> 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 >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
