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.
