Didier Yes it is, and it can only usually be justified if one has an antenna array to distribute low phase noise RF to. One then also needs to add a means of compensating for fiber delay tempco, which adds yet more cost. A cleanup PLL using an ultra low noise OCXO locked to each photomixer output is usually advisable as well.
Achieving more than about 120 dB of isolation at 10MHz is difficult without shielding. NIST claimed about 144dB of reverse isolation for one of their designs. Bruce Didier wrote: > All this sounds quite a bit more expensive and expansive than 3 ECL gates, > even if one uses 3 packages to improve isolation... > > Didier > > >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of Bruce Griffiths >> Sent: Monday, March 09, 2009 9:08 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Reverse isolation >> >> Didier >> >> A 10-1000mW of single mode ECDL helps. >> But then you need a modulator. >> You would also need to avoid frying any photomixer at the other end. >> >> Bruce >> >> Didier wrote: >> >>> But not necessarily lowest noise >>> >>> Didier >>> >>> >>> >>>> -----Original Message----- >>>> From: [email protected] >>>> [mailto:[email protected]] On Behalf Of Don Latham >>>> Sent: Sunday, March 08, 2009 8:48 PM >>>> To: Discussion of precise time and frequency measurement >>>> Subject: Re: [time-nuts] Reverse isolation >>>> >>>> Best isolation is via a piece of fiber optics. >>>> Don >>>> >>>> > > > _______________________________________________ > 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.
