Not sure if the NVE Isoloop range of GMR based high speed data couplers would have any advantages in this regard-their data is a bit sketchy but they would likely have similar issues- aside from certainly being fast enough. DaveB
----- Original Message ----- From: "Dr Bruce Griffiths" <[EMAIL PROTECTED]> To: "Don Collie" <[EMAIL PROTECTED]>; "Discussion of precise time and frequency measurement" <[email protected]> Sent: Saturday, February 03, 2007 6:43 PM Subject: Re: [time-nuts] Stepping up the output of an OCXO > Don > Don Collie wrote: >> Why not use an optocoupler as an isolation amplifier? - to the best >> of my >> knowledge it would provide infinite isolation. >> Cheers,.......................................Don Collie >> >> >> > And lots of noise. > You will need a cleanup PLL on the output side. > Also optocoupler isolation isn't infinite, there is a finite > capacitance > between the closely spaced emitter and detector. > Not all optoisolators are fast enough. > The most effective way of using optical isolation is in fact to > modulate > a stabilised laser and then couple the output into a fibre. > This technique is employed to distribute stable frequencies to Radio > telescope antennas especially when a large number are employed in an > array. > A phase locked loo is used at the other end to cleanup the signal > after > the photodetector. > Fibre has the advantage in this and other applications where long > runs > are involved that its propagation delay tempco is significantly > lower > than that of coax. > It is also possible to use fibre stretchers and other techniques to > actively compensate variations in the fibre propagation delay. > > Isolation becomes particularly important when one mixes a pair of > signals a few Hz apart and then analyses the zero crossing times of > the > mixer output beat signal. > It is easier to achieve a high isolation between RF frequencies than > at > frequencies of a few Hz, JPL found fibre optic isolation can be > invaluable in this case. > > Bruce > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.432 / Virus Database: 268.17.19/663 - Release Date: > 1/02/2007 14:28 > > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
