); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY The 8640B has an FLL, if turned on by the front panel switch. The frequency display number is stored and compared to. - Mike
Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of WB6BNQ Sent: Sunday, September 02, 2007 4:48 PM To: Tom Van Baak; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPSDO Question ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Tom Van Baak wrote: > > Jerry > > > > It is amusing/distressing to see that the myth that using an FLL to lock > > an oscillator to the PPS output of a GPS receiver is a good approach > > still persists. > > The optimum solution is a phase lock loop. > > Whilst building an FLL is instructive/educational, if you want the best > > GPSDO performance you should really use a PLL. > > > > Bruce > > It would seem for timekeeping applications, a PLL-based > GPSDO will inherit the long-term accuracy of GPS with > great fidelity. > > But for many frequency (e.g., transmitters) or time interval > applications (e.g., frequency counters with finite gate times), > I'd like to understand, in detail, what the difference between > a PLL- and FLL-based GPSDO really is. > > Can someone point me to real data or even simulations > with plots that show rms or adev differences between the > two camps? > > Thanks, > /tvb > Hi Tom, I have seen and am familiar with only one FLL loop. It compared a counter's registers to a static register loaded with the wanted value. This loop was read to just -1x10^6. With this scheme the granularity is obviously the +/- LSB count, not counting the time base error. Bill....WB6BNQ _______________________________________________ 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.
