Oh yes they do...... Extract from Zyfer CSII Manual.....
"In the Time Locked mode the GTF module's output signals and the system's time are synchronized to UTC. The 1 PPS output from the GPS receiver is used as reference to discipline the module's oscillator and to align the 1 PPS output pulse." Further.... "2.1.6 Discipline in Time Locked Mode The first time a module enters the Time Locked mode after power is applied, the time and frequency output signals are "jam" synchronized to GPS, and are phase and frequency corrected as needed to maintain the specified accuracy of the output signals. The Frequency Discipline Machine (FDM) continuously compares the module's GPS receiver 1 PPS output with the generated 1 PPS derived from the module's oscillator to determine the correction necessary to discipline the oscillator. The FDM filters out the short-term variations inherent in the GPS 1 PPS". If you want more, then http://www.zyfer.com/prod_manuals/385-8000V.pdf Cheers Rob K -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matt Ettus Sent: 19 January 2006 19:01 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Some More questions On 1/19/06, Hal Murray <[EMAIL PROTECTED]> wrote: > > > Then, I am not sure all GPS receivers actually use their internal > > crystal oscillator in a PLL as the timebase. I have read that some > > work by removing or adding pulses in a discrete fashion rather than > > phase locking, and this offers significant jitter, making the 1 PPS > > only useable to phase lock a reference oscillator with a very long > > integration period to eliminate the jitter. To my knowledge, nobody tunes the frequency of the oscillator in their GPS receiver. Matt _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
