For clarification, from reading the Symmetricom manual, the TS-2500 was designed as a reliable Stratum 1, 10 MHz source for communications systems. In addition to GPS, the unit monitors the internal SRI PRS-10, and other 10 MHz frequency references that are presented to it. It tracks and compares these with GPS and keeps long-term records of their behavior. In the event the GPS signal is lost, the TS-2500 generates a 10 MHz output from its internal oscillator, using the PRS-10 and any other monitored reference inputs as references, after first applying weighting factors developed from experience to determine the appropriate frequency offsets. In other words, the PRS-10 output is not utilized directly, but only as a reference. An offset is applied, based upon the retained past monitoring data of the PRS-10 frequency versus GPS.
Should the unit suddenly see the GPS departing from its expected frequency, as compared with multiple other references, it might switch to the holdover-mode, after computing the required offsets from past experience. A key point is that no provision is made to control the frequency of the PRS-10; it is simply monitored and the offset from GPS continually recorded. In other words, the PRS-10 does not influence the accuracy or noise of the 10 MHz output unless the GPS reference is lost. Bruce Hunter, KG6OJI _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
