[EMAIL PROTECTED] wrote: > > The Clock Granularity message is to be applied to the next following 1PPS > pulse in Motorola speak. Typically, the 1PPS is captured by a > Microcontroller, > which can then add the granularity message data to the capture time, and thus > > improve the measurement over the long term. >
The hardware granularity message can be used to provide a hardware correction to the time of the next one-pulse-per-second pulse. Richard Hambly, who does business as CNS Systems <http://www.cnssys.com/> will sell you his "CNS Clock II) with a "Precise PPS" option that includes this hardware-corrected 1 PPS output. The $1500 price includes the M12+ timing receiver nicely packages, together with the hardware clock correction option, power supply, etc., and his SynTac32 software to control it from a PC. You supply (or purchase from him) the external antenna with 5 volt or 3 volt low noise amplifier (LNA) and the antenna cable. In recent correspondence with me, Hambly claims: "Recent tests of the CNS Clock II with the precision PPS option shows short term noise of about ± 3 nsec pk-pk with drift over a 10-minute period, probably due to ionoshperic variations, creating an overall error of ± 10 nsec pk-pk (zero mean, 3.7 nsec 1-sigma) as referenced to an HP5065A Rubidium Standard, itself calibrated to GPS." (I presume he's using "nsec" to mean "nanosecond" -- even though the standard SI symbol for the nanosecond is "ns" rather than "nsec.") -- James Maynard Salem, Oregon, USA _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
