Javier, I think SJ's answer (quoted below) didn't really address the question posed about ionospheric and tropospheric corrections. He spoke to the time constants for the Rb oscillator's phase-lock-loop rather than to the question of applying ionospheric and tropospheric corrections that are broadcast in the GPS signal.
I'm also trying to discipline a Rb oscillator (SRS model PRS10) to the one herz pulses from an M12+ timing receiver. I am using both the ionospheric and tropospheric corrections. I think though, that I may have have set too long a time constant for the PLL time that disciplines the PRS10 to the M12+T's 1 Hz output. (I have it set to about 18 hours, the maximum value.) I'll experiment some more with it.) Poul-Henning Kamp advised me to try a little higher mask angle, as a way of reducing jitter due to multipath on the measurements from satellites that are low on the horizon. I currently have the mask angle set at 15 degrees above the horizontal, but I still see about 9 or 10 ns of jitter on the 1 PPS from the M12+ -- even with Rick Hambly's new "CNS Clock II" receiver with the hardware sawtooth correction option. I am not yet seeing the 3 ns or so jitter that Rick claims to have achieved. It puzzles me. Perhaps I need to install a ground plane under the antenna, or even a choke ring! James Maynard, K7KK Salem, Oregon, USA [EMAIL PROTECTED] wrote: > Hello Javier, > > this depends on your Rb oscillator, and if you use an external DAC circuitry > then the DAC and DAC reference thermal sensitivity as well. > > Typically, the Rb including the DAC and DAC reference will be better than > the GPS for time frames from 1000 to 10000s. The GPS will probably be better > than the Rb above 10000s and should thus be allowed to correct the Rb at > such > longer intervalls. > > So try starting with a cut off frequency of around 3000s, then try 10K or > even 20K intervalls for really good Rb's. Keep in mind that your DAC and DAC > reference likely have 2-5ppm temperature coefficient themselves, and may thus > > affect your Rb accuracy. > > Simple OCXO's seem to work well with a time constant of around 1000s or less > since they are much worse than the GPS at those times and benefit from the > GPS corrections above 1000s measurement intervalls. > > bye, > SJ > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts