In article <82f3qcfg1...@mid.individual.net>, sn...@lordynet.org says... > > Hi > > Latest experiment is to attempt to make a backup PPS source and > I've now made a start with a watch xtal oscillator and divider > that can be synchronised by a PPS source when present (except > I've not yet wired up for synchronisation). > > remote refid st t when poll reach delay offset > jitter > ============================================================================== > +GPS_NMEA(0) .GPSb. 0 l 57 64 377 0.000 1.865 > 0.381 > oPPS(0) .PPSb. 1 l - 16 377 0.000 -0.004 > 0.002 > PPS(2) .OSCc. 1 l 10 16 377 0.000 1.859 > 0.006 > -k6x400.home.lor 192.168.59.64 2 u 3 64 377 0.951 3.837 > 0.447 > +me6000g.home.lo .MSFa. 1 u 29 64 377 0.905 3.190 > 0.451 > -p4x2400c.home.l 192.168.59.64 2 u 34 64 377 0.832 3.078 > 0.343 > > PPS(2) was time1 fudged to get it < 2ms. > > I can see there being problems already with full rotation of trim > cap giving about +/- 6 us/s variation and temperature changes > have already shown a minor problem (south facing window, very hot > day, rapidly going cold tonight). Of course putting the whole > oscillator module in a temperature controlled box is in the plan. > > Earlier this afternoon I had trimmer set so that offset change > between poll periods was < +1us, but that started increasing and > change has now reversed direction with offset over last hour > having dropped from 1867us, steps at 6min intervals being: > -31 -43 -54 -61 -59 -60 -58 -60 -59 -68 -75 -76us > ie total 0.63ms over last hour. > > The temperature swings today have also has adverse effect on the > three peers shown that on a good day can all be < 500us. > > Any hints/tips welcome, I'm also considering an oscillator using > an AT cut xtal but design for that is considerably more complex, > however it's then a possibility to convert the HF to be used as > system clock. > > I also keep googling for rubidium sources but not found any > within my budget, cheapest I've found (new) starting at ukp 900. >
Sounds like a candidate for membership of the "Time Nuts" mailing list! https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts :) (The certificate is self signed.) Dave B. _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
