In article <[email protected]>, [email protected] says... > > G8KBV wrote: > > In article <[email protected]>, [email protected] 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
I bet the first 'birds nest' version works better. Nice job sir. Dave B(G8KBV) _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
