Hi Sounds like it's time to get a better counter
Bob On Nov 20, 2010, at 6:49 AM, Magnus Danielson wrote: > Fellow time-nuts, > > Björn and I have been having some fun during our get-together in his basement > time-lab. I pulled with me some gear (CNT-90 and SR620) for him to play with, > so a good warmup exercise was to measure the offset between the PPS and the > clock output (5 MHz or 10 MHz). > > The results was uhm... spread out... so we felt like sending you guys a > report. > > First out was a RAPCO 1804M which has a HCD 66 SC 5 MHz oven diciplined by an > old Trimble SV6+ (?) GPS receiver. We popped the lid for other purposes... :) > It had the 5 MHz rising edge 32,17 ns behind the PPS rising edge, with 100 ps > RMS jitter. Quite noticeable offset but fair jitter. > > The good old RAPCO was jumperable to be on "OSC" or "GPS" on the mysterious > jumper LK9 and it was stuck hard on the "OSC" setting, but some physical > exercise later we got it into GPS setting and it had a about 200 ns peak to > peak sawtooth... nice and pedagogical exercise. > > We then had a look at the Brandywine GPS-4 (mine on loan to Björn) and found > it had fairly nice numbers... until we discovered it has a periodically > reoccuring glitch of unknown system-source. > > Natually we hooked in to Björns Thunderbolt and found the offset so tight > that we ran into trigger-problems, but offsetting the clock by about 8 ns of > coax cable we had a about 4 ns in average and 6 ns peak-to-peak. The PPS thus > jumped between two distinct offsets with their respective gaussian > distribution around them. Not all that neat, and the RAPCO was the quietest > in this shoot-out. > > Over and out, > Magnus and Björn > > _______________________________________________ > 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. _______________________________________________ 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.
