Post #4347436

Constantly coming across interesting things while making demo setups for showing off ngscopeclient filters. Here, I'm looking at the fall time of a 10 MHz reference clock coming off my Leo Bodnar GPS NTP server. This isn't quite as clean as the 10 MHz off the SRS FS752 GPSDO on the other side of the lab, but the NTP server lives on the main IT rack next to the scope in the VM server that I'm using for this test, so it was a convenient test signal source. I expected it to be constant with some noise, but if you average it a bit, there's actually some periodicity, about +/- 150ps varying at about 1 kHz. Seems like an aliasing artifact? The signal is pretty sharp, with fall time on the order of the ADC sampling period. So even with some interpolation the spectral content of the edge might just be too much to measure on this setup.