Hi Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing two PPS signals?
Bob > On Jun 30, 2015, at 2:47 PM, Dan Watson <watsondani...@gmail.com> wrote: > > Hi, > > I'm trying to take some ADEV measurements with my 53131A, and I'm having > some issues. This is my setup: > > - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the > TI Quik cal and it passed > - I'm using RS-232 out with a null modem cable into a Serial-USB converter > - Software is TimeLab in talk-only mode. 53131A check box is checked. > - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 > - A delay of 1 second is set on the counter. TimeLab seems to accurately > detect this interval > > I started measuring various devices, and could never seem to get better > than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. > Finally I put the T-bolt on channel 1 with common mode on to both channels, > and it still measures around 10^-6. A picture of that is attached. Surely > this can't be right. > > I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, > as expected. I understand the issues with filtering that the 53131A does > internally on this mode, but at least it shows my setup is working to some > degree. It's TI mode that seems to be wonky. > > I'm probably doing something really stupid. > > Thanks for any help you all can suggest. > > Regards, > > Dan W > <adevtest.png>_______________________________________________ > 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.