Thanks for all the hints and suggestion. The problem seems to be anRS-232 receiver. I haven't seen any glitches like those since I moved the PPS line to a different PC.
Has anybody seen anything like that before? Anybody got any ideas on how a receiver can turn into a driver? The typical level shifters have separate receivers and transmitters rather than a tri-state and enable. Maybe I'll take it apart and see what chip it uses. There is a 1K resistor in series with the output of the wall wart so it makes some sense if a current/slew limited (aka weak) driver got turned on. Looks like I got a lemon in that box. (That's the box that has crazy stuff on the audio input like this: http://www.megapathdsl.net/~hmurray/time-nuts/li ne/2012-Aug-07-a0.png) Anyway, I'm back to looking at things that seem reasonable. Sometimes, glitches happen when the line voltage changes. Here are a few graphs: Here is a sample voltage change: http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-02-b0.png These are the beginning and end of the above: http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-02-b1.png http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-02-b2.png A pair of glitches that were close together: http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-02-c0.png http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-02-c1.png http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-02-c2.png Isolated glitches: http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-02-a0.png http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-03-a0.png http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-03-b0.png http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-03-c0.png http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-03-d0.png -- These are my opinions. I hate spam. _______________________________________________ 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.