Hi Set it up on your 53132 and see what happens …
Bob > On Sep 16, 2016, at 8:35 PM, Scott Stobbe <[email protected]> wrote: > > For a low duty cycle pulse, the ac coupled signal will be approximately the > same as if it were dc coupled. Not sure I follow what you mean. There will > be only one rising edge for a narrow pulse ac coupled, as the falling edge > occurs much quicker than the HPF time constant. > > On Friday, 16 September 2016, Bob kb8tq <[email protected]> wrote: > >> Hi >> >> Most PPS signals these days are very low duty cycle. If you AC couple >> them, you can easily be triggering on the wrong edge. With the narrow pulse >> it may not be very obvious. >> >> Bob >> >>> On Sep 16, 2016, at 5:46 PM, Charles Steinmetz <[email protected] >> <javascript:;>> wrote: >>> >>> Bob wrote: >>> >>>> Set it to: >>>> >>>> 1) DC coupled (AC does not go low enough) >>>> 2) 50 ohms if your driving source will tolerate it, otherwise 1 meg ohm. >>>> 3) Manual trigger mode (Auto is to fast and it forgets where the >> trigger should be) >>>> 4) Trigger level around 1/2 the PPS P-P voltage >>> >>> I would just add the following: >>> >>> 1) I'd be very surprised if AC coupling wouldn't work fine with a >> typical PPS pulse, which has very fast edges (low nS). No LF response is >> required. Indeed, AC coupling will keep any LF noise out (not that we >> expect much in this application). This is true even if the PPS is a 50% >> duty-cycle square wave -- the spikes that get through every 500mS, >> alternating positive and negative, will have fast, accurate leading edges >> and will be way longer than necessary for proper triggering. >>> >>> 2) If your source will not tolerate a 50 ohm load, buffer it. Any >> significant length of cable between the source and a 1M termination will >> just slaughter your pulse. >>> >>> 4) The relevant peak voltage is the actual voltage at the counter input >> connector -- which may be only 1/2, or possibly even less, of the nominal >> logic level, depending on the source impedance. >>> >>> Best regards, >>> >>> Charles >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] <javascript:;> >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >>> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- [email protected] <javascript:;> >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
