); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Glad it works. I found the same here and that's why the better pictures were made with a 5600pF cap that just happened to lay on the bench...
Didier > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Brooke Clarke > Sent: Thursday, October 25, 2007 1:25 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Scopes and 1 PPS signals? > > Hi Didier: > > When just a diode is used the stretching is only at the > bottom of the trailing edge and not enough to help. But when > a little capacitance is added it works. > > The period is the same as what the SR620 reported, 1/ 32 Hz. > Seems a strange number. > > Have Fun, > > Brooke Clarke > http://www.PRC68.com > http://www.precisionclock.com > http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam > > > Didier Juges wrote: > > Some DSOs (my lowly Tek 210 does) have a peak detect > acquisition mode > > where it will analyze the signal at the highest speed of the A/D > > converter regardless of sweep speed and report the min and max for > > each displayed pixel line. Main advantages are 1) to make aliasing > > obvious and 2) to be able to see very narrow pulses at low sweep > > speed. I can see 20nS wide pulses at 1 PPS easily. Of course, the > > precision of the measurement (if you use the period function) is > > limited to the display resolution, but at least you can get in the > > ballpark. My scope is in that mode all the time, little > reason not to. > > > > If you do not have such mode, put a diode (i.e. 1N4148) in > series with > > the probe. The diode will charge the input capacitance of > the probe, > > which will discharge exponentially in the 10 Mohm > resistance and give > > you something you can see. Can't beat that for cost. Add some > > capacitance in parallel with the probe if needed to widen the pulse. > > > > Didier KO4BB > > > > > >>-----Original Message----- > >>From: [EMAIL PROTECTED] > >>[mailto:[EMAIL PROTECTED] On Behalf Of Brooke Clarke > >>Sent: Tuesday, October 23, 2007 6:24 PM > >>To: Discussion of precise time and frequency measurement > >>Subject: Re: [time-nuts] Scopes and 1 PPS signals? > >> > >>Hi Bill: > >> > >>I'm sure that would work, but it's something else that needs to be > >>done sometime in the future. > >> > >>I checked the pulse coming from the M12+T and it's more like 100 ms > >>wide, probably for this reason. > >> > >>Have Fun, > >> > >>Brooke Clarke > >>http://www.PRC68.com > >>http://www.precisionclock.com > >>http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam > >> > >> > >>WB6BNQ wrote: > >> > >>>Hi Brook, > >>> > >>>You could try using a 74123 (or newer variants) > >> > >>retriggerable one shot > >> > >>>to extend the pulse width to a level that would allow you > >> > >>to see it on the scope. > >> > >>>Bill....WB6BNQ > >>> > >>>Brooke Clarke wrote: > >>> > >>> > >>> > >>>>Hi: > >>>> > >>>>While trying to figure out the O-1814 Rb source I found a 1 > >> > >>PPS signal > >> > >>>>that's less than 10 us wide. But using an HP 54501A DSO > >> > >>it's almost > >> > >>>>impossible to determine the period. > >>>>http://www.prc68.com/I/O1814.shtml > >>>> > >>>>If the display is 1,000 dots wide: > >>>>at 2 us/sq the trace takes up about 4.5 squares or 450 > dots, at 200 > >>>>us/sq the trace takes up about 0.045 squares or 4 dots but > >> > >>the second > >> > >>>>pulse is way off screen. At slower sweep speeds you can't > >> > >>see the pulse. > >> > >>>>Are there scopes that allow the period of a narrow pulse to be > >>>>measured that don't cost an arm and leg? > >>>> > >>>>-- > >>>>Have Fun, > >>>> > >>>>Brooke Clarke > > > > > > > > _______________________________________________ > > 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. _______________________________________________ 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.