Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY From the info given, the TOD will be a HaveQuick serial time string. Need to know what version of HaveQuick. I have some info on an Excel spreadsheet which may help. Will dig it out. Rob -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brooke Clarke Sent: 25 October 2007 02:54 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Dave: The problem is I don't have any documentation on the O-1814. The label does not say Frequency Standard or anything else about what it does. There is a very nice Rb source (M-100) inside and front panel connectors labeled 5 MHz In, 5 Mhz Out and 10 MHz Out so this may be a frequency standard. But it's not clear how any of the radios in the GRC-106 Pacer Speak system can take advantage of a reference frequency. http://www.prc68.com/I/PRC104.shtml#206 I'm beginning to think this is a Time Of Day standard. There are buttons for Rvc TOD and Send TOD as well as a lamp labeled Set Clock. I was looking for a serial clock stream that would be used to clock in the TOD serial data stream when I found the narrow pulse. I tried the SR620. It's bouncing around a 32 Hz period. My web host has changed the server that's hosting PRC68.com and I've sort of been distracted, but will try the diode pulse stretcher. If you look at the link above just below the GRC-206 system photo let me know if you see (new server) Starting with the top row: First VRC-83 Aircraft Radio - bold title (or the old server) GRC-206(V)1 can be fitted with 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 Dave Brown wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY But he knows the period already to parts in 10e-9 or better. His email sez it's a PPS signal ex an Rb source. Not much point in trying to measure that with a scope timebase! So I still think he wanted to measure the ~10uS pulse width.. g DaveB, NZ - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, October 24, 2007 5:27 PM Subject: Re: [time-nuts] Scopes and 1 PPS signals? ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I read this: But using an HP 54501A DSO it's almost impossible to determine the period. http://www.prc68.com/I/O1814.shtml; It seems he wanted to measure the period. For once, the thread actually was about the original question :-) Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dave Brown Sent: Tuesday, October 23, 2007 11:21 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? I took Brookes original inquiry to be about measuring the width of the nominally 10 uS wide PPS pulse-in which case anything that alters the pulse width is a no-no. Precise and stable triggering delay to place one of the pulses in the on-screen area is all that is required. DaveB, NZ ___ 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. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.15.6/1086 - Release Date: 22/10/2007 19:57 ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY 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. BillWB6BNQ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); 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. BillWB6BNQ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY But he knows the period already to parts in 10e-9 or better. His email sez it's a PPS signal ex an Rb source. Not much point in trying to measure that with a scope timebase! So I still think he wanted to measure the ~10uS pulse width.. g DaveB, NZ - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, October 24, 2007 5:27 PM Subject: Re: [time-nuts] Scopes and 1 PPS signals? ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I read this: But using an HP 54501A DSO it's almost impossible to determine the period. http://www.prc68.com/I/O1814.shtml; It seems he wanted to measure the period. For once, the thread actually was about the original question :-) Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dave Brown Sent: Tuesday, October 23, 2007 11:21 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? I took Brookes original inquiry to be about measuring the width of the nominally 10 uS wide PPS pulse-in which case anything that alters the pulse width is a no-no. Precise and stable triggering delay to place one of the pulses in the on-screen area is all that is required. DaveB, NZ ___ 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. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.15.6/1086 - Release Date: 22/10/2007 19:57 ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Dave: The problem is I don't have any documentation on the O-1814. The label does not say Frequency Standard or anything else about what it does. There is a very nice Rb source (M-100) inside and front panel connectors labeled 5 MHz In, 5 Mhz Out and 10 MHz Out so this may be a frequency standard. But it's not clear how any of the radios in the GRC-106 Pacer Speak system can take advantage of a reference frequency. http://www.prc68.com/I/PRC104.shtml#206 I'm beginning to think this is a Time Of Day standard. There are buttons for Rvc TOD and Send TOD as well as a lamp labeled Set Clock. I was looking for a serial clock stream that would be used to clock in the TOD serial data stream when I found the narrow pulse. I tried the SR620. It's bouncing around a 32 Hz period. My web host has changed the server that's hosting PRC68.com and I've sort of been distracted, but will try the diode pulse stretcher. If you look at the link above just below the GRC-206 system photo let me know if you see (new server) Starting with the top row: First VRC-83 Aircraft Radio - bold title (or the old server) GRC-206(V)1 can be fitted with 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 Dave Brown wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY But he knows the period already to parts in 10e-9 or better. His email sez it's a PPS signal ex an Rb source. Not much point in trying to measure that with a scope timebase! So I still think he wanted to measure the ~10uS pulse width.. g DaveB, NZ - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, October 24, 2007 5:27 PM Subject: Re: [time-nuts] Scopes and 1 PPS signals? ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I read this: But using an HP 54501A DSO it's almost impossible to determine the period. http://www.prc68.com/I/O1814.shtml; It seems he wanted to measure the period. For once, the thread actually was about the original question :-) Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dave Brown Sent: Tuesday, October 23, 2007 11:21 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? I took Brookes original inquiry to be about measuring the width of the nominally 10 uS wide PPS pulse-in which case anything that alters the pulse width is a no-no. Precise and stable triggering delay to place one of the pulses in the on-screen area is all that is required. DaveB, NZ ___ 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. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.15.6/1086 - Release Date: 22/10/2007 19:57 ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I tried the SR620. It's bouncing around a 32 Hz period. Brooke, You have a house standard, right? (GPSDO or cesium). Use your SR620 to take a set of N (10 or 100) TI measurements between your local reference and the O-1814 *rising edge*. Then again using the O-1814 *falling edge*. The difference between these two measurements is the average width of the O-1814 pulse. Easy to do very high accuracy. Check the sdev of each measurement to make sure nothing funny is going on; a couple of ns is OK. Hint: you get better data if you 1) sync the O-1814 1PPS to less than, say, 10 uS of UTC, and 2) if the O-1814 is tuned to within, say, 1e-11, of your house reference. /tvb ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I presume it has a calibrated delayed TB how about using that ?? Alan G3NYK - Original Message - From: Brooke Clarke [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, October 23, 2007 11:05 PM Subject: [time-nuts] Scopes and 1 PPS signals? 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 http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY 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. BillWB6BNQ 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 http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi , Isn't 5370 ownership a prerequisite for this group ? Brooke Clarke [EMAIL PROTECTED] 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 http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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. __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY - Original Message - From: Brooke Clarke [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, October 24, 2007 11:05 AM Subject: [time-nuts] Scopes and 1 PPS signals? ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY 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? If your DSO has external triggering capability then using an external digital delay unit will do the trick. Something as simple as a one shot driven from the preceding pulse to do the triggering? This sort of thing is one of the reasons some analog scopes are still useful. A tek 7K mainframe with a 7D11 delay unit is a good solution. That has up to 1 second precise low jitter delay available. DaveB, NZ ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Are there scopes that allow the period of a narrow pulse to be measured that don't cost an arm and leg? Can you use delayed sweep to look at the next pulse? If you have a good PPS source, that's a handy way to calibrate your scope. -- These are my opinions, not necessarily my employer's. 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Alan: I tried. At 100 ms/sq the second pulse would be just off screen to the right. At 200 ms/sq the second pulse should be at center screen. Using the window function the window time base can be no more than 10X faster than the main trace which would be 20 ms/sq, way too slow to see the pulse. 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 Alan Melia wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I presume it has a calibrated delayed TB how about using that ?? Alan G3NYK - Original Message - From: Brooke Clarke [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, October 23, 2007 11:05 PM Subject: [time-nuts] Scopes and 1 PPS signals? 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 http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY 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. BillWB6BNQ 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 http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY 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. BillWB6BNQ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Brooke, ah well its probably a case of not the right instrument for the job but that's a bit tough if its all you got, maybe the extra delay mentioned by others is what's called for. My old analogue scopes will do it :-)) Im surprised you can only get 10 screens worth delay. Some scopes will allow delay and sweep on different ranges of the TB. Alan - Original Message - From: Brooke Clarke [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, October 24, 2007 12:20 AM Subject: Re: [time-nuts] Scopes and 1 PPS signals? Hi Alan: I tried. At 100 ms/sq the second pulse would be just off screen to the right. At 200 ms/sq the second pulse should be at center screen. Using the window function the window time base can be no more than 10X faster than the main trace which would be 20 ms/sq, way too slow to see the pulse. 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 Alan Melia wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I presume it has a calibrated delayed TB how about using that ?? Alan G3NYK - Original Message - From: Brooke Clarke [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, October 23, 2007 11:05 PM Subject: [time-nuts] Scopes and 1 PPS signals? 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 http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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. ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Daun: The previous message suggested using a 74123 one shot, and the FatPPS uses a 74HC123. But $45 seems a bit high for just this measurement. 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 Daun Yeagley wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY What you need then is the FatPPS from TAPR. Our own John Ackermann (N8UR) designed it primarily for use with time servers by stretching the 1PPS pulse out to several milliseconds so that the computer could see it. I suspect the same principle would be useful for a scope. Check out: http://www.tapr.org/kits_fatpps.html Daun -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of WB6BNQ Sent: Tuesday, October 23, 2007 6:29 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? 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. BillWB6BNQ 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 http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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. ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Alan: It's not the delay that's limited, it's the sweep speed, or maybe that's saying the same thing. I do have a SR DG535 that can be used to generate the needed delay per Dave's suggestion, but I'm already short of 50 Ohm coax cables. Tried to get them at Radio shack but they no longer carry any 50 Ohm cables or bulk cable. Any recommendations for good value coax that's on line? 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 Alan Melia wrote: Hi Brooke, ah well its probably a case of not the right instrument for the job but that's a bit tough if its all you got, maybe the extra delay mentioned by others is what's called for. My old analogue scopes will do it :-)) Im surprised you can only get 10 screens worth delay. Some scopes will allow delay and sweep on different ranges of the TB. Alan - Original Message - From: Brooke Clarke [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, October 24, 2007 12:20 AM Subject: Re: [time-nuts] Scopes and 1 PPS signals? Hi Alan: I tried. At 100 ms/sq the second pulse would be just off screen to the right. At 200 ms/sq the second pulse should be at center screen. Using the window function the window time base can be no more than 10X faster than the main trace which would be 20 ms/sq, way too slow to see the pulse. 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 Alan Melia wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I presume it has a calibrated delayed TB how about using that ?? Alan G3NYK - Original Message - From: Brooke Clarke [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, October 23, 2007 11:05 PM Subject: [time-nuts] Scopes and 1 PPS signals? 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 http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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. ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I took some pictures of my Thunderbolt's PPS output. While it's pulse is not quite as narrow as what you report, it's 10uS, way too narrow for the scope to display it in normal (Sample) mode at 250mS/div (the fastest setting that will allow to measure the period of a PPS signal) on my TDS-210 digital storage scope. There are at http://www.ko4bb.com/Test_Equipment/Thunderbolt/PulseStretching The names are self explanatory, but just in case :-) 1_PPS_10xProbe is the PPS measured at the end of a 3 foot cable with a 10x probe 2_PPS_Sample Mode is the PPS signal in normal (sample) mode, as you probably would see it on any DSO without any special mode. It's fair to say it would be hard to make sure what you are seing or measuring. Please note that some of the time, the scope triggers, but the trace is flat. I had to wait to make this shot, which was the best I saw in about 30 seconds. 3_PPS_PeakDetect_Mode is the same signal, with the scope in Peak-Detect mode. It is easy to check the period (if not very acurate). In this mode, all sweeps look the same. 4_PPS_Diode is with a 1N4148 between the PPS output and the scope probe. See how the 10uS pulse is now a solid 250uS at 1/3 the height. It would be much easier to see on any scope, I need to pull the old trusty Tek 2245A and see what it does on it. 5_PPS_Diode_5.6nF is the same diode with a 5600pF capacitor across the probe. The pulse is now strecthed to ~10mS. 6_PPS_Diode_5.6nF is the same signal at the 250mS/div sweep rate. That's a heck of a lot cheaper than $45. Does not even need a power supply :-) Didier KO4BB ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Dider: I'll give that a try tomorrow. What does your camera setup look like? Digital SLR on tripod? Does that mean the TDS-210 can not do a screen dump to file? I've been looking at the Rigol DS1102CD mixed signal scope. The 100 MHz 2 analog channel 16 digital channels is very reasonably priced. But after 3 emails I still have not been able to see a programming manual for it. Although they do have a software package. 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: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I took some pictures of my Thunderbolt's PPS output. While it's pulse is not quite as narrow as what you report, it's 10uS, way too narrow for the scope to display it in normal (Sample) mode at 250mS/div (the fastest setting that will allow to measure the period of a PPS signal) on my TDS-210 digital storage scope. There are at http://www.ko4bb.com/Test_Equipment/Thunderbolt/PulseStretching The names are self explanatory, but just in case :-) 1_PPS_10xProbe is the PPS measured at the end of a 3 foot cable with a 10x probe 2_PPS_Sample Mode is the PPS signal in normal (sample) mode, as you probably would see it on any DSO without any special mode. It's fair to say it would be hard to make sure what you are seing or measuring. Please note that some of the time, the scope triggers, but the trace is flat. I had to wait to make this shot, which was the best I saw in about 30 seconds. 3_PPS_PeakDetect_Mode is the same signal, with the scope in Peak-Detect mode. It is easy to check the period (if not very acurate). In this mode, all sweeps look the same. 4_PPS_Diode is with a 1N4148 between the PPS output and the scope probe. See how the 10uS pulse is now a solid 250uS at 1/3 the height. It would be much easier to see on any scope, I need to pull the old trusty Tek 2245A and see what it does on it. 5_PPS_Diode_5.6nF is the same diode with a 5600pF capacitor across the probe. The pulse is now strecthed to ~10mS. 6_PPS_Diode_5.6nF is the same signal at the 250mS/div sweep rate. That's a heck of a lot cheaper than $45. Does not even need a power supply :-) Didier KO4BB ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Digital camera (Samsung D53, 5Mpx, 3x optical zoom, 2.4 LCD, was $88 at WalMart last year) on a bipod, my arms :-) Flash is turned off, scope contrast adjusted for normal use. I have the Comm module for the TDS-210, and I have the GPIB controller and John Miles' software, which I use with the spectrum analyzer. But, my main computer is not very close to the lab bench, and the laptop is in another room at the moment, so it's just easier to take the digital camera. I bought my TDS-210 at a local hamfest a few years ago and I never regretted it. It's a great little instrument. I only have a couple of gripes with it: 1) the contrast voltage is not temperature compensated, so you have to adjust it when you turn the scope on, then a couple more times during the first few dozen minutes of operation, then it will stay good forever, not a biggie. 2) the trigger point wants to be at the center of the screen, and if it's not, it's going to be so many mS or uS from the center of the screen when you adjust it for instance. From that point, if you change the time base, the trigger point moves to remain at the same time delay from the center of the screen. You can very rapidly have the trigger point a mile or so to the left of the screen, so to speak, and that can be aggravating when you turn the horizontal control knob to bring it back into the screen :-) I'm still not used to it after many years. I wish we could set the scope to have the trigger point at one or nine divisions, and it would not move when you change the time base, like the old 468. These are nothing major, the scope is great. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brooke Clarke Sent: Tuesday, October 23, 2007 10:20 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? Hi Dider: I'll give that a try tomorrow. What does your camera setup look like? Digital SLR on tripod? Does that mean the TDS-210 can not do a screen dump to file? I've been looking at the Rigol DS1102CD mixed signal scope. The 100 MHz 2 analog channel 16 digital channels is very reasonably priced. But after 3 emails I still have not been able to see a programming manual for it. Although they do have a software package. 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: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I took some pictures of my Thunderbolt's PPS output. While it's pulse is not quite as narrow as what you report, it's 10uS, way too narrow for the scope to display it in normal (Sample) mode at 250mS/div (the fastest setting that will allow to measure the period of a PPS signal) on my TDS-210 digital storage scope. There are at http://www.ko4bb.com/Test_Equipment/Thunderbolt/PulseStretching The names are self explanatory, but just in case :-) 1_PPS_10xProbe is the PPS measured at the end of a 3 foot cable with a 10x probe 2_PPS_Sample Mode is the PPS signal in normal (sample) mode, as you probably would see it on any DSO without any special mode. It's fair to say it would be hard to make sure what you are seing or measuring. Please note that some of the time, the scope triggers, but the trace is flat. I had to wait to make this shot, which was the best I saw in about 30 seconds. 3_PPS_PeakDetect_Mode is the same signal, with the scope in Peak-Detect mode. It is easy to check the period (if not very acurate). In this mode, all sweeps look the same. 4_PPS_Diode is with a 1N4148 between the PPS output and the scope probe. See how the 10uS pulse is now a solid 250uS at 1/3 the height. It would be much easier to see on any scope, I need to pull the old trusty Tek 2245A and see what it does on it. 5_PPS_Diode_5.6nF is the same diode with a 5600pF capacitor across the probe. The pulse is now strecthed to ~10mS. 6_PPS_Diode_5.6nF is the same signal at the 250mS/div sweep rate. That's a heck of a lot cheaper than $45. Does not even need a power supply :-) Didier KO4BB ___ 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
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi there, One option that I've used is to put a flip-flop on the signal, turning the 1 PPS short pulse into a 1/2 Hz square wave. You can always see that on the DSO, and it may even be easier to catch the rising and falling edges on other assorted equipment (depending on the equipment). Regards, Dean Weiten. ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, October 24, 2007 3:58 PM Subject: Re: [time-nuts] Scopes and 1 PPS signals? ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I took some pictures of my Thunderbolt's PPS output. While it's pulse is not quite as narrow as what you report, it's 10uS, way too narrow for the scope to display it in normal (Sample) mode at 250mS/div (the fastest setting that will allow to measure the period of a PPS signal) on my TDS-210 digital storage scope. There are at http://www.ko4bb.com/Test_Equipment/Thunderbolt/PulseStretching The names are self explanatory, but just in case :-) 1_PPS_10xProbe is the PPS measured at the end of a 3 foot cable with a 10x probe 2_PPS_Sample Mode is the PPS signal in normal (sample) mode, as you probably would see it on any DSO without any special mode. It's fair to say it would be hard to make sure what you are seing or measuring. Please note that some of the time, the scope triggers, but the trace is flat. I had to wait to make this shot, which was the best I saw in about 30 seconds. 3_PPS_PeakDetect_Mode is the same signal, with the scope in Peak-Detect mode. It is easy to check the period (if not very acurate). In this mode, all sweeps look the same. 4_PPS_Diode is with a 1N4148 between the PPS output and the scope probe. See how the 10uS pulse is now a solid 250uS at 1/3 the height. It would be much easier to see on any scope, I need to pull the old trusty Tek 2245A and see what it does on it. 5_PPS_Diode_5.6nF is the same diode with a 5600pF capacitor across the probe. The pulse is now strecthed to ~10mS. 6_PPS_Diode_5.6nF is the same signal at the 250mS/div sweep rate. That's a heck of a lot cheaper than $45. Does not even need a power supply :-) Didier KO4BB I took Brookes original inquiry to be about measuring the width of the nominally 10 uS wide PPS pulse-in which case anything that alters the pulse width is a no-no. Precise and stable triggering delay to place one of the pulses in the on-screen area is all that is required. DaveB, NZ ___ 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.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I read this: But using an HP 54501A DSO it's almost impossible to determine the period. http://www.prc68.com/I/O1814.shtml; It seems he wanted to measure the period. For once, the thread actually was about the original question :-) Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dave Brown Sent: Tuesday, October 23, 2007 11:21 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? I took Brookes original inquiry to be about measuring the width of the nominally 10 uS wide PPS pulse-in which case anything that alters the pulse width is a no-no. Precise and stable triggering delay to place one of the pulses in the on-screen area is all that is required. DaveB, NZ ___ 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.
