Re: [time-nuts] Trimble T Lassen 2 - suitableantenna....advice.....questions
You can see it easily with any 50+ MHz analog scope that has a working DC trigger function. If it is a 1 us pulse width TTL output or close, set the H sweep to 1 us/div, The vertical to 1 volt/div, the triggering to normal, and the trigger input to DC. Then adjust the trigger point to +1 volt. You should see a sweep every second. If you turn up the intensity and dim the room lighting, the pulse should be visible. If you are using a Tek scope and need help setting it up, just ping me and I'll assist. Others on this list can also give good advise in seeing this signal. Regards, Tom - Original Message - From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, August 20, 2012 1:52 AM Subject: Re: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions On Sun, Aug 19, 2012 at 9:27 PM, Robert Darlington rdarling...@gmail.comwrote: It's a pain to capture on any scope, but really easy to see with an LED across the output. it's not bright, but definitely easy to see on my tbolt. That is true. One must have very good eyes to see a one microsecond pulse that only happens one per second. Blink and you miss it. The LED might work but the for sure way is to send the PPS to a flip flop so you can see the state change at 1Hz. Use a solderless bread board and 5V power supply. -- Chris Albertson Redondo Beach, California ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
Yes, the oscilloscope PPS detection is really a FAQ and already discussed here. The use of a digital 'scope is recommended but the idea of dividing the PPS by 2 with a FF is useful and simple to implement, to detect if the PPS output is working or not. A more sophisticated one uses a monostable to stretch the 1uS pulse to 200mS to let it be solid visible. I use a CD4538 with 22nF and 10K to give a good pulse visibility. On Mon, Aug 20, 2012 at 8:44 AM, Tom Miller tmil...@skylinenet.net wrote: You can see it easily with any 50+ MHz analog scope that has a working DC trigger function. If it is a 1 us pulse width TTL output or close, set the H sweep to 1 us/div, The vertical to 1 volt/div, the triggering to normal, and the trigger input to DC. Then adjust the trigger point to +1 volt. You should see a sweep every second. If you turn up the intensity and dim the room lighting, the pulse should be visible. If you are using a Tek scope and need help setting it up, just ping me and I'll assist. Others on this list can also give good advise in seeing this signal. Regards, Tom - Original Message - From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, August 20, 2012 1:52 AM Subject: Re: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions On Sun, Aug 19, 2012 at 9:27 PM, Robert Darlington rdarling...@gmail.com wrote: It's a pain to capture on any scope, but really easy to see with an LED across the output. it's not bright, but definitely easy to see on my tbolt. That is true. One must have very good eyes to see a one microsecond pulse that only happens one per second. Blink and you miss it. The LED might work but the for sure way is to send the PPS to a flip flop so you can see the state change at 1Hz. Use a solderless bread board and 5V power supply. -- Chris Albertson Redondo Beach, California ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
A DSO works great for this. One of the few things that I prefer a DSO for over an analog scope. For an analog scope, it's easier to tell the scope is triggering once per second than actually see the pulse. To see the pulse, turn the lights out, turn the sweep and intensity up and don't blink. IIRC, my TBolt 1 PPS is about 5 uSec wide and about 5 VDC. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Monday, August 20, 2012 12:53 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions On Sun, Aug 19, 2012 at 9:27 PM, Robert Darlington rdarling...@gmail.comwrote: It's a pain to capture on any scope, but really easy to see with an LED across the output. it's not bright, but definitely easy to see on my tbolt. That is true. One must have very good eyes to see a one microsecond pulse that only happens one per second. Blink and you miss it. The LED might work but the for sure way is to send the PPS to a flip flop so you can see the state change at 1Hz. Use a solderless bread board and 5V power supply. -- Chris Albertson Redondo Beach, California ___ 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] Trimble T Lassen 2 - suitable antenna....advice.....questions
It's a pain to capture on any scope, but really easy to see with an LED across the output. it's not bright, but definitely easy to see on my tbolt. -Bob On Mon, Jul 23, 2012 at 10:11 AM, Stephen Farthing squir...@gmail.com wrote: Hi Guys, I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - the guy told me they were left over from a contract he had and were brand new. He had a load and i bought a couple for use as a precision 1 PPS output for radio stuff. They were packed in static protection. When I apply power to both units I can hear the oscillator (12.504 MHz) on my comms RX. So I am assuming that they work. I bought what claims to be a Trimble compatible active antenna on EBay. I hooked it up to one of the boards and applied power, and put the scope on the one pps pin. However after 20 mins (which I assume is much longer than the unit requires to get a lock) I see no 1pps trace on the screen. :-( So my working assumption is that the antenna is not working. The antenna position is fine as my elderly Garmin GPS2 which must be 12 years old sees 6 satellites there. Can anyone recommend a suitable antenna? I have a number of DIY designs I can try (Patch, Turnstile) but the Trimble docs say it needs an active antenna so I guess I'll have to spend money :-( While i am on, can anyone suggest a reasonably priced unit that has a 1pps output, NMEA and a built in antenna. Because I want to use this with an 8 bit embedded system I am probably not going to be able to hack one of the many cheap USB dongle GPS's. Lastly, has anyone found a GPS that will work with an Ipad. What the man in the Apple shop failed to tell me was the non 3g model lacked the built in GPS :-( Thanks in advice Steve -- Wisdom demands a new orientation of science and technology towards the organic, the gentle, the non-violent, the elegant and beautiful. E. F. Schumacher ___ 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] Trimble T Lassen 2 - suitable antenna....advice.....questions
On Sun, Aug 19, 2012 at 9:27 PM, Robert Darlington rdarling...@gmail.comwrote: It's a pain to capture on any scope, but really easy to see with an LED across the output. it's not bright, but definitely easy to see on my tbolt. That is true. One must have very good eyes to see a one microsecond pulse that only happens one per second. Blink and you miss it. The LED might work but the for sure way is to send the PPS to a flip flop so you can see the state change at 1Hz. Use a solderless bread board and 5V power supply. -- Chris Albertson Redondo Beach, California ___ 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] Trimble T Lassen 2 - suitable antenna....advice.....questions
Hi Guys, I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - the guy told me they were left over from a contract he had and were brand new. He had a load and i bought a couple for use as a precision 1 PPS output for radio stuff. They were packed in static protection. When I apply power to both units I can hear the oscillator (12.504 MHz) on my comms RX. So I am assuming that they work. I bought what claims to be a Trimble compatible active antenna on EBay. I hooked it up to one of the boards and applied power, and put the scope on the one pps pin. However after 20 mins (which I assume is much longer than the unit requires to get a lock) I see no 1pps trace on the screen. :-( So my working assumption is that the antenna is not working. The antenna position is fine as my elderly Garmin GPS2 which must be 12 years old sees 6 satellites there. Can anyone recommend a suitable antenna? I have a number of DIY designs I can try (Patch, Turnstile) but the Trimble docs say it needs an active antenna so I guess I'll have to spend money :-( While i am on, can anyone suggest a reasonably priced unit that has a 1pps output, NMEA and a built in antenna. Because I want to use this with an 8 bit embedded system I am probably not going to be able to hack one of the many cheap USB dongle GPS's. Lastly, has anyone found a GPS that will work with an Ipad. What the man in the Apple shop failed to tell me was the non 3g model lacked the built in GPS :-( Thanks in advice Steve -- Wisdom demands a new orientation of science and technology towards the organic, the gentle, the non-violent, the elegant and beautiful. E. F. Schumacher ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
Do not be too quick to toss out the antennas. Some receivers need the antenna power to be connected to a pin on the receiver connector that is then internally routed to the antenna. John WA4WDL -- From: Stephen Farthing squir...@gmail.com Sent: Monday, July 23, 2012 12:11 PM To: time-nuts@febo.com Subject: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions Hi Guys, I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - the guy told me they were left over from a contract he had and were brand new. He had a load and i bought a couple for use as a precision 1 PPS output for radio stuff. They were packed in static protection. When I apply power to both units I can hear the oscillator (12.504 MHz) on my comms RX. So I am assuming that they work. I bought what claims to be a Trimble compatible active antenna on EBay. I hooked it up to one of the boards and applied power, and put the scope on the one pps pin. However after 20 mins (which I assume is much longer than the unit requires to get a lock) I see no 1pps trace on the screen. :-( So my working assumption is that the antenna is not working. The antenna position is fine as my elderly Garmin GPS2 which must be 12 years old sees 6 satellites there. Can anyone recommend a suitable antenna? I have a number of DIY designs I can try (Patch, Turnstile) but the Trimble docs say it needs an active antenna so I guess I'll have to spend money :-( While i am on, can anyone suggest a reasonably priced unit that has a 1pps output, NMEA and a built in antenna. Because I want to use this with an 8 bit embedded system I am probably not going to be able to hack one of the many cheap USB dongle GPS's. Lastly, has anyone found a GPS that will work with an Ipad. What the man in the Apple shop failed to tell me was the non 3g model lacked the built in GPS :-( Thanks in advice Steve -- Wisdom demands a new orientation of science and technology towards the organic, the gentle, the non-violent, the elegant and beautiful. E. F. Schumacher ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
...And don't forget that the PPS pulse is very narrow so you have to use a 'scope with memory, a digital 'scope or turn the brightness at max. On Mon, Jul 23, 2012 at 6:31 PM, jmfranke jmfra...@cox.net wrote: Do not be too quick to toss out the antennas. Some receivers need the antenna power to be connected to a pin on the receiver connector that is then internally routed to the antenna. John WA4WDL -- From: Stephen Farthing squir...@gmail.com Sent: Monday, July 23, 2012 12:11 PM To: time-nuts@febo.com Subject: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions Hi Guys, I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - the guy told me they were left over from a contract he had and were brand new. He had a load and i bought a couple for use as a precision 1 PPS output for radio stuff. They were packed in static protection. When I apply power to both units I can hear the oscillator (12.504 MHz) on my comms RX. So I am assuming that they work. I bought what claims to be a Trimble compatible active antenna on EBay. I hooked it up to one of the boards and applied power, and put the scope on the one pps pin. However after 20 mins (which I assume is much longer than the unit requires to get a lock) I see no 1pps trace on the screen. :-( So my working assumption is that the antenna is not working. The antenna position is fine as my elderly Garmin GPS2 which must be 12 years old sees 6 satellites there. Can anyone recommend a suitable antenna? I have a number of DIY designs I can try (Patch, Turnstile) but the Trimble docs say it needs an active antenna so I guess I'll have to spend money :-( While i am on, can anyone suggest a reasonably priced unit that has a 1pps output, NMEA and a built in antenna. Because I want to use this with an 8 bit embedded system I am probably not going to be able to hack one of the many cheap USB dongle GPS's. Lastly, has anyone found a GPS that will work with an Ipad. What the man in the Apple shop failed to tell me was the non 3g model lacked the built in GPS :-( Thanks in advice Steve -- Wisdom demands a new orientation of science and technology towards the organic, the gentle, the non-violent, the elegant and beautiful. E. F. Schumacher ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. http://www.fastbobs.com/pictures/1pps.jpg Bob On Mon, Jul 23, 2012 at 12:58 PM, Chris Albertson albertson.ch...@gmail.com wrote: I wass fooled by this too. My analog scope does not sync on athe1Hz pulse. You have to breadboard something that will detect it, maybe a flip flop and then look at the FF's output. On Mon, Jul 23, 2012 at 9:49 AM, Azelio Boriani azelio.bori...@screen.it wrote: ...And don't forget that the PPS pulse is very narrow so you have to use a 'scope with memory, a digital 'scope or turn the brightness at max. On Mon, Jul 23, 2012 at 6:31 PM, jmfranke jmfra...@cox.net wrote: Do not be too quick to toss out the antennas. Some receivers need the antenna power to be connected to a pin on the receiver connector that is then internally routed to the antenna. John WA4WDL -- From: Stephen Farthing squir...@gmail.com Sent: Monday, July 23, 2012 12:11 PM To: time-nuts@febo.com Subject: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions Hi Guys, I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - the guy told me they were left over from a contract he had and were brand new. He had a load and i bought a couple for use as a precision 1 PPS output for radio stuff. They were packed in static protection. When I apply power to both units I can hear the oscillator (12.504 MHz) on my comms RX. So I am assuming that they work. I bought what claims to be a Trimble compatible active antenna on EBay. I hooked it up to one of the boards and applied power, and put the scope on the one pps pin. However after 20 mins (which I assume is much longer than the unit requires to get a lock) I see no 1pps trace on the screen. :-( So my working assumption is that the antenna is not working. The antenna position is fine as my elderly Garmin GPS2 which must be 12 years old sees 6 satellites there. Can anyone recommend a suitable antenna? I have a number of DIY designs I can try (Patch, Turnstile) but the Trimble docs say it needs an active antenna so I guess I'll have to spend money :-( While i am on, can anyone suggest a reasonably priced unit that has a 1pps output, NMEA and a built in antenna. Because I want to use this with an 8 bit embedded system I am probably not going to be able to hack one of the many cheap USB dongle GPS's. Lastly, has anyone found a GPS that will work with an Ipad. What the man in the Apple shop failed to tell me was the non 3g model lacked the built in GPS :-( Thanks in advice Steve -- Wisdom demands a new orientation of science and technology towards the organic, the gentle, the non-violent, the elegant and beautiful. E. F. Schumacher ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
Wow, that is indeed narrow. Only 1us out of a 1 second rep rate. That is one millionth of the rep rate. No wonder analog scopes will not catch it. I'll have to try it some time. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Bownes Sent: Monday, July 23, 2012 1:06 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. http://www.fastbobs.com/pictures/1pps.jpg Bob ___ 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] Trimble T Lassen 2 - suitable antenna....advice.....questions
squir...@gmail.com said: While i am on, can anyone suggest a reasonably priced unit that has a 1pps output, NMEA and a built in antenna. Because I want to use this with an 8 bit embedded system I am probably not going to be able to hack one of the many cheap USB dongle GPS's. Garmin GPS 18x-LVC GlobalSat MR-350 http://support.ntp.org/bin/view/Support/InexpensiveOemGps azelio.bori...@screen.it said: ...And don't forget that the PPS pulse is very narrow so you have to use a 'scope with memory, a digital 'scope or turn the brightness at max. Most scopes that I've used have some sort of indication if they are/aren't getting triggered, so even if you can't see the pulse you can tell if there is a pulse there. Sometimes, it helps to run in Triggered mode rather than Auto. If you are using Auto, at least with the Rigol DS1102E, it may take a while to lock up. I assume it searches for a while, doesn't find anything, so it stops to display the current buffer. While it is stopped, the pulse happens. I don't know how big the blind spot is, but it takes several seconds to show a PPS signal. Works fine in Triggered mode as long as you are happy without seeing anything when the trigger doesn't happen. bow...@gmail.com said: The pulse from my T-Bolt is on the order of 1uS wide. Interesting. Mine is 10 uS wide. Rev E, 5/31/05 -- 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.
Re: [time-nuts] Trimble T Lassen 2
And here it goes again for about the umpteenth time, how to detect the presents of a short low rep rate pulse. This can be done with ANY analog scope by using the normal trigger mode and setting the trigger correctly. An analog scope can detect the presents of any short pulse no matter how low it's rep rate is, so long as the pulse is wide enough that it is in the scope's (trigger) bandwidth. Under 5ns for a 100 MHz scope. So detecting if there is a very short pulse even once every 10 or 100 seconds sec is NO problem. Now measuring how wide the pulse really is, that is a problem for an analog scope. ** Wow, that is indeed narrow. Only 1us out of a 1 second rep rate. That is one millionth of the rep rate. No wonder analog scopes will not catch it. I'll have to try it some time. Regards The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. *** I was fooled by this too. My analog scope does not sync on the 1Hz pulse. You have to breadboard something that will detect it, maybe a flip flop and then look at the FF's output. * ...And don't forget that the PPS pulse is very narrow so you have to use a 'scope with memory, a digital 'scope or turn the brightness at max. ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
My old '465 will trigger on the 1pps, but it's far easier to see the trigger LED flash than finesse the brightness/sweep to make it visible - something possible only on a 'scope with a decently bright tube. Another cheap/easy trick to detect the 1pps pulse is simply to listen to it with an audio amplifier. While it can be heard on my Tbolt and '3801 with just a headphone connected, a cheap audio amplifier works better, stretching the pulse out and making an obvious tick at the 1 PPS rate. I suppose that a diode/cap (1N914/1000pf) could be used to further stretch it... Clint ___ 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] Trimble T Lassen 2 -suitableantenna....advice.....questions
Set the scope sweep speed to 10 milliseconds per division and then even a dull scope is easy to see. You are looking for trigger events from the 1PPS, not the 1PPS itself. John WA4WDL -- From: C. Turner tur...@ussc.com Sent: Monday, July 23, 2012 2:26 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Trimble T Lassen 2 -suitableantennaadvice.questions My old '465 will trigger on the 1pps, but it's far easier to see the trigger LED flash than finesse the brightness/sweep to make it visible - something possible only on a 'scope with a decently bright tube. Another cheap/easy trick to detect the 1pps pulse is simply to listen to it with an audio amplifier. While it can be heard on my Tbolt and '3801 with just a headphone connected, a cheap audio amplifier works better, stretching the pulse out and making an obvious tick at the 1 PPS rate. I suppose that a diode/cap (1N914/1000pf) could be used to further stretch it... Clint ___ 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] Trimble T Lassen 2
That works when there is a trigger LED, OR Just need to slow down the sweep rate to say 10ms / div or slower and then there will be a nice clear, easy to see, can't miss, white line, across ANY scope with each pulse when the scope is triggered by a short low rep input pulse. * My old '465 will trigger on the 1pps, but it's far easier to see the trigger LED flash than finesse the brightness/sweep to make it visible - something possible only on a 'scope with a decently bright tube. ... * Most scopes that I've used have some sort of indication if they are/aren't getting triggered, so even if you can't see the pulse you can tell if there is a pulse there. ... it helps to run in Triggered mode rather than Auto. Works fine in Triggered mode as long as you are happy without seeing anything when the trigger doesn't happen. * This can be done with ANY analog scope by using the normal trigger mode and setting the trigger correctly. An analog scope can detect the presents of any short pulse no matter how low it's rep rate is, so long as the pulse is wide enough that it is in the scope's (trigger) bandwidth. Under 5ns for a 100 MHz scope. So detecting if there is a very short pulse even once every 10 or 100 seconds sec is NO problem. Now measuring how wide the pulse really is, that is a problem for an analog scope. ** Wow, that is indeed narrow. Only 1us out of a 1 second rep rate. That is one millionth of the rep rate. No wonder analog scopes will not catch it. I'll have to try it some time. Regards The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. *** I was fooled by this too. My analog scope does not sync on the 1Hz pulse. You have to breadboard something that will detect it, maybe a flip flop and then look at the FF's output. * ...And don't forget that the PPS pulse is very narrow so you have to use a 'scope with memory, a digital 'scope or turn the brightness at max. ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
Www. KO4BB.com/Test_Equipment/Thunderbolt/PulseStretching/ It does not have to be complicated Didier KO4BB Mike Feher mfe...@eozinc.com wrote: Wow, that is indeed narrow. Only 1us out of a 1 second rep rate. That is one millionth of the rep rate. No wonder analog scopes will not catch it. I'll have to try it some time. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Bownes Sent: Monday, July 23, 2012 1:06 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. http://www.fastbobs.com/pictures/1pps.jpg Bob ___ 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. -- Sent from my Motorola Droid Razr phone with K-9 Mail. Please excuse my brevity. ___ 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.
