Re: [time-nuts] FE-5680A performance - 1 PPS output issue
I think there is something funny about the 1 PPS output on pin 6 from the currently available cheap FE-5680A units. I have three of these units. On one unit, on one occasion, I did observe a logic-level 1 PPS pulse, exactly 1 microsecond wide. But after a power cycle it never came back, although the unit indicates a locked condition, and is apparently working. The other two units also seem to work (10 MHz output OK, lock OK) but I have never seen a 1 PPS signal on pin 6 from them. My Tek TDS-210 is easily capable of triggering on and displaying a 1 usec pulse. Is it possible the pulse appears only after a RS-232 command, or after some other special condition? ---Original Message--- From: David davidwh...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A performance Sent: 05 Jan '12 07:49 On Thu, 05 Jan 2012 01:44:13 -0800, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: Have an older Tek 465 scope that is in only fair shape and I see nothing on that pin but milivolt level sine wave of about 60MHz. I can't set the scope to show any hint of a PPS ... I do have a 465. You should be able to see a 1 uSec PPS. 60MHz is about a 6nS rise time and is easily fast enough to see it. Now turn up the Intensity until you can see the pulse. It might help to turn down the room lights. This is the problem. With a 1 second repetition rate, the brightness is going to be very low. The old ways of viewing such a low repetition rate signal include using a hood or dark room, special CRT phosphors, photographic film, MCP (micro channel plate) intensified CRTs, and of course analog storage and later digital storage. ___ 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] FE-5680A performance - 1 PPS output issue
On Thu, Jan 5, 2012 at 9:46 AM, beale be...@bealecorner.com wrote: I think there is something funny about the 1 PPS output on pin 6 from the currently available cheap FE-5680A units. I have three of these units. On one unit, on one occasion, I did observe a logic-level 1 PPS pulse, exactly 1 microsecond wide. But after a power cycle it never came back, although the unit indicates a locked condition, and is apparently working. The other two units also seem to work (10 MHz output OK, lock OK) but I have never seen a 1 PPS signal on pin 6 from them. My Tek TDS-210 is easily capable of triggering on and displaying a 1 usec pulse. Is it possible the pulse appears only after a RS-232 command, or after some other special condition? I think the signal is there, it is just very small I tried again this morning. On mine the pulse is there but it's very weak. I can't see it one the scope but I can see the trigger light flash every second if I work to set it just right. I also see an about 0.3V peak to peak, about 60MHz sine wave. I can get the scope to trigger and display the sine wave just fine. I have to use a 10X scope probe or I load the signal to millivolts The PPS signal coming from my Oncore GPS is easy to see on my scope and even on a DMM set to DC Volts The FE-5680's PPS is not usable directly with my counter, I have to amplify it then set the counter to 10X attenuation then mess with the trigger setting so it does not see the 60MHz signal. Maybe I'm lucky that my scope has a BNC output on the back for the vertical amplifier, so I can apply a 20MHz low pass filter and about 20X voltage gain. The documentation I have says pin 6 is N/C but it looks like there is a way to extract a usable PPS but I think I'm going to need and LC filter, some op amps and a one-shot and a TTL level driver. My guess is that pin 6 is either some kind of engineering test/diagnostic signal not intended to use used or the signal is an accident ---Original Message--- From: David davidwh...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A performance Sent: 05 Jan '12 07:49 On Thu, 05 Jan 2012 01:44:13 -0800, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: Have an older Tek 465 scope that is in only fair shape and I see nothing on that pin but milivolt level sine wave of about 60MHz. I can't set the scope to show any hint of a PPS ... I do have a 465. You should be able to see a 1 uSec PPS. 60MHz is about a 6nS rise time and is easily fast enough to see it. Now turn up the Intensity until you can see the pulse. It might help to turn down the room lights. This is the problem. With a 1 second repetition rate, the brightness is going to be very low. The old ways of viewing such a low repetition rate signal include using a hood or dark room, special CRT phosphors, photographic film, MCP (micro channel plate) intensified CRTs, and of course analog storage and later digital storage. ___ 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.
Re: [time-nuts] FE-5680A performance - 1 PPS output issue
If you use a Tektronix TDS series scope you can set the acquiring to peak detect instead of sample to let the PPS be visible even for long timebase run. That is: usually, with the trigger set to normal and the timebase to 100nS/div or 1uS/div you can see the PPS anyway. If you set the timebase to 100mS/div then you can no longer see the pulse even if the trigger triggers the scan: setting the acquire to peak detect then the pulse returns visible and you can see the repetition rate. On Thu, Jan 5, 2012 at 7:17 PM, Chris Albertson albertson.ch...@gmail.comwrote: On Thu, Jan 5, 2012 at 9:46 AM, beale be...@bealecorner.com wrote: I think there is something funny about the 1 PPS output on pin 6 from the currently available cheap FE-5680A units. I have three of these units. On one unit, on one occasion, I did observe a logic-level 1 PPS pulse, exactly 1 microsecond wide. But after a power cycle it never came back, although the unit indicates a locked condition, and is apparently working. The other two units also seem to work (10 MHz output OK, lock OK) but I have never seen a 1 PPS signal on pin 6 from them. My Tek TDS-210 is easily capable of triggering on and displaying a 1 usec pulse. Is it possible the pulse appears only after a RS-232 command, or after some other special condition? I think the signal is there, it is just very small I tried again this morning. On mine the pulse is there but it's very weak. I can't see it one the scope but I can see the trigger light flash every second if I work to set it just right. I also see an about 0.3V peak to peak, about 60MHz sine wave. I can get the scope to trigger and display the sine wave just fine. I have to use a 10X scope probe or I load the signal to millivolts The PPS signal coming from my Oncore GPS is easy to see on my scope and even on a DMM set to DC Volts The FE-5680's PPS is not usable directly with my counter, I have to amplify it then set the counter to 10X attenuation then mess with the trigger setting so it does not see the 60MHz signal. Maybe I'm lucky that my scope has a BNC output on the back for the vertical amplifier, so I can apply a 20MHz low pass filter and about 20X voltage gain. The documentation I have says pin 6 is N/C but it looks like there is a way to extract a usable PPS but I think I'm going to need and LC filter, some op amps and a one-shot and a TTL level driver. My guess is that pin 6 is either some kind of engineering test/diagnostic signal not intended to use used or the signal is an accident ---Original Message--- From: David davidwh...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A performance Sent: 05 Jan '12 07:49 On Thu, 05 Jan 2012 01:44:13 -0800, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: Have an older Tek 465 scope that is in only fair shape and I see nothing on that pin but milivolt level sine wave of about 60MHz. I can't set the scope to show any hint of a PPS ... I do have a 465. You should be able to see a 1 uSec PPS. 60MHz is about a 6nS rise time and is easily fast enough to see it. Now turn up the Intensity until you can see the pulse. It might help to turn down the room lights. This is the problem. With a 1 second repetition rate, the brightness is going to be very low. The old ways of viewing such a low repetition rate signal include using a hood or dark room, special CRT phosphors, photographic film, MCP (micro channel plate) intensified CRTs, and of course analog storage and later digital storage. ___ 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] FE-5680A performance - 1 PPS output issue
The 2230 like I have was the earliest Tektronix oscilloscope with peak detect that I know of. Everything after it with some odd exceptions like the TDS 620 series included peak detect. I bought and fixed the 2230 instead of a new Rigol just for the peak detect. The low end Rigol oscilloscopes have envelope detect but it is not clear if it includes peak detect when operating in that mode. On Thu, 5 Jan 2012 19:47:28 +0100, Azelio Boriani azelio.bori...@screen.it wrote: If you use a Tektronix TDS series scope you can set the acquiring to peak detect instead of sample to let the PPS be visible even for long timebase run. That is: usually, with the trigger set to normal and the timebase to 100nS/div or 1uS/div you can see the PPS anyway. If you set the timebase to 100mS/div then you can no longer see the pulse even if the trigger triggers the scan: setting the acquire to peak detect then the pulse returns visible and you can see the repetition rate. On Thu, Jan 5, 2012 at 7:17 PM, Chris Albertson albertson.ch...@gmail.comwrote: On Thu, Jan 5, 2012 at 9:46 AM, beale be...@bealecorner.com wrote: I think there is something funny about the 1 PPS output on pin 6 from the currently available cheap FE-5680A units. I have three of these units. On one unit, on one occasion, I did observe a logic-level 1 PPS pulse, exactly 1 microsecond wide. But after a power cycle it never came back, although the unit indicates a locked condition, and is apparently working. The other two units also seem to work (10 MHz output OK, lock OK) but I have never seen a 1 PPS signal on pin 6 from them. My Tek TDS-210 is easily capable of triggering on and displaying a 1 usec pulse. Is it possible the pulse appears only after a RS-232 command, or after some other special condition? I think the signal is there, it is just very small I tried again this morning. On mine the pulse is there but it's very weak. I can't see it one the scope but I can see the trigger light flash every second if I work to set it just right. I also see an about 0.3V peak to peak, about 60MHz sine wave. I can get the scope to trigger and display the sine wave just fine. I have to use a 10X scope probe or I load the signal to millivolts The PPS signal coming from my Oncore GPS is easy to see on my scope and even on a DMM set to DC Volts The FE-5680's PPS is not usable directly with my counter, I have to amplify it then set the counter to 10X attenuation then mess with the trigger setting so it does not see the 60MHz signal. Maybe I'm lucky that my scope has a BNC output on the back for the vertical amplifier, so I can apply a 20MHz low pass filter and about 20X voltage gain. The documentation I have says pin 6 is N/C but it looks like there is a way to extract a usable PPS but I think I'm going to need and LC filter, some op amps and a one-shot and a TTL level driver. My guess is that pin 6 is either some kind of engineering test/diagnostic signal not intended to use used or the signal is an accident ---Original Message--- From: David davidwh...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A performance Sent: 05 Jan '12 07:49 On Thu, 05 Jan 2012 01:44:13 -0800, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: Have an older Tek 465 scope that is in only fair shape and I see nothing on that pin but milivolt level sine wave of about 60MHz. I can't set the scope to show any hint of a PPS ... I do have a 465. You should be able to see a 1 uSec PPS. 60MHz is about a 6nS rise time and is easily fast enough to see it. Now turn up the Intensity until you can see the pulse. It might help to turn down the room lights. This is the problem. With a 1 second repetition rate, the brightness is going to be very low. The old ways of viewing such a low repetition rate signal include using a hood or dark room, special CRT phosphors, photographic film, MCP (micro channel plate) intensified CRTs, and of course analog storage and later digital storage. ___ 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] FE-5680A performance - 1 PPS output issue
Hi Chris, The documentation I have says pin 6 is N/C but it looks like there is a way to extract a usable PPS but I think I'm going to need and LC filter, some op amps and a one-shot and a TTL level driver. My guess is that pin 6 is either some kind of engineering test/diagnostic signal not intended to use used or the signal is an accident. I have two of the older generation. Here the ONLY output is a 1PPS, which is divided by a fixed 2^23 from the internal DDS-generated frequency (8.3xxxMHz). It is not possible to get both 10MHz and a 1PPS at the same time. On the other hand the 8.3xxxMHz is tunable over many MHz. (One of the units is also suffering from a mishap. 15V connected to the 1PPS output did some damage.) -- Björn ___ 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] FE-5680A performance - 1 PPS output issue
On Thu, Jan 5, 2012 at 1:48 PM, b...@lysator.liu.se wrote: Hi Chris, The documentation I have says pin 6 is N/C but it looks like there is a way to extract a usable PPS but I think I'm going to need and LC filter, some op amps and a one-shot and a TTL level driver. My guess is that pin 6 is either some kind of engineering test/diagnostic signal not intended to use used or the signal is an accident. I have two of the older generation. Here the ONLY output is a 1PPS, which is divided by a fixed 2^23 from the internal DDS-generated frequency (8.3xxxMHz). It is not possible to get both 10MHz and a 1PPS at the same time. On the other hand the 8.3xxxMHz is tunable over many MHz. (One of the units is also suffering from a mishap. 15V connected to the 1PPS output did some damage.) My guess is that these all have the same part numbers because the hardware is the same. But one chip is a CPLD which might have some very different programming depending on what the customer needed I see some components where never installed on my unit, so it maybe more than just programming. -- Björn ___ 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.
Re: [time-nuts] FE-5680A performance - 1 PPS output issue
Chris, On Thu, Jan 5, 2012 at 1:48 PM, b...@lysator.liu.se wrote: Hi Chris, The documentation I have says pin 6 is N/C but it looks like there is a way to extract a usable PPS but I think I'm going to need and LC filter, some op amps and a one-shot and a TTL level driver. My guess is that pin 6 is either some kind of engineering test/diagnostic signal not intended to use used or the signal is an accident. I have two of the older generation. Here the ONLY output is a 1PPS, which is divided by a fixed 2^23 from the internal DDS-generated frequency (8.3xxxMHz). It is not possible to get both 10MHz and a 1PPS at the same time. On the other hand the 8.3xxxMHz is tunable over many MHz. (One of the units is also suffering from a mishap. 15V connected to the 1PPS output did some damage.) My guess is that these all have the same part numbers because the hardware is the same. But one chip is a CPLD which might have some very different programming depending on what the customer needed I see some components where never installed on my unit, so it maybe more than just programming. No, there are two different generations. The older based on 50.xxx MHz, the newer on 60.0MHz (?) The older has a lot of stacked daughtercards on the digital side. There are many differend sub-versions of these as well. The newer generation seem to be one clean PCB. Look for picture links in the recent archives. -- Björn ___ 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] FE-5680A performance - 1 PPS output issue
You've had more progress than I did, I don't get anything out of pin 6. I did see the levels toggle, but that was about it. On various websites I read to get exactly 1pps, you need a programmable 5680 because it needs to be set to something like 8.388MHz (2^23) to divide down properly. I suspect you may not be able to get both; 10MHz and 1pps. Bob - Original Message - From: beale be...@bealecorner.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, January 05, 2012 12:46 PM Subject: Re: [time-nuts]FE-5680A performance - 1 PPS output issue I think there is something funny about the 1 PPS output on pin 6 from the currently available cheap FE-5680A units. I have three of these units. On one unit, on one occasion, I did observe a logic-level 1 PPS pulse, exactly 1 microsecond wide. But after a power cycle it never came back, although the unit indicates a locked condition, and is apparently working. The other two units also seem to work (10 MHz output OK, lock OK) but I have never seen a 1 PPS signal on pin 6 from them. My Tek TDS-210 is easily capable of triggering on and displaying a 1 usec pulse. Is it possible the pulse appears only after a RS-232 command, or after some other special condition? ---Original Message--- From: David davidwh...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A performance Sent: 05 Jan '12 07:49 On Thu, 05 Jan 2012 01:44:13 -0800, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: Have an older Tek 465 scope that is in only fair shape and I see nothing on that pin but milivolt level sine wave of about 60MHz. I can't set the scope to show any hint of a PPS ... I do have a 465. You should be able to see a 1 uSec PPS. 60MHz is about a 6nS rise time and is easily fast enough to see it. Now turn up the Intensity until you can see the pulse. It might help to turn down the room lights. This is the problem. With a 1 second repetition rate, the brightness is going to be very low. The old ways of viewing such a low repetition rate signal include using a hood or dark room, special CRT phosphors, photographic film, MCP (micro channel plate) intensified CRTs, and of course analog storage and later digital storage. ___ 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] FE-5680A performance - 1 PPS output issue
On Thu, Jan 5, 2012 at 8:45 PM, Robert Benward rbenw...@verizon.net wrote: You've had more progress than I did, I don't get anything out of pin 6. I did see the levels toggle, but that was about it. On various websites I read to get exactly 1pps, you need a programmable 5680 because it needs to be set to something like 8.388MHz (2^23) to divide down properly. I suspect you may not be able to get both; 10MHz and 1pps. I just got one of the $38 units on eBay. It has both 10MHz and 1PPS. My HP5328 counter only works at the uSecond level but as far as it can tell my FE5380 tracks my GPS. The new fe5380 can be programmed but only over a very small range right around 10MHz. When we talk about fe5380 there are enough different types that are so very different but all have the same part numbers. We need a name for the types and a why a user can find the name of the unit he has. a Wiki would be great. Is there a FE5380 article yet on wikipeadia? 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.
