Re: [time-nuts] Setting up PRS10 with M12+T GPS
Thanks to all that replied to my questions. I have been off doing the suggestions offered and have found out some interesting things about my unit. Found out that the unit I have does not allow for certain parameters to be changed using the command line. Argh Called SRS and talked with a guy named Dave, and he told me that the unit I have based on Serial Number was originally sold to Symmetricom and they required special settings for TO, TS and a few others that are factory settable only. What's more, there is no way to upgrade the firmware for my unit as it is at least 12 years old. I've been using this unit since 2007 as an un-disiplined unit. They want over $700 to upgrade the unit if I send it back, and that is iffy. So I guess I'll live with it for now, and maybe look at getting another unit with a much higher serial number or buy a new one at $1500. Anyway, I dropped the PT time down to zero and started watching the TT values. TT values were in the high 500 to 700 range which means the 1pps edges were not aligned very well. I slowly started increasing the PT value, letting it settle out for a while, and the TT values started dropping. I'm currently at PT=7 and the TT values are ranging from 999,999,987ns to 20 ns. This much change is probably due to the sawtooth nature of the 1PPS from the M12+T unit I'm guessing, as I don't have sawtooth correction implemented yet. I can adjust the PP (Pulse Position) value from 0 to 999,999,999 ns, but I'm not sure that does anything yet to help me. I'm still looking at this though. I didn't ask the guy at SRS if there was a backdoor method to allow changing these factory only settings, and he probably wouldn't have told me if there was. So does anyone on the list know if this is possible? I guess the bottom line is; while I can't adjust certain parameters like the manual suggests, I do believe the PRS10 is locked to the 1PPS from my M12+T and tracking it. This is clear from the data I'm seeing coming back from the PRS10, especially the TT values. I will press on with the Sawtooth correction and get that working. Thanks again for the help. Jerry Mulchin At 12:46 PM 5/2/2012, Jerry Mulchin wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
You don't have a Cs reference but you have a GPS: in the long term it is the same. By using a TIC (your preferred: HP5370B, HP5372A, SR620, PM6680, PM6681, HP53132A, Racal 2351, Yokogawa TA720, PICTIC II, Wavecrest DTS275 [SIA3000?] and others) keep track of the GPS PPS vs. the PRS10 PPS. On Wed, May 2, 2012 at 9:46 PM, Jerry Mulchin jmulc...@cox.net wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
On 05/02/2012 10:03 PM, Azelio Boriani wrote: You don't have a Cs reference but you have a GPS: in the long term it is the same. By using a TIC (your preferred: HP5370B, HP5372A, SR620, PM6680, PM6681, HP53132A, Racal 2351, Yokogawa TA720, PICTIC II, Wavecrest DTS275 [SIA3000?] and others) keep track of the GPS PPS vs. the PRS10 PPS. Considering the M12+T PPS noise, you won't need anything stellar. A PICTIC II will do just fine... or if you trust the PRS-10 readings, run from that. What would make this better would to use a sawtooth-correction to PPS delay setup, as the PRS-10 measurement resolution will be about on par with that. Would lower the effects of hanging-bridges, even if one suffers less when dealing with a rubidium. Adjust the PRS-10 PLL bandwidth/time-constant, the default value is most probably not optimum, you can go further up in time. Do check the manual. Cheers, Magnus On Wed, May 2, 2012 at 9:46 PM, Jerry Mulchinjmulc...@cox.net wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
Magnus, you are correct but can I avoid to list our beloved counters/analyzers? The time-nut main tool is the TIC. Anyway, to correct the PPS input for the PRS10 the hardware approach is a must: so a delay line and a microprocessor are needed. Unless the SRS can develop a suitable software for the PRS10 (an inverted TTL serial line is already present) to read the M12+. On Wed, May 2, 2012 at 10:11 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 05/02/2012 10:03 PM, Azelio Boriani wrote: You don't have a Cs reference but you have a GPS: in the long term it is the same. By using a TIC (your preferred: HP5370B, HP5372A, SR620, PM6680, PM6681, HP53132A, Racal 2351, Yokogawa TA720, PICTIC II, Wavecrest DTS275 [SIA3000?] and others) keep track of the GPS PPS vs. the PRS10 PPS. Considering the M12+T PPS noise, you won't need anything stellar. A PICTIC II will do just fine... or if you trust the PRS-10 readings, run from that. What would make this better would to use a sawtooth-correction to PPS delay setup, as the PRS-10 measurement resolution will be about on par with that. Would lower the effects of hanging-bridges, even if one suffers less when dealing with a rubidium. Adjust the PRS-10 PLL bandwidth/time-constant, the default value is most probably not optimum, you can go further up in time. Do check the manual. Cheers, Magnus On Wed, May 2, 2012 at 9:46 PM, Jerry Mulchinjmulc...@cox.net wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
Jerry, Magnus, Considering the M12+T PPS noise, you won't need anything stellar. A PICTIC II will do just fine... or if you trust the PRS-10 readings, run from that. What would make this better would to use a sawtooth-correction to PPS delay setup, as the PRS-10 measurement resolution will be about on par with that. Would lower the effects of hanging-bridges, even if one suffers less when dealing with a rubidium. Adjust the PRS-10 PLL bandwidth/time-constant, the default value is most probably not optimum, you can go further up in time. Do check the manual. But do not have a large PLL time-constant, while you are checking basic functionality. Time-constants are shown in a table on page 35 in the manual. With default (PT=8) settings it will take hours for the pll to get close in. Any tinkering with moving the pulse (PP) or delay calibration (TO) will take forever to show if you got the sign right or hade the right offset size... ;-( Calibrate the Time offset (TO) according to the example on page 32 in the manual, by looping the 1pps_out to 1pps_in on the PRS10, keep in mind that you should use the cable, buffers, etc that later will take your GPS 1PPS to the 1PPS_in on the PRS, so that you really take care of all delay from the GPS 1pps to the PRS10, including internal PRS10 delays, that might have changed from previous calibration. Also have in mind that the 1pps disciplining wants 256 good measurements in a row just to start closing the PLL. Take the time constant down to 0, and make yourself confident that all offset calibrations are right and that you are tracking the right edge of the GPS 1PPS etc. After all tinkering to get the basics right then increase the time-constant to filter out 1PPS noise and outliers. To check performance later, you could check that the PRS10 timetag (TT) stays very low, by polling each second and logg these values. I am not at all an expert on PRS10. Have spent the weekend trying to get two units to sync to each other. I would like to have a simple (quick feedback) way of making sure that most time bias'es are removed. A free-running Tbolt for example gives a low noise 1PPS, and quickly tracking that, would make bias elimination much less time consuming. Anyone having an efficiant scheme for setting up a PRS10? -- Björn On Wed, May 2, 2012 at 9:46 PM, Jerry Mulchinjmulc...@cox.net wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
Hi Azelio, On 05/02/2012 10:30 PM, Azelio Boriani wrote: Magnus, you are correct but can I avoid to list our beloved counters/analyzers? The time-nut main tool is the TIC. Hehe, yes. But you can do great things even with a spare HP5335A for instance. It's quite respectable with about 1 ns resolution in this context. I have not tried using the SIA-3000 for TIC purposes. Just getting into the machine GPIB-wise is a bit of a challenge. Anyway, to correct the PPS input for the PRS10 the hardware approach is a must: so a delay line and a microprocessor are needed. Unless the SRS can develop a suitable software for the PRS10 (an inverted TTL serial line is already present) to read the M12+. Well, look at the Spectratime SRO-100, which already has that feature. http://www.spectratime.com/products/isync/gps-disciplined/SRO-100 Architecture-wise it is very similar to the FEI 5680, a 60 MHz VCXO, DDS for FLL and then DDS for output. PPS input and output makes you think about PRS-10. The PPS input has about 1 ns resolution. Now, there is a few things which differs from the PRS-10. It move it's internal (and later also its output) PPS to align up to the PPS reference. It hence does not need an output alignment. This makes the 7,5 MHz clock (133 ns cycle) less critical. BTW I do the same in my products. The phase of the PPSOUT and the generated 10 MHz will probably not align up, something which is critical to some applications. Also, it can take info from Jupiter-T, OnCore, M12+ and SuperStar II receivers for detailed timing info. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
I cannot believe my Guidetech GT4000 was left off your list. Thomas Knox Date: Wed, 2 May 2012 22:11:25 +0200 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] Setting up PRS10 with M12+T GPS On 05/02/2012 10:03 PM, Azelio Boriani wrote: You don't have a Cs reference but you have a GPS: in the long term it is the same. By using a TIC (your preferred: HP5370B, HP5372A, SR620, PM6680, PM6681, HP53132A, Racal 2351, Yokogawa TA720, PICTIC II, Wavecrest DTS275 [SIA3000?] and others) keep track of the GPS PPS vs. the PRS10 PPS. Considering the M12+T PPS noise, you won't need anything stellar. A PICTIC II will do just fine... or if you trust the PRS-10 readings, run from that. What would make this better would to use a sawtooth-correction to PPS delay setup, as the PRS-10 measurement resolution will be about on par with that. Would lower the effects of hanging-bridges, even if one suffers less when dealing with a rubidium. Adjust the PRS-10 PLL bandwidth/time-constant, the default value is most probably not optimum, you can go further up in time. Do check the manual. Cheers, Magnus On Wed, May 2, 2012 at 9:46 PM, Jerry Mulchinjmulc...@cox.net wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
The phase of the PPSOUT and the generated 10 MHz will probably not align up, something which is critical to some applications. Yes, for example the DVB-T SFN requires the PPS and 10MHz phases to be aligned, better, not to move. This requires to slightly alter the 10MHz to keep the PPS aligned. Let me ask Bjorn: did you succeed in aligning the two PRS10? Moreover, what do you mean by each other, a scheme like this: |---| | | | PRS10APRS10B | |---PPS IN PPS OUT--PPS IN PPS OUT--| hoping that the font doesn't mess up the ASCII schematic... On Wed, May 2, 2012 at 11:07 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hi Azelio, On 05/02/2012 10:30 PM, Azelio Boriani wrote: Magnus, you are correct but can I avoid to list our beloved counters/analyzers? The time-nut main tool is the TIC. Hehe, yes. But you can do great things even with a spare HP5335A for instance. It's quite respectable with about 1 ns resolution in this context. I have not tried using the SIA-3000 for TIC purposes. Just getting into the machine GPIB-wise is a bit of a challenge. Anyway, to correct the PPS input for the PRS10 the hardware approach is a must: so a delay line and a microprocessor are needed. Unless the SRS can develop a suitable software for the PRS10 (an inverted TTL serial line is already present) to read the M12+. Well, look at the Spectratime SRO-100, which already has that feature. http://www.spectratime.com/products/isync/gps-disciplined/SRO-100 Architecture-wise it is very similar to the FEI 5680, a 60 MHz VCXO, DDS for FLL and then DDS for output. PPS input and output makes you think about PRS-10. The PPS input has about 1 ns resolution. Now, there is a few things which differs from the PRS-10. It move it's internal (and later also its output) PPS to align up to the PPS reference. It hence does not need an output alignment. This makes the 7,5 MHz clock (133 ns cycle) less critical. BTW I do the same in my products. The phase of the PPSOUT and the generated 10 MHz will probably not align up, something which is critical to some applications. Also, it can take info from Jupiter-T, OnCore, M12+ and SuperStar II receivers for detailed timing info. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
I'm so sorry for the inconvenience but I wasn't aware of this CTIA supreme piece of test equipment... now I know. This CTIA is mainly intended for very high speed serial interconnect and Gigabit ethernet test. On Wed, May 2, 2012 at 11:18 PM, Tom Knox act...@hotmail.com wrote: I cannot believe my Guidetech GT4000 was left off your list. Thomas Knox Date: Wed, 2 May 2012 22:11:25 +0200 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] Setting up PRS10 with M12+T GPS On 05/02/2012 10:03 PM, Azelio Boriani wrote: You don't have a Cs reference but you have a GPS: in the long term it is the same. By using a TIC (your preferred: HP5370B, HP5372A, SR620, PM6680, PM6681, HP53132A, Racal 2351, Yokogawa TA720, PICTIC II, Wavecrest DTS275 [SIA3000?] and others) keep track of the GPS PPS vs. the PRS10 PPS. Considering the M12+T PPS noise, you won't need anything stellar. A PICTIC II will do just fine... or if you trust the PRS-10 readings, run from that. What would make this better would to use a sawtooth-correction to PPS delay setup, as the PRS-10 measurement resolution will be about on par with that. Would lower the effects of hanging-bridges, even if one suffers less when dealing with a rubidium. Adjust the PRS-10 PLL bandwidth/time-constant, the default value is most probably not optimum, you can go further up in time. Do check the manual. Cheers, Magnus On Wed, May 2, 2012 at 9:46 PM, Jerry Mulchinjmulc...@cox.net wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
Björn, On 05/02/2012 10:54 PM, b...@lysator.liu.se wrote: Jerry, Magnus, Considering the M12+T PPS noise, you won't need anything stellar. A PICTIC II will do just fine... or if you trust the PRS-10 readings, run from that. What would make this better would to use a sawtooth-correction to PPS delay setup, as the PRS-10 measurement resolution will be about on par with that. Would lower the effects of hanging-bridges, even if one suffers less when dealing with a rubidium. Adjust the PRS-10 PLL bandwidth/time-constant, the default value is most probably not optimum, you can go further up in time. Do check the manual. But do not have a large PLL time-constant, while you are checking basic functionality. Time-constants are shown in a table on page 35 in the manual. With default (PT=8) settings it will take hours for the pll to get close in. Any tinkering with moving the pulse (PP) or delay calibration (TO) will take forever to show if you got the sign right or hade the right offset size... ;-( Yes, PT8 gives an 18 hour time-constant, forgot that. Calibrate the Time offset (TO) according to the example on page 32 in the manual, by looping the 1pps_out to 1pps_in on the PRS10, keep in mind that you should use the cable, buffers, etc that later will take your GPS 1PPS to the 1PPS_in on the PRS, so that you really take care of all delay from the GPS 1pps to the PRS10, including internal PRS10 delays, that might have changed from previous calibration. Yes, that would be meaningful for the time-offset. It's the second example on page 32, as the first example relates to the time-slope parameter. Also have in mind that the 1pps disciplining wants 256 good measurements in a row just to start closing the PLL. Indeed. See page 17 for the steps. Take the time constant down to 0, and make yourself confident that all offset calibrations are right and that you are tracking the right edge of the GPS 1PPS etc. After all tinkering to get the basics right then increase the time-constant to filter out 1PPS noise and outliers. To check performance later, you could check that the PRS10 timetag (TT) stays very low, by polling each second and logg these values. I am not at all an expert on PRS10. Have spent the weekend trying to get two units to sync to each other. I would like to have a simple (quick feedback) way of making sure that most time bias'es are removed. A free-running Tbolt for example gives a low noise 1PPS, and quickly tracking that, would make bias elimination much less time consuming. Anyone having an efficiant scheme for setting up a PRS10? Well, it is a good idea to lock-in with PT0, to make it quickly track frequency, and then step through PT1, PT2 etc until the final time-constant has been reached. The trick is that you let any remaining frequency error ring out before you step to the next level. Whenever you do a tracking loop, the averaged frequency will vary, and the noise will constitute an frequency error if going into hold-over. The peak noise voltage will be a result of the loop bandwidth filtering. Tracking into the hold-over directly will take time, but stepping it will work as you quickly will track in the coarse part, and then only have to track in the remainder. For longer time-constants, it will still take time to reach it, but you will get there quicker by doing this sequential stepping. I haven't had time to try it on my PRS-10, but I think you get the general idea. A PI-loop is very cooperative to this approach, and the implementation supports this, since the I term is scaled on the input side of the integrator, so the accumulated state would not have to be scaled as you step the time-constant, which could be cumbersome in some other designs. Also, be aware that you may want to use the pre-filtering (LM1) with noisy sources. It should be enabled by default. Pre-filtering when properly used (as in this case) gives you a -12 dB/Oct slope rather than -6 dB/Oct slope, which is really helpful as you can keep the time-constant fairly low for the same suppression capability of noise, giving you a quicker track-in time. A fairly simple PIC/AVR/whatever design should be able to do the magic of re-aligning the PRS-10 input delay compensation (TO) as response to any time-adjustment values, thus simulating the SRO-100 functionality. It could also manage such tuned trackin. A Linux machine and a few lines of code would probably be a good starting-point. ;) Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
Hi Azelio, On 05/02/2012 11:19 PM, Azelio Boriani wrote: The phase of the PPSOUT and the generated 10 MHz will probably not align up,something which is critical to some applications. Yes, for example the DVB-T SFN requires the PPS and 10MHz phases to be aligned, better, not to move. This requires to slightly alter the 10MHz to keep the PPS aligned. Actually, DVB-T SFN doesn't really require that. It is claimed that some transmitters do require it, but I still want hard evidence for that. I keep hearing strange interpretations of what DVB-T SFN really requires. The spec leaves room for improvement. Let me ask Bjorn: did you succeed in aligning the two PRS10? Moreover, what do you mean by each other, a scheme like this: |---| | | | PRS10APRS10B | |---PPS IN PPS OUT--PPS IN PPS OUT--| hoping that the font doesn't mess up the ASCII schematic... PRS10A PRS10B PPSOUT -- PPSIN PPSIN -- PPSOUT I believe he meant. I also believe he used a separate source for the later experiment. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
The phase of the PPSOUT and the generated 10 MHz will probably not align up, something which is critical to some applications. Yes, for example the DVB-T SFN requires the PPS and 10MHz phases to be aligned, better, not to move. This requires to slightly alter the 10MHz to keep the PPS aligned. Let me ask Bjorn: did you succeed in aligning the two PRS10? Somewhat... I had a stable offset between the 10MHz PRS10 signals of almost 8ns, moving +-2.5ns over some hours. Moreover, what do you mean by each other, a scheme like this: |---| | | | PRS10APRS10B | |---PPS IN PPS OUT--PPS IN PPS OUT--| hoping that the font doesn't mess up the ASCII schematic... Almost, I also let the PRS10A be steered by a Tbolt. PLL settings 8 on PRS10A, and 0 on PRS10B, which should make PRS10B quick enough to follow any wiggle the PRS10A do slowly following its Tbolt supplied PPS_in. I had locked Tbolt 1PPS going into PPS_IN of PRS10A PPS Out of PRS10A going into PPS_IN of PRS10B. I watched/measured 1) PPS out from Tbolt on ch 1 (yellow) 2) 10MHz out from PRS10B on ch 2 (green) 3) 10MHz out from PRS10A on ch 3 (blue) 4) 1PPS out from PRS10 B on ch 4 (red) see attached screendump from a 500MHz Scope. I did not have enough time to completely remove offsets between 10MHz signals from PRS10A B. More tuning should have been done on the PRS10A wrt the Tbolt PPS also. Any comments? -- Björn On Wed, May 2, 2012 at 11:07 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hi Azelio, On 05/02/2012 10:30 PM, Azelio Boriani wrote: Magnus, you are correct but can I avoid to list our beloved counters/analyzers? The time-nut main tool is the TIC. Hehe, yes. But you can do great things even with a spare HP5335A for instance. It's quite respectable with about 1 ns resolution in this context. I have not tried using the SIA-3000 for TIC purposes. Just getting into the machine GPIB-wise is a bit of a challenge. Anyway, to correct the PPS input for the PRS10 the hardware approach is a must: so a delay line and a microprocessor are needed. Unless the SRS can develop a suitable software for the PRS10 (an inverted TTL serial line is already present) to read the M12+. Well, look at the Spectratime SRO-100, which already has that feature. http://www.spectratime.com/products/isync/gps-disciplined/SRO-100 Architecture-wise it is very similar to the FEI 5680, a 60 MHz VCXO, DDS for FLL and then DDS for output. PPS input and output makes you think about PRS-10. The PPS input has about 1 ns resolution. Now, there is a few things which differs from the PRS-10. It move it's internal (and later also its output) PPS to align up to the PPS reference. It hence does not need an output alignment. This makes the 7,5 MHz clock (133 ns cycle) less critical. BTW I do the same in my products. The phase of the PPSOUT and the generated 10 MHz will probably not align up, something which is critical to some applications. Also, it can take info from Jupiter-T, OnCore, M12+ and SuperStar II receivers for detailed timing info. Cheers, Magnus ___ 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. attachment: image21273.png___ 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] Setting up PRS10 with M12+T GPS
Hi Magnus, |---| | | | PRS10APRS10B | |---PPS IN PPS OUT--PPS IN PPS OUT--| hoping that the font doesn't mess up the ASCII schematic... PRS10A PRS10B PPSOUT -- PPSIN PPSIN -- PPSOUT I believe he meant. No I would never do that! Take one! let the other follow the first one. I also believe he used a separate source for the later experiment. Tbolt PRS10A PRS10B 1pps -- PPSIN PPSOUT -- PPS IN PRS10A slowly following the Tbolt (PRS10A PT8) PRS10B quickly following the PRS10A (PRS10B PT0) Ok? -- 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] Setting up PRS10 with M12+T GPS
Hi Björn, On 05/03/2012 12:01 AM, b...@lysator.liu.se wrote: Hi Magnus, |---| | | | PRS10APRS10B | |---PPS IN PPS OUT--PPS IN PPS OUT--| hoping that the font doesn't mess up the ASCII schematic... PRS10A PRS10B PPSOUT -- PPSIN PPSIN-- PPSOUT I believe he meant. No I would never do that! Take one! let the other follow the first one. Phew. You had me and obviously others believe so for a while. I'm happier now. I also believe he used a separate source for the later experiment. Tbolt PRS10A PRS10B 1pps --PPSIN PPSOUT -- PPS IN PRS10A slowly following the Tbolt (PRS10A PT8) PRS10B quickly following the PRS10A (PRS10B PT0) Ok? Yes, but if this is a free-running thunderbolt (I think you said something about that) then PT8 will be a bit slow. For a tracking thunderbolt PT8 may work, even if it takes time for it to track in. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
Yes, all made clear. Trigger on Ch.4, I see. You have written green: 10MHz PRS10B but it must be A, otherwise it seems that the PPS and the 10MHz of the PRS10 are not phase aligned. Moreover, the PRS10B seems to track the PRS10A with some delay as the 10MHz from A spreads on more than 5nS (useful, the infinite persistence, isn't it? I use it a lot) On Thu, May 3, 2012 at 12:17 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hi Björn, On 05/03/2012 12:01 AM, b...@lysator.liu.se wrote: Hi Magnus, |---| | | | PRS10APRS10B | |---PPS IN PPS OUT--PPS IN PPS OUT--| hoping that the font doesn't mess up the ASCII schematic... PRS10A PRS10B PPSOUT -- PPSIN PPSIN-- PPSOUT I believe he meant. No I would never do that! Take one! let the other follow the first one. Phew. You had me and obviously others believe so for a while. I'm happier now. I also believe he used a separate source for the later experiment. Tbolt PRS10A PRS10B 1pps --PPSIN PPSOUT -- PPS IN PRS10A slowly following the Tbolt (PRS10A PT8) PRS10B quickly following the PRS10A (PRS10B PT0) Ok? Yes, but if this is a free-running thunderbolt (I think you said something about that) then PT8 will be a bit slow. For a tracking thunderbolt PT8 may work, even if it takes time for it to track in. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
Magnus, Tbolt PRS10A PRS10B 1pps --PPSIN PPSOUT -- PPS IN PRS10A slowly following the Tbolt (PRS10A PT8) PRS10B quickly following the PRS10A (PRS10B PT0) Ok? Yes, but if this is a free-running thunderbolt (I think you said something about that) then PT8 will be a bit slow. For a tracking thunderbolt PT8 may work, even if it takes time for it to track in. No a GPS locked Tbolt. A free-running Tbolt was just an example of a very low noise 1PPS source, where I would find it useful to have a PT-1 bias calibration mode bypassing the PLL, and moving the PPSOUT directly with the PPSIN. -- 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] Setting up PRS10 with M12+T GPS
Or my E1740A :-) On Wed, May 2, 2012 at 2:18 PM, Tom Knox act...@hotmail.com wrote: I cannot believe my Guidetech GT4000 was left off your list. Thomas Knox Date: Wed, 2 May 2012 22:11:25 +0200 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] Setting up PRS10 with M12+T GPS On 05/02/2012 10:03 PM, Azelio Boriani wrote: You don't have a Cs reference but you have a GPS: in the long term it is the same. By using a TIC (your preferred: HP5370B, HP5372A, SR620, PM6680, PM6681, HP53132A, Racal 2351, Yokogawa TA720, PICTIC II, Wavecrest DTS275 [SIA3000?] and others) keep track of the GPS PPS vs. the PRS10 PPS. Considering the M12+T PPS noise, you won't need anything stellar. A PICTIC II will do just fine... or if you trust the PRS-10 readings, run from that. What would make this better would to use a sawtooth-correction to PPS delay setup, as the PRS-10 measurement resolution will be about on par with that. Would lower the effects of hanging-bridges, even if one suffers less when dealing with a rubidium. Adjust the PRS-10 PLL bandwidth/time-constant, the default value is most probably not optimum, you can go further up in time. Do check the manual. Cheers, Magnus On Wed, May 2, 2012 at 9:46 PM, Jerry Mulchinjmulc...@cox.net wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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] Setting up PRS10 with M12+T GPS
Yes, the E1740A it is a VXI plug-in like the Racal 2351. I have the Racal and the VXI C-size small mainframe E1421B. On Thu, May 3, 2012 at 12:31 AM, Pete Lancashire p...@petelancashire.comwrote: Or my E1740A :-) On Wed, May 2, 2012 at 2:18 PM, Tom Knox act...@hotmail.com wrote: I cannot believe my Guidetech GT4000 was left off your list. Thomas Knox Date: Wed, 2 May 2012 22:11:25 +0200 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] Setting up PRS10 with M12+T GPS On 05/02/2012 10:03 PM, Azelio Boriani wrote: You don't have a Cs reference but you have a GPS: in the long term it is the same. By using a TIC (your preferred: HP5370B, HP5372A, SR620, PM6680, PM6681, HP53132A, Racal 2351, Yokogawa TA720, PICTIC II, Wavecrest DTS275 [SIA3000?] and others) keep track of the GPS PPS vs. the PRS10 PPS. Considering the M12+T PPS noise, you won't need anything stellar. A PICTIC II will do just fine... or if you trust the PRS-10 readings, run from that. What would make this better would to use a sawtooth-correction to PPS delay setup, as the PRS-10 measurement resolution will be about on par with that. Would lower the effects of hanging-bridges, even if one suffers less when dealing with a rubidium. Adjust the PRS-10 PLL bandwidth/time-constant, the default value is most probably not optimum, you can go further up in time. Do check the manual. Cheers, Magnus On Wed, May 2, 2012 at 9:46 PM, Jerry Mulchinjmulc...@cox.net wrote: I need some guidance from the collective. I just finished rebuilding my PRS10 lab standard and it is now using a M12+T GPS module. I have completed my site survey and it is now in hold position mode, TRAIM is enabled with 500ns alarm setting and the 1PPS is enabled during non-TRAIM alarm conditions. The PRS10 is set for default 1PPS steering, but all of the other parameters are just as I received the unit 5 years ago. My questions are these; 1.) Should I reset the PRS10 to its Default settings or just adjust selected parameters to align the unit for proper operation with the M12+T unit? And if that is the case, what parameters need adjusting? 2.) Are there any special settings, other than what WinOncore sets, that I should make to the M12+T unit? 3.) After all this is completed, how do I know that the PRS10 is properly tracking GPS and maintaining frequency accurately? I don't have a Cesium reference, but I do have an un-disiplined LPRO-101, but I don't think that really helps me determine frequency accuracy. I will be adding the sawtooth correction eventually to the M12+T 1PPS output, but observed negative sawtooth with WinOncore shows +/- 14ns changes with some bridging occasionally. While I don't ever want to claim NIST traceability, I would like to be a close as possible, and I guess that is the bottom line need here. So what else do I need to do to get as close as possible? Thanks for any help. Jerry Mulchin ___ 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. ___ 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] Setting up PRS10 with M12+T GPS
Yes, all made clear. Trigger on Ch.4, I see. You have written green: 10MHz PRS10B but it must be A, otherwise it seems that the PPS and the 10MHz of the PRS10 are not phase aligned. Moreover, the PRS10B seems to track the PRS10A with some delay as the 10MHz from A spreads on more than 5nS (useful, the infinite persistence, isn't it? I use it a lot) I had locked Tbolt 1PPS going into PPS_IN of PRS10A PPS Out of PRS10A going into PPS_IN of PRS10B. I watched/measured 1) PPS out from Tbolt on ch 1 (yellow) 2) 10MHz out from PRS10A on ch 2 (green) // Corrected 3) 10MHz out from PRS10B on ch 3 (blue)// Corrected 4) 1PPS out from PRS10 B on ch 4 (red) I should do some proper measurements with TIC, instead of just 'watching' on the scope. Yes the 1pps and 10MHz is ofcause stable within the same PRS10. But should not the 10MHz zero crossing be aligned with the 1PPS? Cables were not perfectly matched, but should be within 2-3ns of each other. Yes, persistance is very nice! -- 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] Setting up PRS10 with M12+T GPS
Hi Björn, On 05/02/2012 11:50 PM, b...@lysator.liu.se wrote: The phase of the PPSOUT and the generated 10 MHz will probably not align up,something which is critical to some applications. Yes, for example the DVB-T SFN requires the PPS and 10MHz phases to be aligned, better, not to move. This requires to slightly alter the 10MHz to keep the PPS aligned. Let me ask Bjorn: did you succeed in aligning the two PRS10? Somewhat... I had a stable offset between the 10MHz PRS10 signals of almost 8ns, moving +-2.5ns over some hours. Recall that input resolution is about 0,2 ns and output resolution is about 0,5 ns and that 1 ns seems to be around where input and output precision is really given... so some of that may be traceable to those aspects. Moreover, what do you mean by each other, a scheme like this: |---| | | | PRS10APRS10B | |---PPS IN PPS OUT--PPS IN PPS OUT--| hoping that the font doesn't mess up the ASCII schematic... Almost, I also let the PRS10A be steered by a Tbolt. PLL settings 8 on PRS10A, and 0 on PRS10B, which should make PRS10B quick enough to follow any wiggle the PRS10A do slowly following its Tbolt supplied PPS_in. I had locked Tbolt 1PPS going into PPS_IN of PRS10A PPS Out of PRS10A going into PPS_IN of PRS10B. I watched/measured 1) PPS out from Tbolt on ch 1 (yellow) 2) 10MHz out from PRS10B on ch 2 (green) 3) 10MHz out from PRS10A on ch 3 (blue) 4) 1PPS out from PRS10 B on ch 4 (red) see attached screendump from a 500MHz Scope. I did not have enough time to completely remove offsets between 10MHz signals from PRS10A B. More tuning should have been done on the PRS10A wrt the Tbolt PPS also. Any comments? The timing offsets of both PRS-10s may need a bit adjustment to align up better. The thunderbolt PPS noise is obviously not wonderful. The higher noise on the PRS-10B 10 MHz (green) compared to the PRS-10B PPS (red) is interesting. This may be due to the PPS output delay hiding the error, something which you can grasp from the last sentence of page 33 in the manual. Thus, the PPS output delay is used to cover up the time-error that the PLL loop provides. It looks like it is better locked-up then it actually is, so looking at the loop state will be necessary to really know. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
Maybe the 10MHz and the PPS are not exactly aligned but you can see that the persistance of the 10MHzB (blue trace) is exactly the same of the PPS B (red trace), so they are absolutely consistent and perfectly linked together. On Thu, May 3, 2012 at 12:42 AM, b...@lysator.liu.se wrote: Yes, all made clear. Trigger on Ch.4, I see. You have written green: 10MHz PRS10B but it must be A, otherwise it seems that the PPS and the 10MHz of the PRS10 are not phase aligned. Moreover, the PRS10B seems to track the PRS10A with some delay as the 10MHz from A spreads on more than 5nS (useful, the infinite persistence, isn't it? I use it a lot) I had locked Tbolt 1PPS going into PPS_IN of PRS10A PPS Out of PRS10A going into PPS_IN of PRS10B. I watched/measured 1) PPS out from Tbolt on ch 1 (yellow) 2) 10MHz out from PRS10A on ch 2 (green) // Corrected 3) 10MHz out from PRS10B on ch 3 (blue)// Corrected 4) 1PPS out from PRS10 B on ch 4 (red) I should do some proper measurements with TIC, instead of just 'watching' on the scope. Yes the 1pps and 10MHz is ofcause stable within the same PRS10. But should not the 10MHz zero crossing be aligned with the 1PPS? Cables were not perfectly matched, but should be within 2-3ns of each other. Yes, persistance is very nice! -- 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. ___ 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] Setting up PRS10 with M12+T GPS
Björn, On 05/03/2012 12:30 AM, b...@lysator.liu.se wrote: Magnus, Tbolt PRS10A PRS10B 1pps -- PPSIN PPSOUT -- PPS IN PRS10A slowly following the Tbolt (PRS10A PT8) PRS10B quickly following the PRS10A (PRS10B PT0) Ok? Yes, but if this is a free-running thunderbolt (I think you said something about that) then PT8 will be a bit slow. For a tracking thunderbolt PT8 may work, even if it takes time for it to track in. No a GPS locked Tbolt. Thanks for that clarification, I am obviously a bit tired. A free-running Tbolt was just an example of a very low noise 1PPS source, where I would find it useful to have a PT-1 bias calibration mode bypassing the PLL, and moving the PPSOUT directly with the PPSIN. So this does not suffice?: Page 33: When provided with an accurate and stable 1pps source, the unit will automatically align its 1pps output to the 1pps input and then adjust the frequency of the rubidium reference to maintain the alignment over time. Page 17: After receiving 256 consecutive good 1pps inputs, the 1pps pulse delay is set to the last of the 256 time-tag values. I interpret this as this: When the 256s PPS has been approved, the last-time-tag is used to adjust the output delay such that the output signal is aligned, within the precision of the time-offset value. Then, the PLL is running. Either the output delay is not shifted and only the PPS alignment is done on approval, or it is updated in the background. The text only supports the former explicitly, but it would be nice to verify if it is either of these. Doing phase-jump of PPS like this on start-up is expected. I've even has a measurement on it somewhere. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
Björn, On 05/03/2012 12:42 AM, b...@lysator.liu.se wrote: Yes, all made clear. Trigger on Ch.4, I see. You have written green: 10MHz PRS10B but it must be A, otherwise it seems that the PPS and the 10MHz of the PRS10 are not phase aligned. Moreover, the PRS10B seems to track the PRS10A with some delay as the 10MHz from A spreads on more than 5nS (useful, the infinite persistence, isn't it? I use it a lot) I had locked Tbolt 1PPS going into PPS_IN of PRS10A PPS Out of PRS10A going into PPS_IN of PRS10B. I watched/measured 1) PPS out from Tbolt on ch 1 (yellow) 2) 10MHz out from PRS10A on ch 2 (green) // Corrected 3) 10MHz out from PRS10B on ch 3 (blue)// Corrected 4) 1PPS out from PRS10 B on ch 4 (red) I should do some proper measurements with TIC, instead of just 'watching' on the scope. Yes the 1pps and 10MHz is ofcause stable within the same PRS10. But should not the 10MHz zero crossing be aligned with the 1PPS? No. See my other posting. As far as I can see, the PRS-10 does not bother to create relative phase alignment between 10 MHz and PPS. If you want that, you will have to play tricks with the time-offsets (TO) with the hints from the time-tags (TT) and then some separate calibration. It seems like there is still some time-offset calibration to be done. Cables were not perfectly matched, but should be within 2-3ns of each other. Yes, persistance is very nice! Indeed. For stuff like this, I like having a scope in parallel with the signals so I see what happens. The counter gives the quality measures, but the scope gives the overall picture and you get such a more direct response of behaviour as you see the PPS move about. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
Björn, On 05/03/2012 12:30 AM, b...@lysator.liu.se wrote: Magnus, Tbolt PRS10A PRS10B 1pps -- PPSIN PPSOUT -- PPS IN PRS10A slowly following the Tbolt (PRS10A PT8) PRS10B quickly following the PRS10A (PRS10B PT0) Ok? Yes, but if this is a free-running thunderbolt (I think you said something about that) then PT8 will be a bit slow. For a tracking thunderbolt PT8 may work, even if it takes time for it to track in. No a GPS locked Tbolt. Thanks for that clarification, I am obviously a bit tired. A free-running Tbolt was just an example of a very low noise 1PPS source, where I would find it useful to have a PT-1 bias calibration mode bypassing the PLL, and moving the PPSOUT directly with the PPSIN. So this does not suffice?: Page 33: When provided with an accurate and stable 1pps source, the unit will automatically align its 1pps output to the 1pps input and then adjust the frequency of the rubidium reference to maintain the alignment over time. Page 17: After receiving 256 consecutive good 1pps inputs, the 1pps pulse delay is set to the last of the 256 time-tag values. I interpret this as this: When the 256s PPS has been approved, the last-time-tag is used to adjust the output delay such that the output signal is aligned, within the precision of the time-offset value. Then, the PLL is running. Either the output delay is not shifted and only the PPS alignment is done on approval, or it is updated in the background. The text only supports the former explicitly, but it would be nice to verify if it is either of these. Doing phase-jump of PPS like this on start-up is expected. I've even has a measurement on it somewhere. It is surely working alright in the long run. I am not convinced it is appropriate for applications where you fire up the PRS for a few hours and then do a few hours of measurements. Even if it jumps the 1pps, early on the PLL will still be 100s of ns away from its reference. There should be a better way to make this, than how I run the PRS... -- 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] Setting up PRS10 with M12+T GPS
On 05/03/2012 01:09 AM, b...@lysator.liu.se wrote: Björn, On 05/03/2012 12:30 AM, b...@lysator.liu.se wrote: Magnus, Tbolt PRS10A PRS10B 1pps -- PPSIN PPSOUT --PPS IN PRS10A slowly following the Tbolt (PRS10A PT8) PRS10B quickly following the PRS10A (PRS10B PT0) Ok? Yes, but if this is a free-running thunderbolt (I think you said something about that) then PT8 will be a bit slow. For a tracking thunderbolt PT8 may work, even if it takes time for it to track in. No a GPS locked Tbolt. Thanks for that clarification, I am obviously a bit tired. A free-running Tbolt was just an example of a very low noise 1PPS source, where I would find it useful to have a PT-1 bias calibration mode bypassing the PLL, and moving the PPSOUT directly with the PPSIN. So this does not suffice?: Page 33: When provided with an accurate and stable 1pps source, the unit will automatically align its 1pps output to the 1pps input and then adjust the frequency of the rubidium reference to maintain the alignment over time. Page 17: After receiving 256 consecutive good 1pps inputs, the 1pps pulse delay is set to the last of the 256 time-tag values. I interpret this as this: When the 256s PPS has been approved, the last-time-tag is used to adjust the output delay such that the output signal is aligned, within the precision of the time-offset value. Then, the PLL is running. Either the output delay is not shifted and only the PPS alignment is done on approval, or it is updated in the background. The text only supports the former explicitly, but it would be nice to verify if it is either of these. Doing phase-jump of PPS like this on start-up is expected. I've even has a measurement on it somewhere. It is surely working alright in the long run. I am not convinced it is appropriate for applications where you fire up the PRS for a few hours and then do a few hours of measurements. Even if it jumps the 1pps, early on the PLL will still be 100s of ns away from its reference. There should be a better way to make this, than how I run the PRS... Indeed. What you can do is to forward correct the phase error in order hide the loop error. What the PRS-10 approach does is: 1) First degree compensate the PPS offset error 2) Use the phase difference from that point to track in frequency error. The PI-loop will ensure that the phase-error goes towards 0. The end result should be a time-error close to zero. The track-in error would be exposed in the PRS-10, but a feed-forward solution would paper over it. Considering that PRS-10 had telecom applications in mind, this approach would be fine, since we have usually loads of time to average things out on, and we can handle some transients at times. The PRS-10 approach is not ideal for some measurements and some other approaches. You can however lower the initial jump by the trimmer, as the initial frequency offset could be reduced. /|T(0) would however still be there. The relative openness of the PRS-10 would however allow for some smarter tricks to be played. The PRS-10 does not play all the tricks it could play given the hardware capabilities it has. Cheers, Magnus ___ 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] Setting up PRS10 with M12+T GPS
On 5/2/2012 5:18 PM, Tom Knox wrote: I cannot believe my Guidetech GT4000 was left off your list. No worries. He didn't list the HP 5370A, either. ___ 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.