Re: [time-nuts] Quick check of a GPS controller oscillator
Hi You have a situation where you have only one standard. It has nothing to compare to. It is very much like asking for the correct time from a single watch. You can look at the various status outputs. You can look at how it is set up. Past that, all you know is that it *thinks* it is doing ok. As mentioned earlier, there are a number of things you can look at and evaluate in the setup of the device. If they are all done properly, then it is a good bet that the TBolt is good to < 1 ppb. To be *really* sure, you would need another reference or two. With one more you can see if they agree. With two more you can let them “vote” to see which one is most likely wrong. The sub-$100 Symmetricom or Trimble commercial GPSDO’s on eBay are plenty good enough to do this. Another alternative would be a telecom Rb and a cheap GPS module. Use the module pps and a ’scope to get the Rb on frequency. Let it run full time and check it every few months. Past that, all anybody can do is make a guess. It could be a pretty accurate guess, but none the less it is a guess. Mine is that your TBolt is doing fine and it will give you < 1 Hz accuracy at 1 GHz. Bob > On May 9, 2020, at 10:36 AM, Giuseppe Marullo wrote: > > Hi, > could please anybody tell me if it is possible to confirm good operation of > my Trimble? > It is almost three days that is working (position hold mode, operation mode > LOCKED, PLL locked see attach), want to know if it is a reliable source to be > used to compare a 0.01pps oscillator. > I see OSC < 1000ppt, does it mean it its accuracy is better than 1ppb or what? > > Thanks. > > Giuseppe Marullo > IW2JWW - JN45RQ > > > On 5/6/2020 9:23 PM, Giuseppe Marullo wrote: >> Sorry, images where too big, had to repost. >> >> Please use this link >> >> https://www.iw2jww.it/trimble-and-progrock/ >> >> to download them, thanks. >> >> On 5/6/2020 8:57 PM, Giuseppe Marullo wrote: >>> Ok, >>> >>> first of all many thanks for your help. Yep, not exactly a time-nut piece >>> of engineering, but I need more to be reassured about the Trimble accuracy. >>> If the Trimble is good enough, everything will be easier. >>> >>> @Alex: >>> >>> >in Europe you should be able to get one DCF77 signal based 10MHz, which >>> >you could trust >>> I am not planning to add a DCF77 synced 10MHz, I would rather add another >>> Trimble or Rubidium. >>> >>> The whole point is, given my time nuttery is limited, I could be okay with >>> the Trimble provided it is "good enough" to consider it a suitable >>> reference. >>> >>> @Dana: Is the ProgRock GPS disciplined or a Rb, or is it just a free-running crystal oscillator? >>> The ProgRock in itself is a simple Si5351A based programmable oscillator. >>> It may have a OCXO option (that I built and using) and could use a GPS PPS >>> to be calibrated(that I built and using, as the other pieces from QRP labs). >>> The GPS does output NMEA sentences but the ProgRock just use the PPS >>> signal. It is placed in a Clock kit enclosure and the clock does >>> use/display the NMEA sentences but the ProgRock just use the PPS signal. >>> And does LH say that the Trimble is locked OK? >>> I have included a screenshot of LH(20200506LH.png) as per now. >>> Unless the ProgRock is GPS disciplined (or is a Rb), it's a pretty safe bet that it has simply grown old and the crystal has aged. And this notion is much strengthened if LH gives a positive indication that your Trimble is locked OK. >>> Don't think it could be aging related, it should use the GPS to self >>> calibrate anyway within minutes. It does/should use the GPS PPS data, >>> saying it is disciplined may be a little optimistic. >>> >>> @Bob: Hi With any GPSDO (not just the TBolt) you can do some basic checks: (They are in no particular order) >>> 1) Are there > 6 sats in view at all times, if not, move the antenna >>> Yes they are. Antenna is Simmetricom missile head 28dB amplified (timing >>> antenna) clear view of the sky, on a 2m pole on a balcony facing South. >>> 2) Is the unit locked to at least 4 sats at all times, if not, move the antenna. >>> Yes, see LH attachment >>> 3) Has the unit completed its survey process? If not, wait for it to complete. >>> Not at the moment I power cycled it this night. It is powered since this >>> night (>12hours). >>> Do I have to initiate it? >>> 4) Is the EFC > 10% and < 90% of it’s range after an hour on? If not, repair the unit. >>> I don't know what EFC is. If it is the DAC voltage, seems so (looking at >>> its values it never went over the range but I may have not seen it >>> happening) >>> 5) Has the unit been on for at least 3 days? If not wait. >>> Not yet, waiting... >>> 6) Does the output look ok on a ’scope? ( it’s volts not milivolts …) if not repair the unit >>> See attach(20200506_DSO.JPG), it is a vanilla scope nevertheless it seems >>>
Re: [time-nuts] Quick check of a GPS controller oscillator
A "Jim Finlayson" raised eyebrow?! Burt, K6OQK On May 7, 2020 6:42:39 AM PDT, jimlux wrote: >On 5/6/20 7:07 PM, Sanjeev Gupta wrote: >> On Wed, May 6, 2020 at 8:22 PM Bob kb8tq wrote: >> >>> If all of that sounds like a lot of work (or not complete enough), >buy a >>> second ( or third >>> or fourth ….) GPSDO. Next get a couple Rb’s …. maybe a Cs or three >…. have >>> you >>> looked into Masers? :) >>> >> >> AT, AT. He meant "looked AT Masers" :-) >> >You mean with the remaining good eye? > > > >___ >time-nuts mailing list -- time-nuts@lists.febo.com >To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >and follow the instructions there. -- Sent from my Android thingamabob with K-9 Mail. Please pardon the spelling errors as the dog can't spell so good. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quick check of a GPS controller oscillator
> On May 7, 2020, at 9:42 AM, jimlux wrote: > > On 5/6/20 7:07 PM, Sanjeev Gupta wrote: >> On Wed, May 6, 2020 at 8:22 PM Bob kb8tq wrote: >>> If all of that sounds like a lot of work (or not complete enough), buy a >>> second ( or third >>> or fourth ….) GPSDO. Next get a couple Rb’s …. maybe a Cs or three …. have >>> you >>> looked into Masers? :) >>> >> AT, AT. He meant "looked AT Masers" :-) > You mean with the remaining good eye? …… all typing done by dictation due to the inability to see the screen … Bob > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quick check of a GPS controller oscillator
On 5/6/20 7:07 PM, Sanjeev Gupta wrote: On Wed, May 6, 2020 at 8:22 PM Bob kb8tq wrote: If all of that sounds like a lot of work (or not complete enough), buy a second ( or third or fourth ….) GPSDO. Next get a couple Rb’s …. maybe a Cs or three …. have you looked into Masers? :) AT, AT. He meant "looked AT Masers" :-) You mean with the remaining good eye? ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quick check of a GPS controller oscillator
On Wed, May 6, 2020 at 8:22 PM Bob kb8tq wrote: > If all of that sounds like a lot of work (or not complete enough), buy a > second ( or third > or fourth ….) GPSDO. Next get a couple Rb’s …. maybe a Cs or three …. have > you > looked into Masers? :) > AT, AT. He meant "looked AT Masers" :-) -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quick check of a GPS controller oscillator
Sorry, images where too big, had to repost. Please use this link https://www.iw2jww.it/trimble-and-progrock/ to download them, thanks. On 5/6/2020 8:57 PM, Giuseppe Marullo wrote: Ok, first of all many thanks for your help. Yep, not exactly a time-nut piece of engineering, but I need more to be reassured about the Trimble accuracy. If the Trimble is good enough, everything will be easier. @Alex: >in Europe you should be able to get one DCF77 signal based 10MHz, which you could trust I am not planning to add a DCF77 synced 10MHz, I would rather add another Trimble or Rubidium. The whole point is, given my time nuttery is limited, I could be okay with the Trimble provided it is "good enough" to consider it a suitable reference. @Dana: Is the ProgRock GPS disciplined or a Rb, or is it just a free-running crystal oscillator? The ProgRock in itself is a simple Si5351A based programmable oscillator. It may have a OCXO option (that I built and using) and could use a GPS PPS to be calibrated(that I built and using, as the other pieces from QRP labs). The GPS does output NMEA sentences but the ProgRock just use the PPS signal. It is placed in a Clock kit enclosure and the clock does use/display the NMEA sentences but the ProgRock just use the PPS signal. And does LH say that the Trimble is locked OK? I have included a screenshot of LH(20200506LH.png) as per now. Unless the ProgRock is GPS disciplined (or is a Rb), it's a pretty safe bet that it has simply grown old and the crystal has aged. And this notion is much strengthened if LH gives a positive indication that your Trimble is locked OK. Don't think it could be aging related, it should use the GPS to self calibrate anyway within minutes. It does/should use the GPS PPS data, saying it is disciplined may be a little optimistic. @Bob: Hi With any GPSDO (not just the TBolt) you can do some basic checks: (They are in no particular order) 1) Are there > 6 sats in view at all times, if not, move the antenna Yes they are. Antenna is Simmetricom missile head 28dB amplified (timing antenna) clear view of the sky, on a 2m pole on a balcony facing South. 2) Is the unit locked to at least 4 sats at all times, if not, move the antenna. Yes, see LH attachment 3) Has the unit completed its survey process? If not, wait for it to complete. Not at the moment I power cycled it this night. It is powered since this night (>12hours). Do I have to initiate it? 4) Is the EFC > 10% and < 90% of it’s range after an hour on? If not, repair the unit. I don't know what EFC is. If it is the DAC voltage, seems so (looking at its values it never went over the range but I may have not seen it happening) 5) Has the unit been on for at least 3 days? If not wait. Not yet, waiting... 6) Does the output look ok on a ’scope? ( it’s volts not milivolts …) if not repair the unit See attach(20200506_DSO.JPG), it is a vanilla scope nevertheless it seems good to me 7) Does the unit show “locked” or something similar? Yes, it seems so. Operation mode: LOCKED / PLL: LOCK 8) Is the EFC consistent ( = stable) and not wandering around? If not repair the unit. Can't say. If EFC is the DAC, well sort of but not exactly stable. Keep in mind I am opening and closing the window now, so there is a change in temperature. 9) Do the sat’s show SNR’s above 40 db? If not, replace the antenna / coax. They seem fine, according to the screenshot (C/N values, right?). Cable is 10m RG-8X, Yes it could be better but not shorter. I have some meters of Heliax (.5" or 1+5/8" AKA coke can size) not that time nut yet. They could act as a mast for the antenna, LOL. 10) Does it read same / same /same compared to your counter’s internal time base? If not, check the counter / repair the GPSDO. I would say yes. Counter does have high stability option (04E: Ultra High Frequency Ovened Oscillator <5x10 E-10, not 04R rubidium), so last digits may vary. I have included a photo of what is displayed(20200506_FC.jpg). 10.0007 almost all the time ending with a 7 once I saw it briefly flickering to an 8. I added a second photo with overflowing the FC would squeeze out another digit and it is pretty stable at [1]0.00069MHz (20200506_FC_OV.jpg). 11) Does the reported ( survey ) location make sense on Google Maps? If not restart the survey / repair the unit. If the unit passes all those checks, it’s a really good bet that you can trust the output. It likely is good to < 1 ppb, almost regardless of who made the device. Not every check will be possible on every GPSDO. The checks assume you have a ’scope and a counter. They also assume you can talk to the status port on the device. Some readings ( EFC range, SNR, may take a bit of research to put into rational units ….). At the moment it is in position holdover. Previous time was able to complete the survey. Current Reported position is correct within 5m according to Google Earth.
Re: [time-nuts] Quick check of a GPS controller oscillator
Hi Sure, phase lock vs frequency lock is a fun twist to this. Does it matter in the general case? Regardless of phase lock vs frequency lock, the error on the device should be below the 1 ppb limit mentioned in the post. That’s plenty good enough to resolve the 0.25 ppm (ppm not ppb) errors the OP is seeing. Most of the frequency lock devices are down in the <0.05 ppb range for error. In terms of a ham radio or other practical application, that sort of offset simply does not matter. In terms of a frequency measurement, they may actually be more accurate than a phase lock device. Sure, this is Time Nuts and it’s all about finding those little errors. Most of the world is after a device that is ok at the ~ 1 ppb level. Most telecom GPSDO’s were built to a *frequency* spec around 10 ppb (which they vastly exceed in order to hit a time based holdover spec ….). Does this rule out a “I designed it myself” GPSDO with problems? Of course not. The list I gave is by no means adequate for checking out a design from scratch device. It is a reasonable list to figure out if a stand alone GPSDO you happen to have lying there is working right or not. Since the ProgRock is not a GPS disciplined unit unless you add this or that to it, the best bet is that this one is simply the tuned version. Would the list apply to a gizmo like that? Who knows. A lot depends on just how it’s cobbled together. Bob > On May 6, 2020, at 8:49 AM, Tim Shoppa wrote: > > Bob, your list isn't bad, but it completely misses the point whether the > lock is phase-lock (certainly what anyone in telecom trying to lock a wide > network would expect) or frequency-lock (like some BG7BTL's and probably > some other Chinese clone cobbled-together units). > > A large chunk of hobbyist units out there - and I think this includes the > Progrock that the OP has - are frequency locked, not phase locked. And they > usually show systemic frequency offsets due to gating in the frequency > counter. > > Another way of asking the question to the OP, is he a phase-nut or a > frequency-nut? :-) > > Tim N3QE > > On Wed, May 6, 2020 at 8:22 AM Bob kb8tq wrote: > >> Hi >> >> With any GPSDO (not just the TBolt) you can do some basic checks: >> (They are in no particular order) >> >> 1) Are there > 6 sats in view at all times, if not, move the antenna >> 2) Is the unit locked to at least 4 sats at all times, if not, move the >> antenna. >> 3) Has the unit completed its survey process? If not, wait for it to >> complete. >> 4) Is the EFC > 10% and < 90% of it’s range after an hour on? If not, >> repair the unit. >> 5) Has the unit been on for at least 3 days? If not wait. >> 6) Does the output look ok on a ’scope? ( it’s volts not milivolts …) if >> not repair the unit >> 7) Does the unit show “locked” or something similar? >> 8) Is the EFC consistent ( = stable) and not wandering around? If not >> repair the unit. >> 9) Do the sat’s show SNR’s above 40 db? If not, replace the antenna / >> coax. >> 10) Does it read same / same /same compared to your counter’s internal >> timebase? >> If not, check the counter / repair the GPSDO. >> 11) Does the reported ( survey ) location make sense on Google Maps? If >> not restart >> the survey / repair the unit. >> >> If the unit passes all those checks, it’s a really good bet that you can >> trust the output. >> It likely is good to < 1 ppb, almost regardless of who made the device. >> Not every check >> will be possible on every GPSDO. The checks assume you have a ’scope and a >> counter. >> They also assume you can talk to the status port on the device. Some >> readings ( EFC >> range, SNR, may take a bit of research to put into rational units ….). >> >> == >> >> If all of that sounds like a lot of work (or not complete enough), buy a >> second ( or third >> or fourth ….) GPSDO. Next get a couple Rb’s …. maybe a Cs or three …. have >> you >> looked into Masers? :) >> >> Bob >> >>> On May 5, 2020, at 8:16 PM, Giuseppe Marullo >> wrote: >>> >>> Hi, >>> >>> I have a ProgRock oscillator that generates 10MHz and 125MHz signals. >> Checking with my Trimble the ProgRock 10MHz signal is consistently below >> 2.5Hz compared to the Trimble and also the 125MHz is below about 24Hz. >>> >>> My setup: >>> >>> - Simmetricon time antenna (26dB gain) in clear view >>> - about 10m of RG8X cable >>> - Trimble GPS (chinese reboxed) >>> - Racal Dana 1998 frequency counter with Trimble as time base >>> >>> DUT >>> - Progrock (https://www.qrp-labs.com/progrock.html) with >>> - ovenized oscillator (https://www.qrp-labs.com/ocxokit.html) >>> - GPSQ board (https://www.qrp-labs.com/qlg1.html) outside on the >> balcony, first floor facing south (almost clear view except North of >> course). connection is made using rs232 cable (about 6m) >>> >>> I tested for harmonics on my FT857D and Argo, every odd harmonic the >> error increase. The radio has high stability but it is not exact for sure. >> I could test
Re: [time-nuts] Quick check of a GPS controller oscillator
Bob, your list isn't bad, but it completely misses the point whether the lock is phase-lock (certainly what anyone in telecom trying to lock a wide network would expect) or frequency-lock (like some BG7BTL's and probably some other Chinese clone cobbled-together units). A large chunk of hobbyist units out there - and I think this includes the Progrock that the OP has - are frequency locked, not phase locked. And they usually show systemic frequency offsets due to gating in the frequency counter. Another way of asking the question to the OP, is he a phase-nut or a frequency-nut? :-) Tim N3QE On Wed, May 6, 2020 at 8:22 AM Bob kb8tq wrote: > Hi > > With any GPSDO (not just the TBolt) you can do some basic checks: > (They are in no particular order) > > 1) Are there > 6 sats in view at all times, if not, move the antenna > 2) Is the unit locked to at least 4 sats at all times, if not, move the > antenna. > 3) Has the unit completed its survey process? If not, wait for it to > complete. > 4) Is the EFC > 10% and < 90% of it’s range after an hour on? If not, > repair the unit. > 5) Has the unit been on for at least 3 days? If not wait. > 6) Does the output look ok on a ’scope? ( it’s volts not milivolts …) if > not repair the unit > 7) Does the unit show “locked” or something similar? > 8) Is the EFC consistent ( = stable) and not wandering around? If not > repair the unit. > 9) Do the sat’s show SNR’s above 40 db? If not, replace the antenna / > coax. > 10) Does it read same / same /same compared to your counter’s internal > timebase? > If not, check the counter / repair the GPSDO. > 11) Does the reported ( survey ) location make sense on Google Maps? If > not restart > the survey / repair the unit. > > If the unit passes all those checks, it’s a really good bet that you can > trust the output. > It likely is good to < 1 ppb, almost regardless of who made the device. > Not every check > will be possible on every GPSDO. The checks assume you have a ’scope and a > counter. > They also assume you can talk to the status port on the device. Some > readings ( EFC > range, SNR, may take a bit of research to put into rational units ….). > > == > > If all of that sounds like a lot of work (or not complete enough), buy a > second ( or third > or fourth ….) GPSDO. Next get a couple Rb’s …. maybe a Cs or three …. have > you > looked into Masers? :) > > Bob > > > On May 5, 2020, at 8:16 PM, Giuseppe Marullo > wrote: > > > > Hi, > > > > I have a ProgRock oscillator that generates 10MHz and 125MHz signals. > Checking with my Trimble the ProgRock 10MHz signal is consistently below > 2.5Hz compared to the Trimble and also the 125MHz is below about 24Hz. > > > > My setup: > > > > - Simmetricon time antenna (26dB gain) in clear view > > - about 10m of RG8X cable > > - Trimble GPS (chinese reboxed) > > - Racal Dana 1998 frequency counter with Trimble as time base > > > > DUT > > - Progrock (https://www.qrp-labs.com/progrock.html) with > > - ovenized oscillator (https://www.qrp-labs.com/ocxokit.html) > > - GPSQ board (https://www.qrp-labs.com/qlg1.html) outside on the > balcony, first floor facing south (almost clear view except North of > course). connection is made using rs232 cable (about 6m) > > > > I tested for harmonics on my FT857D and Argo, every odd harmonic the > error increase. The radio has high stability but it is not exact for sure. > I could test harmonics with my SA but Trimble would be my only reference. > > > > The question is: how could I be 100% sure that the Trimble frequency is > absolutely trustworthy? I have LH and it says oscillator is within > 300-1000ppt. > > Is it enough to conclude the frequency is okay and the ProgRock is wrong? > > > > TIA > > > > Giuseppe Marullo > > IW2JWW - JN45RQ > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quick check of a GPS controller oscillator
Hi With any GPSDO (not just the TBolt) you can do some basic checks: (They are in no particular order) 1) Are there > 6 sats in view at all times, if not, move the antenna 2) Is the unit locked to at least 4 sats at all times, if not, move the antenna. 3) Has the unit completed its survey process? If not, wait for it to complete. 4) Is the EFC > 10% and < 90% of it’s range after an hour on? If not, repair the unit. 5) Has the unit been on for at least 3 days? If not wait. 6) Does the output look ok on a ’scope? ( it’s volts not milivolts …) if not repair the unit 7) Does the unit show “locked” or something similar? 8) Is the EFC consistent ( = stable) and not wandering around? If not repair the unit. 9) Do the sat’s show SNR’s above 40 db? If not, replace the antenna / coax. 10) Does it read same / same /same compared to your counter’s internal timebase? If not, check the counter / repair the GPSDO. 11) Does the reported ( survey ) location make sense on Google Maps? If not restart the survey / repair the unit. If the unit passes all those checks, it’s a really good bet that you can trust the output. It likely is good to < 1 ppb, almost regardless of who made the device. Not every check will be possible on every GPSDO. The checks assume you have a ’scope and a counter. They also assume you can talk to the status port on the device. Some readings ( EFC range, SNR, may take a bit of research to put into rational units ….). == If all of that sounds like a lot of work (or not complete enough), buy a second ( or third or fourth ….) GPSDO. Next get a couple Rb’s …. maybe a Cs or three …. have you looked into Masers? :) Bob > On May 5, 2020, at 8:16 PM, Giuseppe Marullo wrote: > > Hi, > > I have a ProgRock oscillator that generates 10MHz and 125MHz signals. > Checking with my Trimble the ProgRock 10MHz signal is consistently below > 2.5Hz compared to the Trimble and also the 125MHz is below about 24Hz. > > My setup: > > - Simmetricon time antenna (26dB gain) in clear view > - about 10m of RG8X cable > - Trimble GPS (chinese reboxed) > - Racal Dana 1998 frequency counter with Trimble as time base > > DUT > - Progrock (https://www.qrp-labs.com/progrock.html) with > - ovenized oscillator (https://www.qrp-labs.com/ocxokit.html) > - GPSQ board (https://www.qrp-labs.com/qlg1.html) outside on the balcony, > first floor facing south (almost clear view except North of course). > connection is made using rs232 cable (about 6m) > > I tested for harmonics on my FT857D and Argo, every odd harmonic the error > increase. The radio has high stability but it is not exact for sure. I could > test harmonics with my SA but Trimble would be my only reference. > > The question is: how could I be 100% sure that the Trimble frequency is > absolutely trustworthy? I have LH and it says oscillator is within > 300-1000ppt. > Is it enough to conclude the frequency is okay and the ProgRock is wrong? > > TIA > > Giuseppe Marullo > IW2JWW - JN45RQ > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quick check of a GPS controller oscillator
Is the ProgRock GPS disciplined or a Rb, or is it just a free-running crystal oscillator? And does LH say that the Trimble is locked OK? Unless the PrgRock is GPS disciplined (or is a Rb), it's a pretty safe bet that it has simply grown old and the crystal has aged. And this notion is much strengthened if LH gives a positive indication that your Trimble is locked OK. Dana On Tue, May 5, 2020 at 7:17 PM Giuseppe Marullo wrote: > Hi, > > I have a ProgRock oscillator that generates 10MHz and 125MHz signals. > Checking with my Trimble the ProgRock 10MHz signal is consistently below > 2.5Hz compared to the Trimble and also the 125MHz is below about 24Hz. > > My setup: > > - Simmetricon time antenna (26dB gain) in clear view > - about 10m of RG8X cable > - Trimble GPS (chinese reboxed) > - Racal Dana 1998 frequency counter with Trimble as time base > > DUT > - Progrock (https://www.qrp-labs.com/progrock.html) with > - ovenized oscillator (https://www.qrp-labs.com/ocxokit.html) > - GPSQ board (https://www.qrp-labs.com/qlg1.html) outside on the > balcony, first floor facing south (almost clear view except North of > course). connection is made using rs232 cable (about 6m) > > I tested for harmonics on my FT857D and Argo, every odd harmonic the > error increase. The radio has high stability but it is not exact for > sure. I could test harmonics with my SA but Trimble would be my only > reference. > > The question is: how could I be 100% sure that the Trimble frequency is > absolutely trustworthy? I have LH and it says oscillator is within > 300-1000ppt. > Is it enough to conclude the frequency is okay and the ProgRock is wrong? > > TIA > > Giuseppe Marullo > IW2JWW - JN45RQ > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
