[time-nuts] Tuning a Trimble Thunderbolt
wb6bnq wrote: “I am a little confused. In your screen shot the overdetermined clock says you are at precisely 46.00 North by 7.0 East at 547 Meters.” I think I have the answer. I know when I was selling Tbolts I would PhotoShop out every digit after the decimal point so the displayed JPEG wouldn’t show my location. If Lat. was exactly 46.00 then it would show that, not just 46.(blank). ___ 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] Leica AT-303
Hi Gee… I wonder who got the other one ….:) They are big beasts and are both heavy and a wind load. Both need to be taken into account when mounting them. They most certainly do have preamps in them. Often the preamps do not work down at the 5V that a 3801 puts out. The gain of the antenna may or may not match up well with other gear. They can have some pretty major amps in them. Best way to dig up info it to type AT503 or AT303 or whichever one you have into Google. If you have one of the earlier ones that is just labeled L1/L2, try going after the Leica part number. It’s not real clear that they have a significant advantage for L1 only operation with a Z3801. The receiver in a 3801 really isn’t up to the same level as the antenna. It will in no way *hurt* the timing performance. If you already have a decent antenna with a good view, it may not help a lot. For $100 it’s not a bad thing to play around a bit with. Bob > On Apr 22, 2015, at 5:35 PM, John Green wrote: > > I've been away for a long time. So, I guess that makes me the new guy, all > over again. > I have long coveted a choke ring GPS antenna. Oh, I have several so called > "timing grade" ones but I have always wanted a choke ring. After watching > them on eBay for a long time and seeing them in the $600 range, I recently > saw one up for bid starting at $99. I didn't get it, but did get a second > chance offer and bought it. Now, I have come to realize there isn't much > information available on them. Alas, Google is not my friend here. So, I > was wondering, do they have a built in preamp? I kind of think not since > they are supposed to be L1, L2 antennas. Besides, I wouldn't think you > would need long cables for surveying. I just want to put it on top of what > used to be my TV antenna tower and feed the Z3801 with it. Does anyone here > own one? What do you think of it? Is there some place where I can get more > information on it? > ___ > 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] New ± 1 sec in 100 days mech clock
Hi In some ways this is like: I can buy tubes of paint and some brushes down at Hobby Lobby. That’s what I need to paint the next Mona Lisa. While that’s all quite true, it’s not the whole story :) There’s an enormous amount of training and experience that goes into fitting this sort of thing up. There is even a certain amount of “art” that goes beyond simple training. Not all watch/clock makers are up to this sort of thing. Highly skilled people have been trying to do this kind of clock for a *long* time ….It’s not just an assembly process. Indeed I’d love to see the details of how they did the design. There are some basic challenges that they (obviously) addressed very well. Even with a good description of what they did and a pile of parts, you are still only (maybe) 10% of the way to a duplicate. Note: I’m *not* claiming I am any good at clock making. I’ve simply seen a lot of this sort of work done over the years. Bob > On Apr 22, 2015, at 10:03 AM, Dan Kemppainen wrote: > > Hi, > > In all reality, achieving these results without decades of experience is > probably unlikely. That said, are the specific plans available or published > anywhere? Is is possible that someone willing to build and tinker could make > a 'functional' copy of this unit? > > I would guess that not all of the parts need extreme tolerances. But even > then many mills are holding positioning tolerances well under .001", with > tool deflections of .0001" or under (if run and maintained properly, that > is). My 'list' includes a mechanical clock build. And this one would be a > dandy to try to build! > > In any case, the clock is still interesting to read about! It's great that > some of you are lucky enough to get to see it! :) > > > Dan > > > On 4/21/2015 12:00 PM, time-nuts-requ...@febo.com wrote: >> >> You could always use the traditional method of piercing saw and files. >> Thinking about it I suppose files were the original milling machine. Be >> aware that the horological approach is different from the engineering >> approach and there are numerous traps waiting for the unwary. Harrison >> and Martin's clock B have remarkable performance but could still be >> improved by using multiple pendulums to overcome the noise effects for >> example a two pendulum clock is performing within 1 second in six months >> (so far) so I will have to get the hacksaw out for the three pendulum >> version - or is it back to the GPSDO. >> >> Peter > ___ > 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] Leica AT-303
I've been away for a long time. So, I guess that makes me the new guy, all over again. I have long coveted a choke ring GPS antenna. Oh, I have several so called "timing grade" ones but I have always wanted a choke ring. After watching them on eBay for a long time and seeing them in the $600 range, I recently saw one up for bid starting at $99. I didn't get it, but did get a second chance offer and bought it. Now, I have come to realize there isn't much information available on them. Alas, Google is not my friend here. So, I was wondering, do they have a built in preamp? I kind of think not since they are supposed to be L1, L2 antennas. Besides, I wouldn't think you would need long cables for surveying. I just want to put it on top of what used to be my TV antenna tower and feed the Z3801 with it. Does anyone here own one? What do you think of it? Is there some place where I can get more information on it? ___ 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] Ultra High Stability Time Base Options for 53132A
Hi I suspect that the “more alarming” signatures on the stable sources are a function of them “holding still” (in phase) longer. With the less stable sources, the junk is still there, it just is smeared out more. Bob > On Apr 22, 2015, at 6:17 AM, Hans Holzach wrote: > > during the last days i ran a few tests with different high stability options. > > setup: > channel 1: thunderbolt 10 mhz divided down to 1 pps > channel 2: trimble 73090 DOCXO 10 MHz divided down to 1 pps. frequency offset > about 7e-9 > internal time bases: no additional time base; morion mv89a; trimble 34310-t > external time bases: no external time base; thunderbolt 10 mhz > tapr distribution amplifier, tapr frequency dividers > > strong temperature swings in the attic, about 10°C, thunderbolt not > protected, trimble 73090 (channel 2) in box with a lot of small water > containers. > > internal time base: NO high stability time base, external time base: NONE > adev: https://farm9.staticflickr.com/8742/17196609681_53937b7e5d_b.jpg > spectral density: > https://farm8.staticflickr.com/7688/17197584451_50e359e46f_b.jpg > > internal time base: NO high stability time base, external time base: > thunderbolt 10 mhz > adev: https://farm8.staticflickr.com/7587/16997478560_1a422eb0f2_b.jpg > spectral density: > https://farm8.staticflickr.com/7604/17159258816_743ba1f83a_b.jpg > > > internal time base: morion mv89a, external time base: NONE > adev: https://farm9.staticflickr.com/8802/16962399320_908fea406c_b.jpg > spectral density: > https://farm6.staticflickr.com/5349/16565001513_e3f47482e6_b.jpg > > internal time base: morion mv89a, external time base: thunderbolt 10 mhz > adev: https://farm9.staticflickr.com/8774/16949313140_29937eb5d6_b.jpg > spectral density: > https://farm6.staticflickr.com/5346/17159259246_eb20993753_b.jpg > > > internal time base: trimble 34310-t, external time base: NONE > adev: https://farm9.staticflickr.com/8816/17232552925_4f4e9bc267_b.jpg > spectral density: > https://farm8.staticflickr.com/7644/17044785268_bdb5b2fa97_b.jpg > > internal time base: trimble 34310-t, external time base: thunderbolt 10 mhz > adev: https://farm9.staticflickr.com/8784/16602405264_41fefbed43_b.jpg > spectral density: > https://farm9.staticflickr.com/8710/16604641953_de800d9769_b.jpg > > > more plots (phase and autocorrelation samples) at: > https://www.flickr.com/photos/olmstead/collections/72157651929343312/ > > looking at the ps plots: it seems to be a good idea not to use a high > stability time base if an external time base like a thunderbolt is plugged to > the counter. both external and internal time bases seem to add a lot of spurs > to the power spectrum, at least in my setup with my gear. ugliest combination > is a morion high stability time base AND an external time base. > > best regards, > hans > ___ > 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] Tuning a Trimble Thunderbolt
Hi Looking at that screen shot, something is *very* wrong with your GPS reception. Your GPS is 10X worse than it should be. > On Apr 22, 2015, at 9:37 AM, Pete Stephenson wrote: > > On Wed, Apr 22, 2015 at 1:47 PM, Bob Camp wrote: >> Hi >> >> Backing up a bit to “getting a TBolt running”. >> >> 1) instal Lady Heather and get it connected to the TBolt >> 2) does it fire up and find any sats? > > Yes. It had been working consistently for several days prior to my > first message. > >> 3) are the power supplies holding regulation? > > Yes. > >> 4) nail down the antenna in the best fixed location you can find > > Done. > >> 5) run the auto-calibration feature in LH > > Done. This changed the gain from -5.0Hz/V to -3.132Hz/V and changed > the initial voltage to 0.347V. I switched the time constant and > damping values back to their defaults of 100 seconds and 1.200, > respectively. > >> 6) run a 48 hour survey with LH and write the location to ee memory > > Done. The location matches the averaged location surveyed from my > Motorola Oncore UT+ (the antenna for which was about 10cm away from > that for the Tbolt, some no-name mushroom-type antenna) and a handheld > Garmin eTrex 20 (with GPS+GLONASS+WAAS) within a few meters. It also > matches with Google Maps. > > In the attached screenshot you can clearly see the field of view from > the antenna's current location over the last ~20 hours. > > Interestingly, the Oncore antenna (a cheap patch antenna from eBay) > seems to be causing some intermittent issues with the Tbolt: if the > antennas are too close there appears to be some sort of interference > emitted by the Oncore antenna that makes it difficult for the Tbolt to > lock onto the GPS signal and the Tbolt goes into holdover. Oddly, this > is not consistent: the Tbolt and Oncore had coexisted for a few days > with no problems but today some of the problems started up again. I would bet that the amp on the “Oncore” antenna is oscillating. It may do it intermittently. The frequency may swing back and forth through the GPS band. It may be the source of your GPS problem. Bob > > The same issue occured if the Oncore antenna was too close to my > Garmin GPS 18x LVC. I have since moved the Oncore antenna further away > (it's now about 50cm) and signal reception for the Tbolt is much > better. Weird, but distance seems to resolve the issue, so not really > a problem anymore. > >> 7) Then check the EFC voltage, it should be fairly close to 0V, and not over >> 2.5 >> If you are > 2.5, that’s probably a broken unit. > > Doesn't seem to be a problem. > >> 8) Now start watching the EFC voltage for a few days and see that it’s >> leveling >> out and not spiking. Again spikes = something broke. > > See the attached screenshot. There's a few small EFC voltage spikes > when the unit enters or leaves holdover, but otherwise it seems > reasonably smooth in my (admittedly untrained) view. > >> Until that’s all done, I would not dig to deep into the workings of the >> gizmo. It >> needs to be set up first. > > Other than the intermittent issues with the Oncore antenna, everything > seems to be working reasonably well -- there's no obvious failures > that I can spot. > > Cheers! > -Pete > >> Bob >> >> >>> On Apr 21, 2015, at 4:30 AM, Pete Stephenson wrote: >>> >>> On Tue, Apr 21, 2015 at 4:25 AM, Charles Steinmetz >>> wrote: Pete wrote: > On a related note, is it possible to extract any data regarding the > training from the unit? Not as far as the time-nuts community knows, no (other than looking at the DAC voltage and temperature reporting during holdover and attempting to reverse engineer the prediction algorithm by correlating those with the long-term DAC voltage -- good luck). >>> >>> Finishing my PhD is enough work already. I don't think I'll try >>> reverse-engineering the prediction algorithm quite yet. Perhaps later >>> in my Copious Free Time(tm)? >>> > Are the training parameters saved periodically to non-volatile memory, > or are they purely stored in RAM and so will be lost if powered down? > If the latter, does the RAM have any provisions for backup power I doubt it -- mine always act as if they are training from zero if they have been powered down. Because of the lack of precise retrace of quartz crystals, I don't think you'd want old (pre-power-down) data, anyway. Some crystals will even come up drifting in the opposite direction after being powered down, and they all take some time (days, at least) to settle down after any disturbance (including power interruptions, however brief). >>> >>> Ok. It'd be nice if there was some way to keep the crystal going >>> through power interruptions, even if the oven itself cooled off. I >>> suspect Trimble (correctly) assumed that the vast majority of these >>> units were to be installed in cell sites with reliable power so that >>> w
Re: [time-nuts] Signal/Phase noise analyzer
You might like the SignalHound: http://signalhound.com/ Don Vasco Soares > Hi All, > > > > I'm searching for the less expensive signal analyzer to perform phase noise > measurements on OCXO's. There is no need to go above 400 MHz - 1 GHz. I'm > particularly interested on low frequency offset and good close in phase noise > specs. Any recommendations? > > > > Best regards, > > Vasco Soares > ___ > 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. > > -- "Noli sinere nothos te opprimere" Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road Huson, MT, 59846 mail: POBox 404 Frenchtown MT 59834-0404 VOX 406-626-4304 CEL 406-241-5093 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Signal/Phase noise analyzer
Hi Is this for a business or for a basement? Are you looking for new self contained gear or combinations of used gear? Is a cross comparison device ok or do you need a stand alone device? How low do you need to go how fast? Is -190 dbc/ Hz low enough? Is a 24 hour run to long? Lots of variables…. Bob > On Apr 22, 2015, at 10:07 AM, Vasco Soares wrote: > > Hi All, > > > > I'm searching for the less expensive signal analyzer to perform phase noise > measurements on OCXO's. There is no need to go above 400 MHz - 1 GHz. I'm > particularly interested on low frequency offset and good close in phase noise > specs. Any recommendations? > > > > Best regards, > > Vasco Soares > ___ > 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] Signal/Phase noise analyzer
> I'm searching for the less expensive signal analyzer to perform phase noise > measurements on OCXO's. There is no need to go above 400 MHz - 1 GHz. I'm > particularly interested on low frequency offset and good close in phase noise > specs. Any recommendations? Tough to say without a budget range. Less expensive than what, specifically? You could put together an HP 3048A system from surplus hardware for a couple thousand Euros, or buy a new microwave PN test set from any of several companies (Holzworth, NoiseXT, Berkeley Nucleonics, Wenzel...) at a higher price with factory support included. All of them will be less expensive than, say, a brand-new E5052B, but that doesn't necessarily mean they're affordable. -- john, KE5FX Miles Design LLC ___ 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] Tuning a Trimble Thunderbolt
Hi Pete, I am a little confused. In your screen shot the overdetermined clock says you are at precisely 46.00 North by 7.0 East at 547 Meters. However, Google Earth shows that location at over 10 thousnad feet (>3100 meters) elevation in a remote part of the Switzerland mountains. Is that correct ? If so, how did you get right on the precise spot ? The likelyhood of having no decimal values in the Lat/Long is highly suspect to say the least. If those figures are still at those numbers, I would question the validity of the Thundeerbolt position and altitude. Also it shows you are only receiving two sats at the time of screen capature. BillWB6BNQ Pete Stephenson wrote: On Wed, Apr 22, 2015 at 1:47 PM, Bob Camp wrote: Hi Backing up a bit to “getting a TBolt running”. 1) instal Lady Heather and get it connected to the TBolt 2) does it fire up and find any sats? Yes. It had been working consistently for several days prior to my first message. 3) are the power supplies holding regulation? Yes. 4) nail down the antenna in the best fixed location you can find Done. 5) run the auto-calibration feature in LH Done. This changed the gain from -5.0Hz/V to -3.132Hz/V and changed the initial voltage to 0.347V. I switched the time constant and damping values back to their defaults of 100 seconds and 1.200, respectively. 6) run a 48 hour survey with LH and write the location to ee memory Done. The location matches the averaged location surveyed from my Motorola Oncore UT+ (the antenna for which was about 10cm away from that for the Tbolt, some no-name mushroom-type antenna) and a handheld Garmin eTrex 20 (with GPS+GLONASS+WAAS) within a few meters. It also matches with Google Maps. In the attached screenshot you can clearly see the field of view from the antenna's current location over the last ~20 hours. Interestingly, the Oncore antenna (a cheap patch antenna from eBay) seems to be causing some intermittent issues with the Tbolt: if the antennas are too close there appears to be some sort of interference emitted by the Oncore antenna that makes it difficult for the Tbolt to lock onto the GPS signal and the Tbolt goes into holdover. Oddly, this is not consistent: the Tbolt and Oncore had coexisted for a few days with no problems but today some of the problems started up again. The same issue occured if the Oncore antenna was too close to my Garmin GPS 18x LVC. I have since moved the Oncore antenna further away (it's now about 50cm) and signal reception for the Tbolt is much better. Weird, but distance seems to resolve the issue, so not really a problem anymore. 7) Then check the EFC voltage, it should be fairly close to 0V, and not over 2.5 If you are > 2.5, that’s probably a broken unit. Doesn't seem to be a problem. 8) Now start watching the EFC voltage for a few days and see that it’s leveling out and not spiking. Again spikes = something broke. See the attached screenshot. There's a few small EFC voltage spikes when the unit enters or leaves holdover, but otherwise it seems reasonably smooth in my (admittedly untrained) view. Until that’s all done, I would not dig to deep into the workings of the gizmo. It needs to be set up first. Other than the intermittent issues with the Oncore antenna, everything seems to be working reasonably well -- there's no obvious failures that I can spot. Cheers! -Pete Bob On Apr 21, 2015, at 4:30 AM, Pete Stephenson wrote: On Tue, Apr 21, 2015 at 4:25 AM, Charles Steinmetz wrote: Pete wrote: On a related note, is it possible to extract any data regarding the training from the unit? Not as far as the time-nuts community knows, no (other than looking at the DAC voltage and temperature reporting during holdover and attempting to reverse engineer the prediction algorithm by correlating those with the long-term DAC voltage -- good luck). Finishing my PhD is enough work already. I don't think I'll try reverse-engineering the prediction algorithm quite yet. Perhaps later in my Copious Free Time(tm)? Are the training parameters saved periodically to non-volatile memory, or are they purely stored in RAM and so will be lost if powered down? If the latter, does the RAM have any provisions for backup power I doubt it -- mine always act as if they are training from zero if they have been powered down. Because of the lack of precise retrace of quartz crystals, I don't think you'd want old (pre-power-down) data, anyway. Some crystals will even come up drifting in the opposite direction after being powered down, and they all take some time (days, at least) to settle down after any disturbance (including power interruptions, however brief). Ok. It'd be nice if there was some way to keep the crystal going through power interruptions, even if the oven itself cooled off. I suspect
[time-nuts] Tuning a Trimble Thunderbolt
A couple of thinks to note: Before running the auto-calibration feature, first set the antenna elevation mask angle to a low value and let it run for a few (say 12) hours. This will collect data on the received signal strength vs satellite elevation angle. The auto-calibration routine sets the elevation filter value based upon what it sees. If you don't lower the elevation filter value before running the auto-calibration, Lady Heather can't make a good guess at the appropriate elevation angle filter value to use for your location. And let Lady Heather automatically store the calculated survey-position in EEPROM. The manual location entry is limited to using single-precision numbers and is only accurate to a few feet. Once your oscilllator has settled down (usually takes about a month for a unit fresh off the boat from the Old Kingdom), you should probably re-run the calibration feature and precision survey. --- 5) run the auto-calibration feature in LH 6) run a 48 hour survey with LH and write the location to ee memory ___ 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] Tuning a Trimble Thunderbolt
On a Thunderbolt, you can only manually enter your position with using single-precision floating point numbers... not really accurate enough for a time-nut. When Lady Heather does a precision survey, it stores the high-prescision results of the 48-hour survey by doing repeated single-point survey commands until one just happens to be within one foot of the desired position. Quite a kludge, but we are time-nuts. Also, the Thunderbolt does not have a user-controllable Kalman filter setting, so that option is grayed out. You can let the GPS receiver do a self-survey but you can also enter the location that you determined by other means. ___ 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] New ± 1 sec in 100 days mech clock
Hi, In all reality, achieving these results without decades of experience is probably unlikely. That said, are the specific plans available or published anywhere? Is is possible that someone willing to build and tinker could make a 'functional' copy of this unit? I would guess that not all of the parts need extreme tolerances. But even then many mills are holding positioning tolerances well under .001", with tool deflections of .0001" or under (if run and maintained properly, that is). My 'list' includes a mechanical clock build. And this one would be a dandy to try to build! In any case, the clock is still interesting to read about! It's great that some of you are lucky enough to get to see it! :) Dan On 4/21/2015 12:00 PM, time-nuts-requ...@febo.com wrote: You could always use the traditional method of piercing saw and files. Thinking about it I suppose files were the original milling machine. Be aware that the horological approach is different from the engineering approach and there are numerous traps waiting for the unwary. Harrison and Martin's clock B have remarkable performance but could still be improved by using multiple pendulums to overcome the noise effects for example a two pendulum clock is performing within 1 second in six months (so far) so I will have to get the hacksaw out for the three pendulum version - or is it back to the GPSDO. Peter ___ 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] Signal/Phase noise analyzer
Hi All, I'm searching for the less expensive signal analyzer to perform phase noise measurements on OCXO's. There is no need to go above 400 MHz - 1 GHz. I'm particularly interested on low frequency offset and good close in phase noise specs. Any recommendations? Best regards, Vasco Soares ___ 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] Tuning a Trimble Thunderbolt
On Wed, Apr 22, 2015 at 1:47 PM, Bob Camp wrote: > Hi > > Backing up a bit to “getting a TBolt running”. > > 1) instal Lady Heather and get it connected to the TBolt > 2) does it fire up and find any sats? Yes. It had been working consistently for several days prior to my first message. > 3) are the power supplies holding regulation? Yes. > 4) nail down the antenna in the best fixed location you can find Done. > 5) run the auto-calibration feature in LH Done. This changed the gain from -5.0Hz/V to -3.132Hz/V and changed the initial voltage to 0.347V. I switched the time constant and damping values back to their defaults of 100 seconds and 1.200, respectively. > 6) run a 48 hour survey with LH and write the location to ee memory Done. The location matches the averaged location surveyed from my Motorola Oncore UT+ (the antenna for which was about 10cm away from that for the Tbolt, some no-name mushroom-type antenna) and a handheld Garmin eTrex 20 (with GPS+GLONASS+WAAS) within a few meters. It also matches with Google Maps. In the attached screenshot you can clearly see the field of view from the antenna's current location over the last ~20 hours. Interestingly, the Oncore antenna (a cheap patch antenna from eBay) seems to be causing some intermittent issues with the Tbolt: if the antennas are too close there appears to be some sort of interference emitted by the Oncore antenna that makes it difficult for the Tbolt to lock onto the GPS signal and the Tbolt goes into holdover. Oddly, this is not consistent: the Tbolt and Oncore had coexisted for a few days with no problems but today some of the problems started up again. The same issue occured if the Oncore antenna was too close to my Garmin GPS 18x LVC. I have since moved the Oncore antenna further away (it's now about 50cm) and signal reception for the Tbolt is much better. Weird, but distance seems to resolve the issue, so not really a problem anymore. > 7) Then check the EFC voltage, it should be fairly close to 0V, and not over > 2.5 > If you are > 2.5, that’s probably a broken unit. Doesn't seem to be a problem. > 8) Now start watching the EFC voltage for a few days and see that it’s > leveling > out and not spiking. Again spikes = something broke. See the attached screenshot. There's a few small EFC voltage spikes when the unit enters or leaves holdover, but otherwise it seems reasonably smooth in my (admittedly untrained) view. > Until that’s all done, I would not dig to deep into the workings of the > gizmo. It > needs to be set up first. Other than the intermittent issues with the Oncore antenna, everything seems to be working reasonably well -- there's no obvious failures that I can spot. Cheers! -Pete > Bob > > >> On Apr 21, 2015, at 4:30 AM, Pete Stephenson wrote: >> >> On Tue, Apr 21, 2015 at 4:25 AM, Charles Steinmetz >> wrote: >>> Pete wrote: >>> On a related note, is it possible to extract any data regarding the training from the unit? >>> >>> Not as far as the time-nuts community knows, no (other than looking at the >>> DAC voltage and temperature reporting during holdover and attempting to >>> reverse engineer the prediction algorithm by correlating those with the >>> long-term DAC voltage -- good luck). >> >> Finishing my PhD is enough work already. I don't think I'll try >> reverse-engineering the prediction algorithm quite yet. Perhaps later >> in my Copious Free Time(tm)? >> Are the training parameters saved periodically to non-volatile memory, or are they purely stored in RAM and so will be lost if powered down? If the latter, does the RAM have any provisions for backup power >>> >>> I doubt it -- mine always act as if they are training from zero if they have >>> been powered down. Because of the lack of precise retrace of quartz >>> crystals, I don't think you'd want old (pre-power-down) data, anyway. Some >>> crystals will even come up drifting in the opposite direction after being >>> powered down, and they all take some time (days, at least) to settle down >>> after any disturbance (including power interruptions, however brief). >> >> Ok. It'd be nice if there was some way to keep the crystal going >> through power interruptions, even if the oven itself cooled off. I >> suspect Trimble (correctly) assumed that the vast majority of these >> units were to be installed in cell sites with reliable power so that >> wouldn't be an issue. >> Alas, the location for the antenna is suboptimal: in the best location available to me (an outdoor balcony) I have a clear view of the southern sky from 150-300 degrees (az) and from horizon to zenith with only a few low-elevation obstructions. However, this is only accessible in warm months * * * The surveyed position is within about 10 meters of the actual location according to Google Maps and local building information. >>> >>> That's a problem. Every meter is approximately 3.3nS, so 10m introduce
Re: [time-nuts] Tuning a Trimble Thunderbolt
Hi Backing up a bit to “getting a TBolt running”. 1) instal Lady Heather and get it connected to the TBolt 2) does it fire up and find any sats? 3) are the power supplies holding regulation? 4) nail down the antenna in the best fixed location you can find 5) run the auto-calibration feature in LH 6) run a 48 hour survey with LH and write the location to ee memory 7) Then check the EFC voltage, it should be fairly close to 0V, and not over 2.5 If you are > 2.5, that’s probably a broken unit. 8) Now start watching the EFC voltage for a few days and see that it’s leveling out and not spiking. Again spikes = something broke. Until that’s all done, I would not dig to deep into the workings of the gizmo. It needs to be set up first. Bob > On Apr 21, 2015, at 4:30 AM, Pete Stephenson wrote: > > On Tue, Apr 21, 2015 at 4:25 AM, Charles Steinmetz > wrote: >> Pete wrote: >> >>> On a related note, is it possible to extract any data regarding the >>> training from the unit? >> >> Not as far as the time-nuts community knows, no (other than looking at the >> DAC voltage and temperature reporting during holdover and attempting to >> reverse engineer the prediction algorithm by correlating those with the >> long-term DAC voltage -- good luck). > > Finishing my PhD is enough work already. I don't think I'll try > reverse-engineering the prediction algorithm quite yet. Perhaps later > in my Copious Free Time(tm)? > >>> Are the training parameters saved periodically to non-volatile memory, >>> or are they purely stored in RAM and so will be lost if powered down? >>> If the latter, does the RAM have any provisions for backup power >> >> I doubt it -- mine always act as if they are training from zero if they have >> been powered down. Because of the lack of precise retrace of quartz >> crystals, I don't think you'd want old (pre-power-down) data, anyway. Some >> crystals will even come up drifting in the opposite direction after being >> powered down, and they all take some time (days, at least) to settle down >> after any disturbance (including power interruptions, however brief). > > Ok. It'd be nice if there was some way to keep the crystal going > through power interruptions, even if the oven itself cooled off. I > suspect Trimble (correctly) assumed that the vast majority of these > units were to be installed in cell sites with reliable power so that > wouldn't be an issue. > >>> Alas, the location for the antenna is suboptimal: in the best location >>> available to me (an outdoor balcony) I have a clear view of the >>> southern sky from 150-300 degrees (az) and from horizon to zenith with >>> only a few low-elevation obstructions. However, this is only >>> accessible in warm months >>> * * * >>> The surveyed position is within about 10 meters of the actual location >>> according to Google Maps and local building information. >> >> That's a problem. Every meter is approximately 3.3nS, so 10m introduces a >> +/- 33nS error in the raw data (as much as 33nS closer to some satellites >> and 33nS farther from others). Add in the uncertainty due to noise, and you >> get easily hundreds on nS of error in the computed solution. > > Indeed. I'm running a 48-hour survey with Lady Heather now to see if > that can improve things a bit more. > >> Unfortunately, you are unlikely to do any better than this with the antenna >> location you described. Time to buy a house, with no tall trees nearby. >> (You may already have heard that time-nuttiness can be expensive ;-) > > I won't be looking for a house for at least a few years, but when I do > the skyview is definitely one of the criteria, as is the friendliness > of the community to radio masts. > > Cheers! > -Pete > > -- > Pete Stephenson > ___ > 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] Ultra High Stability Time Base Options for 53132A
during the last days i ran a few tests with different high stability options. setup: channel 1: thunderbolt 10 mhz divided down to 1 pps channel 2: trimble 73090 DOCXO 10 MHz divided down to 1 pps. frequency offset about 7e-9 internal time bases: no additional time base; morion mv89a; trimble 34310-t external time bases: no external time base; thunderbolt 10 mhz tapr distribution amplifier, tapr frequency dividers strong temperature swings in the attic, about 10°C, thunderbolt not protected, trimble 73090 (channel 2) in box with a lot of small water containers. internal time base: NO high stability time base, external time base: NONE adev: https://farm9.staticflickr.com/8742/17196609681_53937b7e5d_b.jpg spectral density: https://farm8.staticflickr.com/7688/17197584451_50e359e46f_b.jpg internal time base: NO high stability time base, external time base: thunderbolt 10 mhz adev: https://farm8.staticflickr.com/7587/16997478560_1a422eb0f2_b.jpg spectral density: https://farm8.staticflickr.com/7604/17159258816_743ba1f83a_b.jpg internal time base: morion mv89a, external time base: NONE adev: https://farm9.staticflickr.com/8802/16962399320_908fea406c_b.jpg spectral density: https://farm6.staticflickr.com/5349/16565001513_e3f47482e6_b.jpg internal time base: morion mv89a, external time base: thunderbolt 10 mhz adev: https://farm9.staticflickr.com/8774/16949313140_29937eb5d6_b.jpg spectral density: https://farm6.staticflickr.com/5346/17159259246_eb20993753_b.jpg internal time base: trimble 34310-t, external time base: NONE adev: https://farm9.staticflickr.com/8816/17232552925_4f4e9bc267_b.jpg spectral density: https://farm8.staticflickr.com/7644/17044785268_bdb5b2fa97_b.jpg internal time base: trimble 34310-t, external time base: thunderbolt 10 mhz adev: https://farm9.staticflickr.com/8784/16602405264_41fefbed43_b.jpg spectral density: https://farm9.staticflickr.com/8710/16604641953_de800d9769_b.jpg more plots (phase and autocorrelation samples) at: https://www.flickr.com/photos/olmstead/collections/72157651929343312/ looking at the ps plots: it seems to be a good idea not to use a high stability time base if an external time base like a thunderbolt is plugged to the counter. both external and internal time bases seem to add a lot of spurs to the power spectrum, at least in my setup with my gear. ugliest combination is a morion high stability time base AND an external time base. best regards, hans ___ 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] Tuning a Trimble Thunderbolt
A week is somewhat optimistic since the thunderbolt consumes around 1.68 kilowatt hours of energy. With a 12V battery a capacity of around 84 ampere hours (for an efficiency of 100%) which is somewhat larger than that provided for most UPS particularly those sold for use with personal computers. .Whilst the UPS may use a higher battery voltage the energy requirements are similar as will be the physical size and weight of the battery/battteries. Bruce On Wednesday, 22 April 2015 6:33 PM, Chris Albertson wrote: On Tue, Apr 21, 2015 at 1:30 AM, Pete Stephenson wrote: > On Tue, Apr 21, 2015 at 4:25 AM, Charles Steinmetz > > Indeed. I'm running a 48-hour survey with Lady Heather now to see if > that can improve things a bit more. > You can let the GPS receiver do a self-survey but you can also enter the location that you determined by other means. I've not done this on a Thunderbolt but have for my Motorola receivers. Just by chance I needed to get my property surveyed and had a crew out and they marked the property with brass markers positioned to a fraction of an inch. (I hope) From this I can figure out the antenna location to likely about one foot or maybe better if I am really carful. One thing to watch out for is that there are different "systems" of measuring latitude and longitude these make different assumptions about the shape of the Earth and where its center is located and so on. You need to be sure everyone is using WGS84. If not it is easy to be "off" by a couple hundred meters You can use Google Earth if you don't have a survey but check it for accuracy. Have Google check the location of a government benchmark that is nearest your house and see if Google gives you the recorded location. It's good to find the antenna location using other means so you can verify the self-survey.. I did this and found it is all OK within some margin of error. But then I have a very good antenna location. I think with a poor antenna location you'd want to verify the self-survey -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tuning a Trimble Thunderbolt
On Tue, Apr 21, 2015 at 1:23 PM, Bob Camp wrote: > Hi > > inevitably on these devices, there is a marketing brochure that hits the high > points > in the specification. That information is public and intended to get “buzz” > going on > the product. Once an OEM gets serious about the product, (the TBolt is > targeted > at OEM’s) a detailed specification gets written. It may be in the form of > detailed > specs or in the form of a test regime / service scenario the unit is expected > to > perform in. That document is rarely available to the public. D'oh. > How are you measuring the holdover performance? You mention that you have > no counter and no other standards. When one uses Lady Heather to switch the Tbolt to manual holdover, Lady Heather continues to monitor the offset between the oscillator and GPS. No doubt this method isn't nearly as good as using a counter or some other standard, but it's what I have. Cheers! -Pete -- Pete Stephenson ___ 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] Tuning a Trimble Thunderbolt
Pete wrote: It'd be nice if there was some way to keep the crystal going through power interruptions, even if the oven itself cooled off. I suspect Trimble (correctly) assumed that the vast majority of these units were to be installed in cell sites with reliable power so that wouldn't be an issue. Put the whole TBolt on a UPS (preferably, the "on-line" or "double-conversion" type). A 2kW UPS should run a TBolt (10W steady state power consumption) for about a week, depending on the efficiency of the power supply you use. Best regards, Charles ___ 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.
