Re: [time-nuts] Hydrogen maser spin exchange
Ole I can only point you toward cesium references I remember reading about the magnet configuration and it did matter. Sorry it was a while ago. Others may know the reference. It was the HP 5060 as I barely recall. On Fri, Jun 17, 2016 at 6:18 PM, Ole Petter Ronningen wrote: > There is indeed a quad- or hexa-pole state selection magnet between the > dissociator and the cavity, required to select the atoms of the correct > state to allow a population inversion resulting in oscillation. > > My understanding is that the spin-exchange of interest takes place between > atoms already bouncing around inside the cavity - having passed that > particular obstacle. > > And while on that subject, if anyone could elaborate on the difference > between the two (quad or hexa-pole), that would be interesting. I have not > found a clear explanation for why one might choose one over the other. > > Ole > > On Fri, Jun 17, 2016 at 11:35 PM, paul swed wrote: > > > Ole, > > Quite looking forward to the replies. Though no intention to own a maser > > currently. > > I thought there was a method of rejecting or reducing types of spin. > > Therefore reducing the impact you mention. Essentially a state selector. > > Pretty sure that thought will get corrected pretty quickly. > > Regards > > Paul > > WB8TSL > > > > On Fri, Jun 17, 2016 at 3:33 PM, Ole Petter Ronningen < > > opronnin...@gmail.com > > > wrote: > > > > > Hi. Apologies for a long post. > > > > > > I'm trying to read up on the "care and feeding of hydrogen masers". > While > > > they are conceptually simple from a distance, there's quite a bit going > > on > > > in the quantum mechanics department when looked at up close. Somewhat > > > frustratingly, I am not mentally equipped to really grasp the finer (or > > > even coarser) points of that particular department. The topic of this > > post > > > is the concept of spin exchange, and it's relation to cavity (auto) > > tuning. > > > I've read papers on the subject, but I am having difficulties building > a > > > "workable intuition", so I turn to the group. > > > > > > Here's what I think I understand, and I respectfully ask for > corrections > > if > > > I am way off base here.. > > > > > > Spin-exchange in a hydrogen maser happens when two atoms collide, and > > > exchange spin, as it were.. (Hazy on the details here..) The number of > > > spin-exchange collisions is directly proportional to the density of > atoms > > > in the cavity. These collisions *will* happen, but is a problem in > > hydrogen > > > masers for two reasons: 1) it takes away energy from the cavity, > > resulting > > > in lower signal output power, which degrades stability, and, 2) more > > > significantly, it results in a frequency shift. > > > > > > The frequency shift, as far as I can gather, is directly related to the > > > cavity resonant frequency - there is no way to *stop* spin exchange > > taking > > > place (apart from reducing the hydrogen density to a level where > > collisions > > > are rare, in which case the density will be too low for oscillation to > > take > > > place), but it is possible to reduce the impact the spin exchange has > on > > > the output frequency. > > > > > > While the resonant frequency obviously influences the output power of > the > > > maser cavity, the "mistuning" of the cavity also increases the effect > > spin > > > exchange has. In other words, in a perfectly tuned cavity, spin > exchange > > > does not result in a frequency shift. In a badly tuned cavity, > increasing > > > or decreasing the hydrogen flux (thereby increasing or decreasing the > > > number of collisions taking place) results in a corresponding > > > increase/decrease of the output frequency. Since the cavity ages, and > the > > > cavity resonant frequency follows that aging, the long term stability > of > > > the maser is degraded unless the aging can be compensated for. Which is > > > what cavity auto-tuning is all about. > > > > > > From my understanding, there are a few ways to implement cavity > > > auto-tuning: > > > 1. From the above, it follows that a modulation of the hydrogen flux > > into a > > > mis-tuned cavity will result in a frequency shift following the > > modulation > > > frequency. Using a stable reference, this shift can be measured, and > > > corrections can be made to the cavity varactor voltage. Once the output > > > frequency no longer shifts in response to the changes in hydrogen flux, > > the > > > cavity is correctly tuned. > > > > > > 2. It is also possible to modulate the cavity varactor voltage. By > > > measuring the output power of the cavity, an error signal can be > obtained > > > and used to correct the average varactor voltage. A square wave of i.e. > > > 100hz, centered on the approximate correct varactor voltate is put in > the > > > varactor, and cavity output power is measured. If the output power > > measured > > > on the "low" of the square wave is lower than the signal measured when > > the > > > "h
[time-nuts] Spin exchange tuning
Ole, Spin exchange tuning for a classic (non-autotuned) Maser is performed to put the cavity to the frequency that corresponds to the point that eliminates the frequency shift caused by changes in the Hydrogen flux. This enhances the short term stability at short time scales. This tunes the cavity OFF of resonance by a small amount! The procedure is to plot the Maser frequency at a few different cavity tuning voltages at one pressure and repeat it for another pressure. Plotting these points against frequency gives you two lines that intersect at the spin exchange tuning point. You then set the cavity tuning voltage to correspond to that spot on the graph. There is a major problem in this however. You need a 2nd Maser as the reference source as you need 1X10-14th resolution at 100 Seconds! On the classic Maser you would repeat this at some interval, Months to years to maintain your tuning point. (some applications can get by without ever doing the Spin exchange tuning!) On an autotuned Maser you still need to determine the point and a corresponding offset to be applied to the servo circuit, once established the servo can be turned on to maintain the tuning at the correct point. (Just servoing the cavity to the peak of the response will NOT put you at the spin exchange tuning point! ) On the EFOS2 Maser that lives here I have never completed the spin exchange tuning. (No 2nd Maser!!!) However for the stuff I do, measuring AD of precision standards, the Maser has performed admirably for 9 years now. I have been planning to try a different method to do the spin exchange tuning that would not require the 2nd Maser. If it works out I will let you know. Cheers, Corby ___ 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] Hydrogen maser spin exchange
There is indeed a quad- or hexa-pole state selection magnet between the dissociator and the cavity, required to select the atoms of the correct state to allow a population inversion resulting in oscillation. My understanding is that the spin-exchange of interest takes place between atoms already bouncing around inside the cavity - having passed that particular obstacle. And while on that subject, if anyone could elaborate on the difference between the two (quad or hexa-pole), that would be interesting. I have not found a clear explanation for why one might choose one over the other. Ole On Fri, Jun 17, 2016 at 11:35 PM, paul swed wrote: > Ole, > Quite looking forward to the replies. Though no intention to own a maser > currently. > I thought there was a method of rejecting or reducing types of spin. > Therefore reducing the impact you mention. Essentially a state selector. > Pretty sure that thought will get corrected pretty quickly. > Regards > Paul > WB8TSL > > On Fri, Jun 17, 2016 at 3:33 PM, Ole Petter Ronningen < > opronnin...@gmail.com > > wrote: > > > Hi. Apologies for a long post. > > > > I'm trying to read up on the "care and feeding of hydrogen masers". While > > they are conceptually simple from a distance, there's quite a bit going > on > > in the quantum mechanics department when looked at up close. Somewhat > > frustratingly, I am not mentally equipped to really grasp the finer (or > > even coarser) points of that particular department. The topic of this > post > > is the concept of spin exchange, and it's relation to cavity (auto) > tuning. > > I've read papers on the subject, but I am having difficulties building a > > "workable intuition", so I turn to the group. > > > > Here's what I think I understand, and I respectfully ask for corrections > if > > I am way off base here.. > > > > Spin-exchange in a hydrogen maser happens when two atoms collide, and > > exchange spin, as it were.. (Hazy on the details here..) The number of > > spin-exchange collisions is directly proportional to the density of atoms > > in the cavity. These collisions *will* happen, but is a problem in > hydrogen > > masers for two reasons: 1) it takes away energy from the cavity, > resulting > > in lower signal output power, which degrades stability, and, 2) more > > significantly, it results in a frequency shift. > > > > The frequency shift, as far as I can gather, is directly related to the > > cavity resonant frequency - there is no way to *stop* spin exchange > taking > > place (apart from reducing the hydrogen density to a level where > collisions > > are rare, in which case the density will be too low for oscillation to > take > > place), but it is possible to reduce the impact the spin exchange has on > > the output frequency. > > > > While the resonant frequency obviously influences the output power of the > > maser cavity, the "mistuning" of the cavity also increases the effect > spin > > exchange has. In other words, in a perfectly tuned cavity, spin exchange > > does not result in a frequency shift. In a badly tuned cavity, increasing > > or decreasing the hydrogen flux (thereby increasing or decreasing the > > number of collisions taking place) results in a corresponding > > increase/decrease of the output frequency. Since the cavity ages, and the > > cavity resonant frequency follows that aging, the long term stability of > > the maser is degraded unless the aging can be compensated for. Which is > > what cavity auto-tuning is all about. > > > > From my understanding, there are a few ways to implement cavity > > auto-tuning: > > 1. From the above, it follows that a modulation of the hydrogen flux > into a > > mis-tuned cavity will result in a frequency shift following the > modulation > > frequency. Using a stable reference, this shift can be measured, and > > corrections can be made to the cavity varactor voltage. Once the output > > frequency no longer shifts in response to the changes in hydrogen flux, > the > > cavity is correctly tuned. > > > > 2. It is also possible to modulate the cavity varactor voltage. By > > measuring the output power of the cavity, an error signal can be obtained > > and used to correct the average varactor voltage. A square wave of i.e. > > 100hz, centered on the approximate correct varactor voltate is put in the > > varactor, and cavity output power is measured. If the output power > measured > > on the "low" of the square wave is lower than the signal measured when > the > > "high", lower the offset by some mV, and vice versa. Suitable filtering > > would of course be required. > > > > The idea is that this method should not result in appreciable degradation > > of the short/medium term stability of the maser, because the frequency of > > the atoms interacting with the electromagnetic field in the maser cavity > > takes time to respond to the changes in the resonant frequency, but the > > output power responds "instantly". (Hazy on those details as well..) By > > modul
[time-nuts] For all : Makes for interesting reading
_http://www.microwavejournal.com/articles/26593-m%C3%B6bius-metamaterial-ins pired-signal-sources-and-sensors_ (http://www.microwavejournal.com/articles/26593-möbius-metamaterial-inspired-signal-sources-and-sensors) Ulrich ___ 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] Hydrogen maser spin exchange
Ole, Quite looking forward to the replies. Though no intention to own a maser currently. I thought there was a method of rejecting or reducing types of spin. Therefore reducing the impact you mention. Essentially a state selector. Pretty sure that thought will get corrected pretty quickly. Regards Paul WB8TSL On Fri, Jun 17, 2016 at 3:33 PM, Ole Petter Ronningen wrote: > Hi. Apologies for a long post. > > I'm trying to read up on the "care and feeding of hydrogen masers". While > they are conceptually simple from a distance, there's quite a bit going on > in the quantum mechanics department when looked at up close. Somewhat > frustratingly, I am not mentally equipped to really grasp the finer (or > even coarser) points of that particular department. The topic of this post > is the concept of spin exchange, and it's relation to cavity (auto) tuning. > I've read papers on the subject, but I am having difficulties building a > "workable intuition", so I turn to the group. > > Here's what I think I understand, and I respectfully ask for corrections if > I am way off base here.. > > Spin-exchange in a hydrogen maser happens when two atoms collide, and > exchange spin, as it were.. (Hazy on the details here..) The number of > spin-exchange collisions is directly proportional to the density of atoms > in the cavity. These collisions *will* happen, but is a problem in hydrogen > masers for two reasons: 1) it takes away energy from the cavity, resulting > in lower signal output power, which degrades stability, and, 2) more > significantly, it results in a frequency shift. > > The frequency shift, as far as I can gather, is directly related to the > cavity resonant frequency - there is no way to *stop* spin exchange taking > place (apart from reducing the hydrogen density to a level where collisions > are rare, in which case the density will be too low for oscillation to take > place), but it is possible to reduce the impact the spin exchange has on > the output frequency. > > While the resonant frequency obviously influences the output power of the > maser cavity, the "mistuning" of the cavity also increases the effect spin > exchange has. In other words, in a perfectly tuned cavity, spin exchange > does not result in a frequency shift. In a badly tuned cavity, increasing > or decreasing the hydrogen flux (thereby increasing or decreasing the > number of collisions taking place) results in a corresponding > increase/decrease of the output frequency. Since the cavity ages, and the > cavity resonant frequency follows that aging, the long term stability of > the maser is degraded unless the aging can be compensated for. Which is > what cavity auto-tuning is all about. > > From my understanding, there are a few ways to implement cavity > auto-tuning: > 1. From the above, it follows that a modulation of the hydrogen flux into a > mis-tuned cavity will result in a frequency shift following the modulation > frequency. Using a stable reference, this shift can be measured, and > corrections can be made to the cavity varactor voltage. Once the output > frequency no longer shifts in response to the changes in hydrogen flux, the > cavity is correctly tuned. > > 2. It is also possible to modulate the cavity varactor voltage. By > measuring the output power of the cavity, an error signal can be obtained > and used to correct the average varactor voltage. A square wave of i.e. > 100hz, centered on the approximate correct varactor voltate is put in the > varactor, and cavity output power is measured. If the output power measured > on the "low" of the square wave is lower than the signal measured when the > "high", lower the offset by some mV, and vice versa. Suitable filtering > would of course be required. > > The idea is that this method should not result in appreciable degradation > of the short/medium term stability of the maser, because the frequency of > the atoms interacting with the electromagnetic field in the maser cavity > takes time to respond to the changes in the resonant frequency, but the > output power responds "instantly". (Hazy on those details as well..) By > modulating the cavity varactor voltage (much) faster that the time constant > of the maser cavity, the modulation is effectively filtered out. > > I am very interested in this method, as it seems to me that it would be > easy (feasible) to retrofit this to older masers never equipped with cavity > auto tuning. > > There is at least one more way, which involves injecting a signal into the > maser cavity through a second coupling loop. At least one vendor I know of > does this in their newest design. I do not understand even the basics of > this method. > > Any insights and/or corrections of my understanding is most welcome. > > Thanks, > Ole > ___ > 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] GPS assisted 10 MHz frequency reference
This looks a lot like my initial GPSDO try. I didn’t create an account on that site, so I couldn’t look at the full schematics, but from the text description, it looks like they’re using 100 second sampling of whole cycle counts. This worked ok, but the addition of the phase discriminator system had a huge impact - more than I even thought possible at the time. > On Jun 17, 2016, at 8:10 AM, Gregory Beat wrote: > > Elector Labs (Netherlands publisher), June 14,2016 > GPS assisted 10 MHz frequency reference > https://www.elektormagazine.com/news/build-a-high-precision-10-mhz-frequency-reference? > -- > > Sent from iPad Air > ___ > 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] Hydrogen maser spin exchange
Hi. Apologies for a long post. I'm trying to read up on the "care and feeding of hydrogen masers". While they are conceptually simple from a distance, there's quite a bit going on in the quantum mechanics department when looked at up close. Somewhat frustratingly, I am not mentally equipped to really grasp the finer (or even coarser) points of that particular department. The topic of this post is the concept of spin exchange, and it's relation to cavity (auto) tuning. I've read papers on the subject, but I am having difficulties building a "workable intuition", so I turn to the group. Here's what I think I understand, and I respectfully ask for corrections if I am way off base here.. Spin-exchange in a hydrogen maser happens when two atoms collide, and exchange spin, as it were.. (Hazy on the details here..) The number of spin-exchange collisions is directly proportional to the density of atoms in the cavity. These collisions *will* happen, but is a problem in hydrogen masers for two reasons: 1) it takes away energy from the cavity, resulting in lower signal output power, which degrades stability, and, 2) more significantly, it results in a frequency shift. The frequency shift, as far as I can gather, is directly related to the cavity resonant frequency - there is no way to *stop* spin exchange taking place (apart from reducing the hydrogen density to a level where collisions are rare, in which case the density will be too low for oscillation to take place), but it is possible to reduce the impact the spin exchange has on the output frequency. While the resonant frequency obviously influences the output power of the maser cavity, the "mistuning" of the cavity also increases the effect spin exchange has. In other words, in a perfectly tuned cavity, spin exchange does not result in a frequency shift. In a badly tuned cavity, increasing or decreasing the hydrogen flux (thereby increasing or decreasing the number of collisions taking place) results in a corresponding increase/decrease of the output frequency. Since the cavity ages, and the cavity resonant frequency follows that aging, the long term stability of the maser is degraded unless the aging can be compensated for. Which is what cavity auto-tuning is all about. >From my understanding, there are a few ways to implement cavity auto-tuning: 1. From the above, it follows that a modulation of the hydrogen flux into a mis-tuned cavity will result in a frequency shift following the modulation frequency. Using a stable reference, this shift can be measured, and corrections can be made to the cavity varactor voltage. Once the output frequency no longer shifts in response to the changes in hydrogen flux, the cavity is correctly tuned. 2. It is also possible to modulate the cavity varactor voltage. By measuring the output power of the cavity, an error signal can be obtained and used to correct the average varactor voltage. A square wave of i.e. 100hz, centered on the approximate correct varactor voltate is put in the varactor, and cavity output power is measured. If the output power measured on the "low" of the square wave is lower than the signal measured when the "high", lower the offset by some mV, and vice versa. Suitable filtering would of course be required. The idea is that this method should not result in appreciable degradation of the short/medium term stability of the maser, because the frequency of the atoms interacting with the electromagnetic field in the maser cavity takes time to respond to the changes in the resonant frequency, but the output power responds "instantly". (Hazy on those details as well..) By modulating the cavity varactor voltage (much) faster that the time constant of the maser cavity, the modulation is effectively filtered out. I am very interested in this method, as it seems to me that it would be easy (feasible) to retrofit this to older masers never equipped with cavity auto tuning. There is at least one more way, which involves injecting a signal into the maser cavity through a second coupling loop. At least one vendor I know of does this in their newest design. I do not understand even the basics of this method. Any insights and/or corrections of my understanding is most welcome. Thanks, Ole ___ 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] Elektor GPSDO
Hi What he has done is best termed an FLL approach. A PLL is indeed a possible solution. Even with a FLL, he has quickly run into the fundamental problem of being able to measure the result. Without that, he is dead in the water. Optimization is the key next step. To do that you need data as you modify things. Bob > On Jun 17, 2016, at 10:18 AM, Clint Jay wrote: > > Just throwing this into the lion's den. > > https://www.elektormagazine.com/labs/gps-assisted-10-mhz-frequency-reference > ___ > 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] Elektor GPSDO
Just throwing this into the lion's den. https://www.elektormagazine.com/labs/gps-assisted-10-mhz-frequency-reference ___ 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] GPS assisted 10 MHz frequency reference
Elector Labs (Netherlands publisher), June 14,2016 GPS assisted 10 MHz frequency reference https://www.elektormagazine.com/news/build-a-high-precision-10-mhz-frequency-reference? -- Sent from iPad Air ___ 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] Improving on basic L1 timing
Hi Michael, Thanks, that plot and the info gives a useful comparison. I think in light of everything, doing some tests with a generally upgraded setup would be the way to go for now. There would actually be several rubidiums, although initially with a bit of cheating - 1 counter, a 10PPS reference and a multiplexer. Later hopefully a separate TDC's though. I'm up in the north of Scotland, so unfortunately not much in the way of reference stations etc nearby, which does rule out some options. Angus. On Thu, 16 Jun 2016 17:53:39 +1000, you wrote: >I promised a plot and here it is. > >In a bit more detail: > >(a) "GPSCV 800 km baseline" is single-frequency transfer between two >5071s with standard tubes. I've divided by sqrt(2), assuming both >clocks contribute equally to TOTDEV. > >(b) "std tube spec" is from the 5071 manual, for comparison > >(c) "sawtooth corrected pps" is Javad receiver + std tube 5071 > >(d) "PPP solution" is precise point positioning (carrier phase) clock >solution, setup (c) but with a receiver which takes external 1 pps and >10 MHz. The win here is that measurements are now made wrt your clock >with very high resolution (ten ps or so for carrier phase) and you >don't have the sawtooth correction introducing noise. >The reference timescale in the PPP solution is a zero-weighted mean of >visible SV clocks. > >(e) "CGTTS" is single frequency, modeled ionosphere in CGGTTS files, setup (c) > >As you can see, you get a factor of two going from the >sawtooth-corrected PPS to CGGTTS. You can get rid of some >ionosphere-induced stability in a common view comparison. > >You get another factor of two going to a carrier-phase time solution. > >So as I said, you have to work hard/spend big to get a relatively >modest improvement. > >Hope this helps. > >Cheers >Michael > > > > > >On Wed, Jun 15, 2016 at 4:21 PM, Michael Wouters > wrote: >> I should have added, if you do all of the above, the improvement in >> stability over just using a sawtooth-corrected PPS is not all that >> spectacular, a factor of two or three. I'll post a plot of some data >> tomorrow. >> >> Cheers >> Michael. >> >> >> On Wednesday, 15 June 2016, Michael Wouters >> wrote: >>> >>> If you followed the link to www.openttp.org and are wondering where the >>> software is, follow the link on the home page to GitHub and then look in the >>> Develop branch. The ublox branch is for the new '8' series receivers. >>> >>> Cheers >>> Michael >>> >>> On Tuesday, 14 June 2016, Michael Wouters >>> wrote: Hello Angus If you have 3 rubidiums of similar stability + 3 counters, you could do a 3-cornered hat. Otherwise, GPS common view to a better clock may be an option. If you are reasonably close to a national standards lab, you might be able to use their time-transfer files to compare your rubidiums with their time scale - not everyone makes them publically available though. Otherwise, if there is an IGS station near you, you could use the station RINEX files and IGS clock solutions which are freely available. Many IGS stations have a H-maser as the local clock. But it may be just as good to simply use the comparison with GPS time inherent in the time-transfer file. The advantage of generating a time-transfer file is the possibility of then improving upon the various corrections broadcast by GPS, effectively repeating what the GPS receiver does to generate its realization of GPS time but with better data. With post-processing, the short to medium term (less than 1 day) performance can be improved a bit as you are suggesting when you referred to "atmospheric issues". Improved ionospheric models are available or if there is an IGS station nearby, for example, the measured ionosphere could be used. Other improvements can be had with good antenna coordinates and using final orbits in the processing. What can you use for your time-transfer receiver ? Some low-cost single-frequency receivers are suitable eg the Trimble Resolution T. The essential requirement is the availability of raw code measurements - with these you can generate CGGTTS time-transfer files and/or RINEX observation files. At least part of the software infrastructure to do this exists: the OpenTTP project (www.openttp.org) has software for CGGTTS and RINEX file generation for a few older,single frequency receivers, with support for some other,current receivers under active development. There is other software around, but it is orientated towards dual frequency receivers and carrier phase processing. Although it would be relatively straightforward to hack in use of improved ionosphere, using final orbits is a bit harder since these are not parameterized the same way as the broadcast orbits. Maybe someone on time-nuts has software to do the convers
[time-nuts] TU60-D120-131 Specs....?
BTW, the Jupiter receivers have a command that can configure the 1PPS output to 100PPS. I got in some V.KSEL Sirf and Ublox receiver modules today and taught Lady Heather to speak SIRF binary. Kind of a waste... SIRF does not give give you any control over the 1PPS signal and the message that gave some 1PPS info is no longer supported. Also no position hold mode, survey mode, etc. But I guess one can't expect too much from an $8 GPS receiver (with antenna). ___ 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] TU60-D120-131 Specs....?
Thanks, sounds like the TU60-D120 series has a completely different firmware numbering system than the TU30-140/410 in the link below. I ordered one and hopefully it will be fine. Suspect they are newer versions than the TU30's http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm -=Bryan=- > From: hol...@hotmail.com > To: time-nuts@febo.com > Date: Thu, 16 Jun 2016 01:02:05 + > Subject: [time-nuts] TU60-D120-131 Specs? > > From the Zodiac binary message, mine reports 12 channels, software ver > 93.07 from 01/16/04, hardware options 5843 (hex). > -- > > I think the firmware version is in one of the NMEA commands. > > > ___ > 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.
