[time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
All the GPS receivers that I have tested get the time message out within a second (either before or after depending upon the model) of the 1PPS pulse... except the Jupiter receivers. For those, the last byte of the time messages arrives 1.25 seconds after the 1PPS pulse. This might cause some problems if the NTP software is not aware of this "feature" of the Jupiter receivers. --- > I think the Jupiter has a jitter of around 15ns, not sure what the Jupiter-T > specs but I believe 10-20ns. ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Hi The target application is NTP with the PPS probably coming in via a RS-232 serial port. Anything that jitters less than 200 ns is probably going to look “same / same “. Bob > On Jan 26, 2018, at 6:48 PM, Bryan _ <bpl...@outlook.com> wrote: > > Thanks, forgot I have a Jupiter-T (D-120?) in my parts box , on that note out > of the two Trimble vs Jupiter-T. I think the Jupiter has a jitter of around > 15ns, not sure what the Jupiter-T specs but I believe 10-20ns. > > > -=Bryan=- > > > > From: time-nuts <time-nuts-boun...@febo.com> on behalf of Mark Sims > <hol...@hotmail.com> > Sent: January 26, 2018 3:00 PM > To: time-nuts@febo.com > Subject: [time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox / > other?) > > The Trimble ... it is a newer design.. The Oncore is getting rather long in > the tooth and some have GPS week rollover issues. The Trimble has a higher > clock rate and less 1PPS jitter. > > > >> Which would be the preference as timing receiver Motorola Oncore or a >> Trimble Resolution T ? > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > time-nuts Info Page - American Febo > Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> > www.febo.com > time-nuts is a low volume, high SNR list for the discussion of precise time > and frequency measurement and related topics. To see the collection of prior > postings to ... > > > > and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Thanks, forgot I have a Jupiter-T (D-120?) in my parts box , on that note out of the two Trimble vs Jupiter-T. I think the Jupiter has a jitter of around 15ns, not sure what the Jupiter-T specs but I believe 10-20ns. -=Bryan=- From: time-nuts <time-nuts-boun...@febo.com> on behalf of Mark Sims <hol...@hotmail.com> Sent: January 26, 2018 3:00 PM To: time-nuts@febo.com Subject: [time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox / other?) The Trimble ... it is a newer design.. The Oncore is getting rather long in the tooth and some have GPS week rollover issues. The Trimble has a higher clock rate and less 1PPS jitter. > Which would be the preference as timing receiver Motorola Oncore or a Trimble > Resolution T ? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> www.febo.com time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
The Trimble ... it is a newer design.. The Oncore is getting rather long in the tooth and some have GPS week rollover issues. The Trimble has a higher clock rate and less 1PPS jitter. > Which would be the preference as timing receiver Motorola Oncore or a Trimble > Resolution T ? ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Hi Which ever you can get for the least money. Anything much over $10 is probably “over budget”. Bob > On Jan 26, 2018, at 3:57 PM, Bryan _ <bpl...@outlook.com> wrote: > > Which would be the preference as timing receiver Motorola Oncore or a Trimble > Resolution T ? > > > -=Bryan=- > > > > From: time-nuts <time-nuts-boun...@febo.com> on behalf of Pete Stephenson > <p...@heypete.com> > Sent: January 26, 2018 12:48 PM > To: Paride Legovini; Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Suggestion for a timing GPS receiver (Trimble / > Ublox / other?) > > On 1/22/2018 4:38 PM, Paride Legovini via time-nuts wrote: >> Dear fellow nuts, >> >> I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm >> looking for a good and possibly affordable timing GPS receiver. > > As others have pointed out, NTP over the internet isn't usually more > accurate than several tens of microseconds, so you have a lot of > flexibility in the receiver you choose. > > If you need something that's simple to interface, has RS-232 polarity > signals, and is generally plug-and-play, the Garmin GPS 18x LVC is a > good choice. It's robust, compact, and easy to wire to whatever device > you want: in my case, I use a USB-A male plug connected to a USB port on > my time server to provide the required 5V power and have the serial and > PPS lines connected to the server's hardware serial port. > > It's not strictly a timing receiver with a position hold mode, but it > does produce a PPS output +/- 1 microsecond, and can do "position > averaging" so it doesn't drift around more than a few meters when > stationary. > > It can output data in either NMEA format or the Garmin binary format, > which is well-documented and supported by GPSd. Garmin's made the > receiver for many years and has generally worked out the kinks with a > bunch of firmware updates over the years. > > Another alternative is the rather older Motorola Oncore UT+ receivers > one can get on eBay for about $15 USD. No longer supported by the > manufacturer and with hardware of unknown age, it might not be the best > choice for critical systems. Still, they're true timing receivers with > sawtooth correction, are easy to power with 5V, output TTL serial (so a > MAX(3)232 can easily convert the data to RS-232 polarity) and a PPS > signal, and are well-supported by NTPd. The Oncore driver for NTPd is a > bit chatty in terms of what it logs every second, but that's easy enough > to deal with. They're cheap enough to get a few to play with. > > 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 > > time-nuts Info Page - American Febo > Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> > www.febo.com > time-nuts is a low volume, high SNR list for the discussion of precise time > and frequency measurement and related topics. To see the collection of prior > postings to ... > > > > and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Which would be the preference as timing receiver Motorola Oncore or a Trimble Resolution T ? -=Bryan=- From: time-nuts <time-nuts-boun...@febo.com> on behalf of Pete Stephenson <p...@heypete.com> Sent: January 26, 2018 12:48 PM To: Paride Legovini; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox / other?) On 1/22/2018 4:38 PM, Paride Legovini via time-nuts wrote: > Dear fellow nuts, > > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. As others have pointed out, NTP over the internet isn't usually more accurate than several tens of microseconds, so you have a lot of flexibility in the receiver you choose. If you need something that's simple to interface, has RS-232 polarity signals, and is generally plug-and-play, the Garmin GPS 18x LVC is a good choice. It's robust, compact, and easy to wire to whatever device you want: in my case, I use a USB-A male plug connected to a USB port on my time server to provide the required 5V power and have the serial and PPS lines connected to the server's hardware serial port. It's not strictly a timing receiver with a position hold mode, but it does produce a PPS output +/- 1 microsecond, and can do "position averaging" so it doesn't drift around more than a few meters when stationary. It can output data in either NMEA format or the Garmin binary format, which is well-documented and supported by GPSd. Garmin's made the receiver for many years and has generally worked out the kinks with a bunch of firmware updates over the years. Another alternative is the rather older Motorola Oncore UT+ receivers one can get on eBay for about $15 USD. No longer supported by the manufacturer and with hardware of unknown age, it might not be the best choice for critical systems. Still, they're true timing receivers with sawtooth correction, are easy to power with 5V, output TTL serial (so a MAX(3)232 can easily convert the data to RS-232 polarity) and a PPS signal, and are well-supported by NTPd. The Oncore driver for NTPd is a bit chatty in terms of what it logs every second, but that's easy enough to deal with. They're cheap enough to get a few to play with. 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 time-nuts Info Page - American Febo Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> www.febo.com time-nuts is a low volume, high SNR list for the discussion of precise time and frequency measurement and related topics. To see the collection of prior postings to ... 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
On 1/22/2018 4:38 PM, Paride Legovini via time-nuts wrote: > Dear fellow nuts, > > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. As others have pointed out, NTP over the internet isn't usually more accurate than several tens of microseconds, so you have a lot of flexibility in the receiver you choose. If you need something that's simple to interface, has RS-232 polarity signals, and is generally plug-and-play, the Garmin GPS 18x LVC is a good choice. It's robust, compact, and easy to wire to whatever device you want: in my case, I use a USB-A male plug connected to a USB port on my time server to provide the required 5V power and have the serial and PPS lines connected to the server's hardware serial port. It's not strictly a timing receiver with a position hold mode, but it does produce a PPS output +/- 1 microsecond, and can do "position averaging" so it doesn't drift around more than a few meters when stationary. It can output data in either NMEA format or the Garmin binary format, which is well-documented and supported by GPSd. Garmin's made the receiver for many years and has generally worked out the kinks with a bunch of firmware updates over the years. Another alternative is the rather older Motorola Oncore UT+ receivers one can get on eBay for about $15 USD. No longer supported by the manufacturer and with hardware of unknown age, it might not be the best choice for critical systems. Still, they're true timing receivers with sawtooth correction, are easy to power with 5V, output TTL serial (so a MAX(3)232 can easily convert the data to RS-232 polarity) and a PPS signal, and are well-supported by NTPd. The Oncore driver for NTPd is a bit chatty in terms of what it logs every second, but that's easy enough to deal with. They're cheap enough to get a few to play with. 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] Suggestion for a timing GPS receiver (Trimble / Ublox /other?)
On Tue, 23 Jan 2018 13:33:08 -0500 ewkehren via time-nutswrote: > The cheapest is not a 5T there are many 6 and 7 for $ 10. T gives you > nothing unless you have saw tooth correction It also gives additional performance when your skyview is very bad. If you see only a small portion of the sky and only have 1-2 satellites most of the time, then the position hold mode is the difference between >1µs jitter and <100ns jitter, as Said Jackson noted a few years ago. Attila Kinali -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox /other?)
Hi The T software does support locked position. If your antenna location is so bad that this is of any use …. move the antenna. I can get full coverage with a modern uBlox from a chair in the family room. A bit more information: If you are in an “urban canyon” (or maybe a real canyon) then indeed you can have some issues. In a normal suburban or urban setting, you should be able to lock to > 4 sat’s pretty much 100% of the time. With the newer modules (the 8 series) able to use multiple systems at one time, that all becomes even more true. Any timing errors you *might* see hopping from system to system are way below what would matter for stratum 1 NTP. As noted earlier, if this stuff matters to you, setting up three NTP servers on your LAN is a really good idea. Run them all off of GPS and all off of independent antennas. If each antenna has it’s own “view” then your odds get even better on being able to keep it all going fine. The GPS part of that is maybe $10 vs $30. The servers are whatever you are paying for good single board computers these days. When they go on sale, that could easily be < $100 for three of them. Bob > On Jan 23, 2018, at 2:22 PM, Hal Murraywrote: > > > time-nuts@febo.com said: >> The cheapest is not a 5T there are many 6 and 7 for $ 10. T gives you >> nothing unless you have saw tooth correctionBerrt Kehren > > Does the T firmware also support known-position mode where it can operate on > only one satellite? > > > -- > These are my opinions. I hate spam. > > > > ___ > 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] Suggestion for a timing GPS receiver (Trimble / Ublox /other?)
time-nuts@febo.com said: > The cheapest is not a 5T there are many 6 and 7 for $ 10. T gives you > nothing unless you have saw tooth correctionBerrt Kehren Does the T firmware also support known-position mode where it can operate on only one satellite? -- These are my opinions. I hate spam. ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox /other?)
The cheapest is not a 5T there are many 6 and 7 for $ 10. T gives you nothing unless you have saw tooth correctionBerrt Kehren Sent from my Galaxy Tab® A Original message From: Paride Legovini via time-nuts <time-nuts@febo.com> Date: 1/23/18 12:24 PM (GMT-05:00) To: time-nuts@febo.com Subject: Re: [time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox /other?) On 2018-01-23 08:11, David J Taylor via time-nuts wrote: > Dear fellow nuts, > > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. > [] > Am I overlooking something or missing interesting options? > > Cheers, > > Paride IZ3SUS > > > Paride, > > As Mark notes, you don't need a timing precision GPS receiver for NTP > > [...] > > Stephen mentioned the newer series-8 ublox modules. These are indeed > excellent (and can receiver Galileo too) Thanks David and thanks to you all for the advice you gave me, I carefully read all your replies and learned quite a few things. At this point I think I'll start tinkering with the cheapest module I can get (and it will probably be a LEA-5T). Once I'll have everything set up, if I'll be still having fun, I'll consider buying a newer module, probably from the Ublox M8 family. We will see. 73, Paride ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox /other?)
On 2018-01-23 08:11, David J Taylor via time-nuts wrote: > Dear fellow nuts, > > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. > [] > Am I overlooking something or missing interesting options? > > Cheers, > > Paride IZ3SUS > > > Paride, > > As Mark notes, you don't need a timing precision GPS receiver for NTP > > [...] > > Stephen mentioned the newer series-8 ublox modules. These are indeed > excellent (and can receiver Galileo too) Thanks David and thanks to you all for the advice you gave me, I carefully read all your replies and learned quite a few things. At this point I think I'll start tinkering with the cheapest module I can get (and it will probably be a LEA-5T). Once I'll have everything set up, if I'll be still having fun, I'll consider buying a newer module, probably from the Ublox M8 family. We will see. 73, Paride ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox /other?)
Dear fellow nuts, I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm looking for a good and possibly affordable timing GPS receiver. [] Am I overlooking something or missing interesting options? Cheers, Paride IZ3SUS Paride, As Mark notes, you don't need a timing precision GPS receiver for NTP, a standard position GPS receiver is quite good enough providing it has a PPS output. If you're thinking Raspberry Pi, there are some ready-made modules such as: https://store.uputronics.com/index.php?route=product/product_id=81 Stephen mentioned the newer series-8 ublox modules. These are indeed excellent (and can receiver Galileo too), but a number of vendors advertising series-8 modules (on both eBay and Amazon) are using remarked series 5 or 6 chips without the series-8 functions. Use the ublox u-center program to check anything you buy. From Amazon, at least, I got an immediate refund. 73, David GM8ARV -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Paride Legovini via time-nuts writes: > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. Unless you plan to use the timing receiver for some other function, it really is overkill for the purpose of setting up an NTP server and otherwise also requires you to set up a proper antenna in order to benefit from the extra precision. > Am I overlooking something or missing interesting options? I think that setting up at least three "good enough" NTP stratum-1 servers in your network gets you much better synchronization than trying to get a single one more precise. To that end, you can set one up for around $60 if you use a raspberryPi and a NavSpark mini w/ patch antenna (if you have reasonable reception with that). You'll find that the NTP clients will not see any measurable improvement once you have the NTP servers down below 10µs deviation and it's possible to get each individual server consistently below 1µs with a bit of care. Having at least three stratum-1 in your network will keep the clients synchronized correctly when inevitably one of the servers will have the occasional problem that makes its time wander off for a while. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ Factory and User Sound Singles for Waldorf Q+, Q and microQ: http://Synth.Stromeko.net/Downloads.html#WaldorfSounds ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Yo Paride! On Mon, 22 Jan 2018 16:38:01 +0100 Paride Legovini via time-nutswrote: > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. Before you bother looking at any GPS, you need to look at your server. Hardly any Intel CPU can give you time resolution much better than 200 nS on a PPS in. Raspberry Pi's actually have slightly better clock resolution than Intel parts, just under 190 nS. That resolution os worse than what you get out of any good modern GPS. By 'local resolution' I mean the shortest time interval you can read by repeatedly doing clock_systime() calls. clock_system() is is many key ntpd paths. The accuracy of your NTP server will be strongly affected by your server choice, and the cheap RasPi is often one of the best for the job. Fot $70 you can get a RasPi and a u-blox-8 hat. Add a few bits here and there and you have a nifty stratum 1. You'll find its harder than it looks to make a better NTP than that combo. Then, once you have a strong baseline, you can see what tricks you can do to improve on that. RGDS GARY --- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 g...@rellim.com Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin pgp_0UNQPV09D.pgp Description: OpenPGP digital signature ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
I put my layout for a GPS RS-232 level converter board up on OSHPARK's shared projects. It has places for mounting the Trimble Res-T, the Adafruit Ultimate GPS, and the CN06 (Ublox 6M). The RS-232 circuit has a selectable polarity 1PPS ouput. You can use a3.3V or 5V regulator or there is a jumper for providing the receiver with the raw input power. https://oshpark.com/shared_projects/YPvKgMYa ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
On Mon, 22 Jan 2018 16:38:01 +0100 Paride Legovini via time-nutswrote: > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. > > As far as I can tell there are a few common options. One is the Trimble > Resolution T (or SMT), that should be good and proven. The major > annoyance is converting the 3.3V TTL serial logic-level to RS232, but > should be doable with a MAX3232 and a few capacitors. > > Another option is this UBLOX LEA-5T: > > https://www.ebay.it/itm/291769145465 > > The seller advertises an RS232 output pin, but I'm not sure it's > actually available, and I'd need at least lines, one for the NMEA > strings and one for the 1PPS signal. So, even if a RS232 TX pin is > actually there, it is probably not enough to build a good reference > clock, and I'd still need to convert some TTL levels to RS232... > > Does anybody have experience with this receiver? > How does it compare to the Resolution T/SMT? For raw GPS PPS output, your performance is limited by multi-path and how much of the sky you see. If you have perfect conditions, I expect both to perform at the same level. Under not so perfect conditions, go for the LEA. I have here a Trimble UCCM and Oscilloquartz Star4 GPSDO (using a LEA-5T). Compared to the Star4, the UCCM is basically deaf. And mind you, the LEA-5 family came out somewhen around 2006, ie is already a more than 10 year old design and probably of the same age as the UCCM. The modern LEA's got a few dB better yet. For an NTP server, where you wont need anything better than 1µs resolution, I think one of the many 10-bucks ublox LEA/NEO boards that you can find on ebay are good enough (standard navigation receivers give you better than 100ns accuracy). If you still want to have a timing receiver, then go for one of the NEO-M8T, LEA-M8T or LEA-6T based boards. Be aware that the NEO modules do not have the circuit to provide power to the antenna, so it must be either passive or you need an external bias-T. The LEA's can provide up to 50mA (so no Zephyr!). If you want to step up your game and get even better stability, take one of the LEA based GPSDOs (like the Star4 mentioned above). Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Hi It is doubtful that the pc board has an RS-232 to TTL converter onboard. The module it’s self “talks” TTL levels rather than RS-232 levels. RS-232 to TTL adapters are dirt cheap and easy to find on eBay. Make sure you get one that has control lines along with the basic RX and TX functions. (You need to buffer the PPS signal). They also allow you to put in a “pulse stretcher” on the PPS if the default is to short for your computer. There is no value in a “timing” GPS vs a “normal” GPS for NTP. As long as you have a PPS output, you are good to go. As noted elsewhere, something like the more modern M8 series is just as cheap and will do a better job. Simply get any of the modules and an adapter. Hook them up and move on. Total cost should come in < $30 delivered. There are tons and tons of details on how do do all this in the archives. Bob > On Jan 22, 2018, at 10:38 AM, Paride Legovini via time-nuts >wrote: > > Dear fellow nuts, > > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. > > As far as I can tell there are a few common options. One is the Trimble > Resolution T (or SMT), that should be good and proven. The major > annoyance is converting the 3.3V TTL serial logic-level to RS232, but > should be doable with a MAX3232 and a few capacitors. > > Another option is this UBLOX LEA-5T: > > https://www.ebay.it/itm/291769145465 > > The seller advertises an RS232 output pin, but I'm not sure it's > actually available, and I'd need at least lines, one for the NMEA > strings and one for the 1PPS signal. So, even if a RS232 TX pin is > actually there, it is probably not enough to build a good reference > clock, and I'd still need to convert some TTL levels to RS232... > > Does anybody have experience with this receiver? > How does it compare to the Resolution T/SMT? > > Another option is the Trimble Thunderbolt. This seems to do exactly what > I need, but it costs at least ten times more than the other modules. > Beside coming with a ready to use RS232 port and a nice case, does it > have other advantages? > > Am I overlooking something or missing interesting options? > > Cheers, > > Paride IZ3SUS > ___ > 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Why not consider a more recent current UBlox module? e.g. the M8T https://www.u-blox.com/en/product/neolea-m8t-series A quick internet search will find several suppliers of ready made boards/modules... On 22/01/2018 15:38, Paride Legovini via time-nuts wrote: > Dear fellow nuts, > > I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm > looking for a good and possibly affordable timing GPS receiver. > > As far as I can tell there are a few common options. One is the Trimble > Resolution T (or SMT), that should be good and proven. The major > annoyance is converting the 3.3V TTL serial logic-level to RS232, but > should be doable with a MAX3232 and a few capacitors. > > Another option is this UBLOX LEA-5T: > > https://www.ebay.it/itm/291769145465 > > The seller advertises an RS232 output pin, but I'm not sure it's > actually available, and I'd need at least lines, one for the NMEA > strings and one for the 1PPS signal. So, even if a RS232 TX pin is > actually there, it is probably not enough to build a good reference > clock, and I'd still need to convert some TTL levels to RS232... > > Does anybody have experience with this receiver? > How does it compare to the Resolution T/SMT? > > Another option is the Trimble Thunderbolt. This seems to do exactly what > I need, but it costs at least ten times more than the other modules. > Beside coming with a ready to use RS232 port and a nice case, does it > have other advantages? > > Am I overlooking something or missing interesting options? > > Cheers, > > Paride IZ3SUS > ___ > 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. > -- Stephen Tompsett ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Paride The LEA-5T differs from other devices only that it has saw tooth information that can be used for correction or in a loop' I did a board and have one with variable delay using the 5T. Looking at the picture I do not even see an output for that information. Any later standard $10 module will be as good or better because he mentions 15 ns. What do you need and please also look at what GPS is able to do without ionospheric correction Bert In a message dated 1/22/2018 11:07:52 AM Eastern Standard Time, time-nuts@febo.com writes: Dear fellow nuts, I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm looking for a good and possibly affordable timing GPS receiver. As far as I can tell there are a few common options. One is the Trimble Resolution T (or SMT), that should be good and proven. The major annoyance is converting the 3.3V TTL serial logic-level to RS232, but should be doable with a MAX3232 and a few capacitors. Another option is this UBLOX LEA-5T: https://www.ebay.it/itm/291769145465 The seller advertises an RS232 output pin, but I'm not sure it's actually available, and I'd need at least lines, one for the NMEA strings and one for the 1PPS signal. So, even if a RS232 TX pin is actually there, it is probably not enough to build a good reference clock, and I'd still need to convert some TTL levels to RS232... Does anybody have experience with this receiver? How does it compare to the Resolution T/SMT? Another option is the Trimble Thunderbolt. This seems to do exactly what I need, but it costs at least ten times more than the other modules. Beside coming with a ready to use RS232 port and a nice case, does it have other advantages? Am I overlooking something or missing interesting options? Cheers, Paride IZ3SUS ___ 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] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)
Dear fellow nuts, I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm looking for a good and possibly affordable timing GPS receiver. As far as I can tell there are a few common options. One is the Trimble Resolution T (or SMT), that should be good and proven. The major annoyance is converting the 3.3V TTL serial logic-level to RS232, but should be doable with a MAX3232 and a few capacitors. Another option is this UBLOX LEA-5T: https://www.ebay.it/itm/291769145465 The seller advertises an RS232 output pin, but I'm not sure it's actually available, and I'd need at least lines, one for the NMEA strings and one for the 1PPS signal. So, even if a RS232 TX pin is actually there, it is probably not enough to build a good reference clock, and I'd still need to convert some TTL levels to RS232... Does anybody have experience with this receiver? How does it compare to the Resolution T/SMT? Another option is the Trimble Thunderbolt. This seems to do exactly what I need, but it costs at least ten times more than the other modules. Beside coming with a ready to use RS232 port and a nice case, does it have other advantages? Am I overlooking something or missing interesting options? Cheers, Paride IZ3SUS ___ 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.