oh wow, thanks. I'll try that. Also, I figured out that typing in "trimble thunderbolt" instead of "thunderbolt gps" gives me zero hits for phone... but fewer hits for the GPSDO too :(
On 8/19/2012 3:21 PM, Willy Willemse wrote: > Sarah, > > If you want to filter in ebay, you can use a"-" for a subject that you don't > want to see. It is the same syntax as you can use in a browser. > > Regards, > > Willy > > -----Oorspronkelijk bericht----- > Van: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Namens > time-nuts-requ...@febo.com > Verzonden: zondag 19 augustus 2012 19:07 > Aan: time-nuts@febo.com > Onderwerp: time-nuts Digest, Vol 97, Issue 48 > > Send time-nuts mailing list submissions to > time-nuts@febo.com > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > or, via email, send a message with subject or body 'help' to > time-nuts-requ...@febo.com > > You can reach the person managing the list at > time-nuts-ow...@febo.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of time-nuts digest..." > > > Today's Topics: > > 1. Re: L1 GPS timing signal(s) into local time on computer(s) > (Sarah White) > 2. Modern motherboard with RS232 port (Stan, W1LE) > 3. Re: L1 GPS timing signal(s) into local time on computer(s) > (KD0GLS) > 4. Embedded NTP servers? (Michael Tharp) > 5. Re: Modern motherboard with RS232 port (Chris Albertson) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 19 Aug 2012 10:41:39 -0400 > From: Sarah White <kuze...@gmail.com> > To: time-nuts@febo.com > Subject: Re: [time-nuts] L1 GPS timing signal(s) into local time on > computer(s) > Message-ID: <5030fb23.7040...@gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Ken: > >>From what I've read, most GPS modules which output PPS, the NMEA > sentence has the timestamp of the next, upcoming pulse. Regardless of > how the NMEA or other time data is, the PPS itself is only a guarantee > "this is the boundary for a second" and NTP documentation typically > recommends a second reference clock to "number the seconds" anyway. > > Everyone: > > Thanks everyone. I got many responses which confirm my initial > conclusions. I had trouble locating a GPS thunderbolt on ebay because > there is an HTC phone with "thunderbolt" in the name. (I got a few hits > for the GPS module, but there is no way to filter out "phones" or I > might just be bad at operating ebay) > > uhm... yeah. As someone pointed out. It is a total nightmare to figure > out which direction my GPS time is wandering, and finding the correct > offset. I'm just gonna give up on this USB module, and get a real one > with PPS > > Also, I really hate google's new "shopping" experience. They started > listing less content, and now push content from stores which charge 2-3 > times as much. > > As far as existing hardware goes, I don't have any slots free in my > desktop for a serial board... > > Despite the new "google shopping" headache, I was able to determine that > many "older" computers from the windows XP era which still have serial > ports, and are available refurbished from walmart of all the crazy > places. (most of the time, better price than the ones being pushed by > google shopping, and even have XP installed and a 1 year warranty) > > So no problem. I can source a suitable machine to run NTP, and for less > than $200, guaranteed. > > Will probably be using gentoo linux, as the default configuration does > NOT expect you to run any specific kernel. I can easily recompile > anything I need without breaking unusual, unforeseen dependencies. > (doesn't hurt that I've been using gentoo since the stage1 install was > preferred, all the way back to the GCC 2.x era) > > I'm really aiming to run a server which ONLY runs NTP, and at most 1 or > two other daemons (light duty on those) > > Thanks so much everyone. > > On 8/19/2012 7:11 AM, Ken Duffill wrote: >> Just one further question. >> >> When the pps input triggers, so my linux box knows a second has just >> ticked; is the time of that second the one the NMEA sentence has just >> sent, or will send next? >> >> Or to put it another way, when I receive an NMEA sentence is this the >> current time (as was when the sentence was constructed) or the time at >> the next PPS 'tick'? >> >> Thanks in advance. >> >> KenD >> >> On 19/08/12 11:23, Bill Dailey wrote: >>> I will jump in a bit. I, and many have been right where you are. You >>> are correct...USB is a no go for accurate time. Same on windows. So >>> you need a Linux box with serial port. Anything from a Beaglebone, >>> pandabox...or pc will work. You certainly need a gps with a pulse per >>> second output (most have) and you can wire that up to the appropriate >>> line on the serial cable or send to the target computer via gpio pin. >>> The pps thing is fairly simple really. If you are receiving gps data >>> via serial connection it takes a variable amount of time to get each >>> status report from the gps...list time etc etc in text format and >>> sends it repeatedly. This gets ntp to within a second or some >>> fraction thereof...the pps part refines that..no text or anything... >>> Just a one pulse per second separate from the gps info that acts as a >>> exclamation point to tell ntp "right here is the actual start of the >>> second!" alone the pps wouldn't be useful for time but with the time >>> info ntp already has from the nmea sentences it is priceless for >>> really precise time. That's about it. Once you have gps and pps >>> configured on Linux you should be in the sub 5 microsecond range. It >>> gets tricky getting better than that and you have to Ntpns and really >>> worry about hardware issues that affect precision (system clock >>> stability etc) but it can be done. >>> >>> Doc >>> KX0O >>> >>> Sent from my iPad >>> >>> On Aug 18, 2012, at 11:25 PM, Sarah White <kuze...@gmail.com> wrote: >>> >>>> Hi, this is my first post. >>>> >>>> First off. Windows 7 USB connection to the GPS (no serial ports / modern >>>> computer) and I'm pretty sure that is my main problem. >>>> >>>> Past few months, I've been trying to figure out my timing issues. Lots >>>> of reading & trying to figure out how to best configure everything. I'm >>>> typically still off (randomly) by 20-100 miliseconds. I'd like to at >>>> least get to within 50 microseconds (nanoseconds would be wonderful) >>>> >>>> 1) I need a computer with a serial port. The curent GPS module I'm using >>>> is INTERNALLY RS232 --> USB converter, and recognized by my windows 7 >>>> computer as: "Prolific USB-to-Serial Comm Port (COM3)" ... the latency >>>> and jitter is horrible, and both are seemingly random. >>>> >>>> 2) I need to run my stratum 1 clock (connected to the stratum 0 time >>>> source via old-school RS232 serial) on linux or a form of BSD with >>>> support for kernel timestamps, and a version of NTP with a driver to >>>> supports my reference clock... points 1 and 2 seem fine. >>>> >>>> 3) I'm clueless about mounting an antenna, running cable, grounding / >>>> lightning protection, etc... Really want an easy to install one. >>>> >>>> For software, I've used 4.2.6 (stable / production) as well as 4.2.7 >>>> (dev version) NTP and haven't been able to tell any difference. >>>> Just using the generic NMEA driver / this is a no-name cheapo SIRF >>>> module. >>>> >>>> Also, trying to wrap my head around these: >>>> >>>> http://linuxpps.org/wiki/index.php/LinuxPPS_installation >>>> http://linuxpps.org/wiki/index.php/LinuxPPS_NTPD_support >>>> >>>> And here is where I give up. As the subject line suggests: >>>> >>>> HELP!!! I'd like to convert L1 GPS timing signal(s) into local time on >>>> computer(s) >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@febo.com >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > > > ------------------------------ > > Message: 2 > Date: Sun, 19 Aug 2012 10:42:10 -0400 > From: "Stan, W1LE" <stanw...@verizon.net> > To: time-nuts@febo.com > Subject: [time-nuts] Modern motherboard with RS232 port > Message-ID: <5030fb42.8030...@verizon.net> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hello The Net, > > For your consideration: > > The INTEL model DN2800mt ITX mother board uses a ATOM CPU and > draws about 11 watts of AC power when configured as: > (I have not measured DC power yet.) > > 30 GB OCZ Nocti mSATA solid state drive, > WIN7 pro, 64 bit, USB keyboard and mouse > APEX MI-0008 case. > > Also has: > parallel port available on mother board, you extend to a connector > RS232 serial port available on mother board, you extend to a connector > a single DC power supply from 11 to 19 V DC. > 1 each PCIe expansion port, I will use with a premium 4 channel sound card > SATA ports available for HDD/SDD, > USB ports are available, > Motherboard sound, and Gigalan. > > I have not played with NTP, (yet), but it sounds like a decent time nut > technical challenge. > > My application is for a remote site with only 13V DC power available > from PV/batteries. > Then use fiber ethernet to get off site. > > The INTEL website would have further details. > > Stan, W1LE Cape Cod FN41sr > > > > > ZZZZz > > > > > ------------------------------ > > Message: 3 > Date: Sun, 19 Aug 2012 10:18:34 -0500 (CDT) > From: KD0GLS <kd0...@mninter.net> > To: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Subject: Re: [time-nuts] L1 GPS timing signal(s) into local time on > computer(s) > Message-ID: <ae1d2790-af2b-40fc-88d8-f13a61d77...@mninter.net> > Content-Type: text/plain; charset=us-ascii > > In my experience (which is admittedly less than that of many others here) > the time reported is that of the PPS pulse that just happened, and the > documentation usually bears that out. There's a real-time clock running > inside the receiver that is synchronized to the PPS. At the top of the > second, the PPS is output and the RTC increments. Some number of > milliseconds later, that RTC time value is output, which is the "current" > time, not that of the next pulse. That's certainly the way the Motorola M12+ > Timing receiver (Motorola binary mode) and all of the SiRFstar-based NMEA > navigation receivers I've used work. > > Beware of the situation where a cold-started receiver hasn't yet acquired > the UTC offset portion of the almanac and will report time some number of > seconds different than UTC. The SiRF receivers are especially misleading, as > they can be off by just one or two seconds depending on when their firmware > was built. They are programmed with default offset values that were valid at > the time of their manufacture. In one case I had, it was sometimes off by > one second, sometimes not. After June 30, 2012, it was now sometimes off by > two seconds, and then I knew what was going on. The M12+ has a default > offset of zero, which I find much more sane. It reports GPS time (a whopping > 16 seconds different) until the UTC offset is received. > > Sent from my iPod > > On Aug 19, 2012, at 9:42, Sarah White <kuze...@gmail.com> wrote: > >> Ken: >> >> From what I've read, most GPS modules which output PPS, the NMEA >> sentence has the timestamp of the next, upcoming pulse. Regardless of >> how the NMEA or other time data is, the PPS itself is only a guarantee >> "this is the boundary for a second" and NTP documentation typically >> recommends a second reference clock to "number the seconds" anyway. >> >> Everyone: >> >> Thanks everyone. I got many responses which confirm my initial >> conclusions. I had trouble locating a GPS thunderbolt on ebay because >> there is an HTC phone with "thunderbolt" in the name. (I got a few hits >> for the GPS module, but there is no way to filter out "phones" or I >> might just be bad at operating ebay) >> >> uhm... yeah. As someone pointed out. It is a total nightmare to figure >> out which direction my GPS time is wandering, and finding the correct >> offset. I'm just gonna give up on this USB module, and get a real one >> with PPS >> >> Also, I really hate google's new "shopping" experience. They started >> listing less content, and now push content from stores which charge 2-3 >> times as much. >> >> As far as existing hardware goes, I don't have any slots free in my >> desktop for a serial board... >> >> Despite the new "google shopping" headache, I was able to determine that >> many "older" computers from the windows XP era which still have serial >> ports, and are available refurbished from walmart of all the crazy >> places. (most of the time, better price than the ones being pushed by >> google shopping, and even have XP installed and a 1 year warranty) >> >> So no problem. I can source a suitable machine to run NTP, and for less >> than $200, guaranteed. >> >> Will probably be using gentoo linux, as the default configuration does >> NOT expect you to run any specific kernel. I can easily recompile >> anything I need without breaking unusual, unforeseen dependencies. >> (doesn't hurt that I've been using gentoo since the stage1 install was >> preferred, all the way back to the GCC 2.x era) >> >> I'm really aiming to run a server which ONLY runs NTP, and at most 1 or >> two other daemons (light duty on those) >> >> Thanks so much everyone. >> >> On 8/19/2012 7:11 AM, Ken Duffill wrote: >>> Just one further question. >>> >>> When the pps input triggers, so my linux box knows a second has just >>> ticked; is the time of that second the one the NMEA sentence has just >>> sent, or will send next? >>> >>> Or to put it another way, when I receive an NMEA sentence is this the >>> current time (as was when the sentence was constructed) or the time at >>> the next PPS 'tick'? >>> >>> Thanks in advance. >>> >>> KenD >>> >>> On 19/08/12 11:23, Bill Dailey wrote: >>>> I will jump in a bit. I, and many have been right where you are. You >>>> are correct...USB is a no go for accurate time. Same on windows. So >>>> you need a Linux box with serial port. Anything from a Beaglebone, >>>> pandabox...or pc will work. You certainly need a gps with a pulse per >>>> second output (most have) and you can wire that up to the appropriate >>>> line on the serial cable or send to the target computer via gpio pin. >>>> The pps thing is fairly simple really. If you are receiving gps data >>>> via serial connection it takes a variable amount of time to get each >>>> status report from the gps...list time etc etc in text format and >>>> sends it repeatedly. This gets ntp to within a second or some >>>> fraction thereof...the pps part refines that..no text or anything... >>>> Just a one pulse per second separate from the gps info that acts as a >>>> exclamation point to tell ntp "right here is the actual start of the >>>> second!" alone the pps wouldn't be useful for time but with the time >>>> info ntp already has from the nmea sentences it is priceless for >>>> really precise time. That's about it. Once you have gps and pps >>>> configured on Linux you should be in the sub 5 microsecond range. It >>>> gets tricky getting better than that and you have to Ntpns and really >>>> worry about hardware issues that affect precision (system clock >>>> stability etc) but it can be done. >>>> >>>> Doc >>>> KX0O >>>> >>>> Sent from my iPad >>>> >>>> On Aug 18, 2012, at 11:25 PM, Sarah White <kuze...@gmail.com> wrote: >>>> >>>>> Hi, this is my first post. >>>>> >>>>> First off. Windows 7 USB connection to the GPS (no serial ports / > modern >>>>> computer) and I'm pretty sure that is my main problem. >>>>> >>>>> Past few months, I've been trying to figure out my timing issues. Lots >>>>> of reading & trying to figure out how to best configure everything. I'm >>>>> typically still off (randomly) by 20-100 miliseconds. I'd like to at >>>>> least get to within 50 microseconds (nanoseconds would be wonderful) >>>>> >>>>> 1) I need a computer with a serial port. The curent GPS module I'm > using >>>>> is INTERNALLY RS232 --> USB converter, and recognized by my windows 7 >>>>> computer as: "Prolific USB-to-Serial Comm Port (COM3)" ... the latency >>>>> and jitter is horrible, and both are seemingly random. >>>>> >>>>> 2) I need to run my stratum 1 clock (connected to the stratum 0 time >>>>> source via old-school RS232 serial) on linux or a form of BSD with >>>>> support for kernel timestamps, and a version of NTP with a driver to >>>>> supports my reference clock... points 1 and 2 seem fine. >>>>> >>>>> 3) I'm clueless about mounting an antenna, running cable, grounding / >>>>> lightning protection, etc... Really want an easy to install one. >>>>> >>>>> For software, I've used 4.2.6 (stable / production) as well as 4.2.7 >>>>> (dev version) NTP and haven't been able to tell any difference. >>>>> Just using the generic NMEA driver / this is a no-name cheapo SIRF >>>>> module. >>>>> >>>>> Also, trying to wrap my head around these: >>>>> >>>>> http://linuxpps.org/wiki/index.php/LinuxPPS_installation >>>>> http://linuxpps.org/wiki/index.php/LinuxPPS_NTPD_support >>>>> >>>>> And here is where I give up. As the subject line suggests: >>>>> >>>>> HELP!!! I'd like to convert L1 GPS timing signal(s) into local time on >>>>> computer(s) >>>>> >>>>> _______________________________________________ >>>>> time-nuts mailing list -- time-nuts@febo.com >>>>> To unsubscribe, go to >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>> and follow the instructions there. >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@febo.com >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > > ------------------------------ > > Message: 4 > Date: Sun, 19 Aug 2012 11:21:21 -0400 > From: Michael Tharp <g...@partiallystapled.com> > To: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Subject: [time-nuts] Embedded NTP servers? > Message-ID: <50310471.1090...@partiallystapled.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Greetings nuts, > > All this recent NTP discussion has me thinking about a dedicated NTP > server again. The usual solution is to use commodity hardware of some > persuasion (PC, mini-itx or even ARM) running ntpd, but I'm thinking we > can do better. The only reason a full ntpd is needed is for its software > PLLs that measure and compensate for deficiencies in the local > oscillator. But if that local oscillator is replaced by a disciplined > 10MHz clock, and a coincident pulse-per-second and NMEA from the GPSDO > fed in, then a reasonably fitted microcontroller should do the trick. > > I happen to have a Ethernet-enabled widget I put together for another > project as a kind of drop-in module, built on a PIC18F66J60 which has a > built-in 10mbit Ethernet controller. The problem with it seems to be > relatively poor and unpredictable packet servicing latency. Usually > pings are 1.02ms but with some significant deviation. I imagine a lot of > the deficiencies with this arrangement come from the vendor-supplied IP > stack, which is not latency-optimized, but also the 10mbit link > contributes some "quantization" type problems. Microchip also makes a > 100mbit-capable standalone controller, ENC624J600. I'd probably use that > and pair it with any 72MHz ARM microcontroller. The micro would be > clocked by a (multiplied) 10MHz disciplined input and the > pulse-per-second would come in on a "input capture" channel that can > timestamp the pulse relative to a local counter. And since ntp is such a > simple protocol, it should be pretty easy to write a appropriate ntp > server routine that just hands out the time from GPS, including leap > second indications. > > Thoughts? Has it been done before, preferably with open source? I'd love > to make it myself but I have to finish the GPSDO first :-) > > -- m. tharp > > > > ------------------------------ > > Message: 5 > Date: Sun, 19 Aug 2012 10:06:27 -0700 > From: Chris Albertson <albertson.ch...@gmail.com> > To: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Subject: Re: [time-nuts] Modern motherboard with RS232 port > Message-ID: > <cabbxvhuv_hkjmnmelkphumyvtjfa11ybye-cn45tf6uevpn...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > This sounds like a newer version of the board I use. The thing to check > is if the CPU heat sink has a fan or not. Having no fan indicates that the > CPU is not using much power. It also removes a common failure point. > > To reduce power even more. On an NTP server you can unplug the keyboard, > mouse and monitor and if you have other servers on the LAN configure one as > a "boot server" and have it run TFTP then your NTP server does not need a > disk drive. It can run off a "RAM disk". This makes it very fast, even > faster than a SSD and it saves some cash. Makes backup easy too as there > is nothing to backup if there is no local storage. If you don't have a > TFTP server use a small notebook size disk drive. Even a 80GB drive is > overkill. You can also boot from a USB thumb drive and run a RAM disk. > > It is worth it to look at your electric bill to find how much you pay for > power. Here I'm at $0.21 per KWH. A full size PC server can use 250W or > more. There are 8760 hours in a year so you get $460 per year to run that > 250W PC. The little Atom will pay for itself in just a few months. The > first time I did that calculation, my "power hogs" where given away. > > > > > On Sun, Aug 19, 2012 at 7:42 AM, Stan, W1LE <stanw...@verizon.net> wrote: > >> Hello The Net, >> >> For your consideration: >> >> The INTEL model DN2800mt ITX mother board uses a ATOM CPU and >> draws about 11 watts of AC power when configured as: >> (I have not measured DC power yet.) >> >> 30 GB OCZ Nocti mSATA solid state drive, >> WIN7 pro, 64 bit, USB keyboard and mouse >> APEX MI-0008 case. >> >> Also has: >> parallel port available on mother board, you extend to a connector >> RS232 serial port available on mother board, you extend to a connector >> a single DC power supply from 11 to 19 V DC. >> 1 each PCIe expansion port, I will use with a premium 4 channel sound card >> SATA ports available for HDD/SDD, >> USB ports are available, >> Motherboard sound, and Gigalan. >> >> I have not played with NTP, (yet), but it sounds like a decent time nut >> technical challenge. >> >> My application is for a remote site with only 13V DC power available from >> PV/batteries. >> Then use fiber ethernet to get off site. >> >> The INTEL website would have further details. >> >> Stan, W1LE Cape Cod FN41sr >> >> >> >> >> ZZZZz >> >> >> ______________________________**_________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/** >> > mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/tim > e-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.