Re: [time-nuts] RPi/ beagle bone-like computer without video
> >If you really need Linux and it needs to be small and low cost and low > >power, then look at the "Pi Zero". It is a very small Pi that sells for > >only $5. It has video but just don't plug in the cable. > > > > The Pizero and Pi A are about the same power: 400 mW with Wifi off, idle; I'm measuring 0.350A with max cpu usage on all cores and the following settings: power off the display /opt/vc/bin/tvservice -o switch off the ethernet blinkenlights llctl f0 l0 d0 Apart from that I read somewhere that the beaglebones have terrible EM characteristics. But I can't find my source so take it with a grain of salt :-) Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
[time-nuts] measuring os latency for pps
Hi, Not sure if it is interesting for you guys but I wrote a simple program for e.g. Linux (or any other system with the pps api implemented) that listens on a pps source waiting for a pulse and then toggles a gpio pin. That way you can measure the latency introduced by the the kernel when listening from userspace. Note that there's a little extra latency due to the gpio-pin handling. It is on github: https://github.com/flok99/pps2gpio Folkert van Heusden -- MultiTail cok yonlu kullanimli bir program, loglari okumak, verilen kommandolari yerine getirebilen. Filter, renk verme, merge, 'diff- view', vs. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] MSF Scheduled Maintenance Periods
Could it be that they changed something with their setup? A couple of years back I could receive MSF fine (Gouda, the Netherlands) but this year (reconnected the radio in January) no bit comes in at all. The led on the radio also flickers dramatically, not once per second. I'm not aware of any significant changes. Could it be that you have more interference at 60 kHz than two years ago? Could be. I replaced a couple of regular pcs with tons of raspberry pi's. Folkert van Heusden -- Ever wonder what is out there? Any alien races? Then please support the seti@home project: setiathome.ssl.berkeley.edu -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] MSF Scheduled Maintenance Periods
MSF Scheduled Maintenance Periods The MSF 60 kHz standard-frequency and time signal, broadcast by Babcock on behalf of NPL, is occasionally taken off-air to allow maintenance work on the masts and antennas at Anthorn Radio Station to be carried out in safety. This means that your radio-controlled clock will not be picking up the MSF signal, so may not be working correctly. Could it be that they changed something with their setup? A couple of years back I could receive MSF fine (Gouda, the Netherlands) but this year (reconnected the radio in January) no bit comes in at all. The led on the radio also flickers dramatically, not once per second. Folkert van Heusden -- MultiTail är ett flexibel redskap för att följa en eller flera logfiler, utföra kommandon, filtrera, färglägga, sammanfoga, o.s.v... -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
[time-nuts] linux kernel pps support
Did a test for a while: every 5 minutes I would look at the output of
ntpq -c pe -n for jitter of the pps source.
This pps source was measured either in the kernel (this newly added
gpio pps support in the raspberry pi) or in user space using my own
rpi_gpio_ntp.
kernel pps interrupt handling
-
root@detijd:/etc# while true ; do echo `date +%s` `ntpq -c pe -n | grep
127.127.22.0` ; sleep 300 ; done | tee -a /pps.log
root@detijd:/etc# cat /pps.log | awk '{ print $11; }' | awk 'BEGIN { max = -1;
min = 1000; } { if ($1 max) { max=$1; } if ($1 min) { min=$1; } t+=$1; n++;
} END { print min, max, t/n, n; }'
0.001 0.124 0.0131945 797
This is minimum, maximum (yes that's 124!) and average. And I took 797
samples which is almost 3 days.
average temperature of soc: 49.7 with stddev of 1.87
userspace
-
note: I looked at ntpq every 30 seconds(!)
root@hetlicht:/var/log/ntpstats# cat /rpn.log | awk '{ print $11; }' | awk
'BEGIN { max = -1; min = 1000; } { if ($1 max) { max=$1; } if ($1 min) {
min=$1; } t+=$1; n++; } END { print min, max, t/n, n; }'
0.001 0.101 0.00955351 27797
This is over 9,6 days.
average temperature of soc: 51,1 with stddev of 4.01
TL;DR:
- kernel : 13.2us jitter on average
- userspace: 9.6us jitter on average
Folkert van Heusden
--
--
www.smartwinning.info
___
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] raspberry pi, pps interrupts by kernel
Hi, I tested it...and could not get it to work. gpsd opens pps0 but strace does not show me the regular ppsapi syscalls and also ppstest gives a time out. e.g. I did an strace and I did not see any PPS_FETCHs passing by. I verified with lsof that gpsd does have pps0 open. With help from Hal I got it to work! I thought you could just poke the gpio pin number in that /sys virtual file. You can't. The bcm2708 code needs to know the pin number at boot time. Then, you can't get the pps via gpsd: when gpsd opens /dev/ttyAMA0 to talk to the gps, a new /dev/pps1 is created, for that AMA0 device. That pps1 is not the one you need; the serial port on the raspberry pi has no dcd pin so pps1 points to nothing. Yes it is connected to the ldisc but that has no (hardware) dcd pin connected to it. So long story short: you need to configure an atom driver in ntpd which then correctly opens /dev/pps0 and then the share memory coupling with gpsd. Yeah or connect ntpd directly to /dev/ttyAMA0 but then you'll miss the possibilities of running the nice gpsmon application. Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] Beaglebone NTP server
On my rpi the jitter is between 2 and 10us iirc but it is a while since I tested it. A quick peak shows me currently 3us jitter. Not bad for a userspace solution imho. Really? The PPS to GPIO interface is handles in user space? It is not interrupt driven? Yes it is. But, until today, I used a software solution which interfaces the interrupt to ntp. I did that because I hate recompiling kernels and the pps code for rpi+gpio was not in the main distrio. Folkert van Heusden -- Ever wonder what is out there? Any alien races? Then please support the seti@home project: setiathome.ssl.berkeley.edu -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] gravity, space and time
If I understood it well, we should occasionally encounter gravitational waves going through, well, the whole galaxy. As time and space are intertwined, those ripples may be measured somehow I guess. Isn't this that we as time nuts community can help the scientific world with? E.g. create some kind of grassroots effort where our very accurate clocks can detect this? I can imagine all kinds of reasons that existing infra for this may not always be able to detect this on its own. What do you think? Thank you all for the replies. Conclusion: not feasible. I got inspired by this project: http://www.uradmonitor.com/ which installs radiation monitors all over the world at peoples homes and then monitors for gamma radiation. Cool project. It's with atmel328 cpus, ethernet and a geiger muller device in a tiny metal box that can be installed outside. Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
[time-nuts] raspberry pi, pps interrupts by kernel
Hi, Years(?) ago I wrote a program rpi_gpio_ntpd to be able to use a pps with a raspberry pi (or any other linux system with standard gpio pin support) and ntp. Works fine altough the jitter is between 0 and 15us. http://www.vanheusden.com/time/rpi_gpio_ntp/ By accident I read https://github.com/raspberrypi/linux/issues/109 where it is written that the standard(?) image (the one installed with the rpi_update script) now includes kernel gpio pps support! I've installed that kernel and indeed, there now is a /sys/module/bcm2708/parameters/pps_gpio_pin file to which you echo the pin number on which you feed the pps signal. I tested it...and could not get it to work. gpsd opens pps0 but strace does not show me the regular ppsapi syscalls and also ppstest gives a time out. I'm probably missing something trivial here but if any other of you would like to give it a try please let me know (here) if and how you succeeded! Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] raspberry pi, pps interrupts by kernel
I tested it...and could not get it to work. gpsd opens pps0 but strace does not show me the regular ppsapi syscalls and also ppstest gives a time out. e.g. I did an strace and I did not see any PPS_FETCHs passing by. I verified with lsof that gpsd does have pps0 open. I'm probably missing something trivial here but if any other of you would like to give it a try please let me know (here) if and how you succeeded! If this special driver is not going to work, I might try this: https://github.com/mholling/rpirtscts maybe the pps-ldisc driver works for that. Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
[time-nuts] gravity, space and time
Hi, If I understood it well, we should occasionally encounter gravitational waves going through, well, the whole galaxy. As time and space are intertwined, those ripples may be measured somehow I guess. Isn't this that we as time nuts community can help the scientific world with? E.g. create some kind of grassroots effort where our very accurate clocks can detect this? I can imagine all kinds of reasons that existing infra for this may not always be able to detect this on its own. What do you think? Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] tcxo
Some of the Arduinos (not sure about Mini 04 but I am suspicious) use ceramic resonators rather than real crystals and thus may have extremely poor frequency stability. See here http://jorisvr.nl/arduino_frequency.html for an example. ah! Very intriguing material, those crystals. I wonder what happens in them that they start to tick(?) at precisely 16MHz for example. Is there some reason you are using a 16.9344 MHz oscillator rather than 16.0? The processor will probably work, but timing of Arduino functions like millis() and software serial baud rates will be affected. Misread I guess :-| Like that time that I bought 20 max690 instead of max680 ics. sigh. On Wed, Dec 10, 2014 at 2:19 PM, folkert folk...@vanheusden.com wrote: I'm experimenting a bit with time keeping. For that I use cheap low power hardware like raspberry pies and arduinos. Hi people, Thanks for all the replies! Took a bit to respond but I had the flu. My objective is, to get the best precision/accuracy possible with said hardware. The first step is preparing an arduino. I found one that has an easy to desolder crystal: http://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Arduino_Mini.jpg/170px-Arduino_Mini.jpg Bought a couple of those and some of these: http://www.aliexpress.com/item/Precision-TCXO-square-wave-oscillator-TCXO-16-9344MHz-line-rectangle/1104200137.html While waiting for these and the parts for the schematics, I'm toying around with implementing ntp servers (well, sntp) for arduino. With lots of blinkenlights of course and with ethernet. Not trivial I can say. This is the jitter plot of a test where time is fed from an RTC module. I did not plot the drift but it is +/- 120 seconds in the 3.8 days I measured it. http://vps001.vanheusden.com/~folkert/aRTC.png Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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. -- --Jim Harman ___ 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. Folkert van Heusden -- Multitail est un outil permettant la visualisation de fichiers de journalisation et/ou le suivi de l'exécution de commandes. Filtrage, mise en couleur de mot-clé, fusions, visualisation de différences (diff-view), etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] tcxo
I'm experimenting a bit with time keeping. For that I use cheap low power hardware like raspberry pies and arduinos. Hi people, Thanks for all the replies! Took a bit to respond but I had the flu. My objective is, to get the best precision/accuracy possible with said hardware. The first step is preparing an arduino. I found one that has an easy to desolder crystal: http://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Arduino_Mini.jpg/170px-Arduino_Mini.jpg Bought a couple of those and some of these: http://www.aliexpress.com/item/Precision-TCXO-square-wave-oscillator-TCXO-16-9344MHz-line-rectangle/1104200137.html While waiting for these and the parts for the schematics, I'm toying around with implementing ntp servers (well, sntp) for arduino. With lots of blinkenlights of course and with ethernet. Not trivial I can say. This is the jitter plot of a test where time is fed from an RTC module. I did not plot the drift but it is +/- 120 seconds in the 3.8 days I measured it. http://vps001.vanheusden.com/~folkert/aRTC.png Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] Beaglebone NTP server
I prefer the Beaglebone to the Pi because of the silly USB glitch but out of three BBBs only one will run for more than a month without wedging. This may be because I run Debian but as with the Pi USB bug it's not much comfort when the box fails. The Pi I use as an NTP server ran for 4 months and developed a filesystem error. It's been up two months post-repair. If I depended on a server built around a dev board I'd be careful to make the SDcard/eMMC read-only and build more than one. Regarding the fs error: consider replacing ext3 for f2fs. F2fs does software wear leveling. Folkert van Heusden -- Nagios user? Check out CoffeeSaint - the versatile Nagios status viewer! http://www.vanheusden.com/java/CoffeeSaint/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] Beaglebone NTP server
I have a Z3805A and a Beaglebone, and would like to set up an NTP server for the lab. Any kernel drivers and/or setup hints would be appreciated :) Actually, I was thinking of doing exactly the same thing. I am interested in any answers for this too. If compiling a kernel is required and too daunting, then there's rpi_gpio_ntp: http://www.vanheusden.com/time/rpi_gpio_ntp/ Initially only for raspberry pi but I noticed I made it generic enough to work on all linux systems with pps via gpio. On my rpi the jitter is between 2 and 10us iirc but it is a while since I tested it. A quick peak shows me currently 3us jitter. Not bad for a userspace solution imho. Folkert van Heusden -- MultiTail è uno flexible tool per seguire di logfiles e effettuazione di commissioni. Feltrare, provedere da colore, merge, 'diff-view', etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
[time-nuts] tcxo
Hi, I'm experimenting a bit with time keeping. For that I use cheap low power hardware like raspberry pies and arduinos. I noticed that the accuracy of a crystal makes a big difference. Did a bit of googling and I learned that a txco may help solve that. Something that keeps a constant temperature that is that I can then glue/solder to the crystal of those systems. My question now is: does anyone know of a simple schema for such a thing? I'm not entirely new to soldering but large schemas with lots of components are a bit daunting as I don't have the background knowledge to debug them if I soldered something wrong. Folkert van Heusden -- MultiTail är ett flexibel redskap för att följa en eller flera logfiler, utföra kommandon, filtrera, färglägga, sammanfoga, o.s.v... -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping NANOSG20
Oh for convenience. I need to patch ntpd to use linux pps (afaik) and on other systems I successfully run gpsd with ntpd (read: low jitter). Using gpsd with ntpd reduces the jitter versus just using ntpd by itself? No I meant that running that combination is successfully because I see low jitter. Folkert van Heusden -- Multitail est un outil permettant la visualisation de fichiers de journalisation et/ou le suivi de l'exécution de commandes. Filtrage, mise en couleur de mot-clé, fusions, visualisation de différences (diff-view), etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping NANOSG20
Hi, I decided to buy a Nanos G20. Not too expensive, real serial port, debian linux pre-installed. I don't want to sound harsh as the people from Nanos probably did their best to produce a good product, but for timekeeping it is totally crap and also useless. Well, unless I did something wrong. I recompiled the kernel to enable PPS support, installed gpsd and ntpd, configured at all and let it run for a while. allan deviation: http://keetweej.vanheusden.com/~folkert/nanosg20/allandev.png offset: http://keetweej.vanheusden.com/~folkert/nanosg20.png remote refid st t when poll reach delay offset jitter == x127.127.28.0.NMEA. 0 l3 16 3770.000 -994.05 7.857 x127.127.28.1.PPS.0 l7 16 3770.000 -250.13 572.812 +192.168.64.18 .PPS.1 u 66 128 3770.553 -0.055 0.033 *192.168.64.2.PPS.1 u 99 128 3770.237 -0.062 0.039 +192.168.64.168 .PPS.1 u 44 128 3770.646 -0.013 0.321 Folkert van Heusden -- MultiTail na wan makriki wrokosani fu tan luku den logfile nanga san den commando spiti puru. Piki puru spesrutu sani, wroko nanga difrenti kroru, tya kon makandra, nanga wan lo moro. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping
Here's a review of several small low power linux systems: http://www.cooking-hacks.com/index.php/blog/new-linux-embedded-devices-comparison-arduino-beagleboard-rascal-raspberry-pi-cubieboard-and-pcduino Folkert van Heusden -- MultiTail is a versatile tool for watching logfiles and output of commands. Filtering, coloring, merging, diff-view, etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping NANOSG20
folk...@vanheusden.com said:
remote refid st t when poll reach delay offset jitter
==
x127.127.28.0.NMEA. 0 l3 16 3770.000 -994.05 7.857
x127.127.28.1.PPS.0 l7 16 3770.000 -250.13 572.812
+192.168.64.18 .PPS.1 u 66 128 3770.553 -0.055 0.033
*192.168.64.2.PPS.1 u 99 128 3770.237 -0.062 0.039
+192.168.64.168 .PPS.1 u 44 128 3770.646 -0.013 0.321
Something is broken. What NMEA device are you using? Why are you using gpsd
It is a garmin 18x lvc.
rather than ntpd's NMEA driver?
Oh for convenience. I need to patch ntpd to use linux pps (afaik) and on
other systems I successfully run gpsd with ntpd (read: low jitter).
It looks like the NMEA side it is off by a second. Some devices do that.
You can fix that with some fudging.
Yes, I'm not so worried about the nmea part, I might even decide to
remove it from the configuration. What I mean is: if I set the clock to
the current time, than it is only a matter of keeping it at that with
the pps.
The PPS stuff is off by 250 ms. Are you using the wrong edge? (Got a scope
handy?)
Well, the offset is not constant. If you look at
http://keetweej.vanheusden.com/~folkert/nanosg20.png you see it is
between 0 and -1ms. I now notice that it is not random-ish but consists
of a few specific values:
folkert@belle:~$ cat peerstats | grep 127.127.28.1 | awk '{ print $5; }' | cut
-c 1-6 | sort | uniq -c | sort -rn
503 -0.874
497 -0.875
486 -0.999
467 -1.000
365 -0.249
332 -0.250
201 -0.857
188 -0.125
184 -0.142
140 -0.124
131 -0.000
113 0.
108 -0.166
24 -0.833
5 -0.200
2 -0.856
2 -0.799
2 -0.199
1 -0.167
1 -0.143
1 0.0002
1 0.0001
This is with 3754 lines.
If I clean it a little:
1000x -0.8745
953x -0.9995
697x -0.2495
328x -0.1245
and so on.
Folkert van Heusden
--
MultiTail är ett flexibel redskap för att följa en eller flera logfiler, utföra
kommandon, filtrera, färglägga, sammanfoga, o.s.v...
--
Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping NANOSG20
Thanks for your graphs, but what are the Y-axis units! http://keetweej.vanheusden.com/~folkert/nanosg20.png is in ms and not the delay, the offset instead. Inn your billboard above, the PPS looks to be on the wrong edge - perhaps the pulse is 250 ms wide and you are syncing to the trailing edge and not the leading. well the offset is not constant. Now it is even 1 second: remote refid st t when poll reach delay offset jitter == x127.127.28.0.NMEA. 0 l5 16 3770.000 -1002.1 0.096 *127.127.28.1.PPS.0 l9 16 3770.000 -1000.2 394.379 +192.168.64.18 .PPS.1 u 64 64 3770.548 -0.360 3.083 +192.168.64.2.PPS.1 u 108 128 3770.251 -1.128 0.918 -192.168.64.168 .PPS.1 u 34 64 3771.153 -0.755 3.958 Can you check that out? I recall that I can but I think (open for telling me I'm wrong) the primary problem is with the offset jumping all over the place: see my mail a couple of minutes ago. it's the positive going transition on the DCD connection which needs to be on the exact second. I think you are using the Garmin GPS 18x LVC. There was a firmware update which ensured that the serial adta arrived /before/ the /next/ second edge rather than after it. Ensure your firmware is 3.70 or later. See: http://www.satsignal.eu/ntp/Garmin-GSP18x-LVC-firmware-issue.htm I see that 3.80 is now out, but I think I am still on 3.70. I'll have a look at it this weekend. Folkert van Heusden -- Multitail es una herramienta flexible que permite visualizar los log file y seguir la ejecución de comandos. Permite filtrar, añadir colores, combinar archivos, la visualización de diferencias (diff- view), etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping
The thing that finally canned the BB for me was the short SD card life. Even though the implementation uses a virtualized root file system, it still writes to the SD card about once a second. The result is that even industrial grade SD cards rarely live over a year. With the Black they tried to address the problem by putting some NAND memory on board but that only prolongs the problem and with components that are not easily changed. I've only ever had one SD card go dead on me on my entire fleet, and I suspect that was actually my fault, not Debian's :) Recent Linux kernels (3.8) have a new filesystem called 'f2fs'. This is a logging filesystem: it appends data instead of overwriting (and does a flush if the fs gets full). This should increase the lifespan. I have a couple (6) of raspberry pi's (pies?) using this filesystem and indeed it seems to help. Folkert van Heusden -- Multitail est un outil permettant la visualisation de fichiers de journalisation et/ou le suivi de l'exécution de commandes. Filtrage, mise en couleur de mot-clé, fusions, visualisation de différences (diff-view), etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping
Yes but how much power do they use? These arm boardjes are 5 watt, some even 1 watt. On Mon, Jul 01, 2013 at 07:43:49AM -0700, Chris Albertson wrote: For a few dollars LESS you can get an Intel dual-core Atom board. It is a standard PC motherboard. These can run a file server, a web server, SSH and NTP all at the same time and have about 90% idle time on the CPU. (Running those other processes does not effect NTP.) Intel-BOXD2500HN-Dual-Core-Mini-ITX-Motherboardhttp://www.amazon.com/Intel-BOXD2500HN-Dual-Core-Mini-ITX-Motherboard/dp/B007BHTMX6/ref=sr_1_5?ie=UTF8qid=1372689454sr=8-5keywords=intel+atom Those tiny Arm boards are best until the price gets about about $45. Above that I think they are not a great value. On Mon, Jul 1, 2013 at 3:57 AM, David J Taylor david-tay...@blueyonder.co.uk wrote: How do folks think that the Odroid/U2 might compare? http://www.hardkernel.com/**renewal_2011/products/prdt_**info.phphttp://www.hardkernel.com/renewal_2011/products/prdt_info.php More expensive than Raspberry Pi or BeagleBone black, but higher performance? __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- 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. Folkert van Heusden -- Always wondered what the latency of your webserver is? Or how much more latency you get when you go through a proxy server/tor? The numbers tell the tale and with HTTPing you know them! http://www.vanheusden.com/httping/ --- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping
I think the problem is that if you are not clear about what your big picture goal is then yu only get a bunch od not so helpful comments like use this is worked for me.. So what exactly do you want. Are you looking for a very low power, say under 5W server. Something that is very easy to set up and maintain. You have two GPSes, will both go on the same NTP server or do you wnt to set up two NTP servers It must be a system 5 watt, so probably an ARM system. It will only run ntpd so not much ram is required. It will have 10 (ntp-)clients so a very powerfull processor is not required. Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
[time-nuts] looking for low-power system for gps ntp timekeeping
Hi, I own a couple of GPS modules (garmin 18(x) lvc) which I would like to use as a time-source. Now my server already has such a module connected (via gpsd and a pci rs232 interface) and my raspberry pies too (adafruit modules) so I'm looking for a low-power computer with a complete RS232 connector (DB9) with all signals attached so that I can feed it a PPS. Also real RS232 so that I don't have to mess with resistors and such. I'm considering either this one: http://www.antratek.com/nanosg20-with-128-mb-sdram-and-512-mb-flash or this one: http://www.antratek.com/ontwikkelboard-met-cirrus-logic-ep9302 What do you guys think: would they be any good for timekeeping? Known issues? Regards, Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] looking for low-power system for gps ntp timekeeping
As you already know, your Raspberry Pi with the Adafruit module alone would make an excellent NTP server. About 4 watts power consumption, and lower cost than those you list. http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#adafruit What else do you need? Well I have the garmins already laying around and I would like to give 'm good use. Folkert van Heusden -- www.TrustedTimestamping.com is a service that enables you to show that at a certain point in time, you had access to a hash-value reflecting the contents of a file (this file can be a word document, a jpeg image, everything). -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] raspberry pi, adafruit gps ntp
Hello, The last 25 hours I measured the jitter of my RPi-with-userspace PPS processing. In the following graph you'll see those measurements. Each row is an hour: http://vps001.vanheusden.com/~folkert/jitter-hm.png There's some kind of wave in it which I cannot explain: everything not related to timekeeping (apart from sshd) is disabled on that device. No cron, no at, not even the processes that monitor the state of the network port. Allan deviation: http://vps001.vanheusden.com/~folkert/allandev.png Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] raspberry pi, adafruit gps ntp
After 51 minutes of ntpd run-time this gives: remote refid st t when poll reach delay offset jitter == *firewall.intran 192.168.64.2 3 u7 64 3770.560 -0.506 0.493 -belle.intranet. 192.168.64.2 3 u 58 64 3770.560 -0.470 0.405 -time2.intranet. 194.109.20.183 u 56 64 3771.034 -1.282 1.392 +auth1.xs4all.nl 193.67.79.2022 u 28 64 377 17.580 -0.160 0.490 xSHM(0) .NMEA. 0 l1 16 3770.000 -359.47 10.670 +SHM(1) .PPS.0 l18 3770.0002.964 0.061 After 12,5 hours: remote refid st t when poll reach delay offset jitter == *192.168.64.1192.168.64.2 3 u 280 1024 3770.534 -0.924 0.579 -192.168.64.100 192.168.64.2 3 u 451 1024 3770.625 -0.920 0.560 -192.168.62.129 194.109.22.183 u 278 1024 3771.661 -2.347 0.665 +194.109.22.18 193.67.79.2022 u 295 1024 377 17.719 -0.357 0.978 x127.127.28.0.NMEA. 0 l5 16 3770.000 -309.57 40.640 +127.127.28.1.PPS.0 l48 3770.0002.231 0.005 Looking good! It is probably selecting 192.168.64.1 due to an accidental prefer keyword for that server in the configuration. I'm surprised that the jitter goes down to 0.005 as I'm now measuring the PPS from userspace. My program runs with real time scheduling and maximum priority but still the kernel needs to do a context switch etc. when it receives the pps pulse. Folkert van Heusden -- MultiTail er et flexible tool for å kontrolere Logfiles og commandoer. Med filtrer, farger, sammenføringer, forskeliger ansikter etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] raspberry pi, adafruit gps ntp
Hi David, That sounds good, Folkert - perhaps you might publish the details somewhere? I'd like to try it myself, but my Linux and C knowledge is limited. Here it is: http://vanheusden.com/time/rpi_gpio_ntp/ Please let me know if anything is unclear: I'll then enhance e.g. the readme.txt and such. For comparison, on three RPi cards here with modified kernels to get PPS from a GPIO pin, using ntpq -pn I see jitter values of 0.002, 0.002 and 0.002/0.004. The 0.002 seems to be near the sys_jitter limit as reported from ntpq -c rv. That's indeed better. The results I see are probably also influenced by the fact that this RPI also does other things (software defined radio, camera and measuring the light intensity outside). Cards 1 and 2 are just doing NTP, the third card is running a data collector processing signals from a DVB receiver stick, and sending the derived data over a Wi-Fi link to a PC running Plane Plotter using the dump1090 program. This gives a CPU load around 35%. It would be interesting to know how your version handles a busy RPi. Hmmm, I'll see if I can setup an RPI which only does the time keeping and see if that gives better results. Folkert van Heusden -- MultiTail na wan makriki wrokosani fu tan luku den logfile nanga san den commando spiti puru. Piki puru spesrutu sani, wroko nanga difrenti kroru, tya kon makandra, nanga wan lo moro. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] raspberry pi, adafruit gps ntp
Thanks, Folkert, that's most helpful! One thing which is unclear to me is what do you mean by pin 8? Is that a programming number, or does it refer to the GPIO header? I did try and find this in the RPi documentation, but it's not clear. Check this picture: http://jeffskinnerbox.files.wordpress.com/2012/11/raspberry-pi-rev-1-gpio-pin-out1.jpg GPIO pin 8 is in the upper right block with SPI in it. GPIO 8 (CE0) is written above it. By the numbering on that diagram it is physical pin 24. I'm currently using NTP driver type 22 on the RPi I would like to test with. If I move to the type 28 driver it doesn't matter that PPS is left supported in the Linux kernel. Please confirm there is no need to revert to a kernel without PPS support. Is there a simple way of stopping the OS stealing that GPIO pin - turning off PPS support with a simple edit? If I remember correctly, the kernel patch uses GPIO 18 (PCM_CLK), so using GPIO 8 will work fine with the patched kernel. What might matter, of course, is that I would need to move the actual PPS signal to a different pin as kernel-PPS and your program would not live together, as both would want to grab that pin. So it may mean making a small hardware change as well if I can't turn off PPS support. Maybe, but I'm not an electronics expert (not at all in fact) you can feed both pins? One thing you might want to try is to pulse one of the GPIO pins in response to the rising-edge interrupt you get, to see what the delay is when measured by a 'scope. Ok, I've uploaded version 0.2 which can do so. This version can also, in debug mode, show the offset of the local clock to the PPS timestamp. Folkert van Heusden -- Nagios user? Check out CoffeeSaint - the versatile Nagios status viewer! http://www.vanheusden.com/java/CoffeeSaint/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] raspberry pi, adafruit gps ntp
David, Fine, Folkert. The GPIO pins are numbered in your program exactly as I would expect, and the diagram just confirms that. Yes, the patched kernel can remain, and PPS operation should be unaffected. I was able to drive the two pins (GPIO 18 and GPIO 8) in parallel, and I have a signal level of about 2.5 V from a resistive divider. I'm actually driving it from a Trimble SMT module where the serial is over the USB, and gpsd see the GPS data perfectly. Ah! Is the serial over usb working stable on your rpi? I have lots of problems with usb devices dropping from the usb bus. Also with a powered hub. Thanks for the monitoring output. The tie delay between the PPS leading edge and the change of the monitoring line varies between 270 to 390 microseconds, so despite the jitter being reported in the 3-5 microsecond range, the internal clock is perhaps running about 1/3 millisecond behind real time. You will be able to see the performance compared to kernel-PPS here: http://www.satsignal.eu/mrtg/performance_raspi-2.php cool! and a comparison with other stratum-1 Raspberry Pi cards here: http://www.satsignal.eu/mrtg/performance_ntp.php The software compiled and installed without any issues. I've yet to figure out how to get it to auto-start - you might like to add that to your instructions. I may add a section to my Web page with a step-by-step guide, as this is so much easier than have to use a non-standard kernel. Will do. For now: edit /etc/rc.local and add the following (BEFORE the exit 0 statement and AFTER the #!/bin/sh line): /usr/local/rpi_gpio_ntp -N 1 -g 8 (replace '8' by the gpio pin) Folkert van Heusden -- Curious about the inner workings of your car? Then check O2OO: it'll tell you all that there is to know about your car's engine! http://www.vanheusden.com/O2OO/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
[time-nuts] raspberry pi, adafruit gps ntp
Hi, Ok today my friend Henk (Henk are you still subscribed here?) soldered the raspberry pi on my adafruit ultimate gps breakout v3. Apart from the soldering things were totally easy to get to work: only a few tweaks to cmdline.txt and inittab and the serial data streamed in. I decided _not_ to patch the kernel after a couple of issues with missing include files and such. But as only watching the nmea stream gives bad results, I needed to find an alternative for the PPS signal. So I wrote a little program which watches the GPIO port using poll (which waits for an interrupt) and then pokes in the shared memory segment of ntpd. After 51 minutes of ntpd run-time this gives: remote refid st t when poll reach delay offset jitter == *firewall.intran 192.168.64.2 3 u7 64 3770.560 -0.506 0.493 -belle.intranet. 192.168.64.2 3 u 58 64 3770.560 -0.470 0.405 -time2.intranet. 194.109.20.183 u 56 64 3771.034 -1.282 1.392 +auth1.xs4all.nl 193.67.79.2022 u 28 64 377 17.580 -0.160 0.490 xSHM(0) .NMEA. 0 l1 16 3770.000 -359.47 10.670 +SHM(1) .PPS.0 l18 3770.0002.964 0.061 I started the program with statistics logging enabled so I will produce some nice graphs after a day or so. Folkert van Heusden -- Feeling generous? - http://www.vanheusden.com/wishlist.php -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] NTP on RaspberryPi
In 3 weeks I have 2 connected to a GPS with PPS, I'll publish the results here. It is great stuff, these RPIs. On Sun, May 26, 2013 at 09:30:47AM -0700, Chris Albertson wrote: NTP does not really sync to a server. What it does is use the set of reference clocks that pas the clock selection criteria. THere is an algorithm that determines if a reference clock is reasonable or not.A reference clock can be a GPS or another NTP server or a cell phone service or any of a dozen other things but GPS and other servers are by far the most common. Your RPI is three leves removed from a GPS. It is operating as stratum 3 the second RPI is stratum 2. Both are doing really good for using a networked ref. clock. I would not blain the RPI. If you are doing better than a millisecond with no local PPS it is good. On Sun, May 26, 2013 at 9:15 AM, folkert folk...@vanheusden.com wrote: Besides I got them to run NTP and they're too jittery for my taste. How good/bad were they? What were you using for a time source? Does it have PPS support? Here's ntpq -c pv for one of my RPIs after 25 days of uptime: associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync, version=ntpd 4.2.6p5@1.2349-o Fri May 18 20:30:57 UTC 2012 (1), processor=armv6l, system=Linux/3.8.10+, leap=00, stratum=3, precision=-20, rootdelay=25.184, rootdisp=73.646, refid=83.98.201.134, reftime=d54cac1f.18aa9126 Sun, May 26 2013 17:43:27.096, clock=d54cb273.b755933f Sun, May 26 2013 18:10:27.716, peer=34195, tc=10, mintc=3, offset=0.182, frequency=-47.006, sys_jitter=0.377, clk_jitter=0.558, clk_wander=0.051 Hmmm found out that it syncs to random hosts on the internet. Ok an other one which syncs against an other pc with PPS (and a few others): folkert@weerpi ~ $ ntpq -c rv associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync, version=ntpd 4.2.6p5@1.2349-o Fri May 18 20:30:57 UTC 2012 (1), processor=armv6l, system=Linux/3.8.10+, leap=00, stratum=2, precision=-20, rootdelay=0.807, rootdisp=7.669, refid=192.168.64.100, reftime=d54cb1e1.9d6e8f07 Sun, May 26 2013 18:08:01.614, clock=d54cb2e4.7d1cdae3 Sun, May 26 2013 18:12:20.488, peer=41936, tc=9, mintc=3, offset=0.220, frequency=-31.405, sys_jitter=0.647, clk_jitter=0.074, clk_wander=0.003 folkert@weerpi ~ $ uptime 18:12:25 up 15 days, 3:48, 1 user, load average: 0.12, 0.17, 0.15 Folkert van Heusden -- Multitail est un outil permettant la visualisation de fichiers de journalisation et/ou le suivi de l'exécution de commandes. Filtrage, mise en couleur de mot-clé, fusions, visualisation de différences (diff-view), etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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. -- 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. Folkert van Heusden -- www.TrustedTimestamping.com is a service that enables you to show that at a certain point in time, you had access to a hash-value reflecting the contents of a file (this file can be a word document, a jpeg image, everything). -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] NTP on RaspberryPi
Besides I got them to run NTP and they're too jittery for my taste. How good/bad were they? What were you using for a time source? Does it have PPS support? Here's ntpq -c pv for one of my RPIs after 25 days of uptime: associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync, version=ntpd 4.2.6p5@1.2349-o Fri May 18 20:30:57 UTC 2012 (1), processor=armv6l, system=Linux/3.8.10+, leap=00, stratum=3, precision=-20, rootdelay=25.184, rootdisp=73.646, refid=83.98.201.134, reftime=d54cac1f.18aa9126 Sun, May 26 2013 17:43:27.096, clock=d54cb273.b755933f Sun, May 26 2013 18:10:27.716, peer=34195, tc=10, mintc=3, offset=0.182, frequency=-47.006, sys_jitter=0.377, clk_jitter=0.558, clk_wander=0.051 Hmmm found out that it syncs to random hosts on the internet. Ok an other one which syncs against an other pc with PPS (and a few others): folkert@weerpi ~ $ ntpq -c rv associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync, version=ntpd 4.2.6p5@1.2349-o Fri May 18 20:30:57 UTC 2012 (1), processor=armv6l, system=Linux/3.8.10+, leap=00, stratum=2, precision=-20, rootdelay=0.807, rootdisp=7.669, refid=192.168.64.100, reftime=d54cb1e1.9d6e8f07 Sun, May 26 2013 18:08:01.614, clock=d54cb2e4.7d1cdae3 Sun, May 26 2013 18:12:20.488, peer=41936, tc=9, mintc=3, offset=0.220, frequency=-31.405, sys_jitter=0.647, clk_jitter=0.074, clk_wander=0.003 folkert@weerpi ~ $ uptime 18:12:25 up 15 days, 3:48, 1 user, load average: 0.12, 0.17, 0.15 Folkert van Heusden -- Multitail est un outil permettant la visualisation de fichiers de journalisation et/ou le suivi de l'exécution de commandes. Filtrage, mise en couleur de mot-clé, fusions, visualisation de différences (diff-view), etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] DCF77 PPS
Silly 1,2 instead of 0,0012 fudge: indeed a mistake. How I measured when I wrote the first message: - I waited for a bit to be received - exact after the bit was received and read by my testprogram, I would check what the offset was to a second. e.g 13:45:12.456 would be an offset if 456ms - the linux system returns in microseconds, I would simple discard those 3 extra digits. eg. 13:45:12.456987 would become .456 Saturday night I connected the testprogram to NTP: when a bit was received, I would check how many microseconds after the second the system was and send that to NTPd (like above but doing microseconds here). After a couple of days this gives: remote refid st t when poll reach delay offset jitter == o127.127.20.1.GPS.0 l1 16 3770.000 -0.001 0.002 -192.168.64.1.GPS.1 u 52 64 3760.114 -0.021 0.021 x192.168.62.129 SHM(0) 2 u 49 64 372.080 154.251 82.784 x82.95.142.92129.70.132.363 u 25 64 377 36.867 78.199 1.989 x127.127.28.0.SHM0. 1 l58 3770.000 -263.48 3.437 --- -194.109.22.18 193.79.237.142 u 18 64 377 17.321 -3.490 0.468 -194.109.20.18 193.79.237.142 u 12 64 377 17.292 -3.296 0.776 *193.79.237.14 .PPS.1 u 20 64 377 19.607 -2.342 0.294 +192.87.36.4 .GPS.1 u 64 64 377 21.556 -2.370 0.730 +134.221.205.12 .PPS.1 u 40 64 377 20.372 -2.363 0.441 -172.29.0.11 134.221.205.12 2 u 42 64 377 18.350 -2.479 6.184 The 127.127.28.0 (SHM0) source is the dcf77 pps source. 192.168.62.129 does the same trick by the way using an MSF receiver but lets ignore that for now. Allan deviation plot: http://keetweej.vanheusden.com/~folkert/SHM0-peerstats.2013w10.png Offset plot: http://keetweej.vanheusden.com/~folkert/SHM0-offset.png last 800 measurements: http://keetweej.vanheusden.com/~folkert/SHM0-offset-last800.png So my guestimate is that 259 and 263 are the values to look for and I should ignore the others so that I don't confuse ntpd. That doesn't make sense to me, probably because I don't understand your data collection environment and/or maybe it's dong something strange. Hopefully my explanation above makes it more clear. While writing this I got an epiphany: I think I know what causes the 0.26s offset: the serial port is configured at 50Bps, 8, n, 1. So each byte takes 10 bits (8 data-, 1 start- and 1 stop bit). So a maximum of 5 characters per second or 0,2s per character. Each DCF77 bit is signalled as a byte to the system, so that explains 0,2s of the offset seen. Maybe the receiver needs another 0,6s +/- to convert the received bits into something it can transmit over the TX line of the serial port. What I should do, is open the casing of the receiver and connect the signal coming from the antenna to the DCD pin of that serial port. Do you have a scope? The simplest way to see what's going on would be to trigger on the PPS from the GPS unit and look at the DCF77 signal. I don't have one but in a couple of weeks it is my birthday so maybe then. The result was neither! From visual inspection it looked as if only 3 or 4 different offsets were registered. So I ran 3 tests where I took 120 offset-samples, masked of the microseconds ... How did you mask off the microseconds? Did you do that in binary or drop the right part of an ascii string? If you masked in binary, maybe you got 2 extra bits. I did it the ascii way. E.g.: value = floor(value * 1000.0) / 1000.0; There are 2 parts to decoding something like the DCF77 signal. One is to get an accurate marker for the PPS signal. The other is to figure out the time for each PPS by decoding the pattern of pulse widths. You should be able to see the pulse widths if you capture both sides of the PPS signal. Yes, I read this weekend that 0 and 1 are 100ms versus 200ms. One common way to get a large/strange offset is to use the wrong edge of the PPS signal. If that's what was happening, I'd expect to see several clumps of offsets corresponding to the different pulse widths. I only see one broad clump. It's probably the naive way of measuring (see my epiphany). I wouldn't worry about confusing ntpd, at least not at this level. It has a noise reduction mechanism. It puts all the samples into a fifo. When the driver (PPS/Atom or SHM or ...) gets polled, ntpd sorts the buffer then discards 1/3 of the samples as (potentially crazy) outliers. Thanks regards, Folkert van Heusden -- www.vanheusden.com/multitail - win een vlaai van multivlaai! zorg ervoor dat multitail opgenomen wordt in Fedora Core, AIX, Solaris of HP/UX en win een vlaai naar keuze -- Phone: +31
[time-nuts] DCF77 PPS
Hi, Now that my two servers have a garmin 18x lvc connected to them, their time keeping is nice. E.g. this one: remote refid st t when poll reach delay offset jitter o127.127.20.0.GPS.0 l6 16 3770.000 -0.006 0.003 [ other clocks skipped for brievety ] They can be reached from the internet at: - clock1.trustedtimestamping.com ipv4 ipv6 - clock2.trustedtimestamping.com ipv6 only - I had to restart ntpd on that system 10 minutes ago because I confused ntpd by opening the serial via which the gps is connected accidently with an other program, so it has to settle Both systems run Linux. Clock1 kernel 3.2 and clock2 runs 2.6.38. Without ntpd + gps it looses minutes per day (altough when I checked minutes ago the drift was only 13.637 ppm?!). I used to also have an MSF receiver but a couple of years the radio transmitter in England was replaced by a weaker one so I receive mostly noise now. Now that it works, it is somewhat boring. So I got my DCF77 clock from the attic and decided to use it different then how I'm supposed to use it: as a PPS source! I figured (inspired by http://remco.org/index.php/2008/06/09/dcf77-pps-experiments-with-a-dcf77-radio-module-using-ntpd/ ). As a quick test I hacked the testdcf.c to show the number of milliseconds the clock was at when it had received a bit. If I remember correctly DCF77 sends 60 bits per minute so each bit should be at a second edge. I expected either a small constant difference or values that would be over the whole -0.5s ... 0.5s band. The result was neither! From visual inspection it looked as if only 3 or 4 different offsets were registered. So I ran 3 tests where I took 120 offset-samples, masked of the microseconds and checked how often each offset occured: test run 1: 1 251 17 255 38 259 37 263 22 267 5 271 test run 2: 1 251 10 255 1 257 43 259 1 261 44 263 17 267 3 271 test run 3: 2 255 18 259 60 263 32 267 8 271 Column 1: number of occurences, column 2: the offset. So my guestimate is that 259 and 263 are the values to look for and I should ignore the others so that I don't confuse ntpd. What do you guys think? (Regarding the 250+ ms offset: the distance of my house to Mainflingen in Germany (where the DCF77 atomic clock is located) is +/- 374.766km (I live in Gouda, the Netherlands), so that is an offset of +/- 1.25012s.) Folkert van Heusden -- -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
[time-nuts] garmin 18 lvc versus garmin 18x lvc with pps ntp
Hi, Could not find any help anywhere on the web so you guys are my last hope. I have 2 computers running a linux PPS enabled kernel and ntp. One of the two has a garmin 18 lvc, one has a garmin 18x lvc. The one with the 18 lvc is neatly synced: remote refid st t when poll reach delay offset jitter == *GPS_NMEA(1) .GPS.0 l3 16 3770.0000.014 0.000 --- -muur.intranet.v .DCFa. 1 u6 64 3770.113 -12.192 0.047 -thegateap.intra 134.221.205.12 2 u 13 64 3770.663 -4.427 0.099 xtuinhuis.intran .MSFS. 1 u 43 64 3761.834 -21.121 0.897 xSHM(0) .MSFU. 2 l 39 64 3770.000 26.207 16.002 -ntp1.nl.uu.net .PPS.1 u 18 64 377 17.628 -3.813 0.445 +chime2.surfnet. .GPS.1 u 40 64 327 21.176 -3.315 0.123 +ntp.nmi.nl .PPS.1 u 36 64 377 19.826 -3.448 0.352 the other with the 18x lvc not so much: remote refid st t when poll reach delay offset jitter == *GENERIC(0) .DCFa. 0 l 50 64 3770.0007.370 6.659 xGPS_NMEA(0) .GPS.0 l7 16 3770.000 -657.92 11.250 --- -ntp0.nl.uu.net .PPS.1 u 441 1024 377 20.1478.310 1.973 -chime1.surfnet. .GPS.1 u 498 1024 377 17.6748.282 0.340 +ntp.nmi.nl .PPS.1 u 571 1024 377 20.0658.279 0.383 -belle.intranet. .GPS.1 u 37 64 3760.097 12.165 0.062 -thegateap.intra 192.87.106.3 2 u 962 1024 1760.0956.811 0.720 xtuinhuis.intran .MSFS. 1 u 936 1024 761.971 -8.080 0.559 As you can see it's offset is huge. Somewhere between -600 and -700 and on average around -657ms. Once (or twice) it ran fine; offset and jitter both around 0.00xms. Others seem to have this problem with that lvc version as well. I verified that the system receives pps-signal: mauer:/usr/local# for i in 1 2 3 4 5 ; do cat /sys/class/pps/pps1/assert ; sleep 1 ; done 1242845619.987661535#199682 1242845620.987661473#199683 1242845621.987660915#199684 1242845622.987660504#199685 1242845623.987660454#199686 The assert/clear is also not too short: mauer:/sys/class/pps/pps1# cat assert clear 1242846035.987585645#200094 1242846036.187587528#199624 so no problem there for the system to capture them. Is there a way that i can verify that ntpd also sees these events? Folkert van Heusden -- MultiTail is a versatile tool for watching logfiles and output of commands. Filtering, coloring, merging, diff-view, etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] Linux time servers
You might consider switching to FreeBSD for more reasons than just timing, It's much faster than Fedora and I found the new 7.1 version easy much faster in what respect? tested how? Folkert van Heusden -- www.vanheusden.com/multitail - multitail is tail on steroids. multiple windows, filtering, coloring, anything you can think of -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] Linux time servers
Anyone got any good Linux time systems for PCs ? Make sure you have a recent kernel installed with the PPS patch applied: remote refid st t when poll reach delay offset jitter == *127.127.20.1.GPS.0 l5 16 3770.000 -0.014 0.006 That system is only up for 1 day so the offset (and jitter) will get better later on. Typically the offset outputted by ntpq is around 0.001 and the jitter 0.000. This is with a Garmin 18LVC. http://wiki.enneenne.com/index.php/LinuxPPS_support I also have a DCF77 receiver connected to a system: remote refid st t when poll reach delay offset jitter == *127.127.8.0 .DCFa. 0 l 14 64 3770.000 -2.193 7.711 and an MSF receiver (using my http://vanheusden.com/lpc-ntpd/lindy_precision_clock.php driver), it is a lindy precision clock connected via USB: remote refid st t when poll reach delay offset jitter == x127.127.28.0.SHM0. 2 l 58 6470.000 11.120 6.601 Folkert van Heusden -- To MultiTail einai ena polymorfiko ergaleio gia ta logfiles kai tin eksodo twn entolwn. Prosferei: filtrarisma, xrwmatismo, sygxwneysi, diaforetikes provoles. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] Linux time servers
: You might consider switching to FreeBSD for more reasons than just : timing, It's much faster than Fedora and I found the new 7.1 version easy : : much faster in what respect? tested how? The usual benchmark that's cited here is the mysql tps scaling better than Linux. See for example http://people.freebsd.org/~kris/scaling/mysql.html. The numbers in this paper are a little dated (being for 7.0 and a little over a year old), they show good scaling. Of course, this isn't the place to debate that in extreme detail (for example, there are other pages I can't find right now that show newer versions of Linux, some better, some worse as changes to the scheduler help or hurt performance). It is no longer the case that you can automatically assume Linux performs better. You have to measure things and make sure you use the system that best matches your performance requirements. Also, on a 7.1R system, you need to make sure that you enable tagged queueing. A last minute change botched it. 7.2R is out now too. You can't say that freebsd is faster than linux; you specifically need to specify what version of freebsd and what version of linux you're using. Also the hardware platform matters as well as the compiler (and version) used to compile mysql and numerous other parameters. What would be interesting is how a specific linux-kernel with the pps patches by rodolpho compare to a specific freebsd version with the same ntpd compiled using the same gcc and such. Folkert van Heusden -- Feeling generous? - http://www.vanheusden.com/wishlist.php -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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] Linux time servers
What would be interesting is how a specific linux-kernel with the pps patches by rodolpho compare to a specific freebsd version with the same ntpd compiled using the same gcc and such. I think first of all, it would be interesting what your quality parameters are... Prescision ? Resolution ? Reliability ? Reliability is, I think, for me the most important. E.g. that it doesn't jitter all over the place and that the jitter is also as constant as possible. Folkert van Heusden -- MultiTail na wan makriki wrokosani fu tan luku den logfile nanga san den commando spiti puru. Piki puru spesrutu sani, wroko nanga difrenti kroru, tya kon makandra, nanga wan lo moro. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.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.
