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PPS timing investigation
by Håkan Johansson-5
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Hi, In order to figure out how the ntpshm.c PPS and serial handling can be improved, data on the behaviour of various module models is needed. By slight extension of the existing log messages (attachment gpsd_pps_timing_log.diff), the necessary data can be collected. The following almost does the trick: gpsd -n -N /dev/ttyXXX -D6 2>&1 | \ egrep "pps-detect|ntpshm_put|driver|speed" | \ head -n 100 > ~/pps_log_YYY.txt (except that head does not stop the execution when done, so a Ctrl-C is needed, other variations may be needed...) I've tried it on the two types I have at hand, with the following results (see attached files): motorola oncore UT+ with the oncore binary format (@ 9600 bps): PPS pulse is 200 ms long ntpshm_put gets called @~180 ms after the second, with the time of the preceding pulse (first edge). Note that 160 ms of the time stamp are due to the magic shift in the ntpshm_put call) (the remaining sub-second information seems to be wrong) (the initial missing ntpshm_put calls and the bad pulses are due to a hard reset at program startup to position hold mode - it takes some time before it finds a satellite again) garmin 18 lvc with nmea output format (@ 4800 bps) (1 pps): PPS pulse is 40 ms long ntpshm_put gets called @~175 ms after the second, with time of preceding pulse. no ntpshm_put magic (the offset in the times is due to the machine's ntpd tracking a network reference - I'm not in charge of that ntpd.conf...) Further notes: The effect of running gpsd at -D6 is with a 1.6 GHz machine approximately a delay of 1 ms in the @ timing of the ntpshm_put information due to previous log message production. The PPS pulse @ timing has no such effects. It would be nice if other developers/users also could provide similar data, so we can get to the bottom of this issue. I'm not aware of this information already existing. I'm sure someone will correct me... Cheers, and thanks in advance Håkan [gpsd_pps_timing_log.diff] Index: libgpsd_core.c =================================================================== --- libgpsd_core.c (revision 6426) +++ libgpsd_core.c (arbetskopia) @@ -148,9 +148,10 @@ break; } } else { - gpsd_report(LOG_RAW, "pps-detect (%s) on %s changed to %d\n", + gpsd_report(LOG_RAW, "pps-detect (%s) on %s changed to %d @ %lu.%06lu\n", ((pps_device==TIOCM_CAR) ? "DCD" : "CTS"), - session->gpsdata.dev.path, state); + session->gpsdata.dev.path, state, + (unsigned long)tv.tv_sec, (unsigned long)tv.tv_usec); laststate = state; unchanged = 0; } Index: ntpshm.c =================================================================== --- ntpshm.c (revision 6426) +++ ntpshm.c (arbetskopia) @@ -141,9 +141,10 @@ shmTime->count++; shmTime->valid = 1; - gpsd_report(LOG_RAW, "ntpshm_put: Clock: %lu @ %lu.%06lu\n" - , (unsigned long)seconds, (unsigned long)tv.tv_sec - , (unsigned long)tv.tv_usec); + gpsd_report(LOG_RAW, "ntpshm_put: Clock: %lu.%06lu @ %lu.%06lu (pktlen %d)\n" + , (unsigned long)seconds, (unsigned long)microseconds + , (unsigned long)tv.tv_sec, (unsigned long)tv.tv_usec + , session->packet.outbuflen); return 1; } gpsd: speed 4800, 8N1 gpsd: switch_driver(Generic NMEA) called... gpsd: selecting Generic NMEA driver... gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637878.999640 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637879.039657 gpsd: ntpshm_put: Clock: 1257637879.000000 @ 1257637879.200069 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637879.999645 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637880.039648 gpsd: ntpshm_put: Clock: 1257637880.000000 @ 1257637880.176019 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637880.999655 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637881.039654 gpsd: ntpshm_put: Clock: 1257637881.000000 @ 1257637881.176013 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637881.999647 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637882.039644 gpsd: ntpshm_put: Clock: 1257637882.000000 @ 1257637882.196006 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637882.999644 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637883.039647 gpsd: ntpshm_put: Clock: 1257637883.000000 @ 1257637883.176010 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637883.999645 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637884.039672 gpsd: ntpshm_put: Clock: 1257637884.000000 @ 1257637884.176015 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637884.999640 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637885.039656 gpsd: ntpshm_put: Clock: 1257637885.000000 @ 1257637885.176006 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637885.999641 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637886.039680 gpsd: ntpshm_put: Clock: 1257637886.000000 @ 1257637886.175998 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637886.999642 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637887.039651 gpsd: ntpshm_put: Clock: 1257637887.000000 @ 1257637887.176011 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637887.999647 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637888.039656 gpsd: ntpshm_put: Clock: 1257637888.000000 @ 1257637888.176000 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637888.999641 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637889.039654 gpsd: ntpshm_put: Clock: 1257637889.000000 @ 1257637889.176007 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637889.999646 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637890.039646 gpsd: ntpshm_put: Clock: 1257637890.000000 @ 1257637890.176022 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637890.999640 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637891.039650 gpsd: ntpshm_put: Clock: 1257637891.000000 @ 1257637891.176884 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637891.999641 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637892.039647 gpsd: ntpshm_put: Clock: 1257637892.000000 @ 1257637892.175977 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637892.999641 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637893.039667 gpsd: ntpshm_put: Clock: 1257637893.000000 @ 1257637893.175998 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637893.999642 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637894.039649 gpsd: ntpshm_put: Clock: 1257637894.000000 @ 1257637894.176008 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637894.999643 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637895.039650 gpsd: ntpshm_put: Clock: 1257637895.000000 @ 1257637895.179992 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637895.999642 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637896.039645 gpsd: ntpshm_put: Clock: 1257637896.000000 @ 1257637896.175997 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637896.999645 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637897.039659 gpsd: ntpshm_put: Clock: 1257637897.000000 @ 1257637897.176002 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637897.999644 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637898.039646 gpsd: ntpshm_put: Clock: 1257637898.000000 @ 1257637898.183994 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637898.999659 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637899.039648 gpsd: ntpshm_put: Clock: 1257637899.000000 @ 1257637899.175969 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637899.999645 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637900.039649 gpsd: ntpshm_put: Clock: 1257637900.000000 @ 1257637900.183994 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637900.999641 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637901.039645 gpsd: ntpshm_put: Clock: 1257637901.000000 @ 1257637901.175997 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637901.999658 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637902.039656 gpsd: ntpshm_put: Clock: 1257637902.000000 @ 1257637902.176003 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637902.999659 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637903.039647 gpsd: ntpshm_put: Clock: 1257637903.000000 @ 1257637903.175995 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637903.999643 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637904.039648 gpsd: ntpshm_put: Clock: 1257637904.000000 @ 1257637904.184008 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637904.999646 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637905.039645 gpsd: ntpshm_put: Clock: 1257637905.000000 @ 1257637905.175990 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637905.999642 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637906.039646 gpsd: ntpshm_put: Clock: 1257637906.000000 @ 1257637906.176007 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637906.999640 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637907.039652 gpsd: ntpshm_put: Clock: 1257637907.000000 @ 1257637907.176005 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637907.999645 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637908.039649 gpsd: ntpshm_put: Clock: 1257637908.000000 @ 1257637908.175993 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637908.999652 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637909.039651 gpsd: ntpshm_put: Clock: 1257637909.000000 @ 1257637909.175991 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637909.999642 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257637910.039652 gpsd: ntpshm_put: Clock: 1257637910.000000 @ 1257637910.175988 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257637910.999641 gpsd: speed 9600, 8N1 gpsd: switch_driver(oncore binary) called... gpsd: selecting oncore binary driver... gpsd: ntpshm_put: Clock: 1257638185.160882 @ 1257638185.386469 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638186.000001 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638186.046939 gpsd: ntpshm_put: Clock: 1257638186.160941 @ 1257638186.193690 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638192.334584 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638192.532729 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638193.334582 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638193.532791 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638194.334590 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638194.532853 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638195.334599 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638195.532934 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638196.334584 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638196.532959 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638197.334583 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638197.533029 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638198.334583 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638198.533093 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638199.334582 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638199.533152 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638200.334583 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638200.533212 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638201.334583 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638201.533257 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638202.334583 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638202.533335 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638203.334582 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638203.533386 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638204.334581 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638204.533448 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638205.334583 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638205.533655 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638206.334583 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638206.533570 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638207.334585 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638207.532623 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638208.334583 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638208.532670 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638209.078857 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638209.277714 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638211.078857 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638211.277854 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638212.078855 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638212.276913 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638213.078858 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638213.276957 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638214.078856 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638214.277017 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638215.078856 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638215.277093 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638216.078855 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638216.277152 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638217.078856 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638217.277209 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638218.078857 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638218.277268 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638219.078857 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638219.277331 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638220.078856 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638220.277388 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638221.078859 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638221.277448 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638222.078859 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638222.277507 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638223.078857 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638223.277571 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638224.078858 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638224.277628 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638225.078857 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638225.277685 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638226.078858 gpsd: ntpshm_put: Clock: 1257638226.239719 @ 1257638226.261710 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638226.277749 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638227.000001 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638227.198785 gpsd: ntpshm_put: Clock: 1257638228.160834 @ 1257638228.181678 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638229.000001 gpsd: ntpshm_put: Clock: 1257638229.160894 @ 1257638229.193662 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638229.198913 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638230.000000 gpsd: ntpshm_put: Clock: 1257638230.160953 @ 1257638230.181893 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638230.198960 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638231.000001 gpsd: ntpshm_put: Clock: 1257638231.160013 @ 1257638231.181903 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638231.198040 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638232.000001 gpsd: ntpshm_put: Clock: 1257638232.160073 @ 1257638232.181892 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638232.198101 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638233.000000 gpsd: ntpshm_put: Clock: 1257638233.160132 @ 1257638233.189943 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638233.198166 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638234.000001 gpsd: ntpshm_put: Clock: 1257638234.160192 @ 1257638234.181892 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638234.198220 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638235.000000 gpsd: ntpshm_put: Clock: 1257638235.160252 @ 1257638235.181890 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638235.198279 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638236.000002 gpsd: ntpshm_put: Clock: 1257638236.160312 @ 1257638236.181892 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638236.198340 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638237.000003 gpsd: ntpshm_put: Clock: 1257638237.160371 @ 1257638237.181889 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638237.198404 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638238.000002 gpsd: ntpshm_put: Clock: 1257638238.160431 @ 1257638238.189951 (pktlen 76) gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 1 @ 1257638238.198435 gpsd: pps-detect (CTS) on /dev/ttyS0 changed to 0 @ 1257638239.000001 _______________________________________________ Gpsd-dev mailing list Gpsd-dev@... https://lists.berlios.de/mailman/listinfo/gpsd-dev |
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Re: PPS timing investigation
by Miroslav Lichvar
::
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On Sun, Nov 08, 2009 at 01:28:33AM +0100, Håkan Johansson wrote:
> In order to figure out how the ntpshm.c PPS and serial handling can > be improved, data on the behaviour of various module models is > needed. By slight extension of the existing log messages > (attachment gpsd_pps_timing_log.diff), the necessary data can be > collected. Here is my log from GPS 18x LVC in NMEA mode. Note that most of the GPRMC message don't make the 0.5 second locking limit in ntpshm_pps(), so they are ignored. Also, the pulse width is only 40 ms by default, which makes gpsd report both edges and ntpd is most likely (96% chance) syncing to the wrong edge. -- Miroslav Lichvar gpsd: speed 9600, 8N1 gpsd: switch_driver(Generic NMEA) called... gpsd: selecting Generic NMEA driver... gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853974.000039 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853974.040021 gpsd: ntpshm_put: Clock: 1257853974.000000 @ 1257853974.560483 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853975.000024 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853975.040023 gpsd: ntpshm_put: Clock: 1257853975.000000 @ 1257853975.546411 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853976.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853976.040021 gpsd: ntpshm_put: Clock: 1257853976.000000 @ 1257853976.533423 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853977.000022 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853977.040023 gpsd: ntpshm_put: Clock: 1257853977.000000 @ 1257853977.519405 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853978.000025 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853978.040023 gpsd: ntpshm_put: Clock: 1257853978.000000 @ 1257853978.532420 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853979.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853979.040022 gpsd: ntpshm_put: Clock: 1257853979.000000 @ 1257853979.525426 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853980.000024 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853980.040022 gpsd: ntpshm_put: Clock: 1257853980.000000 @ 1257853980.535420 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853981.000022 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853981.040024 gpsd: ntpshm_put: Clock: 1257853981.000000 @ 1257853981.544426 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853982.000025 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853982.040023 gpsd: ntpshm_put: Clock: 1257853982.000000 @ 1257853982.535420 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853983.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853983.040022 gpsd: ntpshm_put: Clock: 1257853983.000000 @ 1257853983.536423 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853984.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853984.040022 gpsd: ntpshm_put: Clock: 1257853984.000000 @ 1257853984.526422 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853985.000022 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853985.040024 gpsd: ntpshm_put: Clock: 1257853985.000000 @ 1257853985.490414 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853986.000024 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853986.040023 gpsd: ntpshm_put: Clock: 1257853986.000000 @ 1257853986.522422 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853987.000026 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853987.040023 gpsd: ntpshm_put: Clock: 1257853987.000000 @ 1257853987.489423 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853988.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853988.040021 gpsd: ntpshm_put: Clock: 1257853988.000000 @ 1257853988.524381 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853989.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853989.040023 gpsd: ntpshm_put: Clock: 1257853989.000000 @ 1257853989.522423 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853990.000025 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853990.040023 gpsd: ntpshm_put: Clock: 1257853990.000000 @ 1257853990.497423 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853991.000022 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853991.040022 gpsd: ntpshm_put: Clock: 1257853991.000000 @ 1257853991.525380 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853992.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853992.040022 gpsd: ntpshm_put: Clock: 1257853992.000000 @ 1257853992.490412 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853993.000022 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853993.040024 gpsd: ntpshm_put: Clock: 1257853993.000000 @ 1257853993.499427 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853994.000024 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853994.040023 gpsd: ntpshm_put: Clock: 1257853994.000000 @ 1257853994.524423 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853995.000027 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853995.040032 gpsd: ntpshm_put: Clock: 1257853995.000000 @ 1257853995.502428 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853996.000024 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853996.040021 gpsd: ntpshm_put: Clock: 1257853996.000000 @ 1257853996.538379 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853997.000022 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853997.040024 gpsd: ntpshm_put: Clock: 1257853997.000000 @ 1257853997.501426 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853998.000025 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853998.040024 gpsd: ntpshm_put: Clock: 1257853998.000000 @ 1257853998.556427 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257853999.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257853999.040022 gpsd: ntpshm_put: Clock: 1257853999.000000 @ 1257853999.518394 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257854000.000024 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257854000.040021 gpsd: ntpshm_put: Clock: 1257854000.000000 @ 1257854000.492342 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257854001.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257854001.040023 gpsd: ntpshm_put: Clock: 1257854001.000000 @ 1257854001.498425 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257854002.000024 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257854002.040022 gpsd: ntpshm_put: Clock: 1257854002.000000 @ 1257854002.502424 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257854003.000026 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257854003.040022 gpsd: ntpshm_put: Clock: 1257854003.000000 @ 1257854003.505355 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257854004.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257854004.040021 gpsd: ntpshm_put: Clock: 1257854004.000000 @ 1257854004.497425 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257854005.000023 gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 0 @ 1257854005.040022 gpsd: ntpshm_put: Clock: 1257854005.000000 @ 1257854005.497353 (pktlen 74) gpsd: pps-detect (DCD) on /dev/ttyS0 changed to 1 @ 1257854006.000025 _______________________________________________ Gpsd-dev mailing list Gpsd-dev@... https://lists.berlios.de/mailman/listinfo/gpsd-dev |
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Re: PPS timing investigation
by Håkan Johansson-5
::
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Some more partial information, scavenged from old posts: -- http://developer.berlios.de/support/?func=detailsupport&support_id=102840&group_id=2116 GPS18xLVC, NMEA, DCD @ 0 -> 1 dur (of 0): 960 ms -> 0 dur (of 1): 40 ms _put + 430 ms, report after pulse offset 420 ms supported by ntpd.conf entry -- https://lists.berlios.de/pipermail/gpsd-users/2008-February/003161.html unknown NMEA device, DCD -> 0 dur (of 1): 802 ms -> 1 dur (of 0): 198 ms _put + 333 ms, report after pulse(?) _put offset could be wrong - lock lost. -- http://osdir.com/ml/hardware.gps.gpsd.user/2008-01/msg00033.html Furuno Electric unit, NMEA, DCD @0 -> 1 dur (of 0): 500 ms _put + 200 ms, report after pulse -> 0 dur (of 1): 500 ms -- http://old.nabble.com/Missing-PPS-signal-after-midnight-td16761435.html Garmin HVS17, DCD @0 -> 1 dur (of 0): 960 ms -> 0 dur (of 1): 40 ms _put + 340 ms, report after pulse -- Håkan _______________________________________________ Gpsd-dev mailing list Gpsd-dev@... https://lists.berlios.de/mailman/listinfo/gpsd-dev |
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