diff options
Diffstat (limited to 'driver_nmea.c')
| -rw-r--r-- | driver_nmea.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/driver_nmea.c b/driver_nmea.c index 40fc42fb..a3a5d23b 100644 --- a/driver_nmea.c +++ b/driver_nmea.c @@ -327,6 +327,25 @@ static gps_mask_t processGPGGA(int c UNUSED, char *field[], session->gpsdata.status = atoi(field[6]); mask = STATUS_IS; + /* + * There are some receivers (the Trimble Placer 450 is an example) that + * don't ship a GSA with mode 1 when they lose satellite lock. Instead + * they just keep reporting GGA and GSA on subsequent cycles with the + * timestamp not advancing and a bogus mode. On the assumption that GGA + * is only issued once per cycle we can detect this here (it would be + * nicer to do it on GSA but GSA has no timestamp). + */ + session->driver.nmea.latch_mode = strncmp(field[1], + session->driver.nmea.last_gga_timestamp, + sizeof(session->driver.nmea.last_gga_timestamp))==0; + if (session->driver.nmea.latch_mode) { + session->gpsdata.status = STATUS_NO_FIX; + session->newdata.mode = MODE_NO_FIX; + } else + (void)strncpy(session->driver.nmea.last_gga_timestamp, + field[1], + sizeof(session->driver.nmea.last_gga_timestamp)); + /* if we have a fix and the mode latch is off, go... */ if (session->gpsdata.status > STATUS_NO_FIX) { char *altitude; @@ -415,6 +434,9 @@ static gps_mask_t processGPGSA(int count, char *field[], if (count < 17) { gpsd_report(LOG_DATA, "GPGSA: malformed, setting ONLINE_IS only.\n"); mask = ONLINE_IS; + } else if (session->driver.nmea.latch_mode) { + /* last GGA had a non-advancing timestamp; don't trust this GSA */ + mask = ONLINE_IS; } else { int i; session->newdata.mode = atoi(field[2]); |