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driver_nmea0183.c
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driver_nmea0183.c
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/*
* This file is Copyright (c) 2010 by the GPSD project
* BSD terms apply: see the file COPYING in the distribution root for details.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <math.h>
#include <string.h>
#include <stdarg.h>
#include <time.h>
#include "gpsd.h"
#ifdef NMEA_ENABLE
/**************************************************************************
*
* Parser helpers begin here
*
**************************************************************************/
static void do_lat_lon(char *field[], struct gps_fix_t *out)
/* process a pair of latitude/longitude fields starting at field index BEGIN */
{
double d, m;
char str[20], *p;
if (*(p = field[0]) != '\0') {
double lat;
(void)strlcpy(str, p, sizeof(str));
lat = atof(str);
m = 100.0 * modf(lat / 100.0, &d);
lat = d + m / 60.0;
p = field[1];
if (*p == 'S')
lat = -lat;
out->latitude = lat;
}
if (*(p = field[2]) != '\0') {
double lon;
(void)strlcpy(str, p, sizeof(str));
lon = atof(str);
m = 100.0 * modf(lon / 100.0, &d);
lon = d + m / 60.0;
p = field[3];
if (*p == 'W')
lon = -lon;
out->longitude = lon;
}
}
/**************************************************************************
*
* Scary timestamp fudging begins here
*
* Four sentences, GGA and GLL and RMC and ZDA, contain timestamps.
* GGA/GLL/RMC timestamps look like hhmmss.ss, with the trailing .ss
* part optional. RMC has a date field, in the format ddmmyy. ZDA
* has separate fields for day/month/year, with a 4-digit year. This
* means that for RMC we must supply a century and for GGA and GLL we
* must supply a century, year, and day. We get the missing data from
* a previous RMC or ZDA; century in RMC is supplied from the daemon's
* context (initialized at startup time) if there has been no previous
* ZDA.
*
**************************************************************************/
#define DD(s) ((int)((s)[0]-'0')*10+(int)((s)[1]-'0'))
static void merge_ddmmyy(char *ddmmyy, struct gps_device_t *session)
/* sentence supplied ddmmyy, but no century part */
{
int yy = DD(ddmmyy + 4);
int mon = DD(ddmmyy + 2);
int mday = DD(ddmmyy);
int year;
/* check for century wrap */
if (session->driver.nmea.date.tm_year % 100 == 99 && yy == 0)
gpsd_century_update(session, session->context->century + 100);
year = (session->context->century + yy);
if ( (1 > mon ) || (12 < mon ) ) {
gpsd_report(session->context->debug, LOG_WARN,
"merge_ddmmyy(%s), malformed month\n", ddmmyy);
} else if ( (1 > mday ) || (31 < mday ) ) {
gpsd_report(session->context->debug, LOG_WARN,
"merge_ddmmyy(%s), malformed day\n", ddmmyy);
} else {
gpsd_report(session->context->debug, LOG_DATA,
"merge_ddmmyy(%s) sets year %d\n",
ddmmyy, year);
session->driver.nmea.date.tm_year = year - 1900;
session->driver.nmea.date.tm_mon = mon - 1;
session->driver.nmea.date.tm_mday = mday;
}
}
static void merge_hhmmss(char *hhmmss, struct gps_device_t *session)
/* update from a UTC time */
{
int old_hour = session->driver.nmea.date.tm_hour;
session->driver.nmea.date.tm_hour = DD(hhmmss);
if (session->driver.nmea.date.tm_hour < old_hour) /* midnight wrap */
session->driver.nmea.date.tm_mday++;
session->driver.nmea.date.tm_min = DD(hhmmss + 2);
session->driver.nmea.date.tm_sec = DD(hhmmss + 4);
session->driver.nmea.subseconds =
safe_atof(hhmmss + 4) - session->driver.nmea.date.tm_sec;
}
static void register_fractional_time(const char *tag, const char *fld,
struct gps_device_t *session)
{
if (fld[0] != '\0') {
session->driver.nmea.last_frac_time =
session->driver.nmea.this_frac_time;
session->driver.nmea.this_frac_time = safe_atof(fld);
session->driver.nmea.latch_frac_time = true;
gpsd_report(session->context->debug, LOG_DATA,
"%s: registers fractional time %.2f\n",
tag, session->driver.nmea.this_frac_time);
}
}
/**************************************************************************
*
* Compare GPS timestamps for equality. Depends on the fact that the
* timestamp granularity of GPS is 1/100th of a second. Use this to avoid
* naive float comparisons.
*
**************************************************************************/
#define GPS_TIME_EQUAL(a, b) (fabs((a) - (b)) < 0.01)
/**************************************************************************
*
* NMEA sentence handling begins here
*
**************************************************************************/
static gps_mask_t processGPRMC(int count, char *field[],
struct gps_device_t *session)
/* Recommend Minimum Course Specific GPS/TRANSIT Data */
{
/*
* RMC,225446.33,A,4916.45,N,12311.12,W,000.5,054.7,191194,020.3,E,A*68
* 1 225446.33 Time of fix 22:54:46 UTC
* 2 A Status of Fix: A = Autonomous, valid;
* D = Differential, valid; V = invalid
* 3,4 4916.45,N Latitude 49 deg. 16.45 min North
* 5,6 12311.12,W Longitude 123 deg. 11.12 min West
* 7 000.5 Speed over ground, Knots
* 8 054.7 Course Made Good, True north
* 9 181194 Date of fix 18 November 1994
* 10,11 020.3,E Magnetic variation 20.3 deg East
* 12 A FAA mode indicator (NMEA 2.3 and later)
* A=autonomous, D=differential, E=Estimated,
* N=not valid, S=Simulator, M=Manual input mode
* *68 mandatory nmea_checksum
*
* * SiRF chipsets don't return either Mode Indicator or magnetic variation.
*/
gps_mask_t mask = 0;
if (strcmp(field[2], "V") == 0) {
/* copes with Magellan EC-10X, see below */
if (session->gpsdata.status != STATUS_NO_FIX) {
session->gpsdata.status = STATUS_NO_FIX;
mask |= STATUS_SET;
}
if (session->newdata.mode >= MODE_2D) {
session->newdata.mode = MODE_NO_FIX;
mask |= MODE_SET;
}
/* set something nz, so it won't look like an unknown sentence */
mask |= ONLINE_SET;
} else if (strcmp(field[2], "A") == 0) {
/*
* The MTK3301, Royaltek RGM-3800, and possibly other
* devices deliver bogus time values when the navigation
* warning bit is set.
*/
if (count > 9 && field[1][0] != '\0' && field[9][0] != '\0') {
merge_hhmmss(field[1], session);
merge_ddmmyy(field[9], session);
mask |= TIME_SET;
register_fractional_time(field[0], field[1], session);
}
do_lat_lon(&field[3], &session->newdata);
mask |= LATLON_SET;
session->gpsdata.navigation.speed_over_ground = safe_atof(field[7]) * KNOTS_TO_MPS;
session->gpsdata.navigation.set |= NAV_SOG_PSET;
session->gpsdata.navigation.course_over_ground = safe_atof(field[8]);
session->gpsdata.navigation.set |= NAV_COG_PSET;
mask |= NAVIGATION_SET;
/*
* This copes with GPSes like the Magellan EC-10X that *only* emit
* GPRMC. In this case we set mode and status here so the client
* code that relies on them won't mistakenly believe it has never
* received a fix.
*/
if (session->gpsdata.status == STATUS_NO_FIX) {
session->gpsdata.status = STATUS_FIX; /* could be DGPS_FIX, we can't tell */
mask |= STATUS_SET;
}
if (session->newdata.mode < MODE_2D) {
session->newdata.mode = MODE_2D;
mask |= MODE_SET;
}
}
gpsd_report(session->context->debug, LOG_DATA,
"RMC: ddmmyy=%s hhmmss=%s lat=%.2f lon=%.2f "
"speed=%.2f track=%.2f mode=%d status=%d\n",
field[9], field[1],
session->newdata.latitude,
session->newdata.longitude,
session->gpsdata.navigation.speed_over_ground,
session->gpsdata.navigation.course_over_ground,
session->newdata.mode,
session->gpsdata.status);
return mask;
}
static gps_mask_t processGPGLL(int count, char *field[],
struct gps_device_t *session)
/* Geographic position - Latitude, Longitude */
{
/* Introduced in NMEA 3.0.
*
* $GPGLL,4916.45,N,12311.12,W,225444,A,A*5C
*
* 1,2: 4916.46,N Latitude 49 deg. 16.45 min. North
* 3,4: 12311.12,W Longitude 123 deg. 11.12 min. West
* 5: 225444 Fix taken at 22:54:44 UTC
* 6: A Data valid
* 7: A Autonomous mode
* 8: *5C Mandatory NMEA checksum
*
* 1,2 Latitude, N (North) or S (South)
* 3,4 Longitude, E (East) or W (West)
* 5 UTC of position
* 6 A=Active, V=Void
* 7 Mode Indicator
* A = Autonomous mode
* D = Differential Mode
* E = Estimated (dead-reckoning) mode
* M = Manual Input Mode
* S = Simulated Mode
* N = Data Not Valid
*
* I found a note at <http://www.secoh.ru/windows/gps/nmfqexep.txt>
* indicating that the Garmin 65 does not return time and status.
* SiRF chipsets don't return the Mode Indicator.
* This code copes gracefully with both quirks.
*
* Unless you care about the FAA indicator, this sentence supplies nothing
* that GPRMC doesn't already. But at least one Garmin GPS -- the 48
* actually ships updates in GLL that aren't redundant.
*/
char *status = field[7];
gps_mask_t mask = 0;
if (field[5][0] != '\0') {
merge_hhmmss(field[5], session);
register_fractional_time(field[0], field[5], session);
if (session->driver.nmea.date.tm_year == 0)
gpsd_report(session->context->debug, LOG_WARN,
"can't use GLL time until after ZDA or RMC has supplied a year.\n");
else {
mask = TIME_SET;
}
}
if (strcmp(field[6], "A") == 0 && (count < 8 || *status != 'N')) {
int newstatus;
do_lat_lon(&field[1], &session->newdata);
mask |= LATLON_SET;
if (count >= 8 && *status == 'D')
newstatus = STATUS_DGPS_FIX; /* differential */
else
newstatus = STATUS_FIX;
/*
* This is a bit dodgy. Technically we shouldn't set the mode
* bit until we see GSA. But it may be later in the cycle,
* some devices like the FV-18 don't send it by default, and
* elsewhere in the code we want to be able to test for the
* presence of a valid fix with mode > MODE_NO_FIX.
*/
if (session->newdata.mode < MODE_2D) {
session->newdata.mode = MODE_2D;
mask |= MODE_SET;
}
session->gpsdata.status = newstatus;
mask |= STATUS_SET;
}
gpsd_report(session->context->debug, LOG_DATA,
"GLL: hhmmss=%s lat=%.2f lon=%.2f mode=%d status=%d\n",
field[5],
session->newdata.latitude,
session->newdata.longitude,
session->newdata.mode,
session->gpsdata.status);
return mask;
}
static gps_mask_t processGPGGA(int c UNUSED, char *field[],
struct gps_device_t *session)
/* Global Positioning System Fix Data */
{
/*
* GGA,123519,4807.038,N,01131.324,E,1,08,0.9,545.4,M,46.9,M, , *42
* 1 123519 Fix taken at 12:35:19 UTC
* 2,3 4807.038,N Latitude 48 deg 07.038' N
* 4,5 01131.324,E Longitude 11 deg 31.324' E
* 6 1 Fix quality: 0 = invalid, 1 = GPS, 2 = DGPS,
* 3=PPS (Precise Position Service),
* 4=RTK (Real Time Kinematic) with fixed integers,
* 5=Float RTK, 6=Estimated, 7=Manual, 8=Simulator
* 7 08 Number of satellites being tracked
* 8 0.9 Horizontal dilution of position
* 9,10 545.4,M Altitude, Metres above mean sea level
* 11,12 46.9,M Height of geoid (mean sea level) above WGS84
* ellipsoid, in Meters
* (empty field) time in seconds since last DGPS update
* (empty field) DGPS station ID number (0000-1023)
*/
gps_mask_t mask;
session->gpsdata.status = atoi(field[6]);
mask = STATUS_SET;
/*
* 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)strlcpy(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;
merge_hhmmss(field[1], session);
register_fractional_time(field[0], field[1], session);
if (session->driver.nmea.date.tm_year == 0)
gpsd_report(session->context->debug, LOG_WARN,
"can't use GGA time until after ZDA or RMC has supplied a year.\n");
else {
mask |= TIME_SET;
}
do_lat_lon(&field[2], &session->newdata);
mask |= LATLON_SET;
session->gpsdata.satellites_used = atoi(field[7]);
altitude = field[9];
/*
* SiRF chipsets up to version 2.2 report a null altitude field.
* See <http://www.sirf.com/Downloads/Technical/apnt0033.pdf>.
* If we see this, force mode to 2D at most.
*/
if (altitude[0] == '\0') {
if (session->newdata.mode > MODE_2D) {
session->newdata.mode = MODE_2D;
mask |= MODE_SET;
}
} else {
session->newdata.altitude = safe_atof(altitude);
mask |= ALTITUDE_SET;
/*
* This is a bit dodgy. Technically we shouldn't set the mode
* bit until we see GSA. But it may be later in the cycle,
* some devices like the FV-18 don't send it by default, and
* elsewhere in the code we want to be able to test for the
* presence of a valid fix with mode > MODE_NO_FIX.
*/
if (session->newdata.mode < MODE_3D) {
session->newdata.mode = MODE_3D;
mask |= MODE_SET;
}
}
if (strlen(field[11]) > 0) {
session->gpsdata.separation = safe_atof(field[11]);
} else {
session->gpsdata.separation =
wgs84_separation(session->newdata.latitude,
session->newdata.longitude);
}
}
gpsd_report(session->context->debug, LOG_DATA,
"GGA: hhmmss=%s lat=%.2f lon=%.2f alt=%.2f mode=%d status=%d\n",
field[1],
session->newdata.latitude,
session->newdata.longitude,
session->newdata.altitude,
session->newdata.mode,
session->gpsdata.status);
return mask;
}
static gps_mask_t processGPGST(int count, char *field[], struct gps_device_t *session)
/* GST - GPS Pseudorange Noise Statistics */
{
/*
* GST,hhmmss.ss,x,x,x,x,x,x,x,*hh
* 1 TC time of associated GGA fix
* 2 Total RMS standard deviation of ranges inputs to the navigation solution
* 3 Standard deviation (meters) of semi-major axis of error ellipse
* 4 Standard deviation (meters) of semi-minor axis of error ellipse
* 5 Orientation of semi-major axis of error ellipse (true north degrees)
* 6 Standard deviation (meters) of latitude error
* 7 Standard deviation (meters) of longitude error
* 8 Standard deviation (meters) of altitude error
* 9 Checksum
*/
if (count < 8) {
return 0;
}
#define PARSE_FIELD(n) (*field[n]!='\0' ? safe_atof(field[n]) : NAN)
session->gpsdata.gst.utctime = PARSE_FIELD(1);
session->gpsdata.gst.rms_deviation = PARSE_FIELD(2);
session->gpsdata.gst.smajor_deviation = PARSE_FIELD(3);
session->gpsdata.gst.sminor_deviation = PARSE_FIELD(4);
session->gpsdata.gst.smajor_orientation = PARSE_FIELD(5);
session->gpsdata.gst.lat_err_deviation = PARSE_FIELD(6);
session->gpsdata.gst.lon_err_deviation = PARSE_FIELD(7);
session->gpsdata.gst.alt_err_deviation = PARSE_FIELD(8);
#undef PARSE_FIELD
register_fractional_time(field[0], field[1], session);
gpsd_report(session->context->debug, LOG_DATA,
"GST: utc = %.2f, rms = %.2f, maj = %.2f, min = %.2f, ori = %.2f, lat = %.2f, lon = %.2f, alt = %.2f\n",
session->gpsdata.gst.utctime,
session->gpsdata.gst.rms_deviation,
session->gpsdata.gst.smajor_deviation,
session->gpsdata.gst.sminor_deviation,
session->gpsdata.gst.smajor_orientation,
session->gpsdata.gst.lat_err_deviation,
session->gpsdata.gst.lon_err_deviation,
session->gpsdata.gst.alt_err_deviation);
return GST_SET | ONLINE_SET;
}
static gps_mask_t processGPGSA(int count, char *field[],
struct gps_device_t *session)
/* GPS DOP and Active Satellites */
{
/*
* eg1. $GPGSA,A,3,,,,,,16,18,,22,24,,,3.6,2.1,2.2*3C
* eg2. $GPGSA,A,3,19,28,14,18,27,22,31,39,,,,,1.7,1.0,1.3*35
* 1 = Mode:
* M=Manual, forced to operate in 2D or 3D
* A=Automatic, 3D/2D
* 2 = Mode: 1=Fix not available, 2=2D, 3=3D
* 3-14 = PRNs of satellites used in position fix (null for unused fields)
* 15 = PDOP
* 16 = HDOP
* 17 = VDOP
*/
gps_mask_t mask;
/*
* One chipset called the i.Trek M3 issues GPGSA lines that look like
* this: "$GPGSA,A,1,,,,*32" when it has no fix. This is broken
* in at least two ways: it's got the wrong number of fields, and
* it claims to be a valid sentence (A flag) when it isn't.
* Alarmingly, it's possible this error may be generic to SiRFstarIII.
*/
if (count < 17) {
gpsd_report(session->context->debug, LOG_DATA,
"GPGSA: malformed, setting ONLINE_SET only.\n");
mask = ONLINE_SET;
} else if (session->driver.nmea.latch_mode) {
/* last GGA had a non-advancing timestamp; don't trust this GSA */
mask = ONLINE_SET;
} else {
int i;
session->newdata.mode = atoi(field[2]);
/*
* The first arm of this conditional ignores dead-reckoning
* fixes from an Antaris chipset. which returns E in field 2
* for a dead-reckoning estimate. Fix by Andreas Stricker.
*/
if (session->newdata.mode == 0 && field[2][0] == 'E')
mask = 0;
else
mask = MODE_SET;
gpsd_report(session->context->debug, LOG_PROG,
"GPGSA sets mode %d\n", session->newdata.mode);
session->gpsdata.dop.pdop = safe_atof(field[15]);
session->gpsdata.dop.hdop = safe_atof(field[16]);
session->gpsdata.dop.vdop = safe_atof(field[17]);
session->gpsdata.satellites_used = 0;
memset(session->gpsdata.used, 0, sizeof(session->gpsdata.used));
/* the magic 6 here counts the tag, two mode fields, and the DOP fields */
for (i = 0; i < count - 6; i++) {
int prn = atoi(field[i + 3]);
if (prn > 0)
session->gpsdata.used[session->gpsdata.satellites_used++] =
prn;
}
mask |= DOP_SET | USED_IS;
gpsd_report(session->context->debug, LOG_DATA,
"GPGSA: mode=%d used=%d pdop=%.2f hdop=%.2f vdop=%.2f\n",
session->newdata.mode,
session->gpsdata.satellites_used,
session->gpsdata.dop.pdop,
session->gpsdata.dop.hdop,
session->gpsdata.dop.vdop);
}
return mask;
}
static gps_mask_t processGPGSV(int count, char *field[],
struct gps_device_t *session)
/* GPS Satellites in View */
{
/*
* GSV,2,1,08,01,40,083,46,02,17,308,41,12,07,344,39,14,22,228,45*75
* 2 Number of sentences for full data
* 1 Sentence 1 of 2
* 08 Total number of satellites in view
* 01 Satellite PRN number
* 40 Elevation, degrees
* 083 Azimuth, degrees
* 46 Signal-to-noise ratio in decibels
* <repeat for up to 4 satellites per sentence>
* There my be up to three GSV sentences in a data packet
*/
int n, fldnum;
if (count <= 3) {
gpsd_report(session->context->debug, LOG_WARN,
"malformed GPGSV - fieldcount %d <= 3\n",
count);
gpsd_zero_satellites(&session->gpsdata);
session->gpsdata.satellites_visible = 0;
return ONLINE_SET;
}
if (count % 4 != 0) {
gpsd_report(session->context->debug, LOG_WARN,
"malformed GPGSV - fieldcount %d %% 4 != 0\n",
count);
gpsd_zero_satellites(&session->gpsdata);
session->gpsdata.satellites_visible = 0;
return ONLINE_SET;
}
session->driver.nmea.await = atoi(field[1]);
if ((session->driver.nmea.part = atoi(field[2])) < 1) {
gpsd_report(session->context->debug, LOG_WARN, "malformed GPGSV - bad part\n");
gpsd_zero_satellites(&session->gpsdata);
return ONLINE_SET;
} else if (session->driver.nmea.part == 1)
gpsd_zero_satellites(&session->gpsdata);
for (fldnum = 4; fldnum < count;) {
if (session->gpsdata.satellites_visible >= MAXCHANNELS) {
gpsd_report(session->context->debug, LOG_ERROR,
"internal error - too many satellites [%d]!\n",
session->gpsdata.satellites_visible);
gpsd_zero_satellites(&session->gpsdata);
break;
}
session->gpsdata.PRN[session->gpsdata.satellites_visible] =
atoi(field[fldnum++]);
// NMEA-ID (33..64) to SBAS PRN.
if (session->gpsdata.PRN[session->gpsdata.satellites_visible] >= 33
&& session->gpsdata.PRN[session->gpsdata.satellites_visible] <= 64)
session->gpsdata.PRN[session->gpsdata.satellites_visible] += 87;
session->gpsdata.elevation[session->gpsdata.satellites_visible] =
atoi(field[fldnum++]);
session->gpsdata.azimuth[session->gpsdata.satellites_visible] =
atoi(field[fldnum++]);
session->gpsdata.ss[session->gpsdata.satellites_visible] =
(float)atoi(field[fldnum++]);
/*
* Incrementing this unconditionally falls afoul of chipsets like
* the Motorola Oncore GT+ that emit empty fields at the end of the
* last sentence in a GPGSV set if the number of satellites is not
* a multiple of 4.
*/
if (session->gpsdata.PRN[session->gpsdata.satellites_visible] != 0)
session->gpsdata.satellites_visible++;
}
if (session->driver.nmea.part == session->driver.nmea.await
&& atoi(field[3]) != session->gpsdata.satellites_visible)
gpsd_report(session->context->debug, LOG_WARN,
"GPGSV field 3 value of %d != actual count %d\n",
atoi(field[3]), session->gpsdata.satellites_visible);
/* not valid data until we've seen a complete set of parts */
if (session->driver.nmea.part < session->driver.nmea.await) {
gpsd_report(session->context->debug, LOG_PROG,
"Partial satellite data (%d of %d).\n",
session->driver.nmea.part, session->driver.nmea.await);
return ONLINE_SET;
}
/*
* This sanity check catches an odd behavior of SiRFstarII receivers.
* When they can't see any satellites at all (like, inside a
* building) they sometimes cough up a hairball in the form of a
* GSV packet with all the azimuth entries 0 (but nonzero
* elevations). This behavior was observed under SiRF firmware
* revision 231.000.000_A2.
*/
for (n = 0; n < session->gpsdata.satellites_visible; n++)
if (session->gpsdata.azimuth[n] != 0)
goto sane;
gpsd_report(session->context->debug, LOG_WARN,
"Satellite data no good (%d of %d).\n",
session->driver.nmea.part, session->driver.nmea.await);
gpsd_zero_satellites(&session->gpsdata);
return ONLINE_SET;
sane:
session->gpsdata.skyview_time = NAN;
gpsd_report(session->context->debug, LOG_DATA,
"GSV: Satellite data OK (%d of %d).\n",
session->driver.nmea.part, session->driver.nmea.await);
return SATELLITE_SET;
}
static gps_mask_t processPGRME(int c UNUSED, char *field[],
struct gps_device_t *session)
/* Garmin Estimated Position Error */
{
/*
* $PGRME,15.0,M,45.0,M,25.0,M*22
* 1 = horizontal error estimate
* 2 = units
* 3 = vertical error estimate
* 4 = units
* 5 = spherical error estimate
* 6 = units
* *
* * Garmin won't say, but the general belief is that these are 50% CEP.
* * We follow the advice at <http://gpsinformation.net/main/errors.htm>.
* * If this assumption changes here, it should also change in garmin.c
* * where we scale error estimates from Garmin binary packets, and
* * in libgpsd_core.c where we generate $PGRME.
*/
gps_mask_t mask;
if ((strcmp(field[2], "M") != 0) ||
(strcmp(field[4], "M") != 0) || (strcmp(field[6], "M") != 0)) {
session->newdata.epx =
session->newdata.epy =
session->newdata.epv = session->gpsdata.epe = 100;
mask = 0;
} else {
session->newdata.epx = session->newdata.epy =
safe_atof(field[1]) * (1 / sqrt(2)) * (GPSD_CONFIDENCE / CEP50_SIGMA);
session->newdata.epv =
safe_atof(field[3]) * (GPSD_CONFIDENCE / CEP50_SIGMA);
session->gpsdata.epe =
safe_atof(field[5]) * (GPSD_CONFIDENCE / CEP50_SIGMA);
mask = HERR_SET | VERR_SET | PERR_IS;
}
gpsd_report(session->context->debug, LOG_DATA,
"PGRME: epx=%.2f epy=%.2f epv=%.2f\n",
session->newdata.epx,
session->newdata.epy,
session->newdata.epv);
return mask;
}
static gps_mask_t processGPGBS(int c UNUSED, char *field[],
struct gps_device_t *session)
/* NMEA 3.0 Estimated Position Error */
{
/*
* $GPGBS,082941.00,2.4,1.5,3.9,25,,-43.7,27.5*65
* 1) UTC time of the fix associated with this sentence (hhmmss.ss)
* 2) Expected error in latitude (meters)
* 3) Expected error in longitude (meters)
* 4) Expected error in altitude (meters)
* 5) PRN of most likely failed satellite
* 6) Probability of missed detection for most likely failed satellite
* 7) Estimate of bias in meters on most likely failed satellite
* 8) Standard deviation of bias estimate
* 9) Checksum
*/
/* register fractional time for end-of-cycle detection */
register_fractional_time(field[0], field[1], session);
/* check that we're associated with the current fix */
if (session->driver.nmea.date.tm_hour == DD(field[1])
&& session->driver.nmea.date.tm_min == DD(field[1] + 2)
&& session->driver.nmea.date.tm_sec == DD(field[1] + 4)) {
session->newdata.epy = safe_atof(field[2]);
session->newdata.epx = safe_atof(field[3]);
session->newdata.epv = safe_atof(field[4]);
gpsd_report(session->context->debug, LOG_DATA,
"GBS: epx=%.2f epy=%.2f epv=%.2f\n",
session->newdata.epx,
session->newdata.epy,
session->newdata.epv);
return HERR_SET | VERR_SET;
} else {
gpsd_report(session->context->debug, LOG_PROG,
"second in $GPGBS error estimates doesn't match.\n");
return 0;
}
}
static gps_mask_t processGPZDA(int c UNUSED, char *field[],
struct gps_device_t *session)
/* Time & Date */
{
/*
* $GPZDA,160012.71,11,03,2004,-1,00*7D
* 1) UTC time (hours, minutes, seconds, may have fractional subsecond)
* 2) Day, 01 to 31
* 3) Month, 01 to 12
* 4) Year (4 digits)
* 5) Local zone description, 00 to +- 13 hours
* 6) Local zone minutes description, apply same sign as local hours
* 7) Checksum
*
* Note: some devices, like the u-blox ANTARIS 4h, are known to ship ZDAs
* with some fields blank under poorly-understood circumstances (probably
* when they don't have satellite lock yet).
*/
gps_mask_t mask = 0;
if (field[1][0] == '\0' || field[2][0] == '\0' || field[3][0] == '\0'
|| field[4][0] == '\0') {
gpsd_report(session->context->debug, LOG_WARN, "ZDA fields are empty\n");
} else {
int year, mon, mday, century;
merge_hhmmss(field[1], session);
/*
* We don't register fractional time here because want to leave
* ZDA out of end-of-cycle detection. Some devices sensibly emit it only
* when they have a fix, so watching for it can make them look
* like they have a variable fix reporting cycle.
*/
year = atoi(field[4]);
mon = atoi(field[3]);
mday = atoi(field[2]);
century = year - year % 100;
if ( (1900 > year ) || (2200 < year ) ) {
gpsd_report(session->context->debug, LOG_WARN,
"malformed ZDA year: %s\n", field[4]);
} else if ( (1 > mon ) || (12 < mon ) ) {
gpsd_report(session->context->debug, LOG_WARN,
"malformed ZDA month: %s\n", field[3]);
} else if ( (1 > mday ) || (31 < mday ) ) {
gpsd_report(session->context->debug, LOG_WARN,
"malformed ZDA day: %s\n", field[2]);
} else {
gpsd_century_update(session, century);
session->driver.nmea.date.tm_year = year - 1900;
session->driver.nmea.date.tm_mon = mon - 1;
session->driver.nmea.date.tm_mday = mday;
mask = TIME_SET;
}
};
return mask;
}
static gps_mask_t processHDT(int c UNUSED, char *field[],
struct gps_device_t *session)
{
/*
* $HEHDT,341.8,T*21
*
* HDT,x.x*hh<cr><lf>
*
* The only data field is true heading in degrees.
* The following field is required to be 'T' indicating a true heading.
* It is followed by a mandatory nmea_checksum.
*/
gps_mask_t mask;
mask = ONLINE_SET;
session->gpsdata.navigation.heading[compass_true] = safe_atof(field[1]);
session->gpsdata.attitude.mag_st = '\0';
session->gpsdata.attitude.pitch = NAN;
session->gpsdata.attitude.pitch_st = '\0';
session->gpsdata.attitude.roll = NAN;
session->gpsdata.attitude.roll_st = '\0';
session->gpsdata.attitude.yaw = NAN;
session->gpsdata.attitude.yaw_st = '\0';
session->gpsdata.attitude.dip = NAN;
session->gpsdata.attitude.mag_len = NAN;
session->gpsdata.attitude.mag_x = NAN;
session->gpsdata.attitude.mag_y = NAN;
session->gpsdata.attitude.mag_z = NAN;
session->gpsdata.attitude.acc_len = NAN;
session->gpsdata.attitude.acc_x = NAN;
session->gpsdata.attitude.acc_y = NAN;
session->gpsdata.attitude.acc_z = NAN;
session->gpsdata.attitude.gyro_x = NAN;
session->gpsdata.attitude.gyro_y = NAN;
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set = NAV_HDG_TRUE_PSET;
gpsd_report(session->context->debug, LOG_RAW,
"time %.3f, heading %lf.\n",
session->newdata.time,
session->gpsdata.navigation.heading[compass_true]);
return mask;
}
static gps_mask_t processDBT(int c UNUSED, char *field[],
struct gps_device_t *session)
{
/*
* $SDDBT,7.7,f,2.3,M,1.3,F*05
* 1) Depth below sounder in feet
* 2) Fixed value 'f' indicating feet
* 3) Depth below sounder in meters
* 4) Fixed value 'M' indicating meters
* 5) Depth below sounder in fathoms
* 6) Fixed value 'F' indicating fathoms
* 7) Checksum.
*
* In real-world sensors, sometimes not all three conversions are reported.
*/
gps_mask_t mask;
mask = ONLINE_SET;
if (field[3][0] != '\0') {
session->gpsdata.navigation.depth = safe_atof(field[3]);
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set = NAV_DPT_PSET;
} else if (field[1][0] != '\0') {
session->gpsdata.navigation.depth = safe_atof(field[1]) / METERS_TO_FEET;
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set = NAV_DPT_PSET;
} else if (field[5][0] != '\0') {
session->gpsdata.navigation.depth = safe_atof(field[5]) / METERS_TO_FATHOMS;
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set = NAV_DPT_PSET;
}
gpsd_report(session->context->debug, LOG_RAW,
"depth %lf.\n",
session->gpsdata.navigation.depth);
return mask;
}
static gps_mask_t processDPT(int c UNUSED, char *field[],
struct gps_device_t *session)
{
/* === DPT - Depth of Water ===
$--DPT,x.x,x.x*hh<CR><LF>
1. Depth, meters
2. Offset from transducer,
positive means distance from tansducer to water line
negative means distance from transducer to keel
3. Checksum
*/
gps_mask_t mask;
mask = ONLINE_SET;
if (field[1][0] != '\0') {
session->gpsdata.navigation.depth = safe_atof(field[1]);
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set = NAV_DPT_PSET;
}
if (field[2][0] != '\0') {
session->gpsdata.navigation.depth_offset = safe_atof(field[2]);
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set |= NAV_DPT_OFF_PSET;
}
gpsd_report(session->context->debug, LOG_INF,
"depth %lf with offset %lf.\n",
session->gpsdata.navigation.depth, session->gpsdata.navigation.depth_offset);
return mask;
}
/*
=== MTW - Mean Temperature of Water ===
------------------------------------------------------------------------------
1 2 3
| | |
$--MTW,x.x,C*hh<CR><LF>
------------------------------------------------------------------------------
Field Number:
1. Degrees
2. Unit of Measurement, Celcius
3. Checksum
<<GLOBALSAT>> lists this as "Meteorological Temperature of Water", which
is probably incorrect.
*/
static gps_mask_t processMTW(int c UNUSED, char *field[],
struct gps_device_t *session)
{
// ENV_TEMP_WATER_PSET, temp[temp_water]
gps_mask_t mask= ONLINE_SET;
if (field[1][0] != '\0') {
session->gpsdata.environment.temp[temp_water] = safe_atof(field[1]);
mask |= (ENVIRONMENT_SET);
session->gpsdata.environment.set = ENV_TEMP_WATER_PSET;
}
gpsd_report(session->context->debug, LOG_INF,
"water temp %lf C.\n",
session->gpsdata.environment.temp[temp_water]);
return mask;
}
/*
=== MWV - Wind Speed and Angle ===
------------------------------------------------------------------------------
1 2 3 4 5
| | | | |
$--MWV,x.x,a,x.x,a*hh<CR><LF>
------------------------------------------------------------------------------
Field Number:
1. Wind Angle, 0 to 360 degrees
2. Reference, R = Relative, T = True
3. Wind Speed
4. Wind Speed Units, K/M/N
5. Status, A = Data Valid
6. Checksum
*/
static gps_mask_t processMWV(int c UNUSED, char *field[],
struct gps_device_t *session)
{
// #define ENV_WIND_APPARENT_SPEED_PSET (1llu<< 1), wind.apparent.speed
// #define ENV_WIND_APPARENT_ANGLE_PSET (1llu<< 2), wind.apparent.angle
gps_mask_t mask= ONLINE_SET;
session->gpsdata.navigation.set = 0;
double d = 0.0;
if(strcmp(field[5], "A") != 0) {
return 0;
}
if(strcmp(field[4], "K") == 0) {
d = 1.0 / KNOTS_TO_KPH;
} else if(strcmp(field[4], "M") == 0) {
d = 1.0 / KNOTS_TO_MPS;
} else if(strcmp(field[4], "N") == 0) {
d = 1.0;
}
if(strcmp(field[2], "T") == 0) {
if (field[1][0] != '\0') {
session->gpsdata.environment.wind.apparent.angle = safe_atof(field[1]);
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set |= ENV_WIND_APPARENT_ANGLE_PSET;
}
if (field[3][0] != '\0') {
session->gpsdata.environment.wind.apparent.speed = safe_atof(field[3]) * d;
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set |= ENV_WIND_APPARENT_SPEED_PSET;
}
} else if(strcmp(field[2], "R") == 0) {
if (field[1][0] != '\0') {
session->gpsdata.environment.wind.true_north.angle = safe_atof(field[1]);
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set |= ENV_WIND_TRUE_GROUND_ANGLE_PSET;
}
if (field[3][0] != '\0') {
session->gpsdata.environment.wind.true_north.speed = safe_atof(field[3]) * d;
mask |= (NAVIGATION_SET);
session->gpsdata.navigation.set |= ENV_WIND_TRUE_GROUND_SPEED_PSET;
}
}
return mask;
}
/*