ugps: add quality measurement parameters

The current version of ugps does not report any quality parameters for
GPS receiver fixation. Considering the positioning error, which can be
up to hundreds of meters, it is helpful to know how accurately the GPS
determines the position.

This PR supports determining the number of satellites and the HDOP
(Horizontal Dilution of Precision) parameter to address this.  The GPGGA
sentence is already parsed in the code, so it just extends the amount of
data it reads.

Fixes: #2 (ugps miss GPS quality parameters)
Signed-off-by: Zbynek Kocur <zbynek.kocur@fel.cvut.cz>
Signed-off-by: Petr Štetiar <ynezz@true.cz> [whitespace fixes, long line wrap]

diff --git a/main.c b/main.c
index f67470e460d7ce66ed411b9d6847df7f4a313344..acd6a42a5c778b5be944bcaa786c8254ede0bb5b 100644 (file)
--- a/main.c
+++ b/main.c
@@ -66,6 +66,10 @@ gps_info(struct ubus_context *ctx, struct ubus_object *obj,
                        blobmsg_add_string(&b, "course", course);
                if (gps_fields & GPS_FIELD_SPD)
                        blobmsg_add_string(&b, "speed", speed);
+               if (gps_fields & GPS_FIELD_SAT)
+                       blobmsg_add_string(&b, "satellites", satellites);
+               if (gps_fields & GPS_FIELD_HDP)
+                       blobmsg_add_string(&b, "HDOP", hdop);
        }
        ubus_send_reply(ctx, req, b.head);
 

diff --git a/nmea.c b/nmea.c
index e86f68f1f8242bfe1b1ef55b28031727cf128f16..195753e80773d5feb940d7080fd8c3851ecf184c 100644 (file)
--- a/nmea.c
+++ b/nmea.c
@@ -52,7 +52,7 @@ struct nmea_param {
 } nmea_params[MAX_NMEA_PARAM];
 
 static int nmea_bad_time;
-char longitude[33] = { 0 }, latitude[33] = { 0 }, course[17] = { 0 }, speed[17] = { 0 }, elevation[17] = { 0 };
+char longitude[33] = { 0 }, latitude[33] = { 0 }, course[17] = { 0 }, speed[17] = { 0 }, elevation[17] = { 0 }, satellites[3] = { 0 }, hdop[5] = { 0 };
 int gps_valid = 0;
 char gps_fields = 0;
 
@@ -222,8 +222,12 @@ nmea_gga_cb(void)
 {
        if (!gps_valid)
                return;
+       strncpy(satellites, nmea_params[7].str, sizeof(satellites));
+       strncpy(hdop, nmea_params[8].str, sizeof(hdop));
        strncpy(elevation, nmea_params[9].str, sizeof(elevation));
-       gps_fields |= GPS_FIELD_ALT;
+       gps_fields |= GPS_FIELD_SAT | GPS_FIELD_HDP | GPS_FIELD_ALT;
+       DEBUG(4, "satellites: %s\n", satellites);
+       DEBUG(4, "HDOP: %s\n", hdop);
        DEBUG(4, "height: %s\n", elevation);
 }
 

diff --git a/nmea.h b/nmea.h
index 2de06dce482b849c45318a6ee761741c4f7b725c..91a41eb977bb479b4a1795617be959e54d167fba 100644 (file)
--- a/nmea.h
+++ b/nmea.h
@@ -23,7 +23,7 @@
 
 #include <libubox/ustream.h>
 
-extern char longitude[33], latitude[33], course[17], speed[17], elevation[17];
+extern char longitude[33], latitude[33], course[17], speed[17], elevation[17], satellites[3], hdop[5];
 extern int nmea_open(char *dev, struct ustream_fd *s, speed_t speed);
 extern void gps_timestamp(void);
 extern unsigned int adjust_clock;
@@ -33,5 +33,7 @@ extern char gps_fields;
 #define GPS_FIELD_COG (1<<2)
 #define GPS_FIELD_SPD (1<<3)
 #define GPS_FIELD_ALT (1<<4)
+#define GPS_FIELD_SAT (1<<5)
+#define GPS_FIELD_HDP (1<<6)
 
 #endif