diff options
| -rw-r--r-- | driver_geostar.c | 2 | ||||
| -rw-r--r-- | gps.h | 3 | ||||
| -rw-r--r-- | www/NMEA.txt | 24 |
3 files changed, 25 insertions, 4 deletions
diff --git a/driver_geostar.c b/driver_geostar.c index 88cd7e6e..47150517 100644 --- a/driver_geostar.c +++ b/driver_geostar.c @@ -29,7 +29,7 @@ static int decode_channel_id (uint32_t ch_id) { int num = 0; num = (int)(ch_id & 0x1F); /* SV ID */ - if((ch_id & (1<<30)) == 0) num += GLONASS_PRN_MAP; /* GLONASS SV */ + if((ch_id & (1<<30)) == 0) num += GLONASS_PRN_OFFSET; /* GLONASS SV */ else if (num == 0 ) num = 32; /* GPS SV */ return num; } @@ -110,8 +110,7 @@ struct gps_fix_t { * it is a GPSD convention to map them to IDs 65..96. * (some other programs push them to 33 and above). */ -#define GLONASS_PRN_MAP 64 -#define GLONASS_PRN(n) (((n) >= 1 + GLONASS_PRN_MAP) && ((n) <= 32 + GLONASS_PRN_MAP) /* GLONASS satellite */ +#define GLONASS_PRN_OFFSET 64 /* * The structure describing the pseudorange errors (GPGST) diff --git a/www/NMEA.txt b/www/NMEA.txt index 5c607319..658ee7a9 100644 --- a/www/NMEA.txt +++ b/www/NMEA.txt @@ -1,6 +1,6 @@ = NMEA Revealed = Eric S. Raymond <esr@thyrsus.com> -v2.11, Mar 2012 +v2.12, Oct 2012 NMEA 0183 is a proprietary protocol issued by the National Marine Electronics Association for use in boat navigation and control @@ -364,6 +364,28 @@ Here is a table of NMEA-ID allocations above 32 as of March 2010: In general, NMEA-ID = PRN - 87. Theoretically, all NMEA-emitting devices should emit NMEA-IDs. In practice, some pass through PRNs. +Documentation on IDs for GLONASS satellites is scanty and +contradictory. The manual for one GLONASS-capable receiver has this to +say (but it is not clear whether the "established convention" +is obeyed by other devices, which may use different GLONASS offsets): + +To avoid possible confusion caused by repetition of satellite ID +numbers when using multiple satellite systems, the following +convention has been adopted: + +a. GPS satellites are identified by their PRN numbers, which range from 1 to 32. + +b. The numbers 33-64 are reserved for WAAS satellites. The WAAS system +PRN numbers are 120-138. The offset from NMEA WAAS SV ID to WAAS PRN +number is 87. A WAAS PRN number of 120 minus 87 yields the SV ID of +33. The addition of 87 to the SV ID yields the WAAS PRN number. + +c. The numbers 65-96 are reserved for GLONASS satellites. GLONASS +satellites are identified by 64+satellite slot number. The slot +numbers are 1 through 24 for the full constellation of 24 satellites, +this gives a range of 65 through 88. The numbers 89 through 96 are +available if slot numbers above 24 are allocated to on-orbit spares. + == Obsolete sentences == The following NMEA sentences have been designated "obsolete" in a |