Other GPS NMEA sentences

Other GPS NMEA sentences.

The following information describes some NMEA GPS sentences that are a little less widely used than the common NMEA GPS sentences. Many of these sentences are only used with high-end GPS and DGPS receivers and aren't available with low-cost GPS receivers.

Sentence	Description
$GPALM	GPS almanac data
$GPGRS	GPS range residuals
$GPGST	GPS pseudorange noise statistics
$GPMSS	Beacon receiver status
$GPZDA	UTC and local date/time data

$GPALM Sentence (Almanac data)

Example: $GPALM,1,1,15,1159,00,441d,4e,16be,fd5e,a10c9f,4a2da4,686e81,58cbe1,0a4,001*5B

Field	Example	Comments
Sentence ID	$GPALM
Number of messages	1	Total number of messages in sequence
Sequence number	1	This is first message in sequence
Satellite PRN	15	Unique ID (PRN) of satellite message relates to
GPS week number	1159
SV health	00	Bits 17-24 of almanac page
Eccentricity	441d
Reference time	4e	Almanac reference time
Inclination angle	16be
Rate of right ascension	fd5e
Roor of semi-major axis	a10c9f
Argument of perigee	4a2da4
Longitude of ascension node	686e81
Mean anomoly	58cbe1
F0 clock parameter	0a4
F1 clock parameter	001
Checksum	*5B
Terminator	CR/LF

$GPGRS Sentence (range residuals)

Example: $GPGRS,024603.00,1,-1.8,-2.7,0.3,,,,,,,,,*6C

Field	Example	Comments
Sentence ID	$GPGRS
UTC Time	024603.00	UTC time of associated GGA fix
Mode	1	0 = Residuals used in GGA, 1 = residuals calculated after GGA
Sat 1 residual	-1.8	Residual (meters) of satellite 1 in solution
Sat 2 residual	-2.7	The order matches the PRN numbers in the GSA sentence
Sat 3 residual	0.3
Sat 4 residual		Unused entries are blank
Sat 5 residual
Sat 6 residual
Sat 7 residual
Sat 8 residual
Sat 9 residual
Sat 10 residual
Sat 11 residual
Sat 12 residual
Checksum	*6C
Terminator	CR/LF

$GPGST Sentence (pseudorange noise statistics)

Example: $GPGST,024603.00,3.2,6.6,4.7,47.3,5.8,5.6,22.0*58

Field	Example	Comments
Sentence ID	$GPGST
UTC Time	024603.00	UTC time of associated GGA fix
RMS deviation	3.2	Total RMS standard deviation of ranges inputs to the navigation solution
Semi-major deviation	6.6	Standard deviation (meters) of semi-major axis of error ellipse
Semi-minor deviation	4.7	Standard deviation (meters) of semi-minor axis of error ellipse
Semi-major orientation	47.3	Orientation of semi-major axis of error ellipse (true north degrees)
Latitude error deviation	5.8	Standard deviation (meters) of latitude error
Longitude error deviation	5.6	Standard deviation (meters) of longitude error
Altitude error deviation	22.0	Standard deviation (meters) of latitude error
Checksum	*58
Terminator	CR/LF

$GPMSS Sentence (beacon receiver status)

Example: $GPMSS,0.0,0.0,0.0,25,2*6D

Field	Example	Comments
Sentence ID	$GPMSS
Signal strength	0.0	Signal strength (dB 1uV)
SNR	0.0	Signal to noise ratio (dB)
Frequency	0.0	Beacon frequency (kHz)
Data rate	25	Beacon data rate (BPS)
Unknown field	2	Unknown field sent by GPS receiver used for test
Checksum	*6D
Terminator	CR/LF

$GPZDA Sentence (UTC and local date/time data)

Example: $GPZDA,024611.08,25,03,2002,00,00*6A

Field	Example	Comments
Sentence ID	$GPZDA
UTC Time	024611.08	UTC time
UTC Day	25	UTC day (01 to 31)
UTC Month	03	UTC day (01 to 12)
UTC Year	2002	UTC year (4 digit format)
Local zone hours	00	Offset to local time zone in hours (+/- 00 to +/- 59)
Local zone minutes	00	Offset to local time zone in minutes (00 to 59)
Checksum	*6A
Terminator	CR/LF