GPS Sentences | NMEA Sentences | GPGGA GPGLL GPVTG GPRMC

This page describes GPS Sentences or NMEA Sentences with example patterns. These GPS Sentences (i.e. NMEA Sentences) covers GPGGA, GPGLL, GPVTG, GPRMC etc.

Introduction:
• A GPS receiver module requires only DC power supply for its operation. It will start outputting data as soon as it has identified GPS satellites within its range.
• GPS module uses plain ASCII protocol known as NMEA developed by National Marine Electronics Association. Hence they are also known as NMEA sentences.
• Each block of data is referred as "sentence". Each of these sentences are parsed independently.
• The default transmission rate of these gps sentences is 4800 bps. Certain GPS modules use serial rate of 9600 bps also. It uses 8 bits for ASCII character, no parity and 1 stop bit.
• Sentence begins with two letters to represent GPS device. For example, "GP" represent GPS device and so on.
• Remainder of sentence consists of letters/numerals in plain ASCII. A sentence can not have more than 80 characters.
• A sentence carry latitude, longitude, altitude and time of readings obtained from satellites.
• Some sentence data structures are proprietary developed by device manufacturers which begins with letter "P".

Following is the generic table which mentions functional description of NMEA output messages.

GPS Sentences or NMEA Sentences

NMEA Sentence	Meaning
GPGGA	Global positioning system fix data (time, position, fix type data)
GPGLL	Geographic position, latitude, longitude
GPVTG	Course and speed information relative to the ground
GPRMC	Time, date, position, course and speed data
GPGSA	GPS receiver operating mode, satellites used in the position solution, and DOP values.
GPGSV	The number of GPS satellites in view satellite ID numbers, elevation, azimuth and SNR values.
GPMSS	Signal to noise ratio, signal strength, frequency, and bit rate from a radio beacon receiver.
GPTRF	Transit fix data
GPSTN	Multiple data ID
GPXTE	cross track error, measured
GPZDA	Date and time (PPS timing message, synchronized to PPS).
150	OK to send message.

GPS sentence | GPGGA

Following table mentions GPGGA sentence description with example.
➤Example of GPGGA GPS sentence:-
$GPGGA, 161229.487, 3723.2475, N, 12158.3416, W, 1, 07, 1.0, 9.0, M, , , , 0000*18

Name or Field	Example	Description
Message ID	$GPGGA	GGA protocol header
UTC time	161229.487	hhmmss.sss
Latitude	3723.2475 (37 degrees, 23.2475 minutes)	ddmm.mmmm
N/S Indicator	N	N = North, S = South
Longitude	12158.3416 (121 degrees, 58.3416 minutes)	dddmm.mmmm
E/W indicator	W	E = East or W = West
Position Fix Indicator	1
Satellites used	07	Range is 0 to 12
HDOP	1.0	Horizontal Dilution of Precision
MSL Altitude	9.0	Meters
Units	M	Meters
Geoid Separation		Meters
Units	M	Meters
Age of diff. corr.		Second
Diff. ref. station ID	0000
Checksum	*18
<CR><LF>		End of message termination

GPS sentence | GPGLL

Following table mentions GPGLL sentence description with example.
➤Example of GPGLL GPS sentence:-
$GPGLL, 3723.2475, N, 12158.3416, W, 161229.487, A, A*41

Name or Field	Example	Description
Message ID	$GPGLL	GLL protocol header
Latitude	3723.2475	ddmm.mmmm
N/S indicator	N	N =North or S = south
Longitude	12158.3416	dddmm.mmmm
E/W indicator	W	E =East or W = West
UTC time	161229.487	hhmmss.sss
Status	A	A = data valid or V = data not valid
Mode	A	A =Autonomous , D =DGPS, E =DR (This field is only present in NMEA version 3.0)
Checksum	*41
<CR><LF>		End of message termination

GPS sentence | GPVTG

Following table mentions GPVTG sentence description with example.
➤Example of GPVTG GPS sentence:-
$GPVTG, 309.62, T, ,M, 0.13, N, 0.2, K, A*23

Name or Field	Example	Description
Message ID	$GPVTG	VTG protocol header
Course	309.62	degrees
Reference	T	True
Course		Degrees
Reference	M	Magnetic
Speed	0.13	Knots, measured horizontal speed
Units	N	Knots
Speed	0.2	Km/Hr, Measured horizontal speed
Units	K	Kilometers per hour
Mode	A	A = Autonomous, D = DGPS, E = DR
Checksum	*23
<CR><LF>		End of message termination

GPS sentence | GPRMC

Following table mentions GPRMC sentence description with example.
➤Example of GPRMC GPS sentence:-
$GPRMC, 161229.487, A, 3723.2475, N, 12158.3416, W, 0.13, 309.62, 120598, , *10

Name or Field	Example	Description
Message ID	$GPRMC	RMC Protocol Header
UTC time	161229.487	hhmmss.sss
Status	A	A = data valid or V = data not valid
Latitude	3723.2475	ddmm.mmmm
N/S indicator	N	N = North or S = South
Longitude	12158.3416	dddmm.mmmm
E/W indicator	W	E = East or W = West
Speed over ground	0.13	knots
Course over ground	309.62	degrees
Date	120598	ddmmyy
Magnetic Variation		Degrees (E= East or W = West)
Mode	A	A = Autonomous, D = DGPS, E =DR
Checksum	*10
<CR><LF>		End of message termination

Refer article on GNSS data processing >> for GNSS data processing blocks used in 5G mobile phone. The article also explains GNSS receiver architecture and its modules.