Hello world 🙂 Welcome to my blog on GPS data. When we connect a GPS transceiver to our computer we get some data in a standard format which is called NMEA sentence, NMEA stands for National Marine Electronics Association. Each sentence begins with a ‘$’ and ends with a carriage return/line feed sequence and can be no longer than 80 characters of visible text. The data is contained within this single line with data items separated by commas. The data itself is just ASCII text and may extend over multiple sentences in certain specialized instances but is normally fully contained in one variable length sentence.

Hardware Connection:
The Hardware interface for GPS module is designed to meet NMEA requirements. They are compatible with the serial RS232 ports however NMEA recommends EIA-422 protocol. The interface can be set to 9600 baud, 8 bit data, no parity, and hardware mode off.
Now at 9600bps you can only send 960 characters in one second so NMEA sentences can be extended to 6 different sentences.
Some of the conman NMEA sentences.

GPGGA : Fix data
GPGLL : LAT/LON data
GPGSA : overall satellite reception data
GPGSV : detailed satellite data
GPVTG : vector track and speed over ground

  • GPGGA – data which provides accurate 3-Dimentional location and accurate data. provdes latitude longitude UTC time height above the sea level.

  • GPGLL – provides geographical latitudes and longitudes

  • GPGSA – provides the detailed nature and fixes of the satellite with the horizontal and vertical dillution.

  • GPGSV – provides the details of satellites in view along with the elevation and azimuth angles in degrees and signal to noise ratio for each satellite.

  • GPVTG – its for the velocity mode and used in the track mode to get the speed over ground and the orientation

You will receive the above NMEA format while tracking from a GPS transreciever which can be used for Geo-positioning in your applications.
Happy Tracking 🙂