NMEA GPS Reads

GPS modules typically put out a series of standard strings of information, under something called the National Marine Electronics Association (NMEA) protocol. More information on NMEA standard data strings can be found at this site.
GPS receiver gives the reading starting with the following strings and each string appended data has its own significant.

$GPGGA: Global Positioning System Fix Data
$GPGSV: GPS satellites in view
$GPGSA: GPS DOP and active satellites
$GPRMC: Recommended minimum specific GPS/Transit data


Each of these sentences contains a wealth of data. For example, here are a few instances of the $GPRMC string.




eg1. $GPRMC,081836,A,3751.65,S,14507.36,E,000.0,360.0,130998,011.3,E*62
eg2. $GPRMC,225446,A,4916.45,N,12311.12,W,000.5,054.7,191194,020.3,E*68




           225446      Time of fix 22:54:46 UTC
           A           Navigation receiver warning A = Valid position, V = Warning
           4916.45,N   Latitude 49 deg. 16.45 min. North
           12311.12,W  Longitude 123 deg. 11.12 min. West
           000.5       Speed over ground, Knots
           054.7       Course Made Good, degrees true
           191194      UTC Date of fix, 19 November 1994
           020.3,E     Magnetic variation, 20.3 deg. East
           *68         mandatory checksum




eg3. $GPRMC,220516,A,5133.82,N,00042.24,W,173.8,231.8,130694,004.2,W*70

             1    2    3    4    5     6    7    8      9     10  11 12

      

      1   220516     Time Stamp
      2   A          validity - A-ok, V-invalid
      3   5133.82    current Latitude
      4   N          North/South
      5   00042.24   current Longitude
      6   W          East/West
      7   173.8      Speed in knots
      8   231.8      True course
      9   130694     Date Stamp
      10  004.2      Variation
      11  W          East/West
      12  *70        checksum




eg4. for NMEA 0183 version 3.00 active the Mode indicator field is added




$GPRMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,ddmmyy,x.x,a,m*hh




Field #


 1 = UTC time of fix
 2 = Data status (A=Valid position, V=navigation receiver warning)
 3 = Latitude of fix
 4 = N or S of longitude
 5 = Longitude of fix
 6 = E or W of longitude
 7 = Speed over ground in knots
 8 = Track made good in degrees True
 9 = UTC date of fix
 10= Magnetic variation degrees (Easterly var. subtracts from true course)
 11= E or W of magnetic variation
 12= Mode indicator, (A=Autonomous, D=Differential, E=Estimated, N=Data not valid)
 13   = Checksum




The full documentation you can get here.