Extracting required information from NMEA GPS data [closed]

Question

I am using raspberry pi to talk to a NMEA GPS module via serial port, everything works fine but i want to extract only latitude and longitude(i am using python language) coordinates so that i can use them in my project* (autonomous vehicle using GPS) ,i will be using a compass module to know the direction of heading.....hope u got my idea ..can anyone help me?

Answer 1

Your best bet would be using NMEA sentence $GPGGA, that's supported by most GPS receivers out there, format is like this:

$GPGGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh
1    = UTC of Position
2    = Latitude
3    = N or S
4    = Longitude
5    = E or W
6    = GPS quality indicator (0=invalid; 1=GPS fix; 2=Diff. GPS fix)
7    = Number of satellites in use [not those in view]
8    = Horizontal dilution of position
9    = Antenna altitude above/below mean sea level (geoid)
10   = Meters  (Antenna height unit)
11   = Geoidal separation (Diff. between WGS-84 earth ellipsoid and
       mean sea level.  -=geoid is below WGS-84 ellipsoid)
12   = Meters  (Units of geoidal separation)
13   = Age in seconds since last update from diff. reference station
14   = Diff. reference station ID#
15   = Checksum

and you may use the following code to parse:

# suppose your GPS NMEA comes as 'data'
for line in data.split('\n') :
    if line.startswith( '$GPGGA' ) :
        lat, _, lon = line.strip().split(',')[2:5]

after that you may convert the strings to floats, or not...

try :
    lat = float( lat )
    lon = float( lon )
except :
    # something wrong happens with your data, print some error messages
    pass

ps. your question is offtopic here, don't get surprised it will be deleted or moved eventually