Entity_and_Attribute_Overview:
Global Positioning System Fix Data
GGA Strings are in comma-delimited ASCII text and each record is in the format:
$GPGGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh
Where the fields represent:
1 = UTC of Position
2 = Latitude (degrees decimal minutes)
3 = N or S
4 = Longitude (degrees decimal minutes)
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
For the GPVTG strings:
VTG=actual track made good and speed over ground
$GPVTG,t,T,m,M,s.ss,N,s.ss,K*hh
1=True course made good over ground, degrees
2=Fixed text 'T' indicates that track made good is relative to true north
3=Magnetic course made good over ground, degrees
4= Fixed text 'M' indicates that track made good is relative to magnetic north
5=Speed over ground in knots
6=Fixed text 'N' indicates that speed over ground in knots
7=Speed over ground in kilometers/hour
8=Fixed text 'K' indicates that speed over ground is in kilometers/hour
9=Checksum.
Entity_and_Attribute_Detail_Citation: