GPS ter trenutna hitrost

Imam vprašanje. GPS mi pošilja podatke v program in dobim takšno obliko:

$GPRMC,140955.00,A,4610.15277,N,01504.99284,E,1.462,126.57,261208,,,A*60
$GPVTG,126.57,T,,M,1.462,N,2.710,K,A*3F
$GPGGA,140955.00,4610.15277,N,01504.99284,E,1,03,3.16,429.5,M,43.7,M,,*56
$GPGSA,A,2,19,03,32,,,,,,,,,,3.31,3.16,1.00*0D
$GPGSV,3,1,11,19,78,229,34,03,47,169,17,32,28,221,33,22,43,056,*74
$GPGSV,3,2,11,20,04,230,,28,12,325,,06,38,158,,06,38,158,*72
$GPGSV,3,3,11,14,39,114,,11,33,288,,18,10,051,*4C
$GPGLL,4610.15277,N,01504.99284,E,140955.00,A,A*6E
$GPZDA,140955.00,26,12,2008,00,00*67

Dokumentacija pa je:

$GPVTG,t,T,,,s.ss,N,s.ss,K*hh

VTG = Actual track made good and speed over ground

1 = Track made good
2 = Fixed text 'T' indicates that track made good is relative to true north
3 = not used
4 = not used
5 = Speed over ground in knots
6 = Fixed text 'N' indicates that speed over ground in in knots
7 = Speed over ground in kilometers/hour
8 = Fixed text 'K' indicates that speed over ground is in kilometers/hour
9 = Checksum

Zanima me 7.točka - speed in km... sedaj pa ne vem zakaj potem dobim vrednost 2.710 in kaj potem ta vrednost pomeni? Kako dobiti aktualne km/h ? Hvala za pomoč

Ma sploh mi ni takoj kapnilo :D hvala

Sem sedaj stvar sprobal na cesti in zelo lepo deluje...