Reference Information
LD900 Installation and Oper ations M anual
70
6.4.7 GLL Sentence
The NMEA GGL sentence provides Latitude and Longitude position data for the present position.
GLL Sentence Structure & Example
$GNGLL, ddmm.mmmmmmm, a, dddmm.mmmmmmm, b, hhmmss.ss, S, I *hh
$GNGLL,
5708.7104685, N,
00217.1169613, W, 062859.00, A, D *72
GLL Sentence Defined
Field
Content
GLL
Geographic position - Latitude and Longitude
ddmm.mmmmmmm
Latitude of position
a
Latitude direction (N or S)
dddmm.mmmmmmm
Longitude of position
b
Longitude direction (E or W)
hhmmss.ss
UTC time of position
S
Status (A = data valid ; V = data not valid)
I
Positioning mode indicator (A = Autonomous, D = Differential,
E = Estimated (Dead reckoning), M = Manual, N = Data not valid)
*hh
Checksum
6.4.8 VTG Sentence
The NMEA VTG sentence provides the actual course and speed relative to the ground.
VTG Sentence Structure & Example
$GNVTG, ppp.ppp, T, qqq.qgg, M, rr.rrr, N, ss.sss, K, U, *hh
$GNVTG, 167.608, T, 167.608, M, 0.006, N, 0.012, K, D, *3D
VTG Sentence Defined
Field
Content
VTG
Course over ground and ground speed
ppp.ppp
True course over ground
T
Degrees True indicator
qqq.qgg
Magnetic course over ground
M
Degrees Magnetic
rr.rrr
Speed over ground , knots
N
Nautical speed indicatior (N = Knots)
ss.sss
Speed over ground , kilometres/hour
K
Speed indicator (K = km/hr)
U
Positioning mode indicator (A = Autonomous, D = Differential,
E = Estimated (Dead reckoning), M = Manual, N = Data not valid)
*hh
Checksum
