Appendix-14 
 
used for satellite system used in multi-frequency, SBAS or Precise Point Positioning (PPP) mode; 
S = Simulator mode. 
NOTE 3 The positioning system mode indicator field supplements the positioning system status field, the status 
field should be set to V = Invalid for all values of indicator mode except for A= Autonomous and D = Differential. The 
positioning system mode indicator and status fields should not be null fields. 
NOTE 4 The navigational status indicator is according to IEC 61108 requirements on ‘Navigational (or Failure) 
warnings and status indications’. This field should not be a NULL field and the character should take one of the 
following values: 
S = Safe when the estimated positioning accuracy (95 % confidence) is within the selected accuracy 
level corresponding to the actual navigation mode, and/or integrity is available and within the 
requirements for the actual navigation mode, and/or a new valid position has been calculated 
within 1 s for a conventional craft and 0,5 s for a high speed craft. 
C = Caution when integrity is not available. 
U = Unsafe when the estimated positioning accuracy (95 % confidence) is less than the selected 
accuracy level corresponding to the actual navigation mode, and/or integrity is available but 
exceeds the requirements for the actual navigation mode, and/or a new valid position has not 
been calculated within 1 s for a conventional craft and 0,5 s for a high speed craft. 
V = Navigational status not valid, equipment is not providing navigational status indication.
 
 
 
・GLL – Geographic position – Latitude/longitude 
 
$--GLL, llll.ll, a, yyyyy.yy, a, hhmmss.ss, A, a *hh<CR><LF> 
1
   2   3       4  5   6 7 
 
1:Latitude, N/S 
2:Latitude, N/S 
3:Longitude, E/W 
4:Longitude, E/W 
5:UTC of position 
6:Status (see Note 2) A=data valid V=data invalid 
7:Mode indicator (see Notes 1 and 2) 
 
NOTE 1 Positioning system mode indicator: 
D = Differential 
S = Simulator 
N = Data not valid 
NOTE 2 The mode indicator field supplements the status field (field 6). The status field should be set to V = invalid 
for all values of operating mode except for A = Autonomous and D = Differential. The positioning system mode 
indicator and status fields should not be null fields.
 
 
 
・VTG – Course over ground and ground speed 
 
$--VTG, x.x, T, x.x, M, x.x, N, x.x, K,a*hh<CR><LF> 
1
   2 3   4    5   6    7 8   9 
 
1:Course over ground, degrees true 
2:Course over ground, degrees true 
3:Course over ground, degrees magnetic 
4:Course over ground, degrees magnetic 
5:Speed over ground, knots (see Note 1) 
6:Speed over ground, knots (see Note 1) 
7:Speed over ground, km/h (see Note 1) 
8:Speed over ground, km/h (see Note 1) 
9:Mode indicator (see Note 2) 
 
NOTE 1 The speed over the ground should always be non-negative. 
NOTE 2 The mode indicator provides status information about the operation of the source device (such as 
positioning systems, velocity sensors, etc.) generating the sentence, and the validity of data being provided. The 
possible indications are as follows: 
A = Autonomous mode; 
D = Differential mode; 
P = Precise. Satellite system used in precision mode. Precision mode is defined as: no deliberate degradation (such 
as selective availability) and higher resolution code (P-code) is used to compute position fix. P is also used for