your position is our focus
Table
15
lists
of
the
status
fields
(valid
flags)
for
the
different
NMEA
message
for
NMEA
standard
0183
Version
2.3:
NMEA
Message
Field
No
Position
Fix
(after
power-up,
after
losing
Satellite
lock)
Valid
Position
Fix
but
User
Limits
exceeded
Dead
Reckoning
(linear
extra-
polation)
EKF
5
2D
Position
Fix
3D
Position
Fix
Combined
GPS/EKF
Position
Fix
0
0
6
6
1/2
1/2
1/2
GGA
Status
0=Fix
not
available/invalid,
1=GPS
SPS
Mode,
Fix
valid
6
,
2=Differential
GPS,
SPS
Mode,
Fix
Valid,
6=Estimated/Dead
Reckoning
V
V
V
A
7
A
A
A
Status
A=Data
VALID,
V=Data
Invalid
(Navigation
Receiver
Warning)
N
N
E
E
A/D
A/D
A/D
GLL
Mode
Indicator
N=No
Fix,
A=Autonomous
GNSS
Fix,
D=Differential
GNSS
Fix,
E=Estimated/Dead
Reckoning
Fix
1
1
2
2
2
3
3
GSA
Nav
Mode
1=Fix
Not
available,
2=2D
Fix,
3=3D
Fix
V
V
V
A
A
A
A
Status
A=Data
VALID,
V=Data
Invalid
(Navigation
Receiver
Warning)
N
N
E
E
A/D
A/D
A/D
RMC
Mode
Indicator
N=No
Fix,
A=Autonomous
GNSS
Fix,
D=Differential
GNSS
Fix,
E=Estimated/Dead
Reckoning
Fix
N
N
E
E
A/D
A/D
A/D
VTG
Mode
Indicator
N=No
Fix,
A=Autonomous
GNSS
Fix,
D=Differential
GNSS
Fix,
E=Estimated/Dead
Reckoning
Fix
Table 15: NMEA Valid Flag (0183 Version 2.3)
5
TIM-LR
/
DR
enabled
receivers
only
6
For
DR
enabled
receiver
a
valid
fix
is
always
a
combination
of
a
GPS
fix
with
a
DR
position
based
on
the
attached
DR
sensor
(turn
rate
sensor,
odometer)-
7
For
DR
enabled
receivers
the
EKF
only
fix
is
considered
as
valid
as
long
as
it’s
within
the
defined
accuracy
range.
LEA-4R
/
TIM-4R
-
System
Integration
Manual
/
Reference
Design
Navigation
GPS.G4-MS4-05043
Page 29
