NavCom Sapphire Rev.J - Manual (Page 305)

Sapphire Technical Reference Manual Rev. J
305
2.59 NMEAGFA (ASCII)
SF-3050 Sapphire SF-3040
Supported Output Rate: OFF ONCE OnChange OnTime
OnChange = when slow nav is completed (1Hz)
OnTime = highest rate licensed
This sentence is used to report the results of the data quality check associated with a position
solution. If only a single constellation (GPS, GLONASS, GALILEO, etc.) is used for the reported
position solution, the talker ID is GP, GL, GA, etc. and the data pertain to the individual system.
If satellites from multiple systems are used to obtain the reported position solution, the talker ID
is GN and the parameters pertain to the combined solution. This provides the quality data of the
position fix and is associated with the GNS sentence.
Table 146: GFA Message Output Format
Output Format: $GPGBS,UTC,Lat,Long,Alt,SVID,Det,Bias,StdDev,*checksum
Field# Field Name Description
F1 UTC UTC time of the associated GGA or GNS fix (hhmmss.ss)
F2 HPL
Horizontal protection level in meters (xxxx.x). Computed as:
HPL = K
H
* Std_X
Where K
H
is default to 4.0; configurable by [CONFIGGFA]
Std_X is defined in F4 in the same message
F3 VPL
Vertical protection level in meters (xxxx.x). Computed as:
VPL = K
V
* Std_H
Where K
V
is default to 3.5; configurable by [CONFIGGFA]
Std_H is defined in F7 in the same message
F4 Std_X
Standard deviation of semi-major axis of error ellipse in
meters (xxx.xx)
F5 Std_Y
Standard deviation of the semi-minor axis of error ellipse in
meters (xxx.xx)
F6 Theta
Orientation of semi-major axis of error ellipse (xxx.xxxx
degrees from true north)
F7 Std_H Standard deviation of altitude in meters (xxx.xx)
F8 SAL Selected accuracy level in meters (xxxx.x)
F9 IntStatus
Integrity status:
The integrity status field is a variable length character field
which indicate the status of the various integrity sources,
with three currently defined; RAIM (first character),
SBAS (second character) and Galileo integrity (GIC).
This field shall not be Null.
The characters shall take one of the following values:
V = Not in use
S = Safe (when integrity is available and Horizontal
Protection Limit (HPL) < Horizontal Alert Level (HAL)
C = Caution (when integrity is not available)
U = Unsafe (when integrity is available and HPL>HAL)