Novatel OM-20000041 用户手册
D
Logs summary
MiLLennium GPSCard Software Version 4.50 Command Descriptions Manual Rev 1
173
NAVA/B
Waypoint Navigation Data
This log reports the status of your waypoint navigation progress. It is used in conjunction with the
SETNAV
command.
REMEMBER:
The
SETNAV
command must be enabled before valid data will be reported from this log.
NAVA
Structure:
Example:
$NAVA,640,333115.00,6399.6305,88.017,6396.9734,184.3929,657,51514.000,0,1
*11[CR][LF]
*11[CR][LF]
NOTE:
All distances and angles are calculated using Vincenty’s long line geodetic equations that operate on the
currently selected user datum.
See Figure D-1, Page 175 for an illustration of navigation parameters.
$NAVA
week
seconds
distance
bearing
along track
xtrack
etaw
etas
nav status
sol status
*xx
[CR][LF]
Field #
Field type
Data Description
Example
1
$NAVA
Log header
$NAVA
2
week
GPS week number
640
3
seconds
GPS seconds into the week
333115.00
4
distance
Straight line horizontal distance from current position to the destination waypoint, in meters
(see Figure C-5, Page 127). This value is positive when approaching the waypoint and
becomes negative on passing the waypoint.
(see Figure C-5, Page 127). This value is positive when approaching the waypoint and
becomes negative on passing the waypoint.
6399.6305
5
bearing
Direction from the current position to the destination waypoint in degrees with respect to True
North (or Magnetic if corrected for magnetic variation by MAGVAR command)
North (or Magnetic if corrected for magnetic variation by MAGVAR command)
88.017
6
along track
Horizontal track distance from the current position to the closest point on the waypoint arrival
perpendicular; expressed in meters. This value is positive when approaching the waypoint
and becomes negative on passing the waypoint.
perpendicular; expressed in meters. This value is positive when approaching the waypoint
and becomes negative on passing the waypoint.
6396.9734
7
xtrack
The horizontal distance (perpendicular track-error) from the vessel’s present position to the
closest point on the great circle line that joins the FROM and TO waypoints. If a "track offset"
has been entered in the SETNAV command, xtrack will be the perpendicular error from the
"offset track". Xtrack is expressed in meters. Positive values indicate the current position is
right of the Track, while negative offset values indicate left.
closest point on the great circle line that joins the FROM and TO waypoints. If a "track offset"
has been entered in the SETNAV command, xtrack will be the perpendicular error from the
"offset track". Xtrack is expressed in meters. Positive values indicate the current position is
right of the Track, while negative offset values indicate left.
184.3929
8
etaw
Estimated GPS week number at time of arrival at the "TO" waypoint along-track arrival
perpendicular based on current position and speed, in units of GPS weeks. If the receiving
antenna is moving at a speed of less than 0.1 m/sec in the direction of the destination, the
value in this field will be"9999".
perpendicular based on current position and speed, in units of GPS weeks. If the receiving
antenna is moving at a speed of less than 0.1 m/sec in the direction of the destination, the
value in this field will be"9999".
657
9
etas
Estimated GPS seconds into week at time of arrival at destination waypoint along-track arrival
perpendicular, based on current position and speed, in units of GPS seconds into the week.
If the receiving antenna is moving at a speed of less than 0.1 m/sec in the direction of the
destination, the value in this field will be"0.000".
perpendicular, based on current position and speed, in units of GPS seconds into the week.
If the receiving antenna is moving at a speed of less than 0.1 m/sec in the direction of the
destination, the value in this field will be"0.000".
51514.000
10
nav status
Navigation data status, where 0 = good, 1 = no velocity, and 2 = bad navigation calculation
0
11
sol status
Solution status as listed in Table D-1, Page 143
1
12
*xx
Checksum
*11
13
[CR][LF]
Sentence terminator
[CR][LF]