SETNAV

Sets start and destination waypoints

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7, SMART2

This command permits entry of one set of navigation waypoints (see Figure: Illustration of SETNAV Parameters). The origin (from) and destination (to) waypoint coordinates entered are considered on the ellipsoidal surface of the current datum (default wgs84). Once SETNAV has been set, monitor the navigation calculations and progress by observing messages in the NAVIGATE log.

Track offset is the perpendicular distance from the great circle line drawn between the from lat-lon and to lat‑lon waypoints. It establishes the desired navigation path or track, that runs parallel to the great circle line, which now becomes the offset track, and is set by entering the track offset value in metres. A negative track offset value indicates that the offset track is to the left of the great circle line track. A positive track offset value (no sign required) indicates the offset track is to the right of the great circle line track (looking from origin to destination). See Figure: Illustration of SETNAV Parameters for clarification.

Message ID: 162

Abbreviated ASCII Syntax:

SETNAV fromlat fromlon tolat tolon trackoffset from-point to-point

Factory Default:

SETNAV 90.0 0.0 90.0 0.0 0.0 from to

ASCII Example:

SETNAV 51.1516 -114.16263 51.16263 -114.1516 -125.23 FROM TO

Consider the case of setting waypoints in a deformation survey along a dam. The surveyor enters the From and To point locations, on either side of the dam using the SETNAV command. They then use the NAVIGATE log messages to record progress and show where they are in relation to the From and To points.

Field	Field Type	ASCII Value	Binary Value	Description	Format	Binary Bytes	Binary Offset
1	Command header	-	-	SETNAV header This field contains the command name for abbreviated ASCII or the message header for ASCII or Binary.	-	H	0
2	fromlat	± 90 degrees		Origin latitude in units of degrees/decimal degrees. A negative sign for South latitude. No sign for North latitude	Double	8	H
3	fromlon	± 180 degrees		Origin longitude in units of degrees/decimal degrees. A negative sign for West longitude. No sign for East longitude	Double	8	H+8
4	tolat	± 90 degrees		Destination latitude in units of degrees/decimal degrees	Double	8	H+16
5	tolon	± 180 degrees		Destination longitude in units of degrees/decimal degrees	Double	8	H+24
6	trackoffset	± 1000 km		Waypoint great circle line offset (in metres) establishes offset track. Positive indicates right of great circle line and negative indicates left of great circle line	Double	8	H+32
7	from-point	5 characters maximum		ASCII origin station name	String [max 5]	Variable1 In the binary case, each string field needs to be NULL terminated and additional bytes of padding added to maintain 4-byte alignment, up to the maximum defined by the string size. The next defined field starts immediately at the next 4-byte alignment following the NULL.	H+40
8	to-point	5 characters maximum		ASCII destination station name	String [max 5]	Variable1	Variable