Garmin GPSMAP 175 - Manual (Page 56)

A. The TracBack
feature uses your
track log to create a
route back to where
you started.
B. Once a TracBack is
activated, the track
log is divided into
segments using
temporary
waypoints, and an inverted route is activated back to the oldest track log point in
memory.
GOTO/MOB
TracBack Navigation
To activate a TracBack route:
1. Press the G key, followed by the O key.
2. Highlight the ‘Start TracBack?’ option and press T.
Once a TracBack has been activated, the GPSMAP 175 will take the track log
currently stored in memory and divide it into segments called “legs”. Up to 30
temporary waypoints (e.g. T001) will be created to mark the most significant
features of the track log in order to duplicate your exact path as closely as possible.
• Always clear the track log at the point that you want to go back to (dock, etc.).
• The ‘RECORD’ option on the track log setup page must be set to ‘Fill’ or ‘Wrap’.
• There must be at least two track log points stored in memory to create a
TracBack route.
• If there are not enough available waypoints in memory to create a
TracBack route, you will be alerted with a ‘waypoint memory full’
message, and the receiver will use available waypoints to create a route
with an emphasis on the track log closest to the destination.
• If the track log interval is set to the ‘Time’ option, the route may not follow
your exact path. (Keep the interval set to resolution for best performance.)
• If the receiver is turned off or satellite coverage is lost during your trip,
the TracBack will draw a straight line between any point where coverage
was lost and where it resumed.
• If the changes of direction and distance of your track log are very
complex, 30 waypoints may not accurately mark your exact path. The
receiver will then assign the 30 waypoints to the most significant points
of your track, and simplify segments with fewer changes in direction.
• Whenever a TracBack route is activated, the receiver will automatically
erase any temporary waypoints (e.g., ‘T001’) that are not contained in
routes 1-20. If there are temporary waypoints stored in routes 1-20, the
receiver will create any new temporary waypoints using the first three
digit number available.
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175 Manual 7/31/98 3:57 PM Page 52