30
OPERATION
The GPS arrow turns yellow and average bearing bar indicator turns red
when 2 or more reported GPS coordinates have been missed. A yellow
arrow indicating last known GPS reference is a perfectly valid waypoint for
users to seek. Often, finding such waypoints will put the user back on the
trail of the target vehicle. When arriving at the GPS coordinate you may
find the reason why the GPS stopped working such as an underground
garage, tunnel or underpass to a highway. Proper interpretation at these
intersections and incoming RDF signal references may put you back on
track. The distance to target displayed on the PDA is valid for all last-
known-reference points. A waypoint has passed when the direction of the
GPS arrow flips from straight ahead to straight behind (Figure 5). Concur-
rently, the distance to target will read “0.0 miles”.
GPS Arrow flops back and forth may indicate that the tracking receiver is
having trouble recognizing its heading. When stopped, there is no specific
bearing heading without a known reference. The tracker vehicle should
proceed in a direction at a minimum of 5 MPH to establish a heading. A
secondary cause may be the inability for the tracking receiver to gain clear
access to GPS satellites and establish a solid fix. Urban canyons created by
tall buildings and road structures may contribute to this. Typically, moving
the tracking vehicle to another location eliminates the confusion.
CH
Mute
Dim
Tracker
2
171.600 MHz
Distance to target 0 2
Fil.
Figure 5
CH
Mute
Dim
Tracker
2
171.600 MHz
Got valid GPS
Fil.
Figure 6
Summary of Contents for 5000
Page 1: ...RDF Pulse and GPS Enhanced Tracking System...
Page 29: ...35 NOTES...
