bca Tracker DTS Instruction Manual page 4

C) Secondary search: flux diagram usage
Use the front side of the BCA flux diagram to illustrate the "flux" or "induction" line search. In the absence of
this diagram, flux lines should be drawn in the snow.
1) Place a transmitting beacon horizontally on the ground, on top of the flux diagram, with the transmitting
antenna attached to the Velcro at the center of the diagram.
2) Perform a small search for the beacon that is attached to the diagram. Perform the search on the same
plane as the transmitting beacon (on top of the vinyl surface). This will eliminate the potential for "spike"
signals, which are discussed in the Advanced Tutorial.
3) Make sure the center light is engaged and the number in the distance window is decreasing. If it is
increasing, turn 180°. If the light to the right (or left) of center engages, rotate your beacon slightly to the
right (or left).
4) Explain that all beacons follow the direction of the electromagnetic field. Perform several small searches,
following the flux lines on the diagram, starting at several different points at the edge of the diagram. Show
how the secondary search path can differ significantly, depending on the relative orientations of the two
beacons.
5) Point out that when performing a secondary search with the Tracker, it is not always necessary to have
the center light engaged. When the signal is first detected, it is adequate if any of the three center lights
are flashing. The searcher should move very quickly to ten meters.
6) Inside ten meters, move slowly and deliberately, keeping the center light engaged.
An effective way to illustrate flux lines is to place a transmitter in the center of the group, preferably on the
flux diagram. Have them follow the directional lights to the transmitter, then look at their footprints in the
snow.
D) Pinpoint search
For novices, we recommend starting with a bracket pinpoint technique, then progressing to "pinpointing
on a line." For more advanced pinpoint techniques, see the Advanced Tutorial.
Bracketing
1) If students are wearing their beacons, demonstrate how to extend the lanyard to increase their range
of motion.
2) Within three meters, place the beacon as close as possible to the snow surface and search in the
general direction they were headed during the latter part of the secondary search. Look for the smallest
distance reading.
3) Ignore sudden fluctuations in distance and direction. The strongest signal is often just past these
fluctuation points, or "spikes."
-Tracker DTS Instruction Guide -
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