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of the bar can also be found by moving the search head in, first from one side and then the other, and noting
in each case where the signal starts; the bar then lies exactly midway between these two points.
If the search head is now rotated whilst being held at a constant distance from the bar, the largest signal
will be given when the handle is parallel to the bar, but little or no signal when at right angles.
This direction-finding feature will be used in all situations.
3.2 PARALLEL BARS
As with a single bar, the handle of the search head should be aligned
with the bars, and the search head scanned across the bars. At
maximum sensitivity, a strong signal may well be produced
everywhere, but as the sensitivity is progressively reduced, the signal
will drop to a minimum when the search head is halfway between
bars. Unless the search head is very close to the bars, further
reduction in sensitivity will produce a "null" of silence between the
bars, and a maximum when the search head is exactly over a bar. In
this way, the centres of the spaces between the bars can be located
just as accurately as the bars themselves.
Note: If the search head is turned through 90 degrees so that the line
of the handle is at right angles to the bars, the signal will be much
weaker and the resolution reduced - so do not use this orientation in normal operation.
DISCONTINUED