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After an acceptable pair of readings has been taken, the result is shown,
for example:
unless there were detectable errors in the calculation, in which case it
shows
To make another measurement, move the head away from all metal, and
repeat the zeroing and then the display will ask for the next pair of Orth/
Para readings.
When finished, press
to return to the Menu.
Please note that this orthogonal sizing method is not suitable for welded
mesh fabric, as the orthogonal reading will be invalid.
However, the
AutoSizing method available in both the Depth and Locate modes may be
used.
Orthogonal sizing precautions
How it works.
When you are using the CM9 as a locator, and making good use of the
directionality of the search head to distinguish between vertical and
horizontal bars, as you rotate the head away from being parallel to a bar,
you will have noticed that: if it is a large bar, the signal merely decreases
somewhat, whereas for a small bar, the signal decreases drastically to
practically nothing by the time the head is at right-angles.
The orthogonal sizing technique utilises this phenomenon and quantifies it
to yield a direct determination of bar size.
Since the orthogonal/parallel comparison is essentially independent of
cover, this method is in principle capable of accurate results on a single
bar in isolation.
However, like all bar-sizing methods, it is sensitive to errors in head-
positioning and also to the presence of neighbouring bars.
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