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If you now bring the head up to a 25mm bar at 30mm distance, the display
might show
The larger bar has caused the indicated cover (based on a ø16 bar) to be
under-estimated; but the AutoSizing estimate of the cover to a bar of
unknown size
is correct, and the estimated bar size
is also
approximately correct.
To return to the main Menu, press
.
Please note that the previous three sections "Bar location techniques",
"Systematic location of bars" and "Welded mesh and joined bars" are also
relevant, and should be read in conjunction with this section.
Audible guide to cover
As explained on the previous page, the sound signal should normally be
turned on during cover measurement in order to assist bar location (both
audibly, and by the indicator lamp on the search head).
The section "Bar Location Techniques" explains that, for optimum
sensitivity, the audio knob should be set to a tickover in the absence of
metal, but that the knob can be turned back to improve the (audible)
resolution of closely-spaced bars.
If the audio knob is set to optimum sensitivity, the loudness and pitch of
the sound will consistently give a good guide to the extent of cover, with
shallower-than-average bars producing a clearly noticeable more intense
sound, which can be used to draw the operator's attention to such bars.
However, if the audio knob had been turned to an arbitrary position, the
necessary degree of consistency may not be achieved.
It is also possible to deliberately back off the audio knob so that bars of
adequate cover are not indicated, but bars of shallower cover are. The
user may find this trick to be a simpler and quicker method (albeit
somewhat less precise) than the "UnderCover" mode described later; but
please note that both methods share the same disadvantage that they only
indicate bars with shallow cover, but do not confirm the presence of bars
with adequate or deeper cover.
13
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