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Although for normal operation, the signal is simply taken to be at a maximum when the head is directly over a bar, and less elsewhere, more information can be gleaned by performing a traverse across the centre-line of the bar, and noting the signal strength (with the MODE switch set to CALib).

It will be seen from the actual results plotted below (obtained with ø20 bars at 45mm cover) that for a pair of touching bars [red], the response is almost indistinguishable from that from a single bar (apart from the much-increased signal strength).

At 20mm separation (40mm pitch) [orange], the curve of signal strength versus sideways displacement is marginally less peaked and marginally broader.
By 30mm separation (50mm pitch) [blue], the peak has become very much flattened, and a little broader still.
At 40mm separation (60mm pitch) [green], not only has the width broadened further, but the "peak" is not only very much flattened but even has a slight dip in the middle, ie the curve (just) resolves into two peaks.

The results suggest that by analysing traverses, the bar-spacing might be estimated if it lies in the range 25 to 40mm.

These plots also demonstrate a consistent characteristic of the CoverMaster that, as the ratio of pitch-to-depth increases towards 1½:1, so the error in indicated cover progressively vanishes until it becomes below the 2mm/5% specified in the British Standard for single bars under ideal conditions; the error is always below the 5mm/15% limit it cites for on-site conditions.

It will also be seen from the right-hand Y-axis, that the indicated cover does not vary particularly rapidly with displacement, and certainly would not furnish the resolution necessary to plot the traverses, nor enable the 40mm-spaced bars to be resolved.
Nevertheless a rough guide as to whether the bars are narrowly or widely separated can be obtained by noticing what span of sideways displacement the head can be moved in before the indicated cover off-centre increases by (say) 2mm.

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