If we choose the following pattern
where n = 6 and where the frequency of the impulse decreases by one step in each subsequent interval, then a diagonal translation in the south-east direction is hard to distinguish from the original pattern: the overlap is 5. For a diagonal pattern of dimension n the overlap is in general n - 1, far from optimal. In particular, if we receive 5 pulses on a diagonal, there are two ways of completing it to the pattern sent out (top left and bottom right), and so we have imprecision.
The following detection pattern of dimension 6 is optimal.
The cool applet of this section allows you to experiment with this and other patterns.