Abstract: Position sensing apparatus in which an unenergized member, such as a ferrite (60), moves relative to an energized primary coil system (12) and a secondary coil system (11). The primary coil system is single phase energized. The coils (11A, 11B etc.) of the secondary coil system are disposed in series connected pairs (coils 11A, 11G in pair 11/1) interspaced with other pairs (coils 11B, 11H in pairs 11/2) as an array of coils along a path (x) which may be straight, curved, circular etc. The coils in the pairs, which are balanced to give a zero output, form sequences (sequences I, II, III etc.) each of which are terminated with a phase-shift network (PC) to give an incremental phase shift as between one sequence and the next. The incremental phase-shifted outputs are combined to give a progressive phase-shifted output (66) which is representative of the position of the ferrite (60). Ambiguity avoidance, when the progressive phase shift exceeds 360.degree., is preferably provided (FIGS.

Abstract: Signature recognition by electronics requires large storage capacity and has rates of rejections of true signatures and acceptances of false signatures which are not entirely satisfactory. An apparatus for signature recognition is described in which signatures written on an input table are segmented by detecting zero slope in a waveform corresponding to the signature using a differentiator and a zero-crossing detector. Feature signals held in RAM, corresponding to one or more characteristics of a limited number of segments, for example the first twelve, are correlated against previously obtained reference values, held in RAM, by moving signals to different locations but always comparing the contents of the same pairs of locations which correspond to respective segments. After correlation has been carried out the feature and reference signals for corresponding segments are compared using the microprocessor system to provide a decision on whether to accept or reject a signature.

Abstract: Position sensing apparatus comprising two coil arrangements movable relative to each other, the first arrangement being a side-by-side array of elongate coil loops defining a writing area and the second coil arrangement being a single or multiple coil loose coupled with the coil loops in the array. The coil loops in the side-by-side array have phase-shifting units between them so that they give an output which is unambiguously and progressively phase-characterized dependent upon the position of the second coil arrangement on the writing area in the direction of the array. Two layers of the elongate coil loops can be provided so that the coil loops in one layer are at right angles to those in the other to give "x" or "y" co-ordinate positioning. The phase shift over the writing area may be less than 360.degree., or greater than 360.degree. with the use of an ambiguity eliminating circuit.