Patent GB-992170-A (GB)
Title: Distinguishing matrix that is capable of learning, for analog signals
IPC: G06V30/194
Filed: 1964-02-13
Abstract: 992,170. Signal translating circuits. STANDARD TELEPHONES & CABLES Ltd. Feb. 13, 1964 [Feb. 20, 1963], No. 6101/64. Addition to 939, 134. Heading G4R. In a translating circuit as claimed in Claim 1 of the parent Specification there is a pair of coupling elements at each cross-over of the matrix, the signals representing the pattern to be learned being applied to the first ones of the pairs of elements and, during recognition, the unknown pattern being applied to the second ones of the pairs together with a control voltage applied to the first ones, acting in an opposite sense, the resulting current on an output lead representing the sum of the differences between the corresponding signals of the learned pattern and the pattern applied for recognition. A detector circuit determines which of the outputs is the least to give an indication as to which most nearly corresponds to the input pattern. A pattern is represented by a set of sample values as shown in Fig. 1a which illustrates three curves of the same class i.e. each can be derived from any other by multiplying all the amplitudes by a suitable factor. Curves of a different class are shown in Fig. 1b The matrix comprises a series of row wires 1-4 Fig. 2 each to be associated with one of the pattern classes. Pairs of column wires A, A<SP>1</SP> are each coupled to the row wires by conductances GIV, G<SP>1</SP>IV &c. During the learning phase the sample values of the pattern are applied to leads A, and the associated row wires earthed. The conductances G1V are set proportionally to the input signal. The other conductances G<SP>1</SP> IV are all the same; nominal value = 1. All the rows are set up in the same way. In the recognition phase the sample signals of the unknown pattern are applied to the leads A<SP>1</SP> so that a proportional voltage is applied to the row wire through the unity valued conductance G<SP>1</SP>IV. At the same time a voltage of-1 volts is applied to the leads A applying a negative voltage to the row proportional to the value of the conductance GIV which is proportional to the sample signal of the learned pattern. The resultant signal on the row wire is therefore the difference between the sample signals of the learned and the unknown patterns and these are added up along the row for each sample point. The lowest signal is found by detector # min to indicate which learned pattern most closely matches the unknown pattern. The coupling elements may be transfluxors which are set in the learning phase by D.C. signals and have high frequency A.C. signals applied during the recognition phase. In a modification both coupling elements of each pair are set during the learning phase, one in proportion to the applied sample signal and the other in proportion to the inverse of this signal. The effect of a pair of coupling elements is therefore to apply to the row wire a signal proportional to the unknown sample divided by the learned sample minus the learned sample divided by the unknown. These values for all the sample points are summed as before and the least value found. By applying a voltage to a row lead a series of signals are obtained at the left hand column leads proportional to the sample signals of the learned pattern. These may be indicated on meters. The coupling elements may consist of toroidal cores or any of those described in the parent Specification. Specification 958,453 also is referred to.