GB1040014A - Improvements in or relating to interpolating and extrapolating devices - Google Patents

Abstract

1,040,014. Electric analogue calculating. ELECTRIC & MUSICAL INDUSTRIES Ltd. May 22, 1963 [May 22, 1962], No. 19586/62. Heading G4G. In an interpolator comprising at least three input terminals, an output terminal, and a plurality of ganged linear interpolating devices interconnecting the terminals, an input of at least one of the linear interpolating devices is connected to the output of another linear interpolating device to provide interpolation of a higher order than linear. In the example shown co-phased alternating voltages V1, V2 and V3 of, for example, 1000 c.p.s. and corresponding to points X1, X2 and X3 of Fig. 2 are respectively applied to input terminals 1, 2 and 3, Fig. 1. Transformers T1 and T2 are identical and each has four pairs of secondary windings K1A, K1B-K4A, K4B and L1A, L1B-L4A, L4B related in size by powers of two. The windings K and L are selectively connected in series by switches S1A, S1B-S4A, S4B. Transformer T3 is similar to T1 and T2 except that it has twice the number of primary turns. Its primary winding is connected to the sum of the outputs of T1 and T2 and a centre tap on the primary winding is connected in series with its secondary windings which are selectively connected in series by switches S1C-S4C. Switches S1AS1C are operated together, e.g. by a relay armature, and the other switches are similarly operated. The switches S1-S4 are operated according to a cyclic permuting code, the effect of which is that the number of secondary turns of T1 and T3 connected in series follow the sequence - 15, - 13, - 11 ... + 13, +15, whilst T2 follows the same sequence in reverse order. As a result the voltage at the mid-point of the primary of T3 follows the line X4-X6 of Fig. 2. The effect of the switches in the secondary of T3 is to give an output on line 6 which follows the parabolic arcs A and B of Fig. 2.