Patent GB-1001096-A (GB)
Title: Apparatus for calculating automatically correlation factors and functions
Inventor: CHEVALIER HENRI
IPC: G06F17/15
Filed: 1964-03-04
Abstract: 1,001,096. Electric digital calculators; selective signalling. COMMISSARIAT A L'ENERGIE ATOMIQUE. March 4, 1964 [March 4, 1963], No. 9247/64. Headings G4A and G4H. In an arrangement for calculating correlation factors and functions between two input variables represented by voltages, the inputs are converted to digital form and then sampled at spaced time intervals, each pair of sampled values being multiplied together, the resulting sum being converted to a representation by a corresponding number of pulses which are applied to a reversible counter. The correlation function C(s) between two functions f 1 (t), f 2 (t) is defined by and when s = 0, the expression on the right is the correlation factor. The correlation factor, for example, is approximated by the expression where the a 1  and b 1  represent digital approximations to the input functions at successive spaced time intervals. Analogue-to-digital converter.-The input voltages e 1 , e 2  representing the functions f 1 , f 2  (shown in full and broken lines, respectively, in Fig. 1) are applied to respective converters. Thus the voltage e 1  is applied to a set of threshold devices in the form of Schmidt trigger circuits 91 (employing triodes or transistors) interconnected by resistors 141. At regular time intervals the states of the triggers 91 are sampled by a pulse d on a line 99 and the state of any set triggers is transferred to a buffer register comprising flip-flops 28, the outputs of which are applied to diode matrices 153, 154 for positive and negative values respectively, which matrices provide an output on one only of their output lines, this output representing in digital form the corresponding analogue input. As described, at each sampling time t 0 , t 1 , t 2  &c., Fig. 1, the effect of the conversion is to give each variable the value of the mid-point of the range within which it falls, the possible output values thus being 0, Œ1, Œ2, Œ3, Œ4. Variable e 1  appears in output digital form as a signal on one of lines 37-40 representing the absolute value and a signal on one of lines 33, 34 according as the sign is positive or negative. Variable e 2  is similarly represented on lines 41-44, 35, 36. Multiplication arrangement.-The absolute value signals are applied to a diode matrix 49 which provided an output on one of nine leads 50-58 representing the appropriate one of the nine possible product values of the values of the inputs (which can each take the values 1, 2, 3, 4). The signals representing the signs are applied over lines 33-36 to a further diode matrix 46 which provides on output a line 47 or 48 according as the product is positive or negative. Product accumulation.-A pulse generator 59 provides output pulses (which after division by 16 at 66 from the sampling pulses d), the pulses being applied to 4-stage binary counter 71 whose outputs are recoded in a diode matrix 72 and compared in a comparator 82 comprising transistor AND gates with the output of the multiplication matrix 49. At the commencement of each sampling operation a flip-flop 68 is set to enable a gate 62 to pass pulses q to a counter 71a, the pulses being applied additively or subtractively according as a gate 160 or 161 is effective to emit a signal representing a positive or a negative product. When the comparator 82 emits an output, the flip-flop 68 is reset thereby cutting off the supply of pulses to the counter 68. If the sampled product value is zero, this is detected by the sign multiplication matrix 46 which provides an output inhibiting the flip-flop 68 so that no pulses q are supplied to the counter 71a. The counter 71a progressively accumulates the required correlation result. Determining probability densities.-By providing an assembly of counters 86 arranged to count the number of times the input voltages e 1 , e 2  are sampled within the various ranges, the probability density of the amplitudes of the input voltages can be determined.