Patent GB-1075375-A (GB)
Title: Signal source direction detecting system
IPC: G01S3/46
Filed: 1964-08-18
Abstract: 1,075,375. Signal source direction-finding. CSF-COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Aug. 18, 1964 [Aug. 26, 1963], No. 33782/64. Heading H4D. In a system for determining the direction of a sound or radio source, a magnetic core matrix and a shift register provide time delays which compensate for the time delays between the arrival of a plane wave at the several receivers of a coplanar array. The output signal h from each receiver H 1 -H n  is amplified and clipped to provide square wave or binary-coded pulses e which are fed to the inputs of respective coincidence (AND) gates ET 1 -ET n . The second input of each ET gate is connected through a respective row winding (1 to n) of the matrix to a control signal generator G, and the outputs of the gates are connected in parallel to the input of a shift register R comprising a series of monostable flip-flops B 1 -B p  in cascade. The output of each flip-flop B is connected to a column winding of the matrix. The magnetic material of the cores has a rectangular hysteresis loop and the cores are arranged to be switched from a "0" state to a " 1 " state or vice versa on coincidence of " half-current " pulses in row and column windings of the matrix or on the application of a single " full-current " pulse to a row winding. In a period T generator G applies a " reading " pulse (3a) (Fig. 3), comprising a positive " full current " part followed by a negative " half-current " part to each of the row windings 1 to n in turn. For each row, (i) the positive part of pulse (3a) leaves all cores in the " 0 " state; (ii) if a core in a particular column j is thereby switched from the "1" state to the " 0 " state, a pulse (3b) is induced in the j column winding and triggers the adjacent flip-flop By +  1 : flip-flop B j  + 1 then gives a negative " half-current " output pulse (3c) which is coincident in time with the negative part of pulse (3a) and co-operates with it to switch the core in column j + 1 to the " 1 " state; (iii) if the positive part of pulse (3a) coincides with a positive part (i.e. a " 1 " state) of a receiver signal e, the associated ET gate triggers flip-flop B 1  to switch the first core in the row to the " 1 " state. In one period T the net result of the core switching is that each core in a row gives its state to the core immediately on its right, the first core taking up the state of the signal e. Reading wires V (each corresponding to a different direction of the sound or radio source) connect the cores along different diagonals of the matrix, and each wire V feeds a pulse counter (10) followed by an integrator (11) (Fig. 7). The reading wire V at whose terminals the largest number of pulses appear in one reading period T is that corresponding to the direction of the sound or radio source. The pulses on each wire V appear successively due to the sequential pulse outputs of generator G and may be further processed to improve the signal/ noise ratio. The receivers H 1 -H n  may be shipborne hydrophones. In a second embodiment (Fig. 4, not shown) a second register and matrix may be used, the reading wires of one matrix being connected in series with those of the second matrix to permit the use of an increased number of hydrophones without increasing the reading period. In a third embodiment (Fig. 5, not shown) signals from the several receivers H may be encoded by a single binary coder (N k ).