Patent GB-207828-A (GB)
IPC: G01S1/72
Filed: 1923-12-03
Abstract: 207,828. Signal Ges. Dec. 4, 1922, [Convention date]. Locating sounds.-Comprises means for determining the direction of sounds by the binaural method employing a minimum number of fixed detectors or microphones, the switching arrangements for connecting the detectors to the telephone receivers being such as to prevent ambiguity in the readings. The detectors can be connected in pairs so as to form base-lines parallel to the consecutive sides of a regular polygon. The connections of each pair to the two telephone receivers can be reversed, and the total effect is the same as that which would be given by a larger number of detectors evenly spaced round the circumference of a circle. Various compact arrangements having this effect are described in the Specification, one employing six microphones 1 - - 5 and 4a (corresponding to a regular dodecagon) being shown in Fig. 8. The detectors may be arranged in sets on different horizontal planes : thus three may be mounted on each of the rings 56, 57 on the tripod 58, Fig. 12, at the bottom of the sea. In judging the direction of a sound, two consecutive bases are found such that the sound appears to come from the left of one and the right of the other; the apparent direction is estimated in each case, and the mean is taken as the true direction. Sounds coming in front of abase are distinguished from sounds coming from behind it by noting whether the apparent change of direction, on switching over from one base to the next, agrees with or is contrary to the direction in which the switch must be turned to effect the change. Switching devices. In the device shown in Fig. 11 the pair of leads from each microphone circuit is connected to a pair of brushes 1 - - 5 or 4a and so by slip-rings 35 and cable 37 to pairs of contacts, such as 39, 40 and 45, 46, mounted on the periphery of a rotatable disc 36, current being taken off to telephone receivers by two pairs of fixed brushes of which 48, 49 are shown. The disc is turned by means of the knob 51 until the sound appears to change sides on passing from one position to the next. Three adjustable pointers 23, 24, 25, slide on a ring 50 and fit loosely round the knob 51. One of these is set to the apparent direction for one of the consecutive settings of the switch, and the other for the next of these settings. The third pointer is set midway between the other two, and gives the true reading on a scale marked at the periphery of the disc 36. In the device shown in Fig. 14, each microphone circuit is connected to a pair, such as 62, 63, of contacts oppositely mounted on fixed discs 60, 61. The telephone receiver circuits are connected to pairs 70, 71 and 72, 73 of slip-rings which can be connected by means of wipers 66, 67, 68, 69 to any two consecutive pairs of contacts by turning the disc 64 by means of the knob 51. The direction is read from a scale of angles on the periphery of the disc 65, and three circumferentially slidable riders, of which one is shown at 24, perform the functions of the pointers 23 - - 25, shown in Fig. 11. In another device (not shown) the pairs of leads from the microphones are connected to pairs of contacts arranged on the circumference of a fixed disc. Circuits are closed through two consecutive pairs of such contacts by four wipers mounted on a forked rotatable arm and connected to slip-rings from which current is taken by brushes to the telephone receiver circuits. The direction of the forked arm is perpendicular to the base in use, and three pointers similar in function to 22 - - 24 assist the accuracy of the estimate of direction.