Patent GB-329403-A (GB)
Title: Improvements in and relating to sound transmitting and receiving apparatus particularly applicable in navigation to recording depths or distances
IPC: G01S1/72
Filed: 1929-02-23
Abstract: 329,403. Murray, A. J. L., and Shuttle worth, N. Feb. 23, 1929. Recording signals. -In subsubmarine echo-sounding apparatus the receiver operates, through thermionic valve amplfying apparatus, electro-chemical recording apparatus to obtain a continuous record of depths or distances. The invention is described with reference to depth-sounding apparatus of the type set forth in Specification 236,601. Referring to Fig. 1 (Prov.), a sound transmitter A emits a highly damped impulse each time a pair of contact fingers X, Y are insulated by a segment on a rotating drum T. The receiver C is connected to telephones I which are short-circuited by adjustable brushes X1, Y1, excepting when the latter are on an insulated segment of the rotating drum R. The receiving circuit is connected to an amplifier H, the telephones being cut-out when desired by a switch E. The recording apparatus comprises a metal drum G rotated with the transmitting drum T, and a stylus P caused to advance along the axis of the drum by bevel gearing L, N and a screw W. The drum G is insulated from the main driving mechanism, and has one connection from the amplifier connected to it, the other connection being to the stylus P, which is also insulated. The surface of the drum is covered with chemically prepared paper, upon which the sound waves travelling directly to the receiver when the transmitter A operates make a mark electrolytically, the waves reflected from the sea bed making a second mark on the paper. A continuous record of depths is thus obtained. Several graphs may be recorded on the same paper by providing additional insulated segments in the transmitting and receiving drums T, R, or, by gearing, causing these two drums to rotate at some speed which is a multiple of that of the recording drum G. In a modification, Fig. 2 (Prov.), the recording drum G is stationary, and the stylus P rotates round it, being carried in a semi-circular frame mounted on screwed shafts W carried at one end by a disc M connected by an insulated coupling 0 to the main driving mechanism. At their opposite ends, the screwed shafts rotate in insulated bearings in the transmitting drum T. As the stylus moves round the drum G it is given a longitudinal motion by the engagement of insulated planet wheels N2 with a stationary sun wheel N1. A two-pole switch F is used to connect the receiver either to the recorder alone or to the telephones and recorder. In modified methods of recording, the sensitized paper may be in strip form and moved at a rate controlled by the ship's log or propellers and the stylus may reciprocate across the paper. An alternative form of continuous recorder is shown in Fig. 1 (Comp.). The sensitized paper passes from a roll A between a roller B and a compression roller C, over a driving roller E and between the reverse side of roller B and a second compression roller D. The rollers B, C, D are carried by a frame hinged on a shaft Q. The sensitizing solution (consisting of a 5 per cent solution of potassium iodide and a 2 per cent solution of starch) may be applied to the paper just before it reaches the roller E, or the paper may be previously sensitized and moistened with water before reaching the roller E. Two insulated pulleys F, G are driven with the roller and axe connected by a metal band J carrying a series of equally-spaced stylus pens P. The circumference of the pulley G is a whole multiple of the spacing between the pens P, which spacing may be equal to the width of the paper. The back of the paper is metallized. The recording current is led to the pens through a brush L contacting with the pulley F and returns through a brush N contacting with the roller B. The fingers X, Y controlling the transmitter are operated from the pulley G, an impulse being emitted just as each pen P touches the paper. A heating element may be placed below the roller E. The apparatus may be adapted for various ranges of soundings by varying the speed of the driving means and by varying the sensitivity of the amplifier. This latter variation may be made automatic by a relay which, when the signal strength is excessive, moves the contact of a resistance or an inductance. The sensitized paper may be ruled' so that depths can be read directly, or a transparent scale may be placed in front of it.