Sounding devices utilising electromagnetic waves

Abstract

Abstract 520,778. Indicating proximity of earth or other bodies. STANDARD TELEPHONES & CABLES, Ltd. (Material Telephonique Soc. Anon.) Sept. 9 1938, No. 26382. [A Specification was laid open to inspection under Sect. 91 of the Acts, April 3, 1939.] [Class 37] A cathode - ray oscillograph apparatus for indicating heights, depths, or for locating objects comprises a short-wave transmitter-receiver controlled by a voltage derived from the sawtooth waves of the time-base circuit which is respectively positive and negative during portions of the saw-tooth cycle of fast amplitude change and slow amplitude change so that the transmitter-receiver functions alternately as a generator and receiver during the positive and negative voltage periods. Fig: 1 shows a transmitter-receiver 1 having a directive aerial 3 supplied through a feed circuit 7 from a source 8, the indications being given on a cathode-ray tube 6. The sweep circuit 5 produces saw-tooth oscillations of the form shown in Fig. 2 by the successive charging and discharging of a condenser through a resistance, the charging portions A of the curves being of exponential form and the discharge portions B taking place in much shorter time. The time derivative of this curve is applied to the generator-receiver 1 and is of the form shown in Fig. 3. The generator-receiver is caused to function as a generator by the positive portions D and as a receiver by the negative portions C. As the portion C constantly increases, the weakening of the signals for a longer distance to be measured is compensated by the continuous increase of sensitivity. The signal received after reflection is applied to the modulation electrode of the cathode ray tube 6 in such a manner that the spot becomes brilliant and indicates the required distance on a scale 9. The aerial 1 and reflector 2 may be oscillated about a pivot so as to. be alternately directed downwards and horizontally. An indication of the shape of an obstacle such as a mountain in front of an aeroplane is thus obtained.

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