GB200123A - Improvements in methods of and apparatus for determining distances by means of reflected sound waves - Google Patents

Abstract

200,123. Baron, H., (Signal Ges.). Feb. 4,1922. Determining distances acoustically.-Relates to means for determining depths and distances in which an echo is timed by comparison with a delayed action of the initial sound, and comprises the use as a delaying device of a record such as a telegraphone or gramophone record, simultaneity being tested by the binaural directional effect or by optical or photographic methods. In the device shown in Fig. 1, the direct sound affects a microphone 14 which, through a coil 22, makes a record on the wire 23 of a Poulsen telegraph one. The detector 14' is shielded by the casing 21' from the direct sound, but communicates the echo to a receiver 15'. The distance between the recording and reproducing coils 22, 22', of the telegraphone is adjusted until the sound reproduced in the earpiece 15 co-incides with that in the earpiece 15<1> due to the echo. The distance travelled by the echo can thus be found when the speed of travel of the telegraph one wire is known. In a modification, the screen 21<1> may be abolished and an electric switch associated with electric striking mechanism may break the circuit of the receiver 15<1> at the moment of striking; and in a further modification this switch mav also break the telegraphone circuit as soon as the stroke is over. In the device shown in Fig. 4, the same (magnetic) instrument 1 is used for emitting the initial sound and for detecting the echo. The instrument 1 is connected through contacts on a revolving cylinder 33, first to a source 2 of alternating current, whereupon a sound is emitted and the coil 23 makes a record on a gramophone disc 37 ; and thereafter to an earpiece 15<1> for observing the echo, the coils 22, 22', serving the same purpose as in Fig. 1. In a modification, the alternator 2 may be replaced by a vibrating-plate device constructed similarly to the instrument 1, the gramophone disc being replaced by a telegraphone, and the revolving switch 33 by a multispring switch operated by the striking mechanism and adapted to connect the instrument 1 either through an amplifier to the receiver 15', the recording coil 22 being meanwhile short-circuited : or through the recording coil 22 to the vibrating plate device.