GB866990A - Submarine echo-sounding apparatus for fishing vessels - Google Patents

Abstract

866,990. [Echo-sounding apparatus; valve pulse generating circuits. PYE Ltd. March 20, 1959 [March 20, 1958], No. 8970/58. Classes 40(6) and 40(7) In a fish-finding echo-sounding apparatus echo signals produced by the sea bed and objects adjacent thereto are selected by a gating circuit, the selected signals are detected and fed through two paths, one path produces an output pulse in response to adjacent-object echoes, the other path produces an output pulse in response to sea bed echoes, and the two output pulses are applied to a coincidence gate whose output pulse operates an audible or visual indicator. Receiving transducer signals are gated in valve V1 by known pulses applied to input 2 to select sea bed and adjacent echoes which are then detected and amplified by valve V3A, Fig. 2c, the output of which triggers Miller transitron V5/V7A to produce, after differentiation by circuit C2, R3, waveform, Fig. 2f, at an input of coincidence gate -V9. Miller transitron V6 is triggered by an input derived from detector MR1 output to give an output, Fig. 2h, the leading edge of which is adjusted by resistor RV1 to coincide with the leading edge of the bottom echo, and the duration of which is adjustable by potentiometer RV2 so that only when a fish shoal is adjacent to the sea bed will loudspeaker LS be energized. Valve V10 output may be applied to a recording device or a counter. The gating pulses applied to input 2 may be generated from the sea bed echoes.