Echo sounder with sensitivity control - stores amplifier output corresponding to max. echo on capacitor for gain control during succeeding cycle

摘要

The echo sounder determines the propagation time between the sending out of an ultrasonic pulse train and the arrival of a reflection as the measure of the distance travelled by the sound. The gain of the selective receiver amplifier (6) is electrically adjustable. The maximum reflection voltage between two transmitted pulse trains is alternately stored as the test value on one or the other of two capacitors (14, 15). During the succeeding cycle each capacitor is connected to a further capacitor (16) whose voltage serves as the measured value for a controller (17, 18) of known design. The controller alters the amplifier's (6) gain by means of a correction voltage, that the maximum value of reflected voltage is automatically set to a required value.