Ultrasonic range-attenuable depth-measuring system

Claim 1

An ultrasonic ranging device including a transducer which comprises: means for receiving and generating a series of recurrent acoustic transmission pulse applying the same to said transducer and propagating the same into water and receiving an echo signal between successive pulses, said means including: an oscillator having a trigger input for activating said oscillator, a transformer output coupling means having said transducer connected to one end thereof, a pulse timing circuit connected to said trigger input for providing periodic pulses, a receiver having its input connected to said transformer coupling means, an output variable resistive element whose resistance is dependent on the current therethrough, having one end connected to said transformer coupling means, a source of current connected to said one end of said variable resistive element through a current control means dependent on the signal current applied to its control element which is connected to said transformer coupling means and to, a charge/discharge network having a selectable time constant, said variable resistive element being connected across the input of said receiver, whereby the attenuation at said receiver will be high for the duration of said oscillator output and decrease with time thereafter, a constant current generator having its output connected to, a current integrator whose output is coupled to, a meter for indicating the average current, Unambiguous switch means connected intermediate the output of said receiving and generating means and said current generator for initiating said current generator when said pulse is generated and terminating when said echo is received, whereby said average current will indicate the transit distance of said propagated pulses.