Method and apparatus for electroacoustic exploration

Claim 1

IN AN ELECTRO-ACOUSTIC EXPLORING CIRCUIT WHICH INVOLVES THE PERIODIC PROPAGATION OF A SIGNAL PULSE AND THE RECEPTION OF A TIME DELAYED ECHO PULSE IN RESPONSE TO SUCH SIGNAL PULSE, THE COMBINATION OF: A FIRST CIRCUIT MEANS FOR GENERATING A PULSE GATING SIGNAL TIME DELAYED WITH RESPECT TO THE SIGNAL PULSE; A GATE CIRCUIT COUPLED TO SAID FIRST CIRCUIT MEANS AND ADAPTED TO RECEIVE THE ECHO PULSE FOR PROVIDING A FIRST OUTPUT SIGNAL RESPONSIVE TO THE ECHO PULSE AND OCCURRENCE THEREOF DURING THE EXISTENCE OF SAID GATING SIGNAL; A SECOND CIRCUIT MEANS COUPLED TO SAID FIRST CIRCUIT MEANS AND SAID GATE CIRCUIT TO PROVIDE A SECOND OUTPUT SIGNAL WHOSE DURATION IS SUBSTANTIALLY PROPORTIONAL TO THE TIME SPAN FROM THE RECEIPT OF SAID FIRST OUTPUT SIGNAL TO THE END OF SAID PULSE GATING SIGNAL OF SAID FIRST CIRCUIT MEANS; A THIRD CIRCUIT MEANS COUPLED FOR RECEIVING SAID SECOND OUTPUT SIGNAL AND PROVIDING A THIRD OUTPUT SIGNAL WHOSE AMPLITUDE IS PROPORTIONAL TO THE DURATION OF SAID SECOND OUTPUT SIGNAL; A SIGNAL STORAGE MEANS COUPLED TO RECEIVE SAID THIRD OUTPUT SIGNAL, AND A RESET MEANS COUPLED TO SAID STORAGE MEANS AND TO SAID GATE CIRCUIT FOR CONDITIONING SAID STORAGE MEANS IN RESPONSE TO SAID FIRST OUTPUT SIGNAL.