Automatic gain control in acoustic well logging systems

Claim 1

AN ACOUSTIC WELL LOGGING SYSTEM COMPRISING AT LEAST ONE ACOUSTIC ENERGY RECEIVER ARRANGED AND ADAPTED TO DEVELOP AN ELECTRICAL SIGNAL FUNCTIONALLY RELATED TO A RECEIVED AND AMPLIFYING SAID ELECAMPLIFIER MEANS FOR RECEIVING AND AMPLIFYING SAID ELECTRICAL SIGNAL; AND LOGICAL CIRCUIT MEANS INTERCONNECTED WITH SAID AMPLIFIER MEANS FOR DEVELOPING INFORMATION RELATIVE TO THE OCCURRENCE OF SAID RECEIVED ACOUSTIC ENERGY SIGNALS; SAID LOGICAL CIRCUIT MEANS INCLUDING MEANS FOR DEVELOPING IN INDICATING SIGNAL INDICATING THAT SAID ACOUSTIC SIGNAL WAS RECEIVED BY SAID RECEIVER DURING A PERIOD OTHER THAN THE PERIOD WITHIN WHICH AN ACOUSTIC SIGNAL SHOULD HAVE BEEN RECEIVED, MEANS FOR DEVELOPING A SYNCHRONIZING PULSE FOR INITIATING A CYCLE OF OPERATION OF SAID SYSTEM, A DELAY MEANS COUPLED TO RECEIVE AND TO DELAY SAID SYNCHRONIZING PULSE, AND AN AND CIRCUIT PRODUCING AN OUTPUT IN RESPONSE TO THE COINCIDENCE OF SAID INDICATING SIGNAL AND THE OUTPUT OF SAID DELAY MEANS; SAID ACOUSTIC WELL LOGGING SYSTEM FURTHER COMPRISING MEANS CONNECTING SAID OUTPUT FROM SAID AND CIRCUIT TO ADJUST THE GAIN OF SAID AMPLIFIER MEANS.