Ultrasonic measuring apparatus

Claim 1

IN AN ULTRASONIC DEVICE FOR INSPECTING OBJECTS THROUGH THE USE OF ULTRASONIC TECHNIQUES, MEANS FOR APPLYING ULTRASONIC WAVES OF SHORT DURATION TO AN OBJECT TO BE INSPECTED AND CONVERTING RESULTING REFLECTED ULTRASONIC WAVES INTO CORRESPONDING ELECTRICAL SIGNAL BURSTS EACH HAVING A FUNDAMENTAL FREQUENCY WHICH IS A FUNCTION OF A CHARACTERISTIC OF THE OBJECT BEING INSPECTED; A CIRCUIT HAVING AN INPUT CONNECTED TO RECEIVE AND SIGNAL BURSTS AND HAVING AT LEAST TWO CHANNELS CONNECTED IN PARALLEL WITH EACH OTHER; EACH CHANNEL HAVING AN UNDERDAMPED L-C-R CIRCUIT TURNED TO RESONATE AT FREQUENCIES RESPECTIVELY ABOVE AND BELOW SAID FUNDAMENTAL FREQUENCY AND ALSO BEING SHOCK EXCITABLY BY A SIGNAL BURST WITHIN A GIVEN FREQUENCY RANGE TO THEREBY GENERATE A DAMPED WAVE TRAIN WHEN EXCITED BY SUCH A SIGNAL, SAID FREQUENCY RANGES OF SAID L-C-R CIRCUIT OVERLAPPING SO THAT A GIVEN SIGNAL SHOCK EXCITIES BOTH L-C-R CIRCUITS; DETECTOR MEANS FOR DETECTING THE ENVELOPES OF THE DAMPED WAVES TRAINS FROM THE L-C-R CIRCUITS, AND MEANS FOR COMPARING THE OUTPUTS OF SAID DETECTOR MEANS TO CHANGES IN THE FUNDAMENTAL FREQUENCY OF SAID SIGNAL BURSTS AND HENCE IN SAID CHARACTERISTIC OF THE OBJECT BEING TESTED.