Ultrasonic flow quantity measuring apparatus

Claim 1

AN ULTRASONIC FLOW QUANTITY MEASURING APPARATUS COMPRISING A PAIR OF PROBES ADAPTED TO BE MOUNTED OPPOSITE TO EACH OTHER AND OBLIQUELY RELATIVE TO THE DIRECTION OF A FLUID FLOW TO BE MEASURED; A DEVICE FOR TRANSMITTING AND RECEIVING ULTRASONIC ELECTRIC PULSES CONNECTED TO SAID PROBES AND SO CONSTRUCTED THAT WHEN AN ULTRASONIC PULSE TRANSMITTED FROM ONE OF SAID PROBES IS RECEIVED AT THE OTHER OF SAID PROBES SAID DEVICE UPON RECEIVING AN ULTRASONIC ELECTRIC PULSE IN RESPONSE TO THE RECEIVED ULTRASONIC PULSE TRANSMITS AN ULTRASONIC ELECTRIC PULSE TO SAID ONE OF SAID PROBES; MEANS FOR PERIODICALLY REVERSING THE RELATION OF TRANSMISSION AND RECEPTION OF SAID PAIR OF PROBES; AN ELECTRONIC ADDITIVE AND SUBTRACTIVE COUNTING CIRCUIT; MEANS FOR INTRODUCING ULTRASONIC ELECTRIC PULSES IN RESPONSE TO ULTRASONIC PULSES RECEIVED IN ONE AND THE OTHER OF SAID PROBES INTO SAID COUNTING CIRCUIT DURING A PREDETERMINED SUBPERIOD OR SUBPERIODS AND ANOTHER PREDETERMINED SUBPERIOD OF SUBPERIODS, RESPECTIVELY, OF PRECISELY EQUAL TIME LENGTH WITH EACH OTHER, WITHIN A REPEATED CYCLE; MEANS FOR CAUSING SAID COUNTING CIRCUIT TO COUNT ADDITIVELY THE NUMBER OF ELECTRIC PULSES INTRODUCED FROM ONE OF SAID PROBES AND TO COUNT SUBSTRACTIVELY THE NUMBER OF ELECTRIC PULSES INTRODUCED FROM THE OTHER OF SAID PROBES; A FLOW QUANTITY INDICATOR; AND MEANS FOR TRANSFERRING THE RESULT COUNTED BY SAID COUNTING CIRCUIT TO SAID INDICATOR IN A SUBPERIOD OR SUBPERIODS WITHIN SAID REPEATED CYCLE OTHER THAN SAID INTRODUCING AND COUNTING SUBPERIODS.