fischbacher

Claim 1

AN ULTRASONIC FLOWMETER FOR MEASURING THE RATE OF FLUID FLOW RELATIVELY TO FIRST AND SECOND TRANSDUCERS SPACED APART UP-STREAM AND DOWN-STREAM OF SAID FLUID FLOW AND DEFINING A TRANSMISSION PATH FOR ULTRASONIC WAVES THEREBETWEEN THROUGH SAID FLUID, COMPRISING A FIRST OSCILLATOR CONNECTED TO ENERGIZE SAID FIRST TRANSDUCER AS A TRANSMITTER, A SECOND OSCILLATOR CONNECTED TO ENERGIZE SAID SECOND TRANSDUCER AS A TRANSMITTER, A FIRST MIXER SUPPLIED WITH SIGNALS BOTH FROM SAID FIRST OSCILLATOR AND FROM SAID FIRST TRANSDUCER OPERATING AS A RECEIVER AND SUPPLYING A SIGNAL TO A FIRST FREQUENCY MULTIPLIER, A SECOND MIXER SUPPLIED WITH SIGNALS BOTH FROM SAID SECOND OSCILLATOR AND FROM SAID SECOND TRANSDUCER OPERATING AS A RECEIVER, AND SUPPLYING A SIGNAL TO SAID FIRST FREQUENCY MULTIPLIER A THIRD MIXER SUPPLIED WITH SIGNALS BOTH FROM SAID FIRST AND SAID SECOND OSCILLATORS AND SUPPLYING A SIGNAL TO A SECOND FREQUENCY MULTIPLIER, A PHASE COMPARATOR CONNECTED TO COMPARE THE OUTPUT SIGNALS FROM SAID FIRST AND SECOND FREQUENCY MULTIPLIERS AND INDICATING MEANS RESPONSIVE TO THE PHASE DIFFERENCE BETWEEN THE TWO SAID OUTPUT SIGNALS.