Multiple-frequency ranging system

Claim 2

A PULSE ECHO SIGNAL LOCATOR SYSTEM COMPRISING: IMPULSE TRANSMITTER MEANS FOR SIMULTANEOUSLY TRANSMITTING TO REMOTE OBJECTS A PAIR OF PULSES EACH HAVING A DISTINCT FREQUENCY CHARACTERISTIC, A RECEIVER FOR RECEIVING SAID PULSES AFTER REFLECTION, HETERODYNE MEANS IN SAID RECEIVER FOR MIXING THE REFLECTED SIGNALS OF SAID PAIR OF PULSES TO PRODUCE A SUM FREQUENCY SIGNAL, AND MEANS FOR INDICATING THE PRESENCE AND EXTENT OF THE DOPPLER FREQUENCY SHIFT IN SAID SUM FREQUENCY SIGNAL.

Claim 3

A SONAR PULSE ECHO SIGNAL LOCATOR SYSTEM COMPRISING: AN IMPULSE TRANSMITTER OPERABLE TO SIMULTANEOUSLY TRANSMIT TO REMOTE OBJECTS A PAIR OF PULSES EACH HAVING A DISTINCT FREQUENCY, A TRANSDUCER OPERABLE TO CONVERT SAID PULSES TO SOUND ENERGY AND OPERABLE TO CONVERT THE SIGNALS REFLECTED FROM SAID REMOTE OBJECTS TO ELECTRICAL SIGNALS, SAID REFLECTED SIGNALS DEVIATING ABOVE AND BELOW THE DISTINCT FREQUENCY CHARACTERISTICS OF SAID PAIR OF PULSERS IN DEPENDENCY ON THE MOVEMENT OF SAID OBJECTS, A RECEIVER FOR RECEIVING PULSE ECHO SIGNALS REFLECTED FROM SAID OBJECTS, ISOLATING MEANS FOR COUPLING SAID RECEIVER AND SAID TRANSMITTER TO SAID TRANSDUCER, HETERODYNE MEANS IN SAID RECEIVER FOR MIXING THE REFLECTED SIGNALS OF SAID PAIR OF PULSES TO PRODUCE A SUM FREQUENCY SIGNAL AND A DIFFERENCE FREQUENCY SIGNAL, MEANS FOR SEPARATING SAID LAST NAMED TWO SIGNALS INTO TWO CHANNELS, FILTER MEANS IN SAID DIFFERENCE FREQUENCY SIGNAL CHANNEL OPERATIVE TO PROVIDE A SUBSTANTIALLY NOISE FREE SIGNAL, INDICATOR MEANS COUPLED TO SAID FILTER TO INDICATE THE PRESENCE OF SAID SIGNAL; AND A FREQUENCY SPECTRUM ANALYZER IN SAID SUM FREQUENCY CHANNEL OPERATIVE RESPONSIVE TO THE ENHANCED FREQUENCY SHIFT OF SAID SUM FREQUENCY SIGNAL TO INDICATE THE MOVEMENT OF SAID OBJECTS.

Claim 4

A SONAR PULSE ECHO SIGNAL LOCATOR SYSTEM COMPRISING: AN IMPULSE TRANSMITTER OPERABLE TO SIMULTANEOUSLY TRANSMIT TO REMOTE OBJECTS A PAIR OF PULSES EACH HAVING A DISTINCT FREQUENCY, A TRANSDUCER OPERABLE TO CONVERT SAID PULSES TO SOUND ENERGY AND OPERABLE TO CONVERT THE SIGNALS REFLECTED FROM SAID REMOTE OBJECTS TO ELECTRICAL SIGNALS, SAID REFLECTED SIGNALS DEVIATING ABOVE AND BELOW THE DISTINCT FREQUENCY CHARACTERISTICS OF SAID PAIR OF PULSERS IN DEPENDENCY ON THE MOVEMENT OF SAID OBJECTS, A RECEIVER FOR RECEIVING PULSE ECHO SIGNALS REFLECTED FROM SAID OBJECTS, ISOLATING MEANS FOR COUPLING SAID RECEIVER AND SAID TRANSMITTER TO SAID TRANSDUCER, HETERODYNE MEANS IN SAID RECEIVER FOR MIXING THE REFLECTED SIGNALS OF SAID PAIR OF PULSES TO PRODUCE A SUM FREQUENCY SIGNAL AND A DIFFERENCE FREQUENCY SIGNAL, MEANS FOR SEPARATING SAID LAST NAMED TWO SIGNALS INTO TWO CHANNELS, FILTER MEANS IN SAID DIFFERENCE FREQUENCY SIGNAL CHANNEL OPERATIVE TO PROVIDE A SUBSTANTIALLY NOISE FREE SIGNAL, INDICATOR MEANS COUPLED TO SAID FILTER TO INDICATE THE PRESENCE OF SAID SIGNAL; AND A FREQUENCY SPECTRUM ANALYZER IN SAID SUM FREQUENCY CHANNEL OPERATIVE RESPONSIVE TO THE ENHANCED FREQUENCY SHIFT OF SAID SUM FREQUENCY SIGNAL TO INDICATE THE MOVEMENT OF SAID OBJECTS.