Radio navigation system

Claim 1

A RADIO NAVIGATION SYSTEM INCLUDING A FIXED TRANSMITTING STATION INCLUDING MEANS FOR TRANSMITTING TWO WAVES HAVING HARMONICALLY RELATED FREQUENCIES AND A RECEIVER AT A MOBILE OBJECT, SAID RECEIVER INCLUDING: MEANS FOR RECEIVING SAID TWO WAVES, SAID WAVES BEING AMBIGUOUSLY REPRESENTATIVE OF THE DISTANCE OF THE MOBILE OBJECT FROM SAID TRANSMITTING STATION; FILTER MEANS COUPLED TO SAID RECEIVING MEANS FOR SEPARATING SAID WAVES FROM ONE ANOTHER; MEANS COUPLED TO SAID FILTER MEANS INCLUDING TWO FREQUENCY MULTIPLIERS FOR MULTIPLYING THE RESPECTIVE WAVES BY A FACTOR SUCH THAT THE FREQUENCIES OF THE MULTIPLIED SIGNALS ARE SUBSTANTIALLY THE SAME; A PHASE ADJUSTER COUPLED TO ONE OF SAID MULTIPLIERS; A PHASE RESOLVER COUPLED TO THE OUTPUT OF SAID PHASE ADJUSTER AND TO THE OTHER OF SAID MULTIPLIERS, THE OUTPUT OF SAID PHASE RESOLVER BEING COUPLED BACK TO SAID PHASE ADJUSTER FOR VARYING THE PHASE SHIFT THEROF; A DETECTOR COUPLED TO THE OUTPUT OF SAID PHASE ADJUSTER AND TO THE OUTPUT OF SAID OTHER MULTIPLIER; A FILTER TUNED TO THE FREQUENCY DIFFERENCE BETWEEN SAID TWO RECEIVED WAVES COUPLED TO THE OUTPUT OF SAID AMPLITUDE DETECTOR; AND PHASE MEASURING MEANS COUPLED TO THE OUTPUT OF SAID FILTER.