Radio frequency interferometer phase channel combiner with heterodyning at predetection level

Claim 1

IN A RADIO INTERFEROMETER SYSTEM FOR PROVIDING AN UNAMBIGUOUS INDICATION OF THE DIRECTION OF A SIGNAL SOURCE COMPRISING: A PLURALITY OF ANTENNA PAIRS, EACH PAIR HAVING A DIFFERENT BASELINE DISTANCE; A PLURALITY OF SIGNAL CHANNELS, EACH CHANNEL BEING CONNECTED TO A DIFFERENT ANTENNA PAIR AND COMPRISING: TWO MIXERS, EACH COUPLED TO A DIFFERENT ANTENNA OF SAID PAIR; TWO PHASE COHERENT OSCILLATORS CONNECTED TO SAID MIXERS AND PRODUCING SIGNALS THAT ARE SEPARATED IN FREQUENCY BY A FREQUENCY DIFFERENCE WHICH IS SUBSTANTIALLY PROPORTIONAL TO THE BASELINE DISTANCE BETWEEN SAID ANTENNA PAIR; AN ADDER COUPLED TO RECEIVE THE OUTPUT OF SAID TWO MIXERS; AND A DETECTOR CONNECTED TO SAID ADDER TO PRODUCE AN OUTPUT SIGNAL RELATED IN PHASE TO ENERGY RECEIVED BY SAID ANTENNAS AND IN FREQUENCY TO THE FREQUENCY DIFFERENCE BETWEEN SAID OSCILLATOR SIGNALS; COINCIDENCE MEANS CONNECTED TO THE OUTPUT OF SAID DETECTORS IN SAID PLURALITY OF CHANNELS FOR PRODUCING A SIGNAL WHEN SAID OUTPUTS OF SAID DETECTORS ACHIEVE A SELECTED PHASE RELATIONSHIP; REFERENCE SIGNAL SOURCE MEANS; AND A PHASE METER CONNECTED TO SAID REFERENCE SIGNAL SOURCE MEANS AND TO SAID COINCIDENCE MEANS FOR PRODUCING AN UNAMBIGUOUS INDICATION OF THE DIRECTION OF SAID SIGNAL SOURCE.