Aircraft doppler measuring system

Claim 1

AN AIRCRAFT DOPPLER MEASURING SYSTEM COMPRISING, ANTENNA MEANS CARRIED BY SAID AIRCRAFT DIRECTING A PLURALITY OF BEAMS OF RADIANT ENERGY, EACH OF WHICH IS COMPOSED OF A PAIR OF INTERSECTING LOBES, TOWARD THE EARTH''S SURFACE AND RECEIVING DOPPLER-SHIFTED ECHO SIGNALS THEREFROM, AT LEAST TWO OF SAID BEAMS BEING DIRECTED TOWARD AREAS OF THE EARTH''S SURFACE LYING ON OPPOSITE SIDES OF THE GROUND TRACK AND DISPLACED FROM THE PLANE OF SAID AIRCRAFT NORMAL TO THE VELOCITY VECTOR THEREOF IN A FIRST DIRECTION PARALLEL TO SAID GROUND TRACK, AND AT LEAST ONE OTHER BEAM BEING DIRECTED TOWARD AN AREA OF THE EARTH''S SURFACE DISPLACED FROM THE PLANE OF SAID AIRCRAFT NORMAL TO SAID VELOCITY VECTOR IN A DIRECTION OPPOSITE TO SAID FIRST DIRECTION, MEANS FOR ALTERNATELY RADIATING THE RESPECTIVE ONES OF EACH OF SAID PAIRS OF INTERSECTING LOBES AT A FIRST SELECTED FREQUENCY, MEANS FOR ALTERNATELY RADIATING THE BEAMS DIRECTED ON OPPOSITE SIDES OF THE GROUND TRACK AT A SECOND SELECTED FREQUENCY, MEANS FOR DERIVING DOPPLER FREQUENCY SPECTRA FROM SAID REFLECTED ECHO SIGNALS, SAID SPECTRA BEING OPPOSITELY DISPLACED IN FREQUENCY RELATIVE TO A SELECTED BASE FREQUENCY, MEANS FOR DERIVING A PAIR OF ERROR SIGNALS FROM SAID OPPOSITELY DISPOSED DOPPLER FREQUENCY SPECTRA, MEANS FOR SUBTRACTING SAID ERROR SIGNALS TO PRODUCE A DIFFERENCE SIGNAL, A PHASE DETECTOR HAVING SAID DIFFERENCE SIGNAL IMPRESSED THEREON AND OPERATED AT SAID FIRST SELECTED FREQUENCY PRODUCING THEREFROM A VELOCITY SIGNAL, MEANS FOR ADDING SAID ERROR SIGNALS TO PRODUCE A SUM SIGNAL, A SECOND PHASE DETECTOR HAVING SAID SUM SIGNAL IMPRESSED THEREON AND OPERATED AT SAID FIRST SELECTED FREQUENCY PRODUCING THEREFROM AN ELEVATION SIGNAL, AND A THIRD PHASE DETECTOR HAVING A SIGNAL REPRESENTATIVE OF SAID SUM SIGNAL IMPRESSED THEREON AND OPERATED AT SAID SECOND SELECTED FREQUENCY PRODUCING THEREFROM A TRAIN SIGNAL.