Fixed antenna terrain clearance system

Claim 1

IN AN AIRCRAFT, A RADAR RANGING SYSTEM OF THE MONOPULSE PHASE COMPARISON TYPE FOR TERRAIN CLEARANCE AND OBSTACLE DETECTION COMPRISING: DIRECTIONAL ANTENNA MEANS FIXED TO THE AIRCRAFT ALTERNATELY PROVIDING AN ILLUMINATING LOBE OF RADIATED ENERGY, SAID LOBE HAVING AN AXIS PARALLEL TO THE AIR MASS VELOCITY VECTOR OF THE AIRCRAFT, AND RECEIVING REFLECTED ENERGY FROM OBSTACLES AND TERRAIN; MEANS COUPLED TO SAID ANTENNA MEANS FOR PROVIDING ENERGY FOR RADIATION; INFORMATION MEANS FOR PRODUCING ANGLE INFORMATION SIGNALS REPRESENTATIVE OF THE ANGLES BETWEEN SAID AXIS AND TERRAIN, AND BETWEEN SAID AXIS AND OBSTACLES, SAID INFORMATION MEANS HAVING A FIRST HYBRID COUPLED TO SAID ANTENNA MEANS FOR DEVELOPING FROM SAID REFLECTED ENERGY A SUM SIGNAL PROPORTIONAL TO THE VECTOR SUM OF TWO COMPONENTS OF REFLECTED ENERGY AND A DIFFERENCE SIGNAL PROPORTIONAL TO THE VECTOR DIFFERENCE OF SAID COMPONENTS, A PHASE SHIFTER COUPLED TO SAID FIRST HYBRID AND RESPONSIVE TO SAID DIFFERENCE SIGNAL TO DISPLACE IT IN PHASE WITH RESPECT TO SAID SUM SIGNAL, A DUPLEXER COUPLED TO SAID FIRST HYBRID TO TRANSMIT SAID SUM SIGNAL AND COUPLED TO SAID MEANS FOR PROVIDING ENERGY FOR RADIATION, A SECOND HYBRID COUPLED TO SAID PHASE SHIFTER AND TO SAID DUPLEXER TO DEVELOP FIRST AND SECOND COMPOSITE SIGNALS PROPORTIONAL RESPECTIVELY TO THE SAID SUM SIGNAL PLUS THE PHASE DISPLACED DIFFERENCE SIGNAL AND THE SAID SUM SIGNAL MINUS THE PHASE DISPLACED DIFFERENCE SIGNAL, FIRST AND SECOND COMPOSITE SIGNAL TRANSLATING CHANNELS COUPLED TO SAID SECOND HYBRID EACH OF SAID CHANNELS HAVING AN I.F. CONVERTER AND AN I.F. PREAMPLIFIER COUPLED IN CASCADE, AND AN ANGLE INFORMATION DETECTION CHANNEL COUPLED TO SAID I.F. PREAMPLIFIERS SAID CHANNEL HAVING A LIMITING I.F. AMPLIFIER COUPLED TO EACH OF SAID I.F. PREMPLIFIERS A PHASE DETECTOR COUPLED TO SAID LIMITING I.F. AMPLIFIERS PRODUCING AN OUTPUT PROPORTIONAL LIMITING I.F. AMPLIFIERS PRODUCING AN OUTPUT PROPORTIONAL TO TRIGONOMETRIC FUNCTIONS OF SAID ANGLES BETWEEN SAID AXIS AND TERRAIN AND BETWEEN SAID AXIS AND OBSTACLES AN INDICATOR CONTROL SYSTEM COUPLED TO SAID PHASE DETECTOR AND AN INDICATOR COUPLED TO SAID INDICATOR CONTROL SYSTEM FOR PROVIDING A VISIBLE PRESENTATION; GATING MEANS COUPLED TO SAID INFORMATION MEANS FOR RESTRICTING SAID ANGLE INFORMATION SIGNALS PRODUCED, TO THOSE REPRESENTATIVE OF TERRAIN OR OBSTACLES EXISTING WITHIN A DESIRED VOLUME OF COVERAGE OF SAID ILLUMINATING LOBE; AND MARKER MEANS COUPLED TO SAID INFORMATION MEANS FOR CALIBRATION THEREOF.