Coherent-angle tracking system

Claim 1

IN A MOVING TARGET INCLUDING SYSTEM OF THE CHARACTER DESCRIBED WHEREIN IT IS DESIRED TO TRACK A TARGET WITH AN ANTENNA UNDER CONDITIONS WHERE TARGET ECHO AND CLUTTER RETURN SIGNALS ARE SIMULTANEOUSLY RECEIVED IN RESPONSE TO EXPLORATORY PULSES PERIODICALLY RADIATED FROM THE ANTENNA AT A PREDETERMINED PULSE-REPETITION FREQUENY, SAID SYSTEM HAVING A STABLE OSCILLATOR FOR PROVIDING LOCAL OSCILLATIONS, A MIXER RESPONSIVE TO THE RECEIVED SIGNALS AND SAID LOCAL OSCILLATIONS FOR PRODUCING AN INTERMEDIATE-FREQUENCY SIGNAL, AND MEANS COUPLED TO SAID MIXER FOR SELECTING A RANGE ELEMENT INCLUDING THE TARGET ECHO SIGNAL FROM SAID SWEEP OF SAID INTERMEDIATE-FREQUENCY SIGNAL; APPARATUS COMPRISING; MEANS RESPONSIVE TO THE EXPLORATORY PULSES AND SAID LOCAL OSCILLATIONS AND INCLUDING A REACTANCE TUBE FOR PRODUCING A REFERENCE SIGNAL OF A FREQUENCY HAVING A PREDETERMINED RELATIONSHIP WITH RESPECT TO THE FREQUENCY OF SAID CLUTTER RETURN SIGNAL, MEANS COUPLED TO THE GATING MEANS AND RESPONSIVE TO SAID REFERENCE SIGNAL FOR VECTORIALLY ADDING SAID INTERMEDIATE-FREQUENCY SIGNAL DURING THE RANGE ELEMETN INTERVALS TO SAID REFERENCE SIGNAL TO PRODUCE A RESULTANTA SIGNAL HAVING A PHASE DEVIATION FROM SAID REFERENCE SIGNAL PROPORTIONAL TO THE COMPONENT OF SAID INTERMEDIATE-FREQUENCY SIGNAL IN QUADRATURE WITH SAID REFERENCE SIGNALS, MEANS RESPONSIVE SIVE TO SAID RESULTANT AND REFERENCE SIGNALS AND INCLUDING A PHASE DETECTOR FOR PRODUCING A VIDEO SIGNAL CONSTITUTED