Passive radio detection and direction finding apparatus

Claim 1

IN PASSIVE RADIO DETECTION AND DIRECTION FINDING APPARATUS, IN COMBINATION, SIGNAL OBTAINING MEANS FOR OBTAINING FROM PULSED RADIANT ENERGY RECEIVED FROM A SOURCE A PULSED OBTAINED SIGNAL HAVING AT LEAST ONE VARYING CHARACTERISTIC WHICH VARIES IN ACCORDANCE WITH VARIATIONS IN THE ANGULAR DIRECTION TO THE SOURCE AS MEASURED IN A PREDETERMINED PLANE WITH RESPECT TO A PREDETERMINED DIRECTION FROM THE PASSIVE DIRECTION FINDING APPARATUS, SAID SIGNAL OBTAINING MEANS INCLUDING MEANS FOR ELIMINATING FROM THE OBTAINED SIGNAL PULSED RADIANT ENERGY ARRIVING WITHIN A PREDETERMINED TIME AFTER OTHER INITIAL PULSED RADIANT ENERGY, SAID LAST-NAMED MEANS INCLUDING SWITCHING MEANS FOR SLICING OFF THE FRONT PORTIONS OF THE FIRST RECEIVED PULSES ONLY AND STRETCHING THESE SLICED PORTIONS TO PROVIDE STRETCHED PULSES RETAINING SAID VARYING CHARACTERISTIC, AND INDICATOR MEANS OPERATIVELY CONNECTED TO SAID SIGNAL OBTAINING MEANS, SAID INDICATOR MEANS BEING CONSTRUCTED AND ARRANGED TO UTILIZE THE VARYING CHARACTERISTIC OF THE STRETCHED PULSES TO PROVIDE AN INDICATION OF THE DIRECTION OF THE SOURCE AS MEASURED IN SAID PREDETERMINED PLANE.