Sonic vehicle detector

Claim 1

IN A VEHICLE DETECTOR OF THE GATED SONIC PULSE-ECHO TYPE, THE COMBINATION OF AN OSCILLATOR FOR GENERATING HIGH FREQUENCY ELECTRICAL WAVES, A TRANSISTOR PULSE SHAPER AMPLIFIER COUPLED TO SAID OSCILLATOR TO RECEIVE SAID WAVES TO PROVIDE A PULSE MODULATED OUTPUT THEREOF, SAID PULSE SHAPER AMPLIFIER INCLUDING REACTIVE CIRCUIT MEANS FOR PROVIDING A SHAPED MODULATION PULSE OUTPUT OF SAID HIGH FREQUENCY WAVES HAVING A RELATIVELY LONG RISE TIME AND FALL TIME IN AMPLITUDE FOR A SUBSTANTIAL PART OF THE PULSE LENGTH WHEN GATED ON FOR A BRIEF TIME, TRANSISTOR AMPLIFIERS COUPLED AS A PULSE REPETITION RATE FREE-RUNNING MULTIVIBRATOR ALTERNATELY SWITCHING BETWEEN TWO CONDUCTION CONDITIONS AT ALTERNATE TIME PERIODS, A PULSE TIMER OPERATED BY SAID MULTIVIBRATOR UPON SWITCHING TO A PARTICULAR ONE OF ITS SAID CONDITIONS TO PROVIDE A BRIEF PULSE HAVING A TIME PERIOD WHICH IS A SMALL PART OF SAID ALTERNATE TIME PERIODS, A TRANSISTOR CLAMP CIRCUIT OPERATED BY SAID PULSE TIMER TO SO GATE SAID PULSE SHAPER AMPLIFIER FOR PROVIDING SAID SHAPED PULSE OUTPUT, AN ELECTRO-SONIC TRANSDUCER FOR SAID HIGH FREQUENCY WAVES, MEANS INCLUDING AN AMPLIFIER AND AN EMITTER-FOLLOWER FOR COUPLING SAID SHAPED PULSE OUTPUT OF SAID PULSE SHAPER AMPLIFER TO SAID TRANSDUCER, MEANS INCLUDING A TUNED RECEIVER TRANSISTOR AMPLIFIER COUPLED TO SAID TRANSDUCER TO AMPLIFY SAID HIGH FREQUENCY WAVES RECEIVED THEREFROM, A TRANSISTOR SWITCHING CIRCUIT HAVING A RESITANCE-CAPACITANCE TIMING CIRCUIT COUPLED TO SAID MULTIVIBRATOR TO GENERATE A BLANKING PULSE, A FURTHER TRANSISTOR SWITCHING CIRCUIT INCLUDING A FURTHER RESISTANCE-CAPACITANCE TIMING CIRCUIT COUPLED THEREIN TO GENERATE A RANGE PERIOD OUTPUT FOLLOWING SAID BLANKING PULSE, A TRANSISTOR GATING CIRCUIT FOR SAID RECEIVING AMPLIFIER CIRCUIT COUPLED TO SAID LAST MENTIONED TWO TRANSISTOR SWITCHNG CIRCUITS FOR GATING SAID RECEIVER AMPLIFIER OFF DURING SAID BLANKING PULSE AND ON TO PROVIDE AN AMPLIFIED RECEIVED SIGNAL OUTPUT IN RESPONSE TO A RECEIVED SIGNAL DURING SAID RANGE PERIOD OUTPUT.