Distance measuring apparatus

摘要

The embodiment of the invention disclosed herein is directed to distance measuring apparatus which includes a directive antenna mounted to a vehicle for directing RF energy toward the surface over which the vehicle is moving. Reflected portions of the RF energy signals are received by the antenna and are mixed in an oscillator-mixer circuit for producing Doppler signals having a repetition rate proportional to the rate of travel of the vehicle. A preamplifier having substantially zero input impedance is connected to the output of the oscillator-mixer circuit. Each Doppler cycle so generated represents a predetermined distance traveled and is delivered to a counter to indicate that distance. The Doppler signal is processed to produce time rate information corresponding to the miles per hour of the vehicle.