Importance

Loading Importance Indicators...

Abstract

Apparatus for detecting the presence of an object moving relative to a vehicle within a location adjacent said vehicle, which location is hidden from the view of the operator of the vehicle; which comprises a first transducer mounted on the vehicle for transmitting sonic signals in a frequency range of about 30 to 40 Khz into the hidden location, a second transducer mounted on the vehicle in spaced relation to the first transducer for receiving a portion of the sonic signals reflected from an object present in the hidden location, a first high frequency (transmitter) audio amplifier powering the first transducer to cause the first transducer to transmit the sonic signals in the frequency range of 30 to 40 Khz, a second high frequency (receiver) audio amplifier for amplifying the signals received by the second transducer, a tuned amplifier for receiving a portion of the amplified signals from the receiver amplifier and being simultaneously coupled to the transmitter amplifier; the transmitting transducer, the transmitter amplifier, the receiver transducer, the receiver amplifier and the tuned amplifier together constituting a feedback oscillator; the tuned amplifier having an output only when there is relative motion between the object and the vehicle, this output from the tuned amplifier comprising a relatively low audio frequency signal representing a differential frequency between the transmitted signals and the received signals resulting from the change in the transmitted signals as produced by the relative motion between the object and the vehicle, a low frequency audio amplifier for amplifying a portion of the output of the tuned amplifier, and means responsive to the amplified signal from the low frequency audio amplifier for actuating an alarm when the output from the tuned amplifier exceeds a predetermined value.

Loading the Abstract Image...

First Claim