| 摘要 |
Apparatus for detecting objects by means of ultrasonic waves and echos reflected from objects within a detection zone, the apparatus including a transmitter for generating electric energy at ultrasonic frequencies; means forming pulses of the electric energy; timing means for selectively determining the frequency of said pulses; transducer means for converting electric pulses into ultrasonic pulses and ultrasonic pulses into electric pulses and for projecting said ultrasonic pulses along a narrow beam into a detection zone and receiving echo pulses from said detection zone; receiver means connected to said transducer for detecting and amplifying said electromagnetic pulses, control means connected to said receiver for indicating the presence of objects in the detection zone, gating means in said connection for limiting the pulses transmitted to said control device to those reflected from within the detection zone and means for simultaneously and selectively controlling the power output of the transmitter and the gain of the receiver.
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