| 摘要 |
PURPOSE:To make it possible to perform speeding requlation without being noticed by a driver, by measuring the speed of a vehicle by emitting a microwave to a running vehicle in a direction at right angles to the running direction. CONSTITUTION:The reflected wave from a vehicle 2 is received by an antenna 10 and a difference signal is detected by a hybrid through a duplexer 9. The output thereof comes to a max. value when the vihicle A is an A-direction or a B- direction. A comparator 16 generates the max. output value of a detector 15, that is, a distance measuring pulse when the vehicle 2 passes the A-direction and the B-direction and a distance signal generating circuit 17 generates a distance signal pulse proportional to the time interval t1 between the output pulse from the reference signal generator 7 and the distance measuring pulse from the comparator 16 and the time interval t2 of two distance measuring pulses. An operation circuit 18 measures t1 and t2 and calculates the speed of the vehicle on the basis of t1, t2 and the parameter theta from an input circuit 19 to output the same to a speed output circuit 20.
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