Traffic flow speed measuring apparatus

Abstract

PURPOSE: To detect the speed of a vehicle running through two points accurately, by providing a function generating circuit which generates exponential function output as being started by a vehicle detection signal from a sensor. CONSTITUTION: Vehicle detection signals outputted from sensors 1a, 1b are differentiated in differentiating circuits 3a, 3b, and the difference is converted into pulse, and a pulse signal beyond the reference level e 1 is taken out in comparators 4a, 4b, and the vehicle detection signal is outputted from monostable multivibrators 5a, 5b as a pulse signal having a specified width. The vehicle detection signal Q 1 is applied to a function generating circuit 7, and a second vehicle detection signal Q 2 is inverted and amplified in NAND gate 8, and is applied to a sample hold circuit 9. When vehicle detection signals Q 1 and Q 2 are generated at time difference of (t), the output voltage Eout will be: Eout=E 0 ε -t 'CR. COPYRIGHT: (C)1979,JPO&Japio

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