GB1144406A - Vehicle speed timing apparatus - Google Patents

Abstract

1,144,406. Vehicle speed timing apparatus. F. V. GEBERT. 14 Feb., 1967 [18 Feb., 19661, No. 7092/67. Heading G4H. Vehicle speed timing apparatus includes two electrical detectors each comprising a cable which transmits an electric pulse generated by the piezo electric effect when a vehicle wheel passes over it, the pulse from the first cable enabling a gate to pass signals from a crystal oscillator to a cascade counter circuit, the other detector closing the gate to stop the count. In the embodiment described the pulse generated on lead 4 (Fig. 4) when a vehicle wheel passes over the first cable is applied to a mechanical safety gate 19 after amplification and shaping, the output from the gate 19 on lead 27 then being applied to a further gate 28 which enables only one pulse to pass through to an electronic gate 30 through which clock pulses from a crystal oscillator 34 then pass to a cascade counter 33. When the wheel passes over the second cable the electric pulse generated on lead 5 is similarly applied to the mechanical safety gate 19 to generate a pulse on lead 35 to close the gate 30. The count in the counter 33 then represents the length of time taken for the vehicle to travel between the two cables. Ammeters 40-43 are connected to the counter boards and display the number of counted pulses. To test the accuracy of the count a test pulse generator 54 supplies test pulses of known frequency via lines 52, 53 to the gate 19. By connecting terminals 25 and 26 and 21 and 22 these pulses similarly enable and close respectively gate 30 so that the counter 33 accumulates pulses from the oscillator 34 between two consecutive pulses from the test pulse generator 54. The number of vehicles passing over the cables may be found by accumulating the pulses on lead 5 in a further counter 56.