| 摘要 |
PURPOSE:To use repeatedly a recording medium irrespectively of its kind and, at the same time, to make computer processing, such as calculation of an average speed, etc., easier, by writing the point of inflection of a car speed, time data, etc., in a memory to use the memory effectively. CONSTITUTION:When the speed of a vehicle changes as the vehicle runs, a car speed pulse (a) from a car speed sensor 1 changes its frequency proportionally to the car speed. An FV converter 3 converts the frequency F of the pulse (a) into an analog voltage V and a quadratically differentiating circuit 4 differentiates the FV converted output two times. Therefore, the output (e) of the circuit 4 becomes to correspond to the point of inflection of an input (b). On the other hand, a frequency counter 2 periodically counts the pulse (a) and its output Si is fetched by a register 6 as car speed data. Then, when the pulse (e) indicating the point of inflection is produced from the circuit 4, the then content of the register 6 and the time data Ti from a time counter 7 corresponding to the content are written on a memory 8. Moreover, if the pulse (e) is not produced even after a prescribed time has passed, the then car speed data Si and time data Ti are written on the memory 8 and data strings are accumulated.
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