| 摘要 |
PURPOSE: To improve the resolution through software, without using a high- priced pulse generator, by repeating pulse number measurement in measuring time to which random correction time is added for fluctuation and then measuring rotation speed based on its average value. CONSTITUTION: A wheel rotation pulse 1 of an object to be measured is inputted into a free run counter 2, and a random pulse generator 4, synchronizing with measurement timing pulse from a measurement timing pulse generator 3, generates random pulses. A counter control part 5 receiving it, to measurement time from the generator 3, adds random correction time whose standard deviation is larger than a half of resolution for fluctuation in measuring time. Based on an command from the control part 5, the counter 2 measures vehicle rotational pulse number in the measuring time where random pulseλis added to interval Ts of the measurement timing pulse. An adder 7 adds them one by one for calculating a total, and then a vehicle speed calculating part 8 divides this total by the number of measurements, and then, from the found average value, vehicle speed V based on rotation speed is calculated.
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