PURPOSE: To make it possible to accurately calculate the distance and speed of a moving body, without increasing the operating load, even if the moving speed of the body becomes high, by controlling the speed etching pulses to be fed a speed operating unit in accordance with the speed.

CONSTITUTION: The pulses of the number corresponding to the speed to be detected by a pulse detecting unit 2 are counted by the counter 11 of a input pulse control circuit 10. When the speed of a moving body become so high as to exceed the preset value of the mask value register 13 of a comparator 12, a speed operating unit 3 is started, and the counter 11 is reset in accordance with the mask value. On the other hand, the operating unit 3 subjects the time elapse by an oscillator 4 and an elapse time counter 5, a constant preset in a diatance contact register 6, and the mask value of the register 13 to the operational processing so that the speed of the body is counted in the register 7. In accordance with the counted result of this register 7, the mask value of the register 13 is preset in accordance with the speed through a presetting unit 14. As a result, the input to the operating unit 3 is controlled in accordance with the speed so that the accurate distance and speed can be calculated without increasing the load.