SPEED MEASURING SYSTEM

PURPOSE:To enable the measurement of a speed with high accuracy over a wide range from an ultralow speed to an ultrahigh speed, by setting obtained center frequency to a predetermined frequency range even if a moving body takes any moving speed. CONSTITUTION:It is assumed that a light receiving elem...

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1. Verfasser: OKAWA SHUJI
Format: Patent
Sprache:eng
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Zusammenfassung:PURPOSE:To enable the measurement of a speed with high accuracy over a wide range from an ultralow speed to an ultrahigh speed, by setting obtained center frequency to a predetermined frequency range even if a moving body takes any moving speed. CONSTITUTION:It is assumed that a light receiving element 21 moves to the direction shown by an arrow at a speed (v). When the detection outputs of light receiving elements a1, a2... arranged on every other element at a pitch P are added because there is random irregularity 22 on the surface floor, the spatial frequency at that time is inversely proportional to the pitch P and a signal with intermediate frequency fc is obtained. When the speed of the moving body reached 2v, the light receiving elements a1, a3... are selected as odd- number-th ones and the light receiving elements a2, a4... are selected as even- number-th ones. Whereupon, the pitch thereof comes to 2P and center frequency is not different from fc. When the speed of the moving body became slow, the intervals between the light receiving elements to be selected may be made narrow. As mentioned above, by holding center frequency to a detectable definite frequency range with high accuracy, highly accurate measurement is enabled.