| 摘要 |
An oscillator is connected to a backward counter to set the backward counter to a count number representative of its frequency of oscillation, the backward counter being stepped down by clock pulses recurring at a frequency high with respect to the cycling rate of the oscillator until it reaches a reference value, for example zero. The difference between the reference value and the count state of the counter when a predetermined counting period has elapsed, as determined by the duration of one cycle of the input signal, forms an error signal which is transmitted over a bi-directional counter to an integrator which, in turn, controls the oscillator. The system is particularly applicable for use in connection with vehicle wheel brake anti-lock arrangements, and permits determination of wheel speed by oscillation of the oscillator as well as acceleration and deceleration by sensing the error signal.
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