Design of a Novel Discerning Direction and Subdivision Circuit with High Anti-interference Ability Based on EPROM Look-up Table Feedback

Bo XU, Tao ZHANG, Guan-sheng HU, Xuan ZHANG


This paper mainly introduced a novel anti-interference discerning direction and subdivision circuit system according to the varying order (phase sequence) of the two signals which have phase difference of 90-degree. The scheme makes clever use of the feedback of EPROM and the look-up table relation between input and output, and the discerning direction and subdivision function is completed by using few devices and very simple circuit. Owing to (1) The interference pulse with not conform to phase sequence is filtered out and will not cause counting; (2) Using a latch, interference pulses only take effect when the rising edge of the clock pulse appears on and therefore the interference sensitive time is reduced; (3) Even on the rising edge of the clock pulse, there appears an interference pulse that conforms to the phase sequence, as long as its width is not more than one signal quadrant(quarter of signal cycle), a pair of in the opposite direction of phase sequence codes will appear, the resulting counting pulse is exactly offset, thus resulting in no measurement count errors; the anti-interference performance of the system is greatly improved. This conclusion is proved by the verification experiment.


Discerning direction, Subdivision, EPROM encoding, Phase sequence


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