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Abstract

A method and device for detecting a cyclic code which detects an n-bit cyclic code or shortened cyclic code based on a degree-m generating polynomial or code with a predetermined bit pattern added to the cyclic code or shortened cyclic code in the bit sequence of a signal containing those codes by utilizing the principle that the remainder of division of those codes by the generating polynomial is zero or the added bit pattern. The method divides serially input receive data by the generating polynomial successively, and removes the remainder of division of X.sup.n by the generating polynomial from the remainder of the division of the bits up to the current bit if the nth bit before the current bit is 1 for each of the nth bit from the first bit and subsequent bits of the receive data. The device comprises a divider which divides serially input receive data by the generating polynomial successively and holds the remainder of the division hitherto performed, an n-stage shift register connected in parallel with the divider with respect to the input signal, and a decoder which receives the values of individual bits of the remainder calculated by the divider and outputs a predetermined detection signal when the values are all zero or form the predetermined bit pattern, and is constructed so as to remove the remainder of division of X.sup.n by the generating polynomial from the remainder calculated by the divider by utilizing the output signal of the last stage of the shift register when the value of the output of the last stage is 1.

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First Claim