Patent ID: 8488649

Claim:
A code converting apparatus comprising: a signal inputting processing circuit configured to input a first signal sampled in a predetermined sampling cycle from a modulation signal modulated by a spreading sequence composed of m elements in a set A having n kinds of symbols as elements where m≧4d, d≧1, n≧2, and m, d and n are integers; a symbol sequence memory configured to store a converted sequence of symbols obtained by concatenating consecutive 2d symbols at the center of each of n 4d kinds of sequence patterns, each sequence pattern being composed of 4d elements in the set A, the converted sequence of symbols being structured so that d symbol immediately preceding the 2d symbols and d symbol immediately following the 2d symbols are identical to d symbol immediately preceding corresponding 2d symbols and d symbol immediately following the corresponding 2d symbols of a corresponding sequence pattern; a symbol sequence specifying processing circuit configured to specify a sequence pattern matching a partial sequence composed of the 2d symbols, the d symbol immediately preceding the 2d symbols and the d symbol immediately following the 2d symbols, among the sequence patterns, for every consecutive 2d symbols included in an input symbol sequence x 1 x 2 . . . x m obtained by assigning a symbol to the first signal inputted by the signal inputting processing circuit in a coding cycle of the spreading sequence; a signal generating processing circuit configured to generate a pattern signal for each sequence pattern specified by the symbol sequence specifying processing circuit for every consecutive 2d symbols included in the input symbol sequence, by adding a partial signal that is a portion to which the 2d symbols are assigned of the first signal inputted by the signal inputting processing circuit; and a signal converting processing circuit configured to generate a second signal by concatenating each pattern signal generated by the signal generating processing circuit for each sequence pattern, in an order equivalent to an order of the 2d symbols at the center of each sequence pattern concatenated in the converted sequence of symbols stored in the symbol sequence memory.