Code converting apparatus, receiver, and code converting method

A code converting apparatus is designed to estimate the incoming time and the like of a signal modulated by a spreading sequence composed of m elements in a set A having n kinds of symbols as elements accurately. A symbol sequence memory section 102 stores a converted sequence of symbols obtained by concatenating consecutive 2d symbols at the center of each sequence pattern pi composed of 4d elements in the set A. The converted sequence of symbols is 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 section 103 specifies a matching sequence pattern for every consecutive 2d symbols in a symbol sequence obtained by assigning a symbol to the signal in a coding cycle of the spreading sequence. A signal generating section 104 adds a portion to which the 2d symbols are assigned of the signal. A signal converting section 105 concatenates each pattern signal added 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.