DATA TRANSMITTING APPARATUS, DATA RECEIVING APPARATUS AND DATA COMMUNICATION APPARATUS

摘要

A data communication apparatus wherein the time required for a wiretapper to analyze a cipher text is significantly increased, thereby achieving a high level of concealment. A multi-level code generating part (156a) generates, from predetermined key information, a multi-level code sequence in which the signal level varies substantially like a random number. A multi-level processing part (111b) combines the multi-level code sequence with information data to generate a multi-level signal having a level corresponding to the combination of the multi-level code sequence and the information data. In the multi-level code generating part (156a), a random sequence generating part (157) generates, based on the predetermined key information, a binary random number sequence. A multi-level converting part (158) generates the multi-level code sequence from the binary random number sequence in accordance with a predetermined coding rule.