| 摘要 |
PURPOSE:To make a third person's radio transceiver not belonging to a system difficult to tap by changing the start point and sequence of reading time piece signals for each frame in accordance with instructions of a cipher signal. CONSTITUTION:When a signal by a switch SW78 flows to side a, since a time piece signal ciphered by a reversible time range memory circuit RTM1 adjusts transmission timing, the time piece signal is stored once in a memory circuit 1, read in accordance with reading instructions to be sent by a timing signal and from a cipher code adder 76, and sent to a signal rate converting circuit 51-1-1. Then, a signal (random number) from the cipher code adder 76 is represented in decimal notation, and if the signal is assumed to consist of more than 2 digits, the numeric value of the lowermost digit and the time length of the time piece signal are equally divided to 10, respectively, and a point of time is determined where a number of times of equally divided time division of the numeric value counting from point P are made to coincide with a number of times of equally divided time division of the time length, and that point of time is designated as reading point A. Next, by choosing the numeric value of the second digit, if it is an even number, the reading sequence is determined as positive, and if it is an odd number, the reading sequence is determined as negative. |
