| 摘要 |
PURPOSE:To obtain the wiretapping preventing method for the cordless telephone set and the cordless telephone set applied with the method. CONSTITUTION:The cordless telephone set consists of a fixed unit 11 which is connected to a telephone line and a slave unit 6 which performs radio transmission to and reception from the fixed unit 11. In addition to circuits 5 and 7 for radio transmission and reception, the slave unit 6 and fixed unit 11 have ciphering and deciphering circuits 4 and 8 for multi-mode cipher which cipher and send out a speech signal to the transmitting and receiving circuits 5 and 7 and decipher the ciphered signal received by the transmitting and receiving circuits and mode setting circuits 3 and 9 which selectively set a mode of cipher to be used according to a user's indication. |
