| 摘要 |
PURPOSE:To obtain a ciphering device with less signal deterioration by applying ciphering processing to a signal at an intermediate frequency region outputted from a band pass filter and synthesizing and transmitting the signal subjected to ciphering processing and a signal extracted by a low-pass filter and a high- pass filter. CONSTITUTION:A band pass filter 11b, a low-pass filter 12b and a high-pass filter 13b are connected to an output of a receiver 17b, and a signal extracted and ciphered from the band pass filter 11b is fed to a decoding circuit 14b for decoding the signal into an original signal. Then the signal of a band required for the decoded signal is extracted by a filter 15b and inputted to a synthesis circuit 16b. Then even when the signal of a low frequency and high frequency is deteriorated by the band limit of a transmission system, the major frequency component (0.3-1kHz) of a sound is transmitted while not being deteriorated. |
