| 摘要 |
PURPOSE:To keep complete information secrecy by subjecting data, which is ciphered with a prescribed cipher code string, to spectrum spread, what is called, double ciphering. CONSTITUTION:The transmission part of each of communication equipments 1-i and 1-j subjects data inputted to a balanced modulator 12 to spectrum spread modulation by a prescribed PN code string generated by a PN code (pseudo random noise code) string generator 11 and modulates a carrier fc in a modulator 14 by its waveform signal. The signal subjected to spectrum spread modulation is superposed on a wire signal transmission line (power line or the like) 2 through a coupling device 20. Meanwhile, the reception side receives ciphered data subjected to spectrum spread modulation through the coupling device 20 coupled to the wire signal transmission line 2 and subjects this data to spectrum spread demodulation and uses a cipher code string to decode ciphered data and reads it as reception data. Thus, secrecy of transmission information is improved. |
