PURPOSE: To improve the privacy of a secret transmission system where the frequency spectrum of information is divided into plural parts and rearranging the order of these divided spectra, by inserting a pseudo spectrum into a specific band of a low level electric power.
CONSTITUTION: An input signal 1 passes through an A/D converting part and a parallel/serial converting part 3, and the frequency spectrum of the signal 1 is obtained at a high-speed Fourier converting part 4. A specific low electric power part is deleted at an undesired spectrum eliminating part 5 for the output of the part 4. Then this output is supplied to an addition part 8. A pseudo spectrum is supplied to the part 8 from a pseudo spectrum generating part 7, and the output of the part 8 is transmitted through a spectrum order rearranging part 9, an adverse high-speed Fourier converting part 10, a parallel-serial converting part 11 and a D/A converting part 12. At the reception side the spectrum order is rearranged and the pseudo spectrum part is deleted. Then an original signal is reproduced.
AKIYAMA RIYOUTA
YATSUHOSHI AKIMASA
| JPS5862948A | 1983-04-14 | |||
| JPS56120239A | 1981-09-21 | |||
| JPS5539642U | 1980-03-14 |