| 摘要 |
The invention relates to communications technology and can be used in broadcast and cable television systems for the transmission of information in the form of digital code. The aim is to simplify the construction and reduce the cost of transmission systems. To that end, an even number of supplementary carriers are transmitted in the upper part of the TV channel band which is free of the spectra of video- and audio TV signal carriers, to produce a consecutive series of pairs shifted in frequency, the spectra of the said pairs being prevented from mixing. Each pair of adjacent supplementary carriers is modulated with its own digital signal by frequency shift without any phase interruption, the modulating frequency being hyperacoustic. The modulation index chosen is below one, and/or the bandwidth of the frequency spectrum of the shifted carriers is initially limited in parts lying outside the said carrier pairs. |
