| 摘要 |
PURPOSE:To improve S/N and to eliminate the deterioration of a transmission capacity by limiting and transmitting the digital signal of a frequency f2 to the frequency of f1/2 (f1<f2), converting a frequency after receiving from f1 to f2 with a receiving side and executing the cosine spectrum correction. CONSTITUTION:The digital signal of a frequency f2, for which a pre-coding processing to execute the duo binary transmission is executed, is band-limited by a LPF2 having the characteristic of a central frequency fc=f1/2 (f1<f2). For a signal 3, a frequency is converted from f2 to f1 with a frequency converter 4. A signal 5 is time-division-multiplexed and outputted with a time division multiplexing means 7 together with a digitizing TV signal 6, frequency-shaped by a spectrum shaping device 9 and PAM-transmitted through a D/A converter 11 by an FM transmission line 12. With a receiving device, a compound TV signal 15 is obtained through an A/D converter 14. A digital signal multiplexed in a TV signal is converted to the signal of the frequency f2 with a frequency converter 16, frequency-shaped by a cosine spectrum shaping device 18 and a delta noise is suppressed. |
