| 摘要 |
A wide band frequency modulated DBS signal of the type having time sequential compressed chrominance and luminance components is converted into a second television signal for transmission via a medium with a lower bandwidth e.g. cable. The wide band signal is received by an aerial 1, frequency converted in a down converter 2 and applied to the input 4 of the conversion unit. The conversion unit has a tuner 5, i.f. stage 9, 10 and a frequency demodulator 11 to produce baseband video which is applied after de- emphasis at 12 to a modulator 27 where the video is amplitude modulated onto a vision carrier from an oscillator 28. The modulated carrier is applied through a vestigial sideband filter 29 and an adder 30 to the output 31. Sound/data bursts present in the DBS signal are recovered in stage 13 and processed in unit 14 where the sound/data bursts are expanded to occupy approximately one line period at a bit rate which is an integral sub-multiple of the bit rate for the sound/data bursts in the received DBS signal. The expanded sound/data and clock frequency are digitally modulated in modulator 32 onto a sound carrier from oscillator 33, the modulated sound carrier being applied through bandpass filter 34 and the adder 30 to the output 31. The output 31 connects the signal to the cable distribution system. <IMAGE> |
