| 摘要 |
The invention relates to a device making it possible to produce, in particular, television broadcasting networks. In this case it comprises devices 30 enabling each video source to be coupled to a single coaxial cable 31 conveying video signals to a plurality of conventional television receivers 19. Each device 30 comprises a frequency changer 21 connected to an oscillator 28 of frequency 200 MHz, a bandpass filter 22 of central frequency 203 MHz and of passband 6 MHz, a frequency changer 23 connected to an oscillator 29 supplying a signal of frequency 1860 MHz, a bandpass filter 24 of central frequency 2063 MHz which rejects the image frequencies whose value is about 1600 MHz, a frequency changer 25 connected to an oscillator 27 supplying a signal of frequency f3 which is distinct for each video channel and lies in the range 1100 to 1500 MHz, a low-pass filter 26 allowing through all frequencies below 1000 MHz. The demultiplexing of the video signals is carried out by each of the television receivers 19, each video channel being selected by adjusting the tuning frequency of a television receiver 19. Application to television broadcasting, to the switching of video signals in television production studios and to the switching of videophone channels. <IMAGE>
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