Transmitting stereo audio programs in cable TV systems

Claim 1

In a cable TV system including a central station at which programmes originate, a customer's end, a switching point, an optical fibre connecting said central station to said switching point, a light source at the central station for directing light down said optical fibre, and a down drop connecting the switching point to the customer's end: apparatus for transmitting stereo audio signals comprising at said central station; means for receiving a plurality of stero radio signals; means for demodulating each of said radio signals to produce respective stereo multiplex signals; means for sampling each of said stereo multiplex signals; producing a digital representation of said samples and multiplexing said digital representations to produce a digital multiplex; means for generating a video carrier; means for modulating the frequency of said video carrier in response to said digital multiplex; and means for modulating the intensity of light emitted by said light source in response to said modulated video carrier: and further comprising at said switching point; means for receiving said demodulating light from the fibre to derive the modulated video carrier, means for demodulating said video carrier to produce the digital multiplex, and converting each digital representation to an analogue signal thus reconstituting the stereo multiplex signals; means for generating an FM carrier for each of said stereo multiplex signals; means for modulating the frequency of each of said FM carriers in response to its respective stereo multiplex signal, and means for applying the modulated FM carriers to the down drop for transmission to the customer by frequency division multiplex.