| 摘要 |
Head-end and receiver for a signal distribution system for signals having a wide frequency band and for accompanying signals having a narrow frequency band, such as the video signal and the sound signal of a television signal, respectively, digital signals being used for the distribution. The head-end comprises a first (4) and a second (5) A/D-converter for the signal having the wide frequency band and the signal having the narrow frequency band, respectively. The receiver comprises corresponding D/A-converters (13, 14). In order to avoid a specific frame structure and corresponding frame synchronization, the digital output signal of the second A/D-converter is modulated in a modulator (7) in the head-end on a subcarrier from a source (6) and thereafter added to the signal having the wide frequency band, and the combined signal is applied to the first A/D-converter (4) which is provided by a one-bit modulator. In the receiver the received digital signal is applied to a demodulator (17) via a bandpass filter (15), the demodulator output signal being applied to the second. |
