| 摘要 |
PURPOSE:To automatically selecting and switching the appropriate sound demodulation output of a satelite broadcasting receiver receiving the BS of a DPSK whose audio signal modulation system is in four-phase and the CS of an FM or MSK and to display whether the sound is PCM or FM sound. CONSTITUTION:As to the changeover of a first switching circuit 8 between a DPSK demodulation circuit 6 and an MSK demodulation circuit 3, a controlling microcomputer 11 monitors the frame synchronization state of a high-order error correction part 7 after MSK demodulation and in the case of synchronization, it selects the side of the MSK demodulation circuit 3. As to the changeover of a second switching circuit 9 between an FM demodulation circuit 4 and the output of a scramble decoder 5, the controlling microcomputer 11 monitors the frame synchronization state at the time of low-order error correction and in the case of synchronization, it selects the output side of the scramble decoder 5. Furthermore, a display signal 26 linked with a second switching signal 25 displays whether the sound is the PCM or FM sound.
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