| 摘要 |
In a normal operation mode, a receiver Rx performs a predetermined processing on a digital broadcasting signal from an artificial satellite to generate sound. In a self-diagnostic mode, a controller 19 of the receiver Rx first sets a receiving frequency band of a tuner 2, and then carries out a diagnostic check whether a PLL circuit 20 is defective or not based on the detection result from a PLL sync detector 3; the receiver input can be either a digital broadcast signal or a simulated broadcast signal. If the PLL circuit 20 is normal, it is checked whether a QPSK demodulator 21 is defective or not based on the detection result from a QPSK sync detector 22. If the QPSK demodulator 21 is normal, it is checked whether frame synchronization is failed or not in a CH decoder 24 based on the detection result from a frame sync detector 25. If frame synchronization is normal, it is checked whether channel synchronization is failed or not in the CH decoder 24 based on the detection result from a CH sync detector 26. If the controller 19 determines that the PLL circuit 20, the QPSK demodulator 21, or the CH decoder 24 is defective, a display 18 notifies an inspector of the diagnostic result. The receiver Rx thus can reliably and quickly carry out a diagnostic check as to whether each of components comprising thereof is defective or not. |
