| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the trouble of a viewer by informing the viewer of that reception quality is degraded by a propagation environment when reception environment is degraded, and a receiver automatically switches a reception modulation system in accordance with the reception environment thereby degrading the reception quality. SOLUTION: A transmission station transmits the same program through plural modulation systems by hierarchized program information. A reception condition measuring part 4 measures the number of demodulated signal errors detected by an error correcting part 7 and sends it to a reception condition judging part 5. The reception condition judging part 5 discriminates whether the reception conditions are good or not from the number of errors and sends the result to a demodulation range control part 8 and a reception condition information part 6. Based on the quality discriminated result of the reception conditions, the demodulation range control part 8 selectively controls the demodulation range of a demodulation part 3. The reception condition reporting part 6 gives the information on the reception conditions judged by the reception condition judging part 5 or the quality of a program capable of being supplied as the result of demodulation range selection to the viewer with image or voice. |
