| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an abnormal television broadcast signal from being retransmitted, by monitoring whether a television broadcast signal to be retransmitted is normal or not, in a system for retransmitting television broadcast signals to viewing/listening difficult areas. <P>SOLUTION: A television broadcast signal for retransmission and a signal representing the number of waves are output from a head end to a transmission device 8, and the transmission device 8 detects the number of waves from the signal and outputs a result to a monitoring apparatus 10. From the transmission device 8 to the monitoring apparatus 10, in addition to data about the number of waves, a retransmission signal to be output to a transmission antenna is branched and input, and a control circuit 70 allows a tuner module 72 to sequentially select retransmission channels from retransmission signals and to obtain a signal level and a modulation error ratio (MER) for each channel, thereby counting the number of waves in the normal television broadcast signal retransmitted by the transmission device 8. If the counted number of waves is not matched with the data on the number of waves from the head end 4, it is determined that the retransmission signal has abnormality, so that retransmission of the television broadcast signal by the transmission device 8 is halted. <P>COPYRIGHT: (C)2010,JPO&INPIT |
