| 摘要 |
PROBLEM TO BE SOLVED: To obtain a television signal changeover device at a low cost that requires no adjustment even when the number of community reception signals is increased. SOLUTION: A relay changeover circuit 38 is provided among an input terminal 32 receiving a broadband community reception signal, an input terminal 34 receiving an antenna reception television broadcast signal and an output terminal 36. The changeover circuit 38 to which an input terminal 32 and the output terminal 36 are connected, selectively takes a 1st state where the input terminal 32 and the output terminal 36 are connected and the input terminal 34 and the output terminal 36 are not connected or a 2nd state where the input terminal 32 and the output terminal 36 are not connected and the input terminal 34 and the output terminal 36 are connected. A weighting circuit 52 receives the common reception signal from the input terminal 32, where a frequency characteristic of the community reception signal is weighted so that an output signal level around a maximum frequency of the community reception signal and an output signal level around a minimum frequency of the community reception signal differ from each other. A level detection circuit 54 receiving an output signal of the weighting circuit 52 generates a level detection signal. A comparator 56 receives the level detection signal and a reference signal from a reference signal source 58, and sets the changeover circuit 38 to the 1st state when the level detection signal is the reference signal or over and sets the changeover circuit 38 to the 2nd state when the level detection signal is less than the reference signal. |
