| 摘要 |
PURPOSE:To inhibit the transmission of a digital broadcast signal to a digital circuit when a digital fixed pattern resides in an output signal from a coder-decoder circuit, by discriminating whether or not the digital fixed pattern resides. CONSTITUTION:Coder-decoder circuit 22 not only codes a broadcast signal from a broadcast station but also decodes a signal sent from the transmission line and generates a digital fixed pattern when the broadcast station sends out no broadcast signal. Here, detection circuits 3a and 3b detect whether or not the output signal from circuit 22 includes the digital fixed pattern, so that if the digital fixed pattern is included, the transmission of the digital broadcast signal to the digital circuit will be inhibited 40. |
