| 摘要 |
PURPOSE:To adjust automatically the phase in response to a reception channel by providing a channel selection discriminating circuit giving an adjusting signal of a phase shifter to a ghost improving phase adjusting device. CONSTITUTION:After a reflected wave from a television input terminal 16 is extracted by a directional coupler 15, reception signal levels of each channel are compared by a channel selection discriminating circuit 19, and a channel whose reception level is lowered extremely is decided to be a channel selection channel and a drive signal is given to a phase shift switching drive circuit 20. A switch S1 is an initial adjustment switch and the switch S1 is opened at first to adjust the phase in advance erasing a ghost at each channel. The phase shift switching drive circuit 20 drives a phase shift switching circuit 18 in response to the channel selection channel to adjust the phase shift of a phase shift circuit 11. Thus, a prescribed phase shift quantity is given to a signal from an antenna 13, the result is mixed with a signal from an antenna 14 by a phase mixing circuit 12 to cause a null point of the directivity pattern in the direction of an undesired wave thereby eliminating a ghost.
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