AUTOMATIC DIRECTIVITY CHANGEOVER ANTENNA DEVICE

摘要

PURPOSE:To eliminate sound picture of a television receiver at directivity control by providing a muting circuit detecting a directivity control signal and activated to the television receiver provided with an automatic directivity changeover antenna device. CONSTITUTION:A best point detecting circuit 4 receives a composite video signal from the television receiver 3 and detects the noise component including ghost. A control circuit 5 allows a changeover circuit 2 to change over the directivity of an indoor antenna 1 so as to minimize the detected output and also activates a video/sound muting circuit 7 so as to eliminate the sound and video image of the television receiver. When the best point detecting circuit 4 detects the best point, the control circuit 5 fixes the changeover circuit 2 and also stops the operation of the video/sound muting circuit 7. Thus, unpleasant sound and video image are eliminated at the directivity control and gives no unpleasant feeling to a viewer. The restart of a control loop is conducted when the channel changeover or power application is detected by a reset circuit 6.