| 摘要 |
PURPOSE:To select automatically the optimum directivity by providing a means detecting the reception frequency changeover and restarting the sequential changeover to an automatic directivity changeover antenna device. CONSTITUTION:When a defeat pulse generated at the channel changeover from a television receiver is inputted to a terminal 10, a frequency-dividing circuit 12 is reset, and a clock signal CK from a main block generating circuit 7 inputted via a switch circuit 9 is frequency-divided and frequency-divided outputs D0, D1 and D2 are transmitted to a decoder 13. A control circuit 14 receives an output of the decoder 13 so as to control sequentially the changeover of the antenna directivity. When a minimum noise component of a composite video signal from the television receiver is detected, a best point detecting circuit 8 closes the switch circuit 9 so as to inperrupt the clock signal CK transmitted to the frequency division circuit 12. Thus, the optimum directivity of the antenna is selected automatically. |
