| 摘要 |
PURPOSE:To reduce the number of cables between an antenna and tuner by superposing the operating power voltage of an active circuit incorporated in the main antenna body and antenna switching control signals together and then by sending them to the main antenna body via a common transmission line. CONSTITUTION:Superposing-synthesizing circuit 5 superposes electric circuit power source +B of receiver 1 and control signals of switching control signal generating circuit 4 that generates antenna switching control signal. To cable 6, on the other hand, an electric power source varying in level with the control signal is sent out. At the antenna side, separating circuit 7 separates electric power voltage +B and the antenna switching control signal. Outputs of two antennas 8 and 9 are selectively selected by change-over circuit 10 and applied to active circuit 11. At this time, the precedent switching control signal is used for this switching. The output of active circuit 11 is led to receiving circuit 13 at the receiver side by way of coaxial cable 12. |
