| 摘要 |
PURPOSE:To decrease the number of cables which connect an indoor and an outdoor unit and to simplify the inside of the outdoor unit by transmitting a positive and a negative source voltage on time-division basis, and further switching the level of the negative source voltage and transmitting switching information for a received plane of polarization. CONSTITUTION:A feeding and changeover information transmitting means 63 transmits the positive and negative source voltages on time-division basis. The positive and negative DC voltages are applied to the outdoor unit 40 through a coaxial cable 50 and supplied to a positive voltage extracting circuit 45 and a negative voltage extracting circuit 46. The positive voltage extracting circuit 45 extracts the positive voltage and supplies it to an amplifying and converting circuit 42 and the positive source voltage terminal of a polarizer control circuit 49. Further, the negative voltage extracting circuit 46 extracts the negative voltage and supplies it to the negative source voltage terminal of the polarizer control circuit 49 through a constant voltage circuit 47. Further, the negative voltage of the negative voltage extracting circuit 46 is supplied to a voltage level detecting circuit 48 to obtain a binary control signal of '0' or '1' in response to the level of the negative voltage, so that the control signal is applied for the control terminal of received polarization plate switching of the polarizer control circuit 49.
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