| 摘要 |
PROBLEM TO BE SOLVED: To provide a digital satellite communication apparatus capable of sure communication at a low cost. SOLUTION: A digital satellite communication apparatus 10 includes a duplexer 12. A reception signal passing the duplexer 12 is subjected to amplification and frequency conversion by a low-noise amplifier 18 and a frequency converter (D/C) 20 for reception. The reception signal subjected to frequency conversion is not only demodulated by a reception circuit 22 and is given to a terminal station device 26 but also given to a beacon signal level detection circuit 24. The beacon signal level detection circuit 24 detects the level of a beacon signal included in the reception signal. The level of the beacon signal is converted to digital data by an A/D converter 34 and is compared with a preset threshold A by a level discrimination circuit 36. If the level of the beacon signal is lower than the threshold A, it is judged that the circuit condition has been degraded, and the transmission rate is set to a lower value in the terminal station device 26 in accordance with the indication of a transmission rate change circuit 38. That is, C/N is raised. |
