| 摘要 |
PROBLEM TO BE SOLVED: To protect power amplifiers while keeping transmission of an amplitude-modulated wave.SOLUTION: A digital amplitude modulation device includes a power supply section, a measurement section, an arithmetic section and a power control section. The power supply section supplies a supply voltage to a plurality of power amplifiers. The measurement section measures an output power and a reflection coefficient of a combiner. The arithmetic section calculates a lost power occurring in each power amplifier in an on state and a reflected power consumed by each power amplifier in an on state on the basis of the output power and reflection coefficient measured by the measurement section and information on input power given from the power supply section. The power control section controls all the power amplifiers to an off state if the sum of the lost power and reflected power calculated by the arithmetic section is larger than a first threshold, performs a normal operation if the sum is smaller than a second threshold, and controls on/off the input voltage of the power supply section or a plurality of power amplifiers as a power-up operation or power-down operation on the basis of a rated power if the sum is not larger than the first threshold nor smaller than the second threshold. |
