| 摘要 |
PROBLEM TO BE SOLVED: To make a traveling wave tube amplifier provided in a repeater of a broadcasting satellite amplified in the most suitable operation point, in all modulation systems even if signals of modulation systems with different back-off quantities are time-division multiplexed.SOLUTION: A transmission control signal analysis control section 251 of a control earth station acquires a measurement value P0 prior to a change of a transmission control signal from a receiver input level measuring section 820 of a satellite repeater 800 and acquires a measurement value P1 after the change of the transmission control signal. Since a ratio P1/P0 of the measurement values reaches level fluctuation caused by the change of a multiplexing ratio of modulation systems with different back-off quantities, the transmission control signal analysis control section 251 outputs, to a command signal generation section 252l an instruction for emitting a command that sets a current setting value Pi of a TWTA input level in an ALC mode to P1/P0×Pi or sets a current setting value OBO1 of TWTA input back-off in the ALC mode to P1/P0×OBO1. |
