DIGITAL DATA RECEIVER, POWER MEASUREMENT DEVICE AND POWER MEASUREMENT METHOD

摘要

PROBLEM TO BE SOLVED: To allow a traveling wave tube amplifier provided in a repeater of a broadcasting satellite for all modulation systems to perform amplification at an optimal operating point even when a signal of a modulation system of different back-off is time-division-multiplexed.SOLUTION: An AGC amplifier 11 of a receiver 10 for monitoring a downlink inputs an AGC level hold instruction signal from a transmission control signal analysis controller 251 of a command signal transmitter 260 in a control earth station, fixes an AGC gain and amplifies an IF signal with the fixed AGC gain. A modulation system gate signal generator 13 generates a gate signal, which becomes valid only during a designated modulation system term, on the basis of a frame synchronizing signal and transmission control information from a transmission control signal decoder 145 and a modulation system instruction signal from the transmission control signal analysis controller 251. A level measuring unit 14 measures an average power of quadrature detection outputs from a quadrature detector 143 for the term of the gate signal and outputs a result of the measurement to the transmission control signal analysis controller 251.