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Automatic Uplink Power Control (AUPC)

AUPC is a feature whereby a local modem is permitted to adjust its own output power level in order to attempt to maintain the Eb/No at the remote modem. AUPC relies upon EDMAC for its operation. The remote modem constantly sends back information about the demodulator Eb/No using reserved bytes in the overhead structure. The local modem then compares this value of Eb/No with a pre-defined target value. If the Remote Eb/No is below the target, the local modem increases its output power, creating a closed-loop feedback system over the satellite link. A particularly attractive benefit of this feature is that whenever framed operation is selected, the remote demodulator’s Eb/No can be viewed from the front panel display of the local modem.