Chapter 8. AUTOMATIC UPLINK POWER CONTROL

8.1Introduction

Automatic Uplink Power Control (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.

WARNING

The user SHALL obtain permission from the Satellite Operator to use this feature.

Improper use of this feature could result in a transmitting terminal seriously exceeding its allocated flux density on the Operator’s satellite. This could produce interference to other carriers, and could cause transponder saturation problems

To accomplish this, the framed (EDMAC) mode of operation must be used. 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 will increase its output power, and hence, a closed-loop feedback system is created 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. Note also that AUPC can be used simultaneously with

EDMAC.

8–1

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Mocomtech CDM-QX operation manual Automatic Uplink Power Control