Paradise P300 specifications Introduction to Aupc Automatic Uplink Power Control

8.11INTRODUCTION TO AUPC (AUTOMATIC UPLINK POWER CONTROL)

Note: Authorisation from the satellite operator is probably required before AUPC is activated.

8.11.1Introduction

AUPC provides a mechanism to counteract changes in atmospheric conditions (eg rain), which in turn affects the attenuation of the atmosphere and can degrade the performance of a satellite link. It does this by monitoring the distant end Eb/No and automatically adjusting the local Tx power of a satellite link to try and maintain the specified distant end Eb/No figure.

To be able to monitor the distant Eb/No the local modem needs to be able to interrogate the distant modem and request the current Eb/No value. It does this by sending messages through the asynchronous ESC channel (which is carried over the satellite multiplexed with the main data channel). For AUPC to operate an async ESC channel must be defined, and on the P300 Series this is available in Closed Network (Closed Net Plus ESC), IBS/SMS and IDR modes.

The AUPC may be set to monitor the distant Eb/No (Mon Dist, shown above) or in its normal mode to maintain a distant Eb/No (Maint' Eb/No, shown overleaf). In both modes the distant Eb/No and BER estimate can be displayed on the local end LCD (Monitor, Dist end), a deferred alarm can be set to activate if the distant Eb/No falls below a user set threshold (Change, User-Opt, Alarm Thresholds, Distant Eb/No), and the distant end Eb/No can be recorded regularly in the local end traffic log using the Autolog feature (Change, Log, Autolog). The distant Eb/No can also be output on the uncommitted analog DAC output if the Monitor / AGC option is fitted (see “uncommittedanalog DAC output”, value = 4 in Appendix E starting on page 201)

P300H P300 Series Modem Installation and Operating Handbook Page 154