P300H
P300 Series Modem Installation and Operating Handbook
Page 156
A `compatibility document` which, describes interworking tests between the Paradise P300/P400
Modems and other manufacturers modems, is available on request.
8.11
INTRODUCTION TO AUPC (AUTOMATIC UPLINK POWER CONTROL)
Note: Authorisation from the satellite operator is probably required before AUPC is activated.
8.11.1 Introduction
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 (
Ó±² Ü·-¬
, shown above) or in its normal mode
to
maintain
a distant Eb/No (
Ó¿·²¬ù Û¾ñÒ±
, shown overleaf). In both modes the
distant
Eb/No and
BER estimate can be displayed on the
local
end LCD (
Ó±²·¬±®ô Ü·-¬ »²¼
), a deferred alarm can be
set to activate if the distant Eb/No falls below a user set threshold (
ݸ¿²¹»ô Ë-»®óÑ°¬ô ß´¿®³
̸®»-¸±´¼-ô Ü·-¬¿²¬ Û¾ñÒ±
), and the distant end Eb/No can be recorded regularly in the local end
traffic log using the Autolog feature (
ݸ¿²¹»ô Ô±¹ô ß«¬±´±¹
). The distant Eb/No can also be output
on the uncommitted analog DAC output if the Monitor / AGC option is fitted (see uncommitted analog
