Comtech EF Data SDM-650B - Manual (Page 268)

Asynchronous Overhead Channel Unit SDM-650B Satellite Modem
F–10 Rev. 5
F.4 Functional Description of ASYNC Overhead Channel Unit with AUPC
The ASYNC overhead channel unit with the AUPC option functions very much the same
as the original ASYNC overhead channel unit, except for some added features.
The connector pinouts and specifications apply to both versions of the ASYNC overhead
channel unit.
There are two added features in the AUPC version:
• Automatic Uplink Power Control
• Modem-to-Modem Channel for Remote M&C
These features are outlined in the following sections.
F.4.1 AUPC
This feature is designed for remote communication between a local modem (A) and a
remote modem (B). This feature allows the local modem to maintain a constant
(
± 0.5 dB) E
b
/N
0
by requesting changes in transmit power level from the remote modem.
The user has the ability to set the following parameters:
• AUPC Enable (turns the AUPC ON or OFF)
• Remote Carrier Loss Action (Nominal, Maximum, Hold)
• Carrier Loss Action (Nominal, Maximum, Hold)
• Set Nominal Power Limit
• Set Maximum Power Limit
• Set Minimum Power Limit
• Set Target E
b
/N
0
• Set Maximum Tracking Rate
When AUPC is turned ON in the local modem, it allows commands from the remote end
to increment or decrement the power in 0.5 dB steps. This feature also allows power to be
changed for remote or local carrier loss.
When AUPC is turned OFF in the local modem, the commands are still sent, but the local
modem will not respond to the commands.