Radyne OM20 Specifications download pdf (Page 45)

DMD1050 Satellite Modem Board Theory of Operation

3.13.2 EF AUPC

In this case, Target E

indicates the local unit wants the remote unit to maintain a power level

sufficient to provide the local E

value.

EF AUPC can be set to operate on either or both directions of a link but always require a bi-

directional channel. Enabling AUPC on one side of the link will activate AUPC on the distant

end of the link. It is necessary that both the Modulator and Demodulator be set to the appropriate

framing for AUPC options to be editable and for the AUPC function to operate properly.

Examples of the basic EF AUPC Operations are described as follows:

Assume that the two modems, one at each end of the link, are set to AUPC operation. Only one

direction is discussed, but the same functions could be occurring in both directions

simultaneously.

The local modem is transmitting to modem at a remote locale under normal conditions. The

remote modem has a receive E

of 7.5 dB. The local modem has been set with a Target E

of 7.5 dB, and has a current power output of –15 dBm.

It begins to raining at the local site, and the E

drops to –7.0 then –6.8 dB. The local modem

is constantly sending update messages of its E

to the remote modem. When the remote

modem sees the drop in the E

, it slowly begins to raise it’s output power, and will continue to

do so until the Target E

is restored at the local site.

When the rain diminishes, the local modem’s E

will begin to increase. The remote modem

will now lower its power level to restore the target value. The operation is therefore a feedback

control loop with the added complication of a significant time delay.

3.13.3 Near Side AUPC

Near Side AUPC is a loop back system that adjusts the broadcast uplink signal when local

conditions change. This is done by having the Near Side AUPC attempt to adjust the outbound

power to compensate for local weather.

The local receiver must be tuned and locked to the transmitter and then the internal E

, is used

for feedback. This creates a Tx-Satellite-Rx control loop is created.

Near Side AUPC is primarily used for broadcast applications since the modem cannot expect to

receive data from a distant location. Near Side AUPC can be utilized with any satellite framing

mode.

There are safeguards built into the AUPC System. First, the modulator has two parameters,

which allow control of the maximum and minimum output power Levels. Second, a nominal, or

default, power level is specified which takes effect if the receive signal or messaging is lost. This

nominal power should be set to a level high enough to re-establish communications regardless of

rain fade.

EF AUPC, also provides some control over the rate of power change; while the Radyne and Near

Side AUPC use a optimized rate for rain fade compensation.

The AUPC Menu Functions and their descriptions are shown on Table 3-2 and Table 3-3.

MN-DMD1050 3–23

Revision 9

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Radyne OM20 Specifications Page 45

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