Comtech EF Data SNM-1001L - Manual (Page 208)

SNM-1001L Satellite Modem Revision 1
Automatic Uplink Power Control MN/SNM1001L.IOM
10–4
With Local AUPC On, set modems (A and B), if modem A loses carrier:
1. Modem A sets its output power (MAXIMUM, MINIMUM, OR HOLD) as specified by
LOCAL CL ACTION.
2. Modem A then sends a “lost carrier” command to modem B.
3. Modem B sets its output power (MAXIMUM, MINIMUM, OR HOLD) as specified by
REMOTE CL ACTION.
4. Once modem A has reacquired the carrier, it sends commands to modem B to achieve the
desired E
b
/N
0
. During this time, modem B sends commands to modem A to increase or
decrease power to maintain modem B’s target E
b
/N
0
.
Notes:
1. Modem B will not make changes to modem A if the E
b
/N
0
is within 0.5 dB of the
target noise.
2. Modem B will not control modem A transmitting output level if the target noise
for modem B is set within 15.5 to 16.0 dB and the receive signal to the modem is
sufficient that the receive noise is 16 dB or better.
3. Modem A will be transmitting at the maximum output if the local carrier loss
action is set to maximum.
4. Caution shall be observed when setting the target E
b
/N
0
above 15.5 dB, the
maximum limit is established at 16.0 dB.
5. Local carrier loss always takes priority over remote carrier loss.
6. The RX AUPC link is dead when the carrier is lost.
10.2.1 AUPC – Between Two Modems
This mode of AUPC operation allows each of the two modems to operate in a closed link
to control the output of the other modem in a manner that preserves a target Eb/No.
Hardware Corresponding Software (FAST)
Overhead Card ASYNC/AUPC. This provides AUPC and an ASYNC channel.
TX and RX Reed-Solomon
Cards AUPC. An ASYNC channel is not available.
Selecting ASYNC from the Modem Type menu when the Overhead Card is installed or
by selecting AUPC from the Modem Type menu the Reed-Solomon cards are installed
enables APUC operation. The Modem type is located under the Utility: Modem Type
menu.
To operate, AUPC is enabled on both modems and they are setup as described in
Table 10-1.