Comtech EF Data CDM-760 - Manual (Page 103)

Front Panel Operation Revision 2
CDM-760 Advanced High-Speed Trunking Modem MN-CDM760
6–17
(CONFIG: Tx) Power  AUPC  LCL or RCL (Local or Remote Carrier
Loss)
This setting directs AUPC how to react to LCL (Local Carrier Loss) or RCL (Remote Carrier
Loss). Because proper functionality of AUPC requires both modems to communicate
over the satellite link, you must determine what power level the modem should be set
for in case the link is lost and there is no local or remote demodulator lock.
Use the arrow keys to select Nom or Max. Press ENTER. Note the following:
Selection Function
Nom (Nominal) This sets the modem’s output power level to the configured Nominal
setting.
As per the (CONFIG: Tx) Power  AUPC  Target example, just as the Nom
selection sets the Tx power to be -25.0 dB, the Max output power selection then
transmits a -22.0 dB carrier.
Max (Maximum) This sets the modem’s output power level to be Nominal + Range
when the modems are not communicating.
1) ‘Nom’ is the suggested LCL and RCL selection, as it will be the lowest
output power level.
2) While selecting ‘Max’ may be better for carrier recovery, it can also
lead to transmission of excessive power when the issue is not Uplink
Fade (such as a remote site power outage).
(CONFIG: Tx) Power  AUPC  Nominal
Consider “Nominal” to be the modem’s lowest possible Tx power needed to achieve the
required Es/No at the remote site.
If the Nominal level is not set in ideal conditions, it will cause overdriving of the link
during ideal conditions. Comtech EF Data strongly suggests that you enter this value
when both sides of the link are in clear sky condition. This gives you the lowest possible
Tx output power, and is ideal for setting the Nominal level.
The Nominal level can be set at any output power level the modem allows for the mode
of operation it is in, as long as the Nominal + Range sum does not exceed the total
output power range of the modem.
As per the (CONFIG: Tx) Power  AUPC  Target example, a Nominal setting of -25 dB
and a Range of 3 dBm gives the modem a Nominal + Range = -22 dBm. This is
acceptable. However, if the Nominal setting is -2 dBm, and the Range is set to 3 dBm,
then this instructs the modem to transmit at Nominal + Range = +1 dBm, which is not
acceptable; the modem will therefore reject this entry.