User's Manual

605-0000-595 Subscriber Terminal Installation and Commissioning
178
ST ODU on a printed ticket and will typically enhance the accuracy of fade margin
measurements made at channels other than the mid channel by approx 2dB.
Open STMON and select Link Check tab.
Link Check Parameters
1. Click 'Set Parameters' to display the data entry window.
The table below shows the fade margin required for each modulation rate
Modulation
Code
Rate SNR ratio
Minimum
QPSK 1/2 8.3 dB
QPSK 3/4 11.4dB
16QAM 1/2 15.4dB
16QAM 3/4 18.5dB
64QAM 24.8dB
2. Each ST ODU has a TX and RX relative gain recorded on a label placed on the ST.
These values are entered as link check parameters. In order to check that there is
sufficient fade margin for the target modulation select the modulation required for the
uplink and downlink, the values of required fade margin. and the required downlink
SNR. In order to enhance the accuracy of the fade margin measurement, the IF
Cable type and length (to the nearest metre) should be entered into STMON.
3. In order to further enhance the accuracy of the fade margin measurement, the Tx &
Rx gain offsets for a particular RF channel can be entered into STMON. These are
supplied with the ST ODU on a printed ticket and will typically enhance the accuracy
of fade margin measurements made at channels other than the mid channel by
approx 2dB.
4. Click OK.
5. Each of these parameters are compared with the entered installation acceptance
criteria and pass/fail indicators displayed on STMON.