Comtech EF Data CDM-625A Installation And Operation Manual page 621

CDM-625A Advanced Satellite Modem
Appendix F
F.2.6 Carrier-in-Carrier Commissioning and Deployment
Prior to commissioning a Carrier-in-Carrier link, it is critical that the link is fully tested in non
Carrier-in-Carrier mode and all system issues including external interference, antenna pointing,
cabling, SSPA backoff are resolved., You should attempt to turn Carrier-in-Carrier on only after
the link is robust.
Comtech EF Data recommends that you do these steps for CnC commissioning and deployment:
Step Task
1 Turn ON the carrier at Site 'A'. Carrier from Site 'B' is OFF. CnC function is OFF at both sites.
•
•
•
•
2
Turn OFF the carrier at Site 'A'. Turn ON the carrier at Site 'B'. CnC function is OFF at both
sites.
•
•
•
•
3 Using Co+No/No readings calculate PSD ratio at Site 'A' and Site 'B'. If it is not within
specification, make necessary adjustments to bring it within specification and repeat
measurements in Steps (1) and (2).
•
4 Now without changing the transmit power levels, turn ON both the carriers (on the same
frequency) and turn CnC ON.
•
•
•
5
The test can be repeated for different PSD ratio and Eb/No.
Using a spectrum analyzer, measure Co+No/No at the input to the modem at Site 'A'.
Using a spectrum analyzer, measure Co+No/No at the input to the modem at Site 'B'.
Measure/record Eb/No at Site 'B'. Make sure there is sufficient margin to account for CnC.
Measure/record Receive Signal Level (RSL) at Site 'B'.
Using a spectrum analyzer, measure Co+No/No at the input to the modem at Site 'A'.
Using a spectrum analyzer, measure Co+No/No at the input to the modem at Site 'B'.
Measure/record Eb/No at Site 'A'. Make sure there is sufficient margin to account for CnC.
Measure/record RSL at Site 'B'.
Also verify that the RSL is within spec.
Measure/record Eb/No at Sites 'A' and 'B'.
Measure/record RSL at Sites 'A' and 'B'.
Now compare Eb/No in presence of 2 over lapping carriers with CnC with Eb/No when
only 1 carrier was ON. Eb/No variation should be within spec for that modulation, FEC
and PSD ratio.
F–15
MN-CDM625A
Revision 4