Comtech EF Data CDM-625 - Manual (Page 347)

CDM-625 Advanced Satellite Modem Revision 15
DoubleTalk Carrier-in-Carrier Option MN-CDM625
10–17
10.5 Operational References
10.5.1 Calculate Carrier-in-Carrier Link Budget
Do these steps to calculate the link budget for a Carrier-in-Carrier Link:
Step Task
1 Calculate the link budget for both carriers in the duplex link, with required CnC margin:
2 Verify that the PDS ration is within spec for the CDM-625.
3 Calculate the Allocated Bandwidth (BW) and Power Equivalent Bandwidth (PEB) for the duplex
link:
• BW
Duplex Link
= Greater of (BW
Carrier 1
, BW
Carrier 2
)
• PEB
Duplex Link
= PEB
Carrier 1
+ PEB
Carrier 2
• Leased BW
Duplex Link
= Greater of (BW
Duplex Link
, PEB
Duplex Link
)
4 For an optimal link, the Leased Bandwidth and the Power Equivalent Bandwidth should be
equal / nearly equal.
5 Repeat the link budget process by selecting different Modulation and FEC, until the BW and
PEB is nearly balanced.