Comtech EF Data CDM-750, Installation And Operation Manual

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CDM-750 Advanced High-Speed Trunking Modem Revision 2
Appendix D MN-CDM750
D–17
D.5 Operational References
D.5.1 Calculating a Carrier-in-Carrier Link Budget
Follow these steps to calculate the link budget for a CnC Link:
Step Task
1 Calculate the link budget for both carriers in the duplex link, with required CnC margin:
2 Verify that the CnC ratio is within spec for the CDM-750.
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 are equal or nearly equal.
5 Repeat the link budget process by selecting different Modulation and FEC until the BW and PEB is nearly
balanced.