Appendix J Revision 4
CDM-760 Advanced High-Speed Trunking Modem MN-CDM760
J–12
The savings summary is (note TPC 7/8 is 20/23 actual):
Item
With Carrier-in-Carrier and LDPC
Savings
Total
Total
If the CnC link was designed using S2-8PSK 3/4 in both directions, it would require:
• Occupied BW – 19.3 MHz;
• Power Eq. BW – 17.9 MHz (a 5.9% increase in Power Eq. BW);
• Leased BW – 19.3 MHz;
• Hub HPA – 310 W;
• Remote HPA – 166 W (a 28.7% increase in Remote power).
J.4.6.2 Power Limited Links
Carrier-in-Carrier can provide substantial savings even when the original link is power limited.
Spreading the carrier by using a lower modulation and/or FEC along with latest FEC such as DVB-
S2 LDPC can substantially reduce the total power which can then be traded with bandwidth
using Carrier-in-Carrier. The concept is illustrated with these examples:
The conventional link is using 8PSK, TPC 3/4:
Switching to DVB-S2 8PSK 3/4 slightly increases the total occupied
bandwidth, while substantially reducing the total power equivalent
bandwidth:
Now, using CnC, the second 8PSK 3/4 carrier can be moved over the first
carrier – thereby significantly reducing the total occupied bandwidth and
total power equivalent bandwidth when compared to the original side-
by-side 8PSK, TPC 3/4 carriers:
To continue, consider this example:
IS-901 @ 342º W, 22/22 (EH/EH)
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