Comtech EF Data DMD50 Installation And Operation Manual page 68

DMD50 Universal Satellite Modem
The link budget summary for the different MODCOD combinations is as follows:
S. No. Modulation & FEC
1 8-QAM, LDPC 2/3
2 QPSK, LDPC 3/4
3 QPSK, LDPC 2/3
4 QPSK, LDPC 1/2
Based on this analysis, QPSK, LDPC 2/3 with Carrier-in-Carrier provides the maximum savings
of 40%.
In addition to 40% reduction in Leased Bandwidth, using Carrier-in-Carrier also reduced the
required HPA Power by almost 40%:
HPA Power
HPA @ 4.6 m
HPA @ 2.4 m
MN-DMD50– Revision 3
Allocated BW
PEB (MHz)
(MHz)
0.3584
0.47785
0.53735
0.7168
Traditional Link
(QPSK, TPC 3/4)
0.7 W
1.5 W
Leased BW
(MHz)
1.1468 1.1468
0.6734 0.6734
0.5777 0.5777
0.5184 0.7168
CnC Link
(QPSK, LDPC 2/3)
0.5 W
1.1 W
Theory of Operation
Savings Compared PSD Ratio
to Original (dB)
-20% 2.1
30% 2.1
40% 2.1
25% 2.1
HPA Power Reduction
40%
36%
3–32