Radyne DMD20 - Page 98

DMD20/20LBST Universal Satellite Modem Theory of Operation
MN-DMD20-20LBST Revision 14 3–36
The link budget summary for the different MODCOD combinations is as follows:
S. No. Modulation & FEC
Allocated BW
(MHz)
PEB (MHz)
Leased BW
(MHz)
Savings Compared
to Original
PSD Ratio
(dB)
1
8-QAM, LDPC 2/3
0.3584
1.1468
1.1468
-20%
2.1
2
QPSK, LDPC 3/4
0.47785
0.6734
0.6734
30%
2.1
3
QPSK, LDPC 2/3
0.53735
0.5777
0.5777
40%
2.1
4
QPSK, LDPC 1/2
0.7168
0.5184
0.7168
25%
2.1
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
Traditional Link
(QPSK, TPC 3/4)
CnC Link
(QPSK, LDPC 2/3)
HPA Power Reduction
HPA @ 4.6 m
0.7 W
0.5 W
40%
HPA @ 2.4 m
1.5 W
1.1 W
36%