Comtech EF Data DMD-2050E - Manual (Page 82)

DMD2050E Universal Satellite Modem Theory of Operation
MN-DMD2050E Revision 2 3–40
While the traditional link was based on QPSK, TPC 3/4 and required 3.9 MHz of leased bandwidth,
the Carrier-in-Carrier link was based on QPSK, LDPC 3/4 and QPSK, LDPC 1/2 and required 2.8
MHz of leased bandwidth.
The savings summary is as follows:
Item
Original Link With Carrier-in-Carrier and LDPC
Savings
Hub to Remote Remote To Hub Total Hub to Remote Remote to Hub Total
Data Rate (kbps) 3000 1000 3000 1000
Modulation QPSK QPSK QPSK QPSK
FEC TPC 3/4 TPC 3/4 LDPC 3/4 LDPC 1/2
Occupied BW (MHZ) 2.8 0.9 3.7 2.8 1.4 2.8
Power Eq. BW (MHz) 3.3 0.6 3.9 2.5 0.3 2.8
Leased BW (MHz) 3.9 2.8 27.5%
Hub HPA (W) 26.0 20.3 22%
Remote HPA (W) 10.6 6.4 40%
If this link was designed using QPSK, LDPC 3/4 in both directions, it would have required:
Occupied BW 2.8 MHz
Power Eq. BW 3.0 MHz 7.2% increase in Power Eq. BW
Leased BW 3.0 MHz 7.2% increase in Leased BW
Hub HPA 20.3 W
Remote HPA 8.3 W 30% increase in Remote power