Comtech EF Data SLM-5650A - Manual (Page 312)

SLM5650A_CDM625 Satellite Modem Revision 8
DoubleTalk Carrier-in-Carrier Option MN-SLM5650A
15–14
To continue, consider this example:
Satellite & Transponder IS-901 @ 342º W, 22/22 (EH/EH)
Earth Station 1 Africa – 9.2 m
Earth Station 2 Africa – 4.5 m
Data Rate 2.048 Mbps / 2.048 Mbps
Whereas the original link used 8-PSK TPC 3/4, the Carrier-in-Carrier link used QPSK VersaFEC
0.803. The savings summary is as follows:
Item
Original Link With Carrier-in-Carrier and VersaFEC
Savings Hub to
Remote
Remote to
Hub
Total
Hub to
Remote
Remote to
Hub
Total
Data Rate (kbps) 2048 2048 2048 2048
Modulation 8-PSK 8-PSK QPSK QPSK
FEC TPC 3/4 TPC 3/4 0.803 0.803
Occupied BW
(MHZ) 1.3 1.3 2.6 1.8 1.8 1.8
Power Eq. BW
(MHz) 2.2 1.0 3.2 1.1 0.5 1.6
Leased BW (MHz) 3.2 1.8 44%
Hub HPA (W) 5.0 2.0 60%
Remote HPA (W) 11.6 4.7 60%
Note: 1 dB HPA BO for QPSK, 2 dB HPA BO for 8-PSK, 1 dB Feed Loss.
Using Carrier-in-Carrier and VersaFEC reduced the leased bandwidth by almost 44% and HPA
power by 60%.