Comtech EF Data CDM-760 - Manual (Page 391)

Appendix J Revision 2
CDM-760 Advanced High-Speed Trunking Modem MN-CDM760
J–13
To continue, consider this example:
Satellite & Transponder IS-901 @ 342º W, 22/22 (EH/EH)
Earth Station 1 Africa – 9.1 m
Earth Station 2 Africa – 4.5 m
Data Rate 20.48 Mbps / 20.48 Mbps
Whereas the original link used 8PSK TPC 3/4, the CnC link uses DVB-S2 8PSK 3/4. Using CnC and
DVB-S2 reduces the leased bandwidth by almost 50% and HPA power by almost 60%. The
savings summary is:
Item
Original Link With Carrier-in-Carrier
Savings Hub to
Remote
Remote
To Hub
Total
Hub to
Remote
Remote to
Hub
Total
Data Rate (kbps) 20.48 20.48 - 20.48 20.48 -
Modulation 8PSK 8PSK - 8PSK 8PSK -
FEC TPC 3/4 TPC 3/4 - S2 3/4 S2 3/4 -
Occupied BW (MHZ) 13.1 13.1 26.2 13.2 13.2 13.2
Power Eq. BW (MHz) 10.3 4.9 15.2 6.4 2.0 8.4
Leased BW (MHz) - - 26.2 - - 13.2 49.6%
Hub HPA (W) 44 27 38.3%
Remote HPA (W) 112 47 58.3%
Note: 1 dB HPA BO for QPSK, 2 dB HPA BO for 8PSK, 1 dB Feed Loss.