Comtech EF Data CDM-760 User 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.