Comtech EF Data CDM-625 - Manual (Page 340)

CDM-625 Advanced Satellite Modem Revision 15
DoubleTalk Carrier-in-Carrier Option MN-CDM625
10–10
10.4.5.1 Symmetric Data Rate Link
Consider the following example:
Satellite & Transponder Galaxy 18 @ 123º W, 13K/13K
Earth Station 1 Phoenix, AZ – 4.6 m
Earth Station 2 Phoenix, AZ – 2.4 m
Data Rate 512 kbps / 512 kbps
The traditional link was based on QPSK TPC 3/4 and required 0.96 MHz of leased BW. The LST 2
summary for the traditional link is as follows:
Carrier-in-Carrier link design involved trying different Modulation & FEC Code Rates to find the
optimal combination:
• 8-QAM, LDPC 2/3 with Carrier-in-Carrier
• QPSK, LDPC 3/4 with Carrier-in-Carrier
• QPSK, LDPC 2/3 with Carrier-in-Carrier
• QPSK, LDPC 1/2 with Carrier-in-Carrier
2 LST is Intelsat’s Lease Transmission Plan Program.