Comtech EF Data DMD-2050E - Manual (Page 96)

DMD2050E Universal Satellite Modem Theory of Operation
MN-DMD2050E Revision 2 3–54
Mode Code Rate/Modulation
Lower Data Rate Limit
(kbps)
Upper Data Rate Limit
(kbps)
Rate 7/8 16-QAM 63.0 25000.0
Rate 0.95 QPSK, OQPSK (aka 17/18) 34.2 23611.1
Rate 0.95 8-PSK , 8-QAM (aka 17/18) 52.0 25000.0
LDPC Rate 1/2 BPSK 18.0 6250.0
Rate 1/2 QPSK, OQPSK 18.0 12500.0
Rate 2/3 QPSK, OQPSK 24.0 16666.6
Rate 2/3 8-PSK , 8-QAM 36.0 25000.0
Rate 3/4 QPSK, OQPSK 27.0 18750.0
Rate 3/4 8-PSK , 8-QAM 40.5 25000.0
Rate 3/4 16-QAM 54.0 25000.0
This new LDPC/TPC codec module may be installed in any existing DMD2050E as a simple field
upgrade, or can be pre-installed in new modems ordered from the factory. It also requires the
appropriate FAST codes for enabling operation beyond the base data rate limit of 5 Mbps.
Please contact the Sales Department at Comtech EF Data for pricing and delivery information.
Table 3-3 compares all TPC and LDPC modes available in Comtech EF Data’s DMD2050E, and
shows Eb/No performance and spectral efficiency (occupied bandwidth) for each case. This
information will be of particular interest to satellite operators wishing to simultaneously balance
transponder power and bandwidth. The large number of modes offered will permit, in the majority
of cases, significant power and/or bandwidth savings when compared with existing schemes such
as concatenated Viterbi/Reed-Solomon, or the popular 8-PSK/Trellis/Reed-Solomon (Intelsat
IESS-310).