Comtech EF Data SDM-300A - Manual (Page 50)

SDM-300A Satellite Modem Revision 6
Functional Description MN/SDM300A.IOM
2–10
The soft decision mapper converts the digital I and Q data to 3-bit soft decision values. These
values are then fed to the programmable vector rotation circuit, providing compatibility with
spectrum reversal of the I and Q channels.
The output of the vector rotation circuit is then sent to the Viterbi decoder and optional
Sequential decoder. The output is then sent to the optional Reed-Solomon or Overhead PCB.
2.4 Description of the Decoder
The SDM-300A can be configured in any of the following configurations:
• Basic SDM-300A (Sequential or Viterbi Decoder)
• FAST options (Sequential or Viterbi Decoder)
• FAST options with Reed-Solomon hardware (Sequential or Viterbi Decoder)
• FAST options with Overhead hardware (Sequential or Viterbi Decoder)
• FAST options with Reed-Solomon and Overhead hardware
(Sequential or Viterbi Decoder)