Hi, If I have a 16-QAM demodulator I know I can use the I and Q values to access a lookup table and output soft codes for a Viterbi uisng LLR What do I do if I'm using 16-PAM? If my information is right its just amplitude modulation. So out of the demodulator I will get 1 of 16 values. How do I then create the soft codes indicating how strong, or weak the '1's and '0's are? Thanks Mike This message was sent using the Comp.DSP web interface on www.DSPRelated.com
16-PAM Demodulation and Viterbi
Started by ●September 9, 2005
Reply by ●January 13, 20062006-01-13
>Hi, >If I have a 16-QAM demodulator I know I can use the I and Q values to >access a lookup table and output soft codes for a Viterbi uisng LLR > >What do I do if I'm using 16-PAM? If my information is right its just >amplitude modulation. So out of the demodulator I will get 1 of 16values.>How do I then create the soft codes indicating how strong, or weak the'1's>and '0's are? > >Thanks >Mike > >This message was sent using the Comp.DSP web interface on >www.DSPRelated.com >It's identical to calculating the LLR in 256-QAM. But here you only need to calculate 4 soft bits in either I- or Q-branch, and not all 8 bits. LBB