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16-PAM Demodulation and Viterbi

Started by m2francis September 9, 2005
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
		
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>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 >
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