Modulate a sine wave after quantizing it

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Help! I am trying to modulate a sine wave after quantizing it, but keep getting an error. =================================
t = [0:.1:2*pi]; % Times at which to sample the sine function
sig = sin(t); % Original signal, a sine wave
partition = [-1:2/15:1]; % Length 15, to represent 16 intervals
codebook = [-1.2:2/15:1]; % Length 16, one entry for each interval
[index,quants] = quantiz(sig,partition,codebook); % Quantize.
plot(t,sig,'x',t,quants,'.')
legend('Original signal','Quantized signal');
axis([-.2 7 -1.2 1.2])
M=16;
y=qammod(quants,M)
==============
??? Error using ==> qammod at 39
Elements of input X must be integers in the range [0, M-1].
>>
I checked the max and min value of quants and found it to be:
>> max(quants)= 0.8000
>> min(quants)= -1
Is there some way i can scale quants so I get in the specified range?

Accepted Answer

Walter Roberson
Walter Roberson on 20 Mar 2011
No. You need to fix your codebook. Your codebook must be integers from 0 to M-1 .
  2 Comments
Walter Roberson
Walter Roberson on 21 Mar 2011
You haven't read the quantiz documentation carefully enough, which has been the source of your problem for several days. The last quantization index will only be used if the signal *exceeds* the last partition parameter, which has never been the case in your calculation as your maximum signal value _equals_ the last partition parameter.

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