MATLAB Answers

Mubasher

Can analog to digital conversion is implemented in matlab (not simulink)?

Asked by Mubasher
on 8 May 2012
clear; 
clc;
data_size=100;
M=2;
freq_sep=500;
nsamp=6;
fs=10000;
y=wavread('voice');
partition=[-.8,-.6,-.5,-.4,-.3,-.2,-.1,0,.1,.2,.3,.4,.5,.6,.8];
codebook=[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15];
% Now optimize, using codebook as an initial guess.
[partition2,codebook2] = lloyds(y,codebook);
[index,quants,distor] = quantiz(y,partition,codebook);
[index2,quant2,distor2] = quantiz(y,partition2,codebook2);
 %Compare mean square distortions from initial and optimized
[distor, distor2] % parameters.
quantization=dec2bin(quants,4);
x=str2num(quantization,1);
fsk_mod=fskmod(x,M,freq_sep,nsamp,fs);
noise=awgn(fsk_mod,0);
fsk_demod=fskdemod(noise,M,freq_sep,nsamp,fs);
[num,rate]=biterr(quants,fsk_demod)
%sound(fsk_demod)

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2 Answers

Answer by Walter Roberson
on 8 May 2012
 Accepted answer

Analog to digital conversion requires hardware to do the conversion, and so cannot be done by the MATLAB programming language itself. However, MATLAB offers interfaces to a number of kinds of A/D hardware, anywhere from microphone input to high-speed external-triggered boards. The more complex facilities are part of the Data Acquisition Toolbox.

If you could be more specific about your A/D hardware or about your conversion needs, someone might be able to offer more specific assistance.

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Mubasher
on 9 May 2012

audio file of .wav format is a digital file. I want to modulate that file. What steps are to be followed to implement it?
i have used wavread command to get sampled data
than quantized it using quantiz
now i could not understand how to generate a binary bit stream out of that quantized data inorder to modulate it?

Walter Roberson
on 9 May 2012

Have you considered reading the file using the 'native' option of wavread() ? You would probably (but not certainly) get an integer data stream as a result instead of a floating point stream. Then if you have the signal processing toolbox (I think it is), de2bi() to get the corresponding numeric bits for each integer.

Mubasher
on 9 May 2012

thanks. It helped me alot. I should start reading things more.


Answer by Walter Roberson
on 9 May 2012

dec2bin() does not produce binary. dec2bin() produces character strings. "binary" as needed for signal processing is always numeric, never character. You must stop using dec2bin() and use something else instead, or you must find a way of converting the output of dec2bin() into numeric binary.

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