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数字通信第四版原书的例程

<TITLE>Communications Toolbox Source Coding</TITLE>
<h2>Source Coding</h2>
The source coding category includes quantization, data
compression, data expander, and differential pulse
code demodulation (DPCM). This toolbox includes a
SIMULINK <A RUN="closebut(gcf);com_frmt">Source Coding
Library</A> and the following MATLAB functions:
<dl>
<dd><b><a run="hthelp compand">compand</a></b> - Source code mu-law or A-law compressor or expander.
<dd><b><a run="hthelp dpcmdeco">dpcmdeco</a></b> - Differential pulse code modulation decode computation.
<dd><b><a run="hthelp dpcmenco">dpcmenco</a></b> - Differential pulse code modulation encode computation.
<dd><b><a run="hthelp dpcmopt">dpcmopt</a></b> - Differential pulse code modulation parameter optimization.
<dd><b><a run="hthelp lloyds">lloyds</a></b> - Scalar quantization optimization using training data.
<dd><b><a run="hthelp quantiz">quantiz</a></b> - Quantization index and quantized output value.
</dl>
<p>
You can view a list of 
 <a href="htb_frmt.html">all SIMULINK blocks</a> in this category. <p>

<A RUN="closebut(gcf);tutdpcm">Example: Using DPCM</A> to quantize a sin signal.
This example uses the following MATLAB commands:
<dl>
<dd><tt>t=[0:.1:40];
<dd>sig = sin(t);
<dd>[p_tran,codebook,partition]=<A RUN="hthelp dpcmopt">dpcmopt</A>(sig,1,8);
<dd>indx = <A RUN="hthelp dpcmenco">dpcmenco</A>(sig, codebook,partition,p_tran);
<dd>quant = <A RUN="hthelp dpcmdeco">dpcmdeco</A>(indx, codebook, p_tran);
<dd>subplot(211);plot(t,indx);
<dd>title('Quantized digital output.');
<dd>subplot(212);plot(t,[sig,quant]');
<dd>title('Quantization recovery and orginal signal.');
</tt></dl><p>

<dd><a href="commhelp.html">Return to the first page of the tutorial</a>
<dd><a href="hmfasb.html">Return to the functionality listing</a><p>

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