matlab-信号的PCM(Pulse-Coded-Modulation)编码matlab仿真-源码

clc; clear; close all; warning off; addpath(genpath(pwd)); samplingFreq = 100; %100Hz sampling frequency timeStamp = 0:1/samplingFreq:10; amplitude = 8; messageSignal = amplitude*sin(timeStamp); % it is 8sin(t) %plotting of message signal figure(1); plot(timeStamp,messageSignal); title("Input Signal"); ylim([-10,10]); ylabel("messageSigmal x(t)"); xlabel("Time") %QUANTIZING noOfBits = 12; quantizedLevels = 2^noOfBits; %as our amplitude range from -m to +m and it divided into L sublevels %size of each level is given as 2*m/l delta = (2*amplitude)/quantizedLevels; %size of each level l_array = (-1*amplitude):delta:amplitude; average_l_array = ((-1*amplitude)-(delta/2)):delta:amplitude+(delta/2); %we will be using inbuilt quantixation function for our signal %description of function %index = quantiz(sig,partition) returns the quantization levels in the real vector signal sig using the parameter partition. partition is a real vector whose entries are in strictly ascending order. If partition has length n, index is a vector whose kth entry is %0 if sig(k) ? partition(1) %m if partition(m) < sig(k) ? partition(m+1) %n if partition(n) < sig(k) %[index,quants] = quantiz(sig,partition,codebook) is the same as the syntax above, except that codebook prescribes a value for each partition in the quantization and quants contains the quantization of sig based on the quantization levels and prescribed values. codebook is a vector whose length exceeds the length of partition by one. quants is a row vector whose length is the same as the length of sig. quants is related to codebook and index by %quants(ii) = codebook(index(ii)+1); %where ii is an integer between 1 and length(sig) [index,quants] = quantiz(messageSignal,l_array,average_l_array); figure(2); plot(timeStamp,quants,"."); title("Enlarged view for Quantization Levels"); xlim([0,1]); ylim([-10,10]); ylabel("Quantization levels"); figure(3); plot(timeStamp,quants,"."); title("Quantization Levels"); ylim([-10,10]); ylabel("Quantization levels"); %"de2bi" built in function to converts decimal number to binary number %b = de2bi(d,...,flg) uses flg to determine whether the first column of %b contains the lowest-order or highest-order digits. binaryCode = de2bi(index,'left-msb'); %using our index value bcdVector = binaryCode'; pcm = bcdVector(:)'; %converting matrix into vector figure(4); stairs(pcm); ylim([-0.5,1.5]); xlim([0,200]); title("PCM signal"); %DEMODULATION %as we will only receive a binary message we will have to decode it %processing of received signal columnsInResult = length(pcm)/(noOfBits+1); rowsInResult = noOfBits+1; %The "reshape function" returns a new array with n rows and m columns %(n*m must equal the number of elements in the original array). receivedSignal = reshape(pcm,rowsInResult,columnsInResult); receivedIndex = bi2de(receivedSignal','left-msb'); % Binary to Decimal %main demodulation part receivedQuants = (delta*receivedIndex)-amplitude+(delta/2); figure(5); plot(receivedQuants); title('Demodulated Signal'); ylabel('Signal'); xlabel('sampling at points'); ylim([-10,10]); xlim([0;1000]); %Thus our dequantised signal is same as our messagle signal