PCMbianma.rar_MATLAB语音pcm_pcm_正弦转pcm_语音 编码_语音PCM

%均匀量化的PCM编码函数 %参数说明： a:输入序列 % n：量化电平数 % q：信号/量化噪声 % a_quan：量化后的电平值 （十进制数） % code：将电平值编码后的输出 （二进制数0101） function [q,a_quan,code]=U_pcm(a,n) %U_PCM uniform PCM encoding of a sequence % [SQNR,A_QUAN,CODE]=U_PCM(A,N) % a=input sequence. % n=number of quantization levels (even). % sqnr=output SQNR (in dB). % a_quan=quantized output before encoding. % code=the encoded output. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %归一化输入 amax=max(abs(a)); a_quan=a/amax; b_quan=a_quan; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %获得量化区间 d=2/n; %delta q=d.*[0:n-1]; q=q-((n-1)/2)*d; %量化区间 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %量化过程 for i=1:n a_quan(find((q(i)-d/2 <= a_quan) & (a_quan <= q(i)+d/2)))=... % ... 代表换行 q(i).*ones(1,length(find((q(i)-d/2 <= a_quan) & (a_quan <= q(i)+d/2)))); % 逐个量化区间内进行量化, (a-delta/2) <= x <= (a+delta/2) b_quan(find( a_quan==q(i) ))=(i-1).*ones(1,length(find( a_quan==q(i) ))); end q=q*amax; a_quan=a_quan*amax; %将归一化的信号还原回电平值 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %编码过程 nu=ceil(log2(n)); code=zeros(length(a),nu); for i=1:length(a) for j=nu:-1:0 if ( fix(b_quan(i)/(2^j)) == 1) code(i,(nu-j)) = 1; %对电平值进行编码 b_quan(i) = b_quan(i) - 2^j; end end end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %求信号/量化噪声比 sqnr=20*log10(norm(a)/norm(a-a_quan));