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小哥，怪我。我没太看懂，但是大体意思懂了。但是不会用。我写了一个MATLAB代码。YOUT1是要求得。辛苦给看看。
%MASH ((Multi Stage Noise Shaping)111 SDM
%this is a simulation of a MASH111 SDM where we look at the noise
%generated after a lengthy simulation time. The inputs are the fraction we
%are trying to synthesize, and the number of bits for the accumulators.
%The values in the accumulators are all positive, and the fraction is only
%valid from 0 to 1
%This has no dither it is just the basic modulator
%The setup is:
% --------> + ----------> + ----> Output
% | diff diff^2
% | | |
% carry1 carry2 carry3
%Fraction=>Accumulator1=>Accumulator2=>Accumulator3
%Carry1 from accumulator 1 is added to the dirivative of carry2 and the
%2nd derivative of carry3 to make the output.
%1/29/2013 fixed the 3 stage differentiation
%1/29/2013 added better plot and description
clear
NumberSamples=2^11;
BusSize=16; %bits
Fraction=.5234; %usable 0 to 1
FractionInternal=2^BusSize*Fraction;
AccumulatorBits=16 ; %bits
AccumulatorSize=2^AccumulatorBits;
C1(1:NumberSamples)=0;%Carry out of the first accumulator
C2(1:NumberSamples)=0;%Carry out of the 2nd accumulator
C3(1:NumberSamples)=0;%Carry out of the 3rd accumulator
U1(1:NumberSamples)=0;%output of the 1st accum
U2(1:NumberSamples)=0;%output of the 2nd accum
U3(1:NumberSamples)=0;%output of the 3rd accum
Yout1(1:NumberSamples)=0;%Corresponding to the S1 value in the figure
Yout2(1:NumberSamples)=0;%Corresponding to the S value in the figure
Yout3(1:NumberSamples)=0;%Final output
for index=3:NumberSamples
U1(index)=FractionInternal+U1(index-1);
U2(index)=U1(index-1)+U2(index-1);
U3(index)=U2(index-1)+U3(index-1);
if U1(index)>AccumulatorSize
C1(index)=1;%carry 1
U1(index)=U1(index)-AccumulatorSize;
end
if U2(index)>AccumulatorSize
C2(index)=1;%carry 2
U2(index)=U2(index)-AccumulatorSize;
end
if U3(index)>AccumulatorSize
C3(index)=1;%carry 3
U3(index)=U3(index)-AccumulatorSize;
end
%The output is the overflow from acc 1, plus the diff of the overflow from
%acc 2, plus the 2nd derivative of the overflow from acc 3
Yout3(index)=C3(index-2)-2*C3(index-1)+C3(index);%output to the divider - 3 stages
Yout2(index)=C2(index-1)-C2(index)-C3(index-2)+2*C3(index-1)-C3(index);%output to the divider - 2 stages
Yout1(index)=C1(index)-C2(index-1)+C2(index)+C3(index-2)-2*C3(index-1)+C3(index);%output to the divider - 1 stages
end
MeanFrac=mean(Yout1);
fprintf('\nMeanFracMASH= %1.4f\n',MeanFrac)
%note how the close in noise improves as the order increases
figure(1)
SignalFreq1=20*log10(abs(fft(Yout1)));
plot(fftshift(SignalFreq1)-max(SignalFreq1),'g')
hold on
grid on
axis([0 NumberSamples -150 0]);
SignalFreq2=20*log10(abs(fft(Yout2)));
SignalFreq3=20*log10(abs(fft(Yout3)));
plot(fftshift(SignalFreq2)-max(SignalFreq2),'r')
plot(fftshift(SignalFreq3)-max(SignalFreq3),'b')
legend('1 stage','2 stage','3 stage')
title('MASH111 SDM Noise')
figure,plo
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楼主
发表于 2021-3-25 10:33:11
代码是哪里出错了呀
