dsdemo2.m

高阶sigma-delta调制器设计matlab工具包, 半波带滤波器设计工具包

% Demonstrate simulateDSM and simulateSNR
clc
fprintf(1,'\t\t\tDiscrete-Time Simulation\n');
if exist('LiveDemo','var') == 0
    LiveDemo=0;
end
echo on
R=32;
H = synthesizeNTF(5,R,1);
N = 8192;
fB = ceil(N/(2*R)); ftest=floor(2/3*fB);
u = 0.5*sin(2*pi*ftest/N*[0:N-1]);	% half-scale sine-wave input
v = simulateDSM(u,H); 
echo off;

figure(1); clf;
t = 0:100;
stairs(t, u(t+1),'r');
hold on;
stairs(t,v(t+1),'g');
axis([0 100 -1.2 1.2]);
xlabel('Sample Number');
ylabel('u, v');
set(gcf,'NumberTitle','off'); 
set(gcf,'Name','Modulator Input & Output');
if LiveDemo
    set(1,'position',[0 372 777 355]);
    changeFig(18,2,12);
else
	fprintf(1,'paused\n');
end
pause
if LiveDemo
    set(1,'position',[8 527 300 200]);
    changeFig;
end

f = linspace(0,0.5,N/2+1);
echo on
spec = fft(v.*hann(N))/(N/4);
echo off;
figure(2); clf;
plot( f, dbv(spec(1:N/2+1)), 'b')
figureMagic([0 0.5], 0.05, 2, [-120 0], 20, 1,[],'Output Spectrum');
xlabel('Normalized Frequency')
ylabel('dBFS')
%title('Output Spectrum');
if LiveDemo
    set(2,'position',[185 372 662 355]);
    changeFig(18,2,12);
else
    fprintf(1,'paused\n');
end
pause

echo on
snr = calculateSNR(spec(3:fB+1),ftest-2);
echo off;
text_handle = text(0.05,-10, sprintf('SNR = %4.1fdB @ OSR = %d',snr,R),'vert','middle');
if LiveDemo
    set(text_handle,'fontsize',18);
end
if ~LiveDemo
    fprintf(1,'paused\n');
end
pause

echo on
NBW = 1.5/N;
Sqq = 4 * evalTF(H,exp(2i*pi*f)).^2 / 3;
echo off
hold on;
plot( f, dbp(Sqq*NBW), 'm', 'Linewidth', 2 );
text(0.5, -90, sprintf('NBW = %4.1E x f_s ',NBW),'Hor','right');
legend('Simulation','Expected PSD',4);

if LiveDemo
    pause;
    set(2,'position',[336 527 450 200]);
    changeFig;
    legend('Simulation','Expected PSD',4);
else
    fprintf(1,'paused\n');
end
pause;

echo on
[snr_pred,amp_pred] = predictSNR(H,R);
[snr,amp] = simulateSNR(H,R);
echo off
figure(3); clf;
plot(amp_pred,snr_pred,'-',amp,snr,'og');
figureMagic([-100 0], 10, 1, [0 100], 10, 1,[],'SQNR');
xlabel('Input Level (dBFS)');
ylabel('SQNR (dB)');
%title('SNR curve- theory and simulation');
[pk_snr pk_amp] = peakSNR(snr,amp);
text(-25,85,sprintf('peak SNR = %4.1fdB\n@ OSR = %d\n',pk_snr,R),'Hor','right');
if LiveDemo
    set(3,'position',[275 365 520 362]);
    changeFig(18,2,12);
else
	fprintf(1,'paused\n');
end
pause
if LiveDemo
    set(3,'position',[815 544 218 183]);
    changeFig;
end

clc; 
fprintf(1,'\t\t\t Bandpass Modulator\n');
echo on
f0 = 1/8; R=64;
H = synthesizeNTF(8,R,1,[],f0);
fB = ceil(N/(2*R)); ftest=round(f0*N + 1/3*fB);
u = 0.5*sin(2*pi*ftest/N*[0:N-1]);	% half-scale sine-wave input
v = simulateDSM(u,H); 
echo off;

figure(1); clf;
t = 0:100;
stairs(t, u(t+1),'r');
hold on;
stairs(t,v(t+1),'g');
axis([0 100 -1.2 1.2]);
xlabel('Sample Number');
ylabel('u, v');
%title('Modulator Input & Output');
if LiveDemo
    set(1,'position',[0 372 777 355]);
    changeFig(18,2,12);
else
	fprintf(1,'paused\n');
end
pause
if LiveDemo
    set(1,'position',[8 527 300 200]);
    changeFig;
end

echo on
spec = fft(v.*hann(N))/(N/4);
echo off;
figure(2); clf;
plot(linspace(0,0.5,N/2+1), dbv(spec(1:N/2+1)))
axis([0 0.5 -140 0]);
f1 = round((f0-0.25/R)*N);
f2 = round((f0+0.25/R)*N);
snr = calculateSNR(spec(f1:f2),ftest-f1+1);
text(0.15,-10, sprintf(' SNR = %4.1f dB @ OSR=%d)',snr,R), 'vert','middle');
grid on;
xlabel('Normalized Frequency')
ylabel('dBFS')
%title('Output Spectrum');
if LiveDemo
    set(2,'position',[185 372 662 355]);
    changeFig(18,2,12);
    pause;
else
    fprintf(1,'paused\n'); pause
end

echo on
NBW = 1.5/N;
Sqq = 4 * evalTF(H,exp(2i*pi*f)).^2 / 3;
echo off
hold on;
plot( f, dbp(Sqq*NBW), 'm', 'Linewidth', 2 );
text(0.5, -90, sprintf('NBW=%4.1E x f_s ',NBW),'Hor','right','Vert','mid');
legend('Simulation','Expected PSD',4);
if ~LiveDemo
    fprintf(1,'paused\n');
end
pause
if LiveDemo
    set(2,'position',[336 527 450 200]);
    changeFig;
    legend('Simulation','Expected PSD',4);
    drawnow;
end

echo on
[snr_pred,amp_pred] = predictSNR(H,R,[],f0);
[snr,amp] = simulateSNR(H,R,[],f0);
echo off
figure(3); clf;
plot(amp_pred,snr_pred,'-b',amp,snr,'og');
figureMagic([-110 0], 10, 1, [0 110], 10, 1,[],'SQNR');
xlabel('Input Level (dBFS)');
ylabel('SQNR (dB)');
%title('SNR curve- theory and simulation');
[pk_snr pk_amp] = peakSNR(snr,amp);
text(-20,95,sprintf('peak SNR = %4.1fdB\n@ OSR = %d\n',pk_snr,R),'Hor','right');
if LiveDemo
    set(3,'position',[275 365 520 362]);
    changeFig(18,2,12);
else
	fprintf(1,'paused\n');
end
pause
if LiveDemo
    set(3,'position',[815 544 218 183]);
    changeFig;
end

clc;
fprintf(1,'\t\t\t 15-step Lowpass\n');
fprintf(1,'\t\t\t(no SNR prediction)\n\n');
echo on
R=16; M = 15;
H = synthesizeNTF(5,R,1,5);
N = 8192;
fB = ceil(N/(2*R)); ftest=floor(2/3*fB);
u = 0.5*M*sin(2*pi*ftest/N*[0:N-1]);	% half-scale sine-wave input
v = simulateDSM(u,H,M+1); 
echo off;

figure(1); clf;
t = 0:100;
stairs(t, u(t+1),'r');
hold on;
stairs(t,v(t+1),'g');
figureMagic([0 100],10,2, [-M M],2,3,[],'Input & Output');
xlabel('Sample Number');
ylabel('u, v');
%title('Modulator Input & Output');
if LiveDemo
    set(1,'position',[0 372 777 355]);
    changeFig(18,2,12);
else
	fprintf(1,'paused\n');
end
pause
if LiveDemo
    set(1,'position',[8 527 300 200]);
    changeFig;
end

f = linspace(0,0.5,N/2+1);
echo on
spec = fft(v.*hann(N))/(M*N/4);
echo off;
figure(2); clf;
plot(f, dbv(spec(1:N/2+1)))
snr = calculateSNR(spec(3:fB+1),ftest-2);
text(0.1,-10, sprintf(' SNR = %4.1fdB @ OSR=%d ',snr,R), 'vert','middle');
figureMagic([0 0.5], 0.05, 2, [-160 0], 20, 1,[],'Output Spectrum');
xlabel('Normalized Frequency')
ylabel('dBFS')
%title('Output Spectrum');
if LiveDemo
    set(2,'position',[185 372 662 355]);
    changeFig(18,2,12);
    pause;
end

echo on
NBW = 1.5/N;
Sqq = 4 * evalTF(H,exp(2i*pi*f)).^2 / (3*M^2);
echo off
hold on;
plot( f, dbp(Sqq*NBW), 'm', 'Linewidth', 2 );
text(0.5, -110, sprintf('NBW=%4.1E x f_s ',NBW),'Hor','right');
legend('Simulation','Expected PSD',4);
pause
if LiveDemo
    set(2,'position',[336 527 450 200]);
    changeFig;
    legend('Simulation','Expected PSD',4);
else
    fprintf(1,'paused\n');
end

echo on
[snr,amp] = simulateSNR(H,R,[],[],M+1);
echo off;
figure(3); clf;
plot(amp,snr,'og',amp,snr,'--b');
figureMagic([-120 0], 10, 2, [0 120], 10, 2, [], 'SQNR');
xlabel('Input Level (dBFS)');
ylabel('SNR (dB)');
%title('SNR curve');
[pk_snr pk_amp] = peakSNR(snr,amp);
text(-20,110,sprintf('peak SNR = %4.1fdB\n@ OSR = %d',pk_snr,R),'Hor','right');
if LiveDemo
    set(3,'position',[275 365 520 362]);
    changeFig(18,2,12);
    pause
    set(3,'position',[815 544 218 183]);
    changeFig;
end