MATLAB ADC 频谱分析问题

needforspeed · 发表于 2015-1-13 21:47:11

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一段做ADC频谱分析的程序，fft的结果出现了-inf，请大家看一下程序有什么问题。
clear;

afs = 1; % 1V full scale
fs = 1e6; %  1MHz sample rate
N = 2^10; % number of samples
cyc = 67;
fx = fs*cyc/N;

t = linspace(0,(N-1)/fs,N);

y = afs*sin(2*pi*fx*t);

B = 10;                      % internal ADC resolution
delta = afs/2^B;
y = cos(2*pi*fx/fs*[0:N-1]);
%quantize samples to delta=1LSB
y=round(y/delta)*delta;
s = 20*log10(abs(fft(y)/N/afs*2));
s = s(1:N/2);  % drop redundant half

f = (0:length(s)-1) / N;  % frequency vector (normalized to fs)

figure(1);
plot(f,s);
grid on;