# High resolution FFT from time domain data.

조회 수: 3(최근 30일)
Jay Vaidya 2020년 12월 19일
댓글: Jay Vaidya 2020년 12월 19일
I have a very large time domain data with a lot of samples, but still I am not getting a good resolution in the FFT spectrum. Is that because I have to change the value of Fs (in the code below)? I have also attached the data file, code and the plot.
I get all the points in the FFT spectrum spaced with 50 Hz spacing. But I need a god resolution. Because the resolution is not good, hence the information and other linked parts of my code are not functioning correctly.
Code:
fft_columns = [];
for i = 2:1:size(data,2)
X = data;
xdft = fft(X(:,i));
DT = X(2,1)-X(1,1);
% sampling frequency
Fs = 1/DT;
DF = Fs/size(X,1);
freq = 0:DF:Fs/2;
N = length(X);
xdft = xdft(1:length(xdft)/2+1)';
Xmag = abs(xdft); % Spectral magnitude
Xdb = 20*log10(Xmag);
Xdb(1,1) = Xdb(1,2);
XdbMax = max(Xdb); % Peak dB magnitude
Xdbn = Xdb - XdbMax;
%Xdbn = Xdb - 0;
dBmin = -120; % Don't show anything lower than this
Xdbp = max(Xdbn,dBmin); % Normalized, clipped, dB mag spec
fft_columns = [fft_columns; Xdbp];
end
%dB = mag2db(abs(xdft))
% psdx = (1/(Fs*N)) * abs(xdft).^2;
% psdx(2:end-1) = 2*psdx(2:end-1);
%%
figure('Position', [1 1 4000 700])
%figure
plot(freq,fft_columns(1,:),'color', [1,0.55,0],'LineWidth',7);
axis([0 5000 -79 2])
Plot:

댓글을 달려면 로그인하십시오.

### 답변(1개)

Matt Gaidica 2020년 12월 19일
##### 댓글 수: 1표시숨기기 없음
Jay Vaidya 2020년 12월 19일
The data is attached above.

댓글을 달려면 로그인하십시오.

R2020b

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by