plot the fundamental harmonic wave

조회 수: 9 (최근 30일)
hamid k
hamid k 2023년 11월 19일
답변: Mathieu NOE 2023년 11월 23일
Hello everyone. I have exported data to an Excel spreadsheet where the x-axis is represented by theta (in radians). How can I plot the fundamental harmonic wave from this wave data?
  댓글 수: 6
hamid k
hamid k 2023년 11월 23일
You can find the attached data and code files here.
Mathieu NOE
Mathieu NOE 2023년 11월 23일
see my answer below

댓글을 달려면 로그인하십시오.

채택된 답변

Mathieu NOE
Mathieu NOE 2023년 11월 23일
hello again
so this is it, we do a single frequency DFT (aka order extraction) at the second harmonic (as we have two period of signal for theta ranging from 0 to 2*pi
result :
code :
%Load Excel file
data = readmatrix('Book1.xlsx'); % theta(Rad) Br(T)
%Extract theta and y columns
theta = data(:,1); % theta (0 - 2pi)
y = data(:,2); % y data
%%%%%%%%%%%%% main code %%%%%%%%%%%%%%%%%
% 2nd order extraction (DFT)
order = 2;
% model fit : X = A*cos(order*theta) + B*sin(order*theta) + C
C = mean(y);
y = y-C;
n = numel(theta);
A = 2/n*trapz(y.*cos(order*theta));
B = 2/n*trapz(y.*sin(order*theta));
yfit = A*cos(order*theta) + B*sin(order*theta) + C;
% plot
figure(1),
plot(theta, y, 'b',theta, yfit, 'r')
legend('data','model fit');

추가 답변 (1개)

Sulaymon Eshkabilov
Sulaymon Eshkabilov 2023년 11월 20일
Here are two MATLAB fcns (bandpass() and fft()) which can be applied to solve your exercise.

카테고리

Help CenterFile Exchange에서 Transforms에 대해 자세히 알아보기

Community Treasure Hunt

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

Start Hunting!

Translated by