![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/275393/image.png)
How to Calculate Vertical Wavelength
3 views (last 30 days)
Show older comments
Hi,
In the attached file "Signal" I have three (3) columns of signals. Please I want to calculate the wavelength?. The dt is 0.02 km. the data ranges from 20 to 40 km.
thanks
0 Comments
Accepted Answer
Star Strider
on 5 Mar 2020
This should get you started:
D = load('Signal.txt');
dt = 0.02;
L = size(D,1);
t = linspace(0, 1, L)*dt;
Fs = 1/dt;
Fn = Fs/2;
FTD = fft(D - mean(D))/L;
Fv = linspace(0, 1, fix(L/2)+1)*Fn;
Iv = 1:numel(Fv);
[Amax,idx] = max(abs(FTD(Iv,:))*2);
FreqAtMaxAmplitude = Fv(idx)
figure
subplot(3,1,1)
plot(Fv, abs(FTD(Iv,1))*2)
xlim([0 5])
grid
subplot(3,1,2)
plot(Fv, abs(FTD(Iv,2))*2)
grid
xlim([0 5])
subplot(3,1,3)
plot(Fv, abs(FTD(Iv,3))*2)
grid
xlim([0 5])
The wavelength is the propagation velocity divided by the frequency in radians/time unit. The ‘FreqAtMaxAmplitude’ gives the frequencies of the peaks in Hz, so multiply these by
to get the radian frequencies. You will then have to provide the propagation velocity in order to calculate the wavelength:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/275393/image.png)
lambda = propagation_velocity ./ (2*pi*FreqAtMaxAmplitude)
4 Comments
More Answers (0)
See Also
Categories
Find more on Multirate Signal Processing in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!