Clear Filters
Clear Filters

Fitting real data curve to a homogeneous diff

1 view (last 30 days)
Hello! I measured accelerations with matlab Mobile and I encountered the problem that the time step was not homogeneous and therefore the measured frequency. Therefore, I created a homogeneous diff (blue curve) and I would like to find a code in MATLAB that adapts the measured function with the real values (red curve) to that homogeneous time increment.
I attach a picture of the problem.

Accepted Answer

Star Strider
Star Strider on 16 May 2023
I am not certain from your description what you want to do. However if you have the Signal Processing Toolbox, the resample function coukld be appropriate. (It is preferable to interp1 for singal processing applications.)
  8 Comments
Daniel Sánchez Muñoz
Daniel Sánchez Muñoz on 28 May 2023
Hello!
Thanks for your help. The problem is that you use the mean frecuency, so there is still a non homogeneus sample frecuency.
I have finally solved the problem.
Pd.: Do I have to accept your answer? I thank you very much for the help.
data=[t,z];
COLTIME = 1;
COLACEL = 1;
tt = (data(:, COLTIME) - data(1, COLTIME));
v = data(:, 2:end);
% Interpolate data to assure constant time interval at fs:
dt = 1 / fs;
ntime = length(data);
tq = zeros(1,ntime);
for i = 2:ntime
tq(i) = tq(i-1) + dt;
end
vq = interp1(tt, v(:,COLACEL), tq,'spline','extrap');
% Reconstruct the data vector:
data = [tq', vq'];
Star Strider
Star Strider on 28 May 2023
I would appreciate it if you would accept my answer.
I actually use the most common frequency, that I derive from the differences in the sampling intervals. I use mean, I also could have used mode.
I notice the the code you posted uses ‘fs’ to define ‘dt’ without first defining ‘fs’. I have no idea how you define ‘fs’.
I also use resample instead of interp1 because resample uses an anti-aliasing filter. This is important for signal processing applications, and signal processing is apprarently what you want to do.
The resample function also has the 'spline' option as an interpolation method. I rarely use it (preferring 'pchip') because it can give some wildly varying results.
.

Sign in to comment.

More Answers (0)

Community Treasure Hunt

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

Start Hunting!