how to sampling the signal in order to match the two signal?

Hi.i am having trouble to set both data (mc & torque) on the same time axis.MC-voltage signal need to sampled at 5 kHz and low-pass filtered with a cutoff frequency 10 Hz in order to match with the torque(maybe).Basically,I need to match the two different time series into one same time series.Hope anyone can help me to figure it out.Thanks in advance

[dpb]

Look at resample in Signal Processing Toolbox...

Answer 1

[Star Strider]

The first 2 column in ‘TORQUE’ are missing, so they are removed here.

% C1 = readcell('https://www.mathworks.com/matlabcentral/answers/uploaded_files/711992/TORQUE.txt')
% nrmissing = [nnz(ismissing([C1{:,1}]))  nnz(ismissing([C1{:,2}])) size(C1,1)]
T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/711992/TORQUE.txt', 'VariableNamingRule','preserve');
T1 = removevars(T1,{'Var1','Var2'})

T1 = 7967×2 table
    TIME    TORQUE
    ____    ______

      0        0  
     10      0.7  
     20      1.1  
     30      6.5  
     40      6.5  
     50      6.4  
     60      6.5  
     70      6.4  
     80      6.1  
     90      6.1  
    100      6.4  
    110      7.1  
    120      7.9  
    130      8.3  
    140      7.9  
    150        8  

T2 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/712562/MC.txt', 'VariableNamingRule','preserve')

T2 = 90483×2 table
      Time      MC[v] 
    ________    ______

           0    1.8297
    0.000999    1.8289
    0.001998    1.8297
    0.002997    1.8297
    0.003996    1.8305
    0.004996    1.8289
    0.005996    1.8297
    0.006997    1.8313
    0.007996    1.8305
    0.008995    1.8281
    0.009994    1.8297
    0.010995    1.8305
    0.011994    1.8305
    0.012995    1.8297
    0.013994    1.8297
    0.014993    1.8305

Fs = 100;                                                   % Resample To 100 Hz Sampling Frequency
[TORQUEr,T_TIMEr] = resample(T1.TORQUE, T1.TIME, Fs);

[MCvr,V_TIMEr] = resample(T2.('MC[v]')-mean(T2.('MC[v]')), T2.Time, Fs);
MCvr = MCvr + mean(T2.('MC[v]'));

figure
subplot(2,1,1)
plot(T_TIMEr, TORQUEr)
grid
xlabel('t')
ylabel('Torque (Resampled)')
subplot(2,1,2)
plot(V_TIMEr, MCvr)
xlabel('t')
ylabel('MC[v] (Resampled)')
grid

They both have the same 100 Hz sampling frequencies, however they retain significantly different time vectors.

.

Answer 2

[Sulaymon Eshkabilov]

% They perfectly match as you can see the plot below.
MC = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/711992/MC.txt');
Torque = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/711992/TORQUE.txt');
plot(MC.TIME, MC.TORQUE, 'bx', Torque.TIME, Torque.TORQUE, 'r'), legend('MC','Torque')

% If you need to resample them then, apply resample()
% See here: https://www.mathworks.com/help/signal/ref/resample.html

[Scott MacKenzie]

@Sulaymon Eshkabilov I think something went wrong with the variables in your code. In the MC table, there is no column named TORQUE and most of the values in the TIME column are nan. But, the non-nan TIME values in both tables are aligned with a 10-ms sampliing period, so you are right that the data -- at least, a subset of the data -- are "matched".

I suspect your plot is just showing the torque values from the second table twice (with different line specs). Here's what I get when I remove the nan samples and plot both signals:

[Sulaymon Eshkabilov]

Yes, it might be. I've written the code on online here and executed it, rightaway. I have not used a desktop matlab since my matlab license was not activated.

[Keshasni Earichappan]

hi @Scott MacKenzie & @Sulaymon Eshkabilov....sorry i had attached the wrong MC.txt file jn..here i have attached the updated one..I need to match the two different time series into one same time series(sampling period).Is it possible? :)