Data won't load

d.data=importdata('a2.txt');                       % import data options 
fs=100;                                       % Sampling frequency
fc=40;                                         % carrier frequency (corner frequency) 
fc_n = fc .* 2 /fs;                            % normalized frequency
B = fir1(10000,fc_n);                          % filter basics 
z1=filter(B,1,d.data(:,2));                    % I channel signal
z2=filter(B,1,d.data(:,4));                    % Q channel signal 

 
 I=z1;                                         % I data filtered
 Q=z2;                                        % Q data filtered 

hiFreq =20;
S = size (I);               % Check the size of data

fs = 100;                   % Sampling Frequency
%fs=1000;                    % Samopling frequency

f = 2440e6;                % Carrier Frequency
%f=24e9;                    % carrier frequency
lambda = 3e8/f;            % Calculate wavelength of carrier signal

% Convert # of samples to time
Array = 1:1:S(1,1);
Array = Array';
Time = Array/fs;
% Time = Time(100:end,1);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% DC_Removing
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

I_no_dc = I - mean (I);
Q_no_dc = Q - mean (Q);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Arctangent demodulation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Xt = atan2(Q_no_dc, I_no_dc);
Xt = unwrap(Xt);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Displacement Calculation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

D = (lambda .* Xt)/(4*pi);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% FFT
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Nsamps = length(Xt);                    % Window length
y_fft = abs(fft(Xt));                   %Retain Magnitude
y_fft = y_fft(1:Nsamps/2);              %Discard Half of Points
% y_fft_dc = abs(fft(Xt_dc));           %Retain Magnitude
% y_fft_dc = y_fft_dc(1:Nsamps/2);      %Discard Half of Points
f = fs*(0:Nsamps/2-1)/Nsamps;           %Prepare freq data for plot

I_fft = abs(fft(I));                    %Retain Magnitude
I_fft = I_fft(1:Nsamps/2);              %Discard Half of Points

Q_fft = abs(fft(Q));                   %Retain Magnitude
Q_fft = Q_fft(1:Nsamps/2);             %Discard Half of Points

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Power Spectrum Density
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

P_I = 1/(Nsamps*fs)*abs(I_fft(1:Nsamps/2)).^2;
P_Q = 1/(Nsamps*fs)*abs(Q_fft(1:Nsamps/2)).^2;

[y_max index] = max(P_I(2:end));

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Plot Graphs
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

figure (1);
subplot(2,1,1)                                    % new subplot option
plot (Time, I,'LineWidth',2);
hold on;
title ('Raw data', 'FontSIze', 20);
subplot(2,1,2)
plot (Time, Q, 'r','LineWidth',2);
legend ('I','Q');
xlabel ('Time [s]', 'FontSize', 20);
ylabel ('Amplitude [V]', 'FontSize', 20);
set(gca,'FontSize',20);


figure(2);
subplot(3,1,1);
plot (I, Q);
title ('IQ Plot', 'FontSIze', 20)
xlabel ('I [V]', 'FontSize', 20);
ylabel ('Q [V]', 'FontSize', 20);
axis equal;
set(gca,'FontSize',20);

figure (3);
plot (Time, D,'LineWidth',2);
title ('Demodulated Signal', 'FontSIze', 20);
xlabel ('Time [s]', 'FontSize', 20);
ylabel ('Displacement[m]', 'FontSize', 20);
set(gca,'FontSize',20);

figure (4);
plot(f, y_fft,'r','LineWidth',4)
xlim([0 2])
xlabel('Frequency (Hz)', 'FontSize', 20)
ylabel('Magnitude', 'FontSize', 20)
axis([0,10,0,3000]);
set(gca,'FontSize',20);
%}
figure (5);
subplot(2,1,1);
plot(f,10*log10(P_I));
title ('Power Spectrum Density I');
xlabel('Hz'); ylabel('dB/Hz');
%xlim([0 10]);

plot(f,10*log10(P_Q));
title ('Power Spectrum Density Q');
xlabel('Hz'); ylabel('dB/Hz');
%xlim([0 10]);

plot(f, I_fft,'LineWidth',2)
xlim([0 10])
xlabel('Frequency (Hz)', 'FontSize', 20)
ylabel('Magnitude', 'FontSize', 20)
axis([0,10,0,2500]);
set(gca,'FontSize',20);

plot(f, Q_fft,'LineWidth',2)
xlim([0 10])
xlabel('Frequency (Hz)', 'FontSize', 20)
ylabel('Magnitude', 'FontSize', 20)
axis([0,10,0,2500]);
set(gca,'FontSize',20);

I keep getting errors for the first line. I've also tried working with a data file that I can clearly see in my Workspace and Current Folder. I'm working with someone elses code whenever I run it, the arc tangent demodulation, a second tab pops up in my editor with code called "importdata.m" I have no idea what that is or why it's there.

"Error using importdata (line 139) Unable to open file. Error in arctangentdemodulationcode (line 2) d.data=importdata('a2.txt'); "

[KSSV]

Looks like there is user defined function on the name importdata.

Try

which importdata

If it is user defined, rename it to other name.

[Walter Roberson]

try readmatrix() instead of importdata if you have r2019b or later