Plot measured Filter data

Hi all,

I got mearsurement data from a real band pass filter. To make a professional plot, I am using matlab. The x-axis is in logarithmic scale. While plotting the magnitude it is working perfectly. Unfortunately, it does not work for the phase. But when I plot it with libre office calc, I get the correct result. The excel file is attached. It would be great if you could give a hint. Thank you in advance!

Plot with libre office calc:

The code is as follows:

T = readtable('Plot.xls');

gain = T{(22:109),1};
frequency = T{(22:109),2}; 
phase = T{(22:109),3};

%plot gain
subplot(2,1,1);
semilogx(gain, frequency); %x axis has log scale
title('Bode Diagram')
xlabel('Frequency [Hz]')
ylabel('Magnitude [dB]')

%plot phase
subplot(2,1,2); 
semilogx(phase, frequency); %x axis has log scale

xlabel('Frequency [Hz]')
ylabel('Phase [deg]')
grid on

Answer 1

[VBBV]

T = readtable('Plot.xls')

T = 121×3 table
       F          A         P   
    _______    _______    ______

        0.1    -19.679     44.63
    0.11221    -30.408    -160.9
     0.1259    -26.056     98.76
    0.14127    -24.935    87.441
    0.15851    -25.049    84.581
    0.17786    -24.997    95.553
    0.19957    -24.801    66.816
    0.22393    -22.482    92.478
    0.25127    -21.834    95.452
    0.28194    -20.728    80.841
    0.31635    -19.421     94.68
    0.35497     -18.53    92.847
    0.39829    -17.533    92.878
    0.44691    -16.923    88.998
    0.50146    -15.615        90
    0.56267    -14.874    90.817

frequency = T{(22:109),1}; % change this to ffequency 
gain = T{(22:109),2}; 
phase = T{(22:109),3};

%plot gain
subplot(2,1,1);
semilogx(frequency,gain); %x frequency as x-scale 
grid 
title('Bode Diagram')
xlabel('Frequency [Hz]')
ylabel('Magnitude [dB]')

%plot phase
subplot(2,1,2); 
semilogx(frequency,phase); %x here too

xlabel('Frequency [Hz]')
ylabel('Phase [deg]')
grid on

[VBBV]

frequency is 1st column of table. while plotting, use frequency as xscale and gain/phase as yscale.

[Sebastian D.]

Thank you very much for your help!