Extract data from a bode plot.

How do I extract an Excel table from the Bode of this transfer function:

format long;

s = tf('s');

HLM = ((2.524e-06)*s^3 + 37.11*s^2 + 37.6*s)/((2.704e-07)*s^3 + 1.767*s^2 + 41.36*s + 80);

Finf = 1e-3; %Hz

Fsup = 1e9; %Hz

options = bodeoptions;

options.FreqUnits = 'Hz';

Wmin = 2*pi*Finf;

Wmax = 2*pi*Fsup;

bode(HLM,{Wmin,Wmax}, options);

The bode was plotted in Hz, degrees, and from 1mHz to 1GHz.

Answer 1

[Star Strider]

s = tf('s');
HLM = ((2.524e-06)*s^3 + 37.11*s^2 + 37.6*s)/((2.704e-07)*s^3 + 1.767*s^2 + 41.36*s + 80);
Finf = 1e-3; %Hz
Fsup = 1e9; %Hz
options = bodeoptions;
options.FreqUnits = 'Hz';
Wmin = 2*pi*Finf;
Wmax = 2*pi*Fsup;

figure
bode(HLM,{Wmin,Wmax}, options)                  % Plot With Options

[mag,phase,wout] = bode(HLM,{Wmin,Wmax});       % Return Calculated Data
mag = squeeze(mag);
phase = squeeze(phase);
fout = wout/(2*pi);                             % Convert To 'Hz'
BodeTable = table(fout,mag,phase)

BodeTable = 154×3 table
      fout          mag       phase 
    _________    _________    ______

        0.001    0.0029531    90.169
    0.0011669    0.0034461    90.197
    0.0013617    0.0040213     90.23
     0.001589    0.0046926    90.269
    0.0018542    0.0054759    90.314
    0.0021637      0.00639    90.366
    0.0025248    0.0074568    90.427
    0.0029463    0.0087018    90.498
    0.0034381     0.010155    90.582
    0.0040119      0.01185    90.679
    0.0046816      0.01383    90.792
     0.005463      0.01614    90.924
    0.0063748     0.018837    91.077
    0.0074389     0.021986    91.257
    0.0086806     0.025663    91.466
     0.010129     0.029959     91.71

Then use writetable to create the Excel file.

EDIT — (10 May 2022 at 22:06)

Initially forgot that frequency vector was to be in Hz. Corrected.

.

[Gabriel Santos]

Right, thank you, how do I get more points? It's getting only 154, I would like to get 1000 or 10000, is it possible?

[Star Strider]

It is. You can supply the ‘w’ argument to provide as many points (radian frequency values) as you want (although there may be practical limits). See the documentation section on Bode Plot at Specified Frequencies .

[Gabriel Santos]

whiting the bode options?

[Star Strider]

The frequency vector is an argument to the bode function (here ‘wv’) not the bodeoptions structure —

s = tf('s');
HLM = ((2.524e-06)*s^3 + 37.11*s^2 + 37.6*s)/((2.704e-07)*s^3 + 1.767*s^2 + 41.36*s + 80);
Finf = 1e-3; %Hz
Fsup = 1e9; %Hz
options = bodeoptions;
options.FreqUnits = 'Hz';
Wmin = 2*pi*Finf;
Wmax = 2*pi*Fsup;

wv = logspace(-3, 9, 1000)*2*pi;                % Vector Of 500 Radian Frequencies (Logarithmically Scaled)

figure
bode(HLM, wv, options)                          % Plot With Options

[mag,phase,wout] = bode(HLM, wv);               % Return Calculated Data
mag = squeeze(mag);
phase = squeeze(phase);
fout = wout/(2*pi);                             % Convert To 'Hz'
BodeTable = table(fout,mag,phase)

BodeTable = 1000×3 table
      fout          mag       phase 
    _________    _________    ______

        0.001    0.0029531    90.169
     0.001028     0.003036    90.174
    0.0010569    0.0031211    90.179
    0.0010865    0.0032086    90.184
     0.001117    0.0032986    90.189
    0.0011483    0.0033911    90.194
    0.0011805    0.0034863      90.2
    0.0012136     0.003584    90.205
    0.0012477    0.0036845    90.211
    0.0012826    0.0037879    90.217
    0.0013186    0.0038941    90.223
    0.0013556    0.0040033    90.229
    0.0013936    0.0041156    90.236
    0.0014327     0.004231    90.242
    0.0014729    0.0043497    90.249
    0.0015142    0.0044717    90.256

As requested, it produces a 1000-element frequency vector, and transfer function results at those values. (The plot does not appear to me to be different from the plot with the default frequencies, except for the higher frequency resolution.)

.