Introduction: Log Frequency Scale in Octave

Picture of Log Frequency Scale in Octave

Say you are defining a filter in GNU Octave. You need the frequency on the horizontal axis to be logarithmic instead of linear. This is done using the semilogx() function. In the next step you can see a high pass filter (HP) that demonstrates just that and generates the above image.

Step 1: Semilogx()

freq = [20:100:20000];
xc = 1 ./ (2 * pi * 0.000000016 * freq); z = sqrt(xc.^2 + 1000^2); vout = 10.0 * 1000 ./ z; semilogx(freq, vout, ‘r-’); grid on; xlabel(‘freq’); ylabel(‘volts’); legend(‘HP filter’);


About This Instructable




Bio: Too much television as a kid.
More by hzimmerman:Computing complex circuits with a TI calculatorHow to make your own delicious and healthy breadControlling a relay board with an Arduino Uno
Add instructable to: