- Generate the sine sweeps
- Open the pd patch sinesweeps.pd,
- Ensure that the patch is not in editing mode, and check the ``compute audio'' box in the main pd window.
- Adjust the ``Output Volume'' so that when you click on ``Record Response
To The Sine Sweeps,'' the system under test is behaving linearly (i.e. not clipping), but
so that the input signal to the sound interface is not too noisy.
- If there is an input volume on the sound interface, adjust it so that the
levels approximately match those shown in Figure 12 when you click
on ``Record Response To The Sine Sweeps.'' If the sound interface
has no input volume, then you will need to adjust the ``Output
sinesweeps.pd after making
a measurement with an appropriate input level
- Once you are satisfied with the results, click the ``Write
Responses to Disk'' button.
- pd will write the file Resp.wav to disk. Rename this file so that the name matches the measurement you just
made. For instance, you might rename it to
if it corresponded to the second time you measured the transfer function of a
weakly nonlinear system.
in MATLAB or Octave to analyze the measured response. This means
that the inverse filter will be restricted to a dynamic range of 100 (40 dB),
which helps avoid exaggerating problems beneath and above
, where the excitation signal has little energy. 0.4
refers to the length in seconds of the linear impulse response term to be extracted.
Plots will be generated, and the file
will be written to disk.