3 ms·

You can choose their version of alpha by picking a cutoff frequency f and setting alpha = exp(-2pif*dt) where dt is your sample rate. f will be the ≈-3dB poin

You can choose their version of alpha by picking a cutoff frequency f and setting alpha = exp(-2*pi*f*dt) where dt is your sample rate. f will be the ≈-3dB point of your filter where frequencies above it are reduced by 0.707 or more.

CamperBob2 2mo ago
That gives you the time constant for the 63% step response, but that's not quite the same thing as the 3-dB cutoff, due to frequency warping. I do this to get an alpha value for cutoff_Hz at a given sampling interval dt_s: double omega_c = TWO_PI * cutoff_Hz * dt_s; double b = 4.0 - (2.0 * cos(omega_c)); return 1.0 - ((b - sqrt(b*b - 4.0)) * 0.5); Probably won't matter most of the time, though, when you're just trying to make some noise go away.