Can only choose pi radians / sample in Passband frequency, not Hz.

As the title says. I'm trying to use preprocessing options in Signal Analyzer and it doesn't present me with a Hz option when inputting the passband frequency, what could the reason be?

Answer 1

[Daniel M]

This toolbox uses the convention that unit frequency is the Nyquist frequency, defined as half the sampling frequency. The cutoff frequency parameter for all basic filter design functions is normalized by the Nyquist frequency. For a system with a 1000 Hz sampling frequency, for example, 300 Hz is 300/500 = 0.6. To convert normalized frequency to angular frequency around the unit circle, multiply by π. To convert normalized frequency back to hertz, multiply by half the sample frequency.

As written here: <https://www.mathworks.com/help/signal/ug/frequency-response.html>