Design a FIR filter with a Kaiser window

Question

Here is the exercise I am working on.

Use the window design method with the Kaiser window to design a linear phase high pass FIR filter of minimum order that meets the following specification: $\omega_P=0.8\pi$,$\omega_S=0.7\pi$, maximum pass band error=0.1dB, minimum stopband attenuation = 75dB ( you can use Matlab but you need to ensure that the final filter meets the spec. Recall that for window design methods, the errors in pass and stopband will be equal. Be sure to take it into account in your answer)

I know how to design a FIR filter using window method. What I do not understand is the last two sentences. What is "the errors in pass and stopband"? What it mean by "take it into account"?

Answer 1

The Kaiser window has a parameter, usually called $\beta$, which is determined by the specified peak error $\delta$. For your specification, you need to determine which of the two requirements (maximum pass band error or minimum stop band attenuation) is more stringent, and choose the allowable peak error $\delta$, and hence the parameter $\beta$, accordingly.