Question

The fir1 command can be used to find _____________

(a) High Pass Filters using IIR method

(b) Low Pass Filters FIR method

(c) Filters using Window Method

(d) FIR filters using Window Method

I have been asked this question by my school principal while I was bunking the class.

This key question is from Fourier Analysis and Filtering in division Beyond the Basics of MATLAB

Answer 1

The correct answer is:

(d) FIR filters using Window Method

Explanation:

• The fir1 command in MATLAB is specifically used to design FIR (Finite Impulse Response) filters using the window method. The window method involves applying a window function (like Hamming, Hanning, or Blackman-Harris) to the ideal impulse response of the filter to make it realizable and to reduce side lobes in the frequency response.

• (a) High Pass Filters using IIR method: This is incorrect because fir1 is used for FIR filters, not IIR (Infinite Impulse Response) filters, and it does not specifically design high-pass filters using the IIR method.

• (b) Low Pass Filters FIR method: While fir1 can design low-pass filters, it is not limited to just low-pass filters. It can design any type of FIR filter, including high-pass and band-pass filters, depending on the parameters used.

• (c) Filters using Window Method: This is partially correct but incomplete. The fir1 command is a specific implementation for designing FIR filters using the window method.

Thus, the correct and most precise answer is (d) FIR filters using Window Method.