MATLAB Signal Processing 2

Question 1

What does `ifft(X)` compute in MATLAB?

Accepted Answer

The inverse discrete Fourier Transform of X

Answer

`ifft(X)` computes the inverse discrete Fourier Transform, converting frequency-domain data back to the time domain.

Question 2

Which MATLAB function designs a Butterworth IIR filter given order n and normalized cutoff frequency Wn?

Accepted Answer

butter(n, Wn)

Answer

`butter(n, Wn)` returns the transfer function coefficients [b, a] of an nth-order Butterworth lowpass filter with cutoff Wn.

Question 3

What does the MATLAB `spectrogram(x, window, noverlap, nfft, fs)` function display?

Accepted Answer

A time-frequency representation showing how spectral content changes over time

Answer

`spectrogram` computes and displays the short-time Fourier transform, showing how the frequency content of a signal varies with time.

Question 4

Which MATLAB function estimates the power spectral density of a signal using Welch's averaged periodogram method?

Accepted Answer

pwelch(x)

Answer

`pwelch(x)` estimates the PSD by dividing the signal into overlapping segments, windowing each, computing FFTs, and averaging.

Question 5

What is the primary purpose of the MATLAB `resample(x, p, q)` function?

Accepted Answer

To change the effective sampling rate of signal x by ratio p/q

Answer

`resample(x, p, q)` resamples signal x at p/q times the original sample rate using a polyphase filter.

MATLAB - MATLAB Technical Computing Practice Test