MATLAB Signal Processing 2

Question 1

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

Accepted Answer

The inverse discrete Fourier Transform of X

Answer

The integer FFT of X

Answer

The imaginary part of the FFT of X

Answer

The iterative approximation of the FFT of X

Question 2

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

Accepted Answer

butter(n, Wn)

Answer

fir1(n, Wn)

Answer

freqz(n, Wn)

Answer

filtfilt(n, 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

A static amplitude-versus-time plot

Answer

The frequency spectrum at a single time instant

Answer

Only the phase response of the signal

Question 4

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

Accepted Answer

pwelch(x)

Answer

fft(x)

Answer

periodogram(x)

Answer

spectrum(x)

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

To add white Gaussian noise to signal x

Answer

To remove high-frequency components above cutoff q

Answer

To compute the envelope of signal x

Question 6

Which MATLAB function finds local maxima (peaks) in a data vector and returns their values and locations?

Accepted Answer

findpeaks(x)

Answer

max(x)

Answer

localmax(x)

Answer

peak(x)

Question 7

The MATLAB `xcorr(x, y)` function computes:

Accepted Answer

The cross-correlation sequence of signals x and y

Answer

The cross-convolution of x and y

Answer

The auto-power spectrum of x

Answer

The normalized inner product of x and y only at zero lag