MATLAB Signal Processing 3

Question 1

What does the MATLAB `fftshift(X)` function do to the output of `fft`?

Accepted Answer

Shifts the zero-frequency component to the center of the spectrum

Answer

Applies a circular shift of one sample to the time-domain signal

Answer

Scales the FFT output by the number of samples N

Answer

Removes negative frequency components from the spectrum

Question 2

Which MATLAB window function call produces a Hamming window of length N?

Accepted Answer

hamming(N)

Answer

rectangular(N)

Answer

hanning(N)

Answer

blackman(N)

Question 3

What does the MATLAB `hilbert(x)` function return?

Accepted Answer

The analytic signal of x, with the original signal as real part and its Hilbert transform as imaginary part

Answer

Only the real part of the complex input x

Answer

A Hermitian symmetric version of x

Answer

The Hilbert-Schmidt norm of matrix x

Question 4

Which MATLAB function designs a Chebyshev Type I IIR lowpass filter with ripple Rp dB in the passband?

Accepted Answer

cheby1(n, Rp, Wn)

Answer

butter(n, Wn)

Answer

ellip(n, Rp, Rs, Wn)

Answer

fir1(n, Wn)

Question 5

Why is `filtfilt(b, a, x)` preferred over `filter(b, a, x)` in many signal processing applications?

Accepted Answer

It achieves zero-phase distortion by filtering the signal forward and backward

Answer

It is faster because it uses a single forward pass

Answer

It automatically increases the filter order by a factor of 2

Answer

It converts FIR coefficients to IIR automatically

Question 6

In MATLAB's `fft(x, N)`, what does the parameter N specify?

Accepted Answer

The number of FFT points (DFT length), zero-padding x if N > length(x)

Answer

The normalization factor applied to the output

Answer

The number of overlapping segments

Answer

The highest frequency bin to compute

Question 7

Which MATLAB function directly computes the signal-to-noise ratio (SNR) in dB of a measured signal relative to a reference?

Accepted Answer

snr(x, ref)

Answer

noise(x, ref)

Answer

ratio(x, ref)

Answer

signalpower(x)