# Spectral Density MCQ [Free PDF] – Objective Question Answer for Spectral Density Quiz

1. Power spectral density function is a?

A. Real and even function
B.Non-negativee function
C. Periodic
D. All of the mentioned

A power signal is a periodic signal and its function is a real even and non-negative function as per the definition.

2. Energy spectral density defines

A. Signal energy per unit area
B. Signal energy per unit bandwidth
C. Signal power per unit area
D. Signal power per unit bandwidth

Energy spectral density gives the signal energy equal to the area under the waveform energy spectral density versus frequency curve.

3. Power spectrum describes distribution of _________ under frequency domain.

A. Mean
B. Variance
C. Gaussian
D. None of the mentioned

Power spectrum gives the distribution of the variance of a signal in the frequency domain, sampled into spectral components.

4. How can the power spectral density of anon-periodic signals calculate?

A. By integrating
B. By truncating
C. By converting to periodic
D. None of the mentioned

A power signal usually is a periodic signal. But power spectral density of a non-periodic signal can be calculated by truncating it and observing it in the range of (-T/2 , T/2).

5. What is the Wiener-Khinchin theorem?

A. Spectral density and auto-covariance make Fourier transform pair
B. Spectral density and autocorrelation make aFourierrtransformm pair
C. Spectral density and variance make aFourierrtransformm pair
D. None of the mentioned

According to the theorem, spectral density of a signal x(t) and autocorrelation function makes aFourierrtransformm pair.

6. According to Parseval’s theorem the energy spectral density curve is equal to?

A. Area under the  magnitude of the signal
B. Area under the  square of the magnitude of the signal
C. Area under the  square root of magnitude of the signal
D. None of the mentioned

According to the  Parseval/s theorem the energy spectral density function can be given as equal to the square of the magnitude of the signal x(t).

7. Spectogram is the graph plotted against?

A. Frequency domain
B. Time domain
C. Frequency & Time domain
D. None of the mentioned

The spectral density function is plotted against the frequency domain and the spectrogram is a graph that is plotted against the time domain.

8. Autocorrelation is a function that matches

A. Two same signals
B. Two different signal
C. One signal with its delayed version
D. None of the mentioned

Autocorrelation is a function that matches a signal with its delayed version.

9. Autocorrelation is a function of

A. Time
B. Frequency
C. Time difference
D. Frequency difference

Autocorrelation is a function of time difference as it matches the signal with its delayed version.

10. Autocorrelation is maximum at _______

A. Unity
B. Origin
C. Infinite point
D. None of the mentioned