Signals and Systems Quizzes - Master Electrical Engineering (MEng)

Question 1

Which technique converts a continuous-time signal into its discrete-time equivalent?

Accepted Answer

Sampling

Answer

Fourier Transform

Answer

Laplace Transform

Answer

Z-Transform

Question 2

What is a defining characteristic of linear time-invariant (LTI) systems?

Accepted Answer

Output is unaffected by time shifts in input

Answer

Output is nonlinear with respect to input

Answer

System response is the same for all inputs

Answer

Output is independent of input

Question 3

What key characteristic differentiates linear time-varying (LTV) systems from linear time-invariant (LTI) systems?

Accepted Answer

Time invariance

Answer

Superposition

Answer

Causality

Answer

Stability

Question 4

Identify the type of continuous-time signal that has a constant amplitude and frequency for a specific duration, remaining at zero for all other time instances:

Accepted Answer

Rectangular signal

Answer

Impulse signal

Answer

Step signal

Answer

Exponential signal

Question 5

A continuous-time signal x(t) is given by x(t) = cos(2πf0t + θ). Which of the following is the frequency of this signal?

Accepted Answer

f0

Answer

2πf0

Answer

θ

Answer

θ/f0

Question 6

Which waveform does NOT represent a continuous-time signal?

Accepted Answer

Discrete values sampled regularly

Answer

Sinusoid with varying amplitude

Answer

Exponential decay

Answer

Parabolic waveform

Question 7

Which attribute is exclusive to discrete-time signals and not applicable to continuous-time signals?

Accepted Answer

Representation as a sequence of values

Answer

Existence of discontinuities

Answer

Possession of infinite energy

Answer

Ability to be periodic or aperiodic

Question 8

Which property is NOT characteristic of linear time-independent (LTI) systems?

Accepted Answer

Nonlinearity

Answer

Superposition

Answer

Time-Independence

Answer

Causality

Question 9

Which of the following is a characteristic of a bandlimited signal?

Accepted Answer

It is a continuous-time signal with a finite bandwidth.

Answer

It is a discrete-time signal with an infinite number of frequency components.

Answer

It is a continuous-time signal that can be represented by a Fourier series.

Answer

It is a discrete-time signal with a finite time duration.

Question 10

Which operation is NOT performed in the time domain?

Accepted Answer

Frequency analysis

Answer

Convolution

Answer

Differentiation

Answer

Correlation

Question 11

Which characteristic is exclusive to continuous-time signals?

Accepted Answer

Time domain representation as a continuous function

Answer

Amplitude

Answer

Frequency

Answer

Phase

Question 12

Which characteristic of the Laplace transform is employed to assess the stability of a system?

Accepted Answer

Location of poles of the Laplace transform of a causal and stable system in the left half of the complex plane

Answer

Linearity of the Laplace transform

Answer

Analytic nature of the Laplace transform in the right half-plane for functions vanishing for t < 0

Answer

Uniqueness of the inverse Laplace transform

Question 13

Which property is NOT characteristic of a linear time-invariant (LTI) system?

Accepted Answer

Causal memory

Answer

Superposition

Answer

Time invariance

Answer

Additivity

Question 14

Consider two continuous-time signals x(t) and y(t). Which operation results in a new signal that is a shifted version of x(t) in the time domain?

Accepted Answer

Delay by τ seconds

Answer

Differentiation with respect to t

Answer

Integration with respect to t

Answer

Convolution with a unit impulse

Question 15

What is the Fourier transform of the unit impulse signal, δ(t), also known as the sifting function?

Accepted Answer

1

Answer

t

Answer

e^-t

Answer

sin(t)

Question 16

Which property is characteristic of continuous-time signals?

Accepted Answer

They can be graphed as amplitude over time.

Answer

They are defined only at specific moments.

Answer

They always have a limited duration.

Answer

They are always periodic.

Question 17

In the quantization process, how is an analog signal converted into a digital signal?

Accepted Answer

By comparing the analog signal to predefined levels and assigning the closest level.

Answer

By averaging the analog signal over time and assigning the average value.

Answer

By sampling the analog signal at a high rate and storing the samples digitally.

Answer

By adding noise to the analog signal to increase its dynamic range.

Question 18

In discrete-time systems, which operation is used to calculate the output sequence for a given input sequence using the system's impulse response?

Accepted Answer

Convolution

Answer

Correlation

Answer

Differentiation

Answer

Integration

Question 19

Given a continuous-time signal x(t) with Fourier transform X(f), find the Fourier transform of the scaled signal y(t) = x(2t).

Accepted Answer

X(f/2)

Answer

2X(f)

Answer

X(2f)

Answer

0.5X(f)

Question 20

In the context of continuous-time signals, what is the defining characteristic of periodicity?

Accepted Answer

A continuous-time signal is periodic if it repeats itself at regular intervals.

Answer

A continuous-time signal is periodic if its amplitude remains constant.

Answer

A continuous-time signal is periodic if its duration is finite.

Answer

A continuous-time signal is periodic if its mean value is zero.

Question 21

Which property is unique to causal Linear Time-Invariant (LTI) systems?

Accepted Answer

Zero impulse response for negative time values (t < 0)

Answer

Periodic frequency response

Answer

Always bounded output

Answer

Poles located solely in the left half of the complex plane

Question 22

Question:

Describe matched filtering. Explain how it's used to detect and estimate signals in the presence of noise.

Accepted Answer

Matched filtering maximizes the output SNR by correlating the received signal with a known reference signal.

Answer

Matched filtering increases the signal's bandwidth.

Answer

Matched filtering removes noise from a signal.

Answer

Matched filtering is only applicable to continuous-time signals.

Question 23

How does the frequency response of a discrete-time LTI system reveal its stability and causality characteristics?

Accepted Answer

A stable system's frequency response is bounded, while a causal system's response is zero for negative frequencies.

Answer

A causal system's frequency response is symmetrical around zero, while a stable system's response is always positive.

Answer

The frequency response of a discrete-time LTI system does not provide any information about its stability or causality.

Question 24

In discrete-time signals, what is aliasing and how does it affect signal processing systems?

Accepted Answer

Aliasing occurs when the sampling rate is too low, causing high-frequency components to appear as lower-frequency components.

Answer

Aliasing only affects analog signals, not discrete-time signals.

Answer

Aliasing has no impact on the accuracy of signal processing systems.

Question 25

In a nonlinear system, what phenomenon arises when the output signal contains frequency components that are not present in the input signal?

Accepted Answer

Harmonic distortion

Answer

Amplitude distortion

Answer

Phase distortion

Question 26

Which of the following signals is periodic with a period of 2π?

Accepted Answer

x(t) = sin(2πt + θ)

Answer

x(t) = e^(-t)

Answer

x(t) = t^2

Answer

x(t) = randn(t)

Question 27

What is the Laplace transform of the unit impulse function δ(t)?

Accepted Answer

1 / s

Answer

s / (s + 1)

Answer

1 / (s + 1)

Answer

s / s

Question 28

What is the order of a system with the following transfer function: H(s) = (s + 2) / (s^4 + 3s^3 + 2s^2 + s + 1)?

Accepted Answer

4

Answer

1

Answer

2

Answer

3

Question 29

Which of the following stability analysis techniques involves plotting the root locus of a system?

Accepted Answer

Root locus plot

Answer

Nyquist stability criterion

Answer

Routh-Hurwitz criterion

Answer

Bode plot

Question 30

A system represented by the transfer function H(s) = 1/(s+2) can be classified as a:

Accepted Answer

Low-pass filter

Answer

High-pass filter

Answer

Band-pass filter

Answer

Band-reject filter

Question 31

The Laplace transform of the unit impulse function δ(t) is:

Accepted Answer

1

Answer

0

Answer

t

Answer

e^(-t)

Question 32

For a stable system, which condition must be satisfied?

Accepted Answer

All poles of the system must have negative real parts.

Answer

All poles of the system must have positive real parts.

Answer

The system must be causal.

Answer

The system must be linear.

Question 33

Which of the following is NOT a type of Fourier transform?

Accepted Answer

Bilateral Laplace transform

Answer

Continuous-time Fourier transform

Answer

Discrete-time Fourier transform

Answer

Discrete Fourier transform

Question 34

A signal x(t) is considered periodic if:

Accepted Answer

It repeats itself after a constant time interval.

Answer

It is bounded.

Answer

It has finite energy.

Answer

It is continuous.

Question 35

Which characteristic is NOT a property of a Linear Time-Invariant (LTI) system?

Accepted Answer

Energy storage

Answer

Linearity

Answer

Time-invariance

Answer

Causality

Question 36

Which of the following is NOT a type of analog filter?

Accepted Answer

All-pass filter

Answer

Low-pass filter

Answer

High-pass filter

Answer

Band-pass filter

Question 37

What is the Nyquist sampling frequency for a signal whose highest frequency component is 10 Hz?

Accepted Answer

20 Hz

Answer

5 Hz

Answer

10 Hz

Answer

40 Hz

Question 38

What is the mathematical definition of the unit impulse function δ(t)?

Accepted Answer

A function that is zero everywhere except at t = 0

Answer

A function that is one everywhere except at t = 0

Answer

A function that is zero for all t < 0 and one for all t ≥ 0

Answer

A function that is one for all t ≥ 0

Question 39

Which of the following is NOT an advantage of using digital signal processing (DSP) techniques?

Accepted Answer

Higher power consumption

Answer

Increased noise immunity

Answer

Lower cost of implementation

Answer

Flexibility in signal manipulation

Question 40

What is the frequency response characteristic of an ideal low-pass filter with a cutoff frequency of ωc?

Accepted Answer

|H(ω)| = 1 for ω < ωc, |H(ω)| = 0 for ω ≥ ωc

Answer

|H(ω)| = 0 for ω < ωc, |H(ω)| = 1 for ω ≥ ωc

Answer

|H(ω)| = ω / ωc for ω < ωc, |H(ω)| = 0 for ω ≥ ωc

Answer

|H(ω)| = 1 for ω ≤ ωc, |H(ω)| = ωc / ω for ω > ωc

Question 41

In a discrete-time linear time-invariant (LTI) system, which operation is used to calculate the system's output, y[n], given an input, x[n]?

Accepted Answer

Convolution

Answer

Correlation

Answer

Differentiation

Answer

Integration

Question 42

Which of the following is NOT a method used for system identification?

Accepted Answer

Guess and check

Answer

Input-output data analysis

Answer

Estimation of model parameters

Answer

Statistical analysis

Question 43

Which of the following accurately represents the Fourier series of a periodic signal with period T?

Accepted Answer

x(t) = a0 + Σ[an cos(nω0t) + bn sin(nω0t)]

Answer

x(t) = Σ[an cos(nω0t) - bn sin(nω0t)]

Answer

x(t) = Σ[an cos(ω0t) + bn sin(ω0t)]

Answer

x(t) = a0 + Σ[an cos(nω0t) - bn sin(nω0t)]

Question 44

Which system property implies that the system's output is a scaled version of the input?

Accepted Answer

Linearity

Answer

Time-invariance

Answer

Causality

Answer

Stability

Question 45

Identify the option that is NOT a common application of signals and systems:

Accepted Answer

Quantum physics

Answer

Audio signal processing

Answer

Image processing

Answer

Control systems

Question 46

According to the sampling theorem, what minimum sampling rate is required to reconstruct a continuous-time signal from its samples?

Accepted Answer

At least twice the highest frequency component

Answer

At least half the highest frequency component

Answer

Equal to the highest frequency component

Answer

Twice the highest frequency component

Question 47

For a system with impulse response h(t), what condition ensures causality?

Accepted Answer

h(t) = 0 for t < 0

Answer

h(t) = 0 for t > 0

Answer

h(t) is an even function

Answer

h(t) is an odd function

Question 48

Define the bandwidth of a signal.

Accepted Answer

Frequency range occupied by the signal

Answer

Signal power

Answer

Signal duration

Answer

Signal amplitude

Question 49

Which of the following is a property of a causal system?

Accepted Answer

The output at any time depends only on present and past inputs.

Answer

The system is stable.

Answer

The system is invertible.

Answer

The system has a finite impulse response.

Question 50

Which of the following is the frequency response of an ideal low-pass filter?

Accepted Answer

A curve that decreases with increasing frequency.

Answer

A straight line with a positive slope.

Answer

A straight line with a negative slope.

Answer

A curve that increases with increasing frequency.

Question 51

The Nyquist rate for a signal with a bandwidth of B Hz is:

Accepted Answer

2B Hz

Answer

B/2 Hz

Answer

B Hz

Answer

4B Hz

Question 52

The impulse response of a system is defined as:

Accepted Answer

The output of the system when the input is a unit impulse.

Answer

The input to the system when the output is a unit impulse.

Answer

The frequency response of the system at zero frequency.

Answer

The Laplace transform of the system's input.

Question 53

The convolution of two signals x(t) and h(t) is:

Accepted Answer

The integral of the product of x(t) and h(t-τ) with respect to τ.

Answer

The product of their Fourier transforms.

Answer

The sum of their Fourier transforms.

Answer

The sum of the products of x(t) and h(t-τ) for all τ.

Question 54

Which property is not applicable to continuous-time signals?

Accepted Answer

Direction

Answer

Energy

Answer

Power

Answer

Periodicity

Question 55

What is the Laplace transform of the unit impulse function δ(t)?

Accepted Answer

1/s

Answer

1

Answer

s

Answer

1/s^2

Question 56

Which characteristic defines a causal system?

Accepted Answer

Its output relies solely on present and past inputs.

Answer

Its output depends exclusively on future inputs.

Answer

Its output is always zero.

Answer

Its input is always zero.

Question 57

State the Sampling Theorem.

Accepted Answer

A signal can be reconstructed from its samples if the sampling rate exceeds twice the highest frequency component of the signal.

Answer

A signal can be reconstructed from its samples if the sampling rate is less than half the highest frequency component of the signal.

Answer

A signal cannot be reconstructed from its samples.

Answer

The sampling rate is independent of the signal frequency.

Question 58

Define the convolution of two signals x(t) and h(t).

Accepted Answer

The integral of the product of x(t) and h(t-τ) over all τ

Answer

The sum of the products of x(t) and h(t-τ) over all τ

Answer

The derivative of the product of x(t) and h(t)

Answer

The Laplace transform of the product of x(t) and h(t)

Question 59

Calculate the Nyquist rate for a signal with a bandwidth of 10 kHz.

Accepted Answer

20 kHz

Answer

5 kHz

Answer

10 kHz

Answer

40 kHz

Question 60

The Fourier transform of a unit step function, u(t), is:

Accepted Answer

1/(jw)

Answer

jw

Answer

e^(-jw)

Answer

-1/(jw)

Question 61

The operation that computes the weighted sum of an input signal with a kernel is known as:

Accepted Answer

Convolution

Answer

Laplace transform

Answer

Fourier transform

Answer

Correlation

Question 62

Which of the following is NOT a characteristic of time-domain signal analysis?

Accepted Answer

Frequency-based representation

Answer

Amplitude and phase analysis

Answer

Plotting

Answer

Time-varying behavior

Question 63

According to the Nyquist-Shannon sampling theorem, the minimum sampling rate to avoid aliasing in a continuous-time signal with the highest frequency component of ωmax is:

Accepted Answer

2ωmax

Answer

ωmax/4

Answer

4ωmax

Answer

ωmax/2

Question 64

Which of the following is NOT a characteristic of random signals?

Accepted Answer

Deterministic values

Answer

Characterization by probability distributions

Answer

Unpredictable behavior

Answer

Statistical properties