Signals and Systems Question & Answers June 5, 2021 By WatElectronics This article lists 100+ Signals and Systems MCQs for engineering students. All the Signals and Systems Questions & Answers given below includes solution and link wherever possible to the relevant topic. A signal is a time-variant and a physical phenomenon. The main intention of the signal is to convey information like the human voice, the voltage on telephone wires, electrical signals, etc. Noise is also a signal but it carries unwanted information. A system is a device or group of devices that do operations on signals. The system may have one or more inputs and outputs. The inputs of the system are always excitation and the outputs of the system are always the response. If two or more inputs and two or more outputs are given to the system then that system is called the MIMO system. In three ways the discrete-time signals are represented are functional, tabular method of representation, and sequence representation. In a memory-less system, the value of the present output depends on the present input. The dynamic system consists of delay elements, differentiation, integration, in their equation. In a memory system, the value of the present output depends on past/future input. The step function, impulse function, and ramp function are the elementary signals. The speech signal is the example of a one-dimensional signal, image is an example of the multi-dimensional signal. The system is said to be linear if it satisfies the scaling and additivity properties. If distinct inputs lead to distinct outputs then the system is said to be invertible. 1). The impulse function is denoted by _______ u(t) δ(t) u(t) or δ(t) None of the above Hint 2). The impulse function is _______ when t=0 One Zero Infinity None of the above Hint 3). Whenever the amplitude of step function is equivalent to one then that is ______ signal Unit Step Impulse None of the above Hint 4). When t≥0, the unit signal amplitude must be ________ One Zero Infinity None of the above Hint 5). When t<0, the unit signal amplitude must be ________ One Zero Infinity None of the above Hint 6). The discrete-time always indicated with n True False Hint 7). Whenever the amplitude of step function is more than one then that is called as ___________ signal Unit Step Impulse None of the above Hint 8). The continuous-time always indicated with t True False Hint 9). How many inputs does the system have? Only one Only two One or more inputs None of the above Hint 10). Signal is a _________ Time variant It is a physical phenomenon Conveys information All of the above Hint 11). ________ are the examples of signal Human voice Electrical signals Voltage on telephone wires All of the above Hint 12). The inputs of the system are called _____ Excitation Response Both a and b None of the above Hint 13). In a ______ signal, we can define the value of the signal at any instant of time? Continuous Discrete Both a and b None of the above Hint 14). In a _________ signal, we can’t define the value of the signal at any instant of time? Continuous Discrete Both a and b None of the above Hint 15). Time scaling won’t work for the ____________ function Unit step Impulse Both a and b None of the above Hint 16). The impulse function is _______ when t≠0 One Zero Infinity None of the above Hint 17). When n=k, δ(n-k) is _______ One Zero Infinity None of the above Hint 18). When n≠k, δ(n-k) is _______ One Zero Infinity None of the above Hint 19). The signum function denoted with ______ s(t), s(n) sgn(t), sgn(n) Both a and b None of the above Hint 20). How many outputs does the system have? Only one Only two One or more outputs None of the above Hint 21). The outputs of the system are called ________ Excitation Response Both a and b None of the above Hint 22). A __________ is an example of the system Communication system Oscilloscopes Modem All of the above Hint 23). The standard form of LTI is ___________ Time-Invariant System Linear Non-linear Either linear or non-linear None of the above Hint 24). The unit step signal is denoted with _______ u(t) u(n) u(t) or u(n) None of the above Hint 25). ________ are the properties of impulse function δ(n)-u(n)-u(n-1) f(t) δ(t)=f(0) δ(-t)= δ(t) All of the above Hint Signals and Systems MCQs with Hints 26). The sgn(t) is equal to one when ______ t>o t<0 t=0 None of the above Hint 27). The relation between u(t) and sgn() is _______ sgn(t)=u(t)-1 sgn(t)=2u(t)-1 sgn(t)=2u(t)+1 None of the above Hint 28). The unit ramp signal denoted by ________ u(t) sgn(t) r(t) or r(n) None of the above Hint 29). The r(t)=t when __________ t<0 t=0 t≥0 None of the above Hint 30). The r(t)=0 when __________ t<0 t=0 t≥0 None of the above Hint 31). The unit parabolic signal is zero when _________ t<0 t=0 t≥0 None of the above Hint 32). x(t)=A rect (t/T) is a representation of ________ Rectangular signal Unit signal Ramp signal None of the above Hint 33). The sgn(t) is equal to zero when ________ t<0 b)c) d) t=0 t≥0 None of the above Hint 34). The sinc function denoted with _________ sinc(λ) sinc(δ) sinc(π) sinc(2λ) Hint 35). The sampling function denoted with _________ sa(λ) sa(δ) sa(π) sa(2λ) Hint 36). Which one is a normalized function? sinc Sampling Both a and b None of the above Hint 37). The operation on signals perform only on ________ Amplitude Frequency Amplitude or time None of the above Hint 38). The sgn(t) is equal to -1 when ___________ t<0 t=0 t≥0 None of the above Hint 39). ______ operations performed on amplitude Scaling Addition, subtraction Multiplication All of the above Hint 40). ______ operations performed on time Scaling Shifting Reversal All of the above Hint 41). For a discrete-time signals time is ______ Continuous Discrete Discrete or continuous None of the above Hint 42). For a discrete-time signals amplitude is ______ Continuous Discrete Discrete or continuous None of the above Hint 43). Which one is not a normalized function? SinC Sampling Both a and b None of the above Hint 44). For discrete-time signals, both amplitude and time are ____ Continuous Discrete Discrete or continuous None of the above Hint 45). The signal is said to be _______whenever we can define a signal at an instant of time Deterministic Non-deterministic Deterministic or non- deterministic None of the above Hint 46). The signal is said to be _______whenever there is un-certainty at any particular instant of time Deterministic Non-deterministic Deterministic or non- deterministic None of the above Hint 47). The signal is said to be even when it satisfies the condition _______ x(t)=x(t) x(t)=x(2t) x(t)=x(-t) x(t)=-x(-t) Hint 48). The sum of two or more even functions, a product of two or more even functions o product of even number and odd functions results ______ function Even Odd Even or odd None of the above Hint 49). A signal said to be periodic if it satisfies the condition _________ x(t)=x(t) x(t)=x(2t) x(t)=x(-t) x(t)=x(t+T) Hint 50). The smallest value of T which satisfies the ___________ condition is called the fundamental time period x(t)=x(t+T) x(t)=x(T) x(t+T)=x(t-1) None of the above Hint Signals and Systems MCQs for Students 51). When two periodic sinusoids added then the result is ________ Sinusoidal signal Periodic signal Both a and b None of the above Hint 52). The signal is said to be odd when it satisfies the condition _____________ x(t)=x(t) x(t)=x(2t) x(t)=x(-t) x(t)=-x(-t) Hint 53). The sum of two or more odd functions or product of the odd number of odd functions results in ______ function Even Odd Even or odd None of the above Hint 54). _______ methods are used to find whether the signal is periodic or not Ratio method GCD method Both a and b None of the above Hint 55). A signal is said to be a power/energy signal if the total energy/power transmitted is ________ One Zero Finite None of the above Hint 56). ________ system satisfies the superposition principle Linear Non-linear Causal Non-causal Hint 57). The system is said to be __________ if its input, output characteristics changes with time Time variant Time invariant Both a and b None of the above Hint 58). The condition for time variance is _____ y(n,k)=y(n-k) y(n,k)=y(n+k) y(n,k)=y(nk) None of the above Hint 59). The system is said to be _______ when it satisfies with linearity and time-variant Linear time-variant Non-linear time-variant Both a and b None of the above Hint 60). ________ system is a memory less system Static Dynamic Both and b None of the above Hint 61). A system is said to be _____ if its response is dependent upon the present and past inputs and doesn’t depend upon future input Causal Non-causal Time variant None of the above Hint 62). All non-causal systems are _________ Dynamic Static Either static or dynamic None of the above Hint 63). All static systems are _____________ Causal Non-causal Either causal or non-causal None of the above Hint 64). A system said to be _______ when it produces bounded output for a bounded input Stable Linear Causal Non-causal Hint 65). The impulse response of a system can be represented with _______ h(t) h(n) h(t) or h(n) None of the above Hint 66). All finite duration signals with finite amplitude are said to be ______ signal Ramp Power Energy None of the above Hint 67). All periodic signals are _________ signals Ramp Power Energy None of the above Hint 68). The continuous impulse is a ________ signal Ramp Power Energy Neither energy nor power Hint 69). A discrete signal x(n) is said to be periodic when _______ x(n)=x(n+N) x(n)=x(n-N) x(n)=x(nN) x(n)=x(2nN) Hint 70). _____ system is a memory system Static Dynamic Static or dynamic None of the above Hint 71). In _______ system, the output depends upon future input also Causal Non-causal Both a and b None of the above Hint 72). The system is said to be _____ when it produces unbounded output for a bounded input Unstable Stable Causal Linear Hint 73). By using __________ we can find the zero state response of the system Convolution Correlation Both a and b None of the above Hint 74). The convolution is a mathematical operation that express _________ relation of an LTI system Input Output Input and output None of the above Hint 75). _______ are the properties of convolution Commutative, distributive Associative, shift Convolution with impulse All of the above Hint Signals and Systems MCQs for Interviews 76). The convolution with impulse property states that ________ x(t)*δ(t)=x(t) x(t)*δ(t)=x(-t) x(t)*δ(t)=x(2t) x(t)*δ(t)=-x(-t) Hint 77). When input signals are scaled by α then the output will be _________ x(αt)*h(αt)=1/| α| y(αt) x(αt)*h(αt)=1/| α| y(α) x(t)*h(t)=1/| α| y(αt) None of the above Hint 78). ______ are the conditions of Dirichlet Function should be absolutely integrable There must be a finite number of maxima and minima in the function There must be a finite number of discontinuous in the function All of the above Hint 79). If x(n) is real and even signal then Fourier series coefficient will be ________ Imaginary and odd Imaginary and even Real and odd Real and even All of the above Hint 80). If the signal that we want to represent in terms of Fourier series is real and even then the fourier series coefficient will be _______ Imaginary and odd Imaginary and even Real and odd Real and even Hint 81). If the signal that we want to represent in terms of Fourier series is real and odd then the Fourier series coefficient will be _______ Imaginary and odd Imaginary and even Real and odd Real and even Hint 82). If the signal that we want to represent in terms of Fourier series is imaginary and even then the Fourier series coefficient will be _______ Imaginary and odd Imaginary and even Real and odd Real and even Hint 83). If the signal that we want to represent in terms of Fourier series is imaginary and odd then the Fourier series coefficient will be _______ Imaginary and odd Imaginary and even Real and odd Real and even Hint 84). The example of real and even signal is _________ Cos t Sin t i cos t None of the above Hint 85). The example of real and odd signal is _________ Cos t Sin t i cos t None of the above Hint 86). The example of imaginary and even signal is _________ Cos t Sin t i cos t None of the above Hint 87). The region of convergence _______ Decides whether the system is variable or stable Decides whether the sequence is non-causal or causal Both a and b None of the above Hint 88). A signal x(t) and its Hilbert transform is having _________ Same amplitude spectrum Same autocorrelation function Same energy spectral density All of the above Hint 89). How many types of correlations are there? One Two Three Four Hint 90). _______________ function gives measure of match or similarity or coherence between a signal and its time shifted version Cross-correlation Auto-correlation Auto or cross-correlation None of the above Hint 91). _______________ is the measure of similarity between one signal and the time delayed version of other signal Cross-correlation Auto-correlation Auto or cross-correlation None of the above Hint 92). What is the ROC of δ(n)? One Zero Infinity None of the above Hint 93). What is the ROC of z-transform of δ(n+1)? One Zero Z None of the above Hint 94). The analysis of discrete-time LTI system is _____________ Z-transforms Hilbert transforms Either Z-transforms or Hilbert transforms None of the above Hint 95). ________ sampling works based on the multiplication Ideal Natural Flat top None of the above Hint 96). The noise interference in ideal sampling is ________ Very high High Less Very less Hint 97). The sampling theory is a process to convert ___________ Continuous to discrete-time signal Discrete-time to continuous time signal Both a and b None of the above Hint 98). How many types of samplings are there? One Two Three Four Hint Read more about Sampling 99). Auto-correlation function of the power signal is maximum at the origin so we can say that _____ R(0)≥R(τ) R(0)=R(τ) R(0) None of the above Hint 100). __________ sampling works based on chopping Ideal Natural Flat top None of the above Hint Signals and Systems MCQs for Quiz 101). The noise interference in natural sampling is _______ Very high High Low Very low Hint 102). If there is no similarity between x(t) and x(t-τ) then autocorrelation will be _______ One Zero Infinite None of the above Hint 103). If a sequence is purely right-sided sequence or causal then region of convergence is entire z-plane except at __________ z is equal to 0 z is equal to ∞ z is equal to 0 and z is equal to ∞ None of the above Hint 104). If a sequence is purely left-sided sequence or anti-causal then region of convergence is entire z-plane except at __________ z is equal to 0 z is equal to ∞ z is equal to 0 and z is equal to ∞ None of the above Hint 105). For a two-sided sequence region of convergence is entire z-plane except at __________ z is equal to 0 z is equal to ∞ z is equal to 0 and z is equal to ∞ None of the above Hint 106). The z-transform for discrete impulse function δ(n) is equivalent to one, for this type of impulse function the region of convergence is entire z-plane ____________ Including z is equal to 0 Including z is equal to ∞ Including z is equal to 0 and z is equal to ∞ None of the above Hint 107). The z-transform for discrete impulse function δ(n+1) is equivalent to z, for this type of impulse function the region of convergence is entire z-plane ____________ Including z is equal to 0 Including z is equal to ∞ Including z is equal to ∞ and excluding z is equal to 0 None of the above Hint 108). The ROC in z-transform indicated as ___________ Square Rectangle Circle None of the above Hint 109). The z-transform of a discrete-time signal x(n) is represented by _________ x(n)↔x(z) x(z)↔x(n) x(n)↔x(t) x(t)↔x(n) Hint 110). _____ sampling works based on a sample and hold Natural Ideal Flat top None of the above Hint 111). The noise interference in flat top sampling is ______ Very high High Less Very less Hint 112). The ZT and DTFT are equal when r is equal to __________ One Zero Infinity None of the above Hint 113). The ROC is the entire Z-plane for ________ sequence Right-hand Left-hand Either right or left hand None of the above Hint 114). The z-transform of u(-n) is _______ 1/z 1/1-z 1/z+1 None of the above Hint 115). The white noise spectral density is _____ Planar Uniform Both a and b None of the above Hint 116). The frequency-domain representation of time-domain u(t) is __________ 2πδω 1/jw+ πδ(ω) πδω None of the above Hint 117). The time-domain representation of frequency domain δ(ω) is ______ One Zero Infinity None of the above Hint 118). The state is the group of_________ , which summarizes the history of the system to predict the future values Variable Bits Bytes None of the above Hint 119). The smallest set of variables that determines the state of the system are known as ______ State State variables State vector None of the above Hint 120). _______ is the vector that contains the state variables as elements State State variables State vector None of the above Hint 121). The advantages of state-space analysis are ______ Analysis is done by considering initial conditions More accurate than transfer function Analysis of multi-input and multi-output system will be made easy by the state space analysis techniques All of the above Hint 122). The disadvantages of state-space analysis are ______ Techniques are complex Many computations are required Both a and b None of the above Hint 123). Which signal is used for processing digital signals? Continuous-time Discrete-time Both a and b None of the above Hint 124). The variable of the continuous-time denoted by _______ t n c t or n None of the above Hint 125). The variable of the discrete-time denoted by _______ t n t or n None of the above Hint Signals and Systems MCQs for Exams 126). ____________ is the process of reconstruction from its sampled output Interpolation Convolution Correlation None of the above Hint 127). The nquist rate of sin4000πt is _____ 1000Hz 2000Hz 3000Hz 4000Hz Hint 128). The maximum frequency of sin4000πt is _____ 1000Hz 2000Hz 3000Hz 4000Hz Hint 129). The nquist rate of sin200πt is _____ 100Hz 200Hz 300Hz 400Hz Hint 130). The nquist rate of sin(400t)*sinc(600t) is _____ 100 samples/sec 200 samples/sec 300 samples/sec 400 samples/sec Hint 131). A ________ is a frequency selective network Filter Comparator Integrator None of the above Hint 132). An LTI system acts as a _______ Filter Comparator Integrator None of the above Hint 133). The nquist rate of cos(2000πt)*sin(6000πt) is _____ 1000 samples/sec 2000 samples/sec 6000 samples/sec 4000 samples/sec Hint 134). Filters allow transmission of signals in a __________________ Certain band of frequencies Out of the band the frequencies will be rejected Both a and b None of the above Hint 135). Whichever the frequencies is allowed by the LTI system or the filter is called _________ Pass-band Stop-band Either pass-band or stop-band None of the above Hint 136). In _______ band, a certain band of frequencies are is allowed and rest of the frequencies are allowed by the filter Pass-band Stop-band Either pass-band or stop-band None of the above Hint 137). How many types of filters are there? Two Five Six Eight Hint Read more about Filters 138). The nyquist rate of sinc(200t)*sinc(600t) is _____ 100 samples/sec 200 samples/sec 600 samples/sec 400 samples/sec Hint 139). The change of input signals shape when it is transmitted through a system is called _________ Distortion Interpolator Discriminator None of the above Hint 140). If one input and one output is given to the system then that system is called ______ SISO MIMO SIMO MISO Hint 141). The ratio of Fourier transform of the output signal to the Fourier transform of the input signal is called ____________ Transfer function Hilbert transform Z-transform None of the above Hint 142). If two or more inputs and two or more outputs are given to the system then that system is called ______ SISO MIMO SIMO MISO Hint 143). The maximum frequency of sinc(200t)*sinc(600t) is _____ 100Hz 300Hz 600Hz 400Hz Hint 144). Which one is a transformation technique? Fourier series Fourier transform Z- transform All of the above Hint 145). The Fourier series, and Fourier transform is given by a french mathematician John Batiste Joseph Fourier in _________ 1768-1830 1990 2000 2001 Hint Read more about Fourier Series and Fourier Transform 146). The periodic signals ________ time signals Continuous Discrete Both a and b None of the above Hint 147). How many types of Fourier transforms are there? One Two Three Four Hint 148). The nyquist rate of sinc(400t)*sinc(600t) is _____ 1000 samples/sec 200 samples/sec 600 samples/sec 400 samples/sec Hint 149). How many types of Fourier series are there? One Two Three Four Hint 150). Which transform is only for a continuous-time? Laplace transform Z-transform Both a and b None of the above Hint Signals and Systems MCQs with Answers 151). Which transform is only for a discrete-time? Laplace transform Z-transform Both a and b None of the above Hint 152). _________ are for the analysis purpose Fourier series Fourier transforms Laplace and z-transform Both a and b Hint 153). _________ transforms are for the design purpose Fourier series Fourier transforms Laplace and z-transform None of the above Hint 154). The number of cycles per second is a ________ Frequency Amplitude Voltage None of the above Hint 155). How much time taken by the signal is called the _____________ Fundamental time period Transfer function Time period None of the above Hint 156). In T seconds one cycle has finished and in one second how many cycles has finished means _____ T cycles 1/T cycles 2T cycles 4T cycles Hint 157). _________ is also used to calculate the power and phase constant of a particular harmonic present in the expansion Fourier series Fourier transforms Laplace and z-transform None of the above Hint 158). There are _______ Fourier series methods One Two Three Four Hint 159). The system output y(t)=x(t),if t=0 then the output is dependent on _______ Present input Past input Both a and b None of the above Hint 160). The system output y(t)=x(t-1),if t=0 then the output is dependent on _______ Present input Past input Both a and b None of the above Hint 161). The system output y(t)=x(t+1),if t=0 then the output is dependent on _______ Present input Past input Future input None of the above Hint 162). The power of energy signals is equivalent to _______ One Zero Infinity None of the above Hint 163). The energy of power signals is equivalent to _______ One Zero Infinity None of the above Hint 164). The real and complex exponential signal can be defined in __________ Only continuous-time Only discrete-time Both in discrete and continuous-time None of the above Hint 165). __________ are the examples of systems Electrical circuits Mechanical systems Chemical and biological systems All of the above Hint 166). If f(t)=f(t+T) then the signal is ________ Continuous-time Discrete-time Both in discrete and continuous-time None of the above Hint 167). If f(t)=f(-t) then the signal is said to be ________ Odd Even Either odd or even None of the above Hint 168). Interconnection patterns are of _________ types One Two Three Four Hint 169). __________ is an example of an invertible system y(t)=αx(t) y(t)=x(t) y(t)=2x(t) None of the above Hint 170). If distinct inputs lead to distinct outputs then the system is said to be ___________ Invertibility Causality Non-causality None of the above Hint 171). The system is said to be linear if it satisfies the ________ properties Scaling Additivity Both a and b None of the above Hint 172). The speech signal is the example of ___________ dimensional signal One Two Multi None of the above Hint 173). ______ is an example of multi-dimensional signal Speech Image Both a and b None of the above Hint 174). Which signal has infinite duration? Power Energy Both a and b None of the above Hint 175). _____ are the elementary signals Step function Impulse function Ramp function All of the above Hint Signals and Systems MCQs for Engineers 176). Which one is an example of causal systems? y[n]=x[n]+1/2x[n-1] y[n]=x[n]+1/2x[n+1] y[n]=x[n]+1/2x[n] None of the above Hint 177). In ________ system the value of the present output depends on past/future input Memory system Memory less system Non-causal None of the above Hint 178). ______ system consists of delay elements, differentiation, integration, in their equation Static system Dynamic system Both a and b None of the above Hint 179). Which one is an example of a non-causal system? y[n]=x[n]+1/2x[n-1] y[n]=x[n+1]+1/2x[n-1] y[n]=x[n]+1/2x[n] None of the above Hint 180). In ________ system the value of the present output depends on present input Memory system Memory less system Dynamic system Static system Hint 181). The sampling rate of telephony is around _______ 2KHz 4KHz 8KHz 10KHz Hint 182). The bandwidth of telephony is around _______ 100-1000KHz 1000-11000KHz 200-1000KHz 300-3400Hz Hint 183). The bit rate of telephony is around _______ 2.4-64 Kbit/sec 2.4-4 Kbit/sec 2.4-8 Kbit/sec 2.4-16 Kbit/sec Hint 184). The sampling rate of high fidelity music is around _______ 2KHz 44.1KHz 8KHz 10KHz Hint 185). The bandwidth of high fidelity music is around _______ 5Hz-1000KHz 5Hz-10KHz 5Hz-20KHz 300-3400Hz Hint 186). The standard audio rate of compact rate is around _________ 10.1KS/s 20.1KS/s 30.1KS/s 44.1KS/s Hint 187). The standard audio rate of a DVD system is around _________ 10KS/s 20KS/s 60KS/s 96KS/s Hint 188). The data rate of FM radio is ______ 22KB/sec 33KB/sec 66KB/sec 88.2KB/sec Hint 189). The frequency band of FM radio is between _____ 0.1-5KHz 0.01-5KHz 0.002-11KHz 0.1-5Hz Hint 190). The sampling rate of AM radio is around _______ 2KHz 11.025KHz 8KHz 10KHz Hint 191). The data rate depends on ________ Available bandwidth Level of the signals we use Quality of the channel All of the above Hint 192). The average frequency of human voices is _________ 10Hz to 10KHz 120Hz to 10KHz 125Hz to 10KHz 125Hz to 8KHz Hint 193). How many ways are there to represent discrete-time signals? One Two Three Four Hint 194). Which system doesn’t have feedback? Recursive Non-recursive Both a and b None of the above Hint 195). Which one is an example of a recursive system? y(n)=x(n)+y(n-2) y(n)=x(n)+y(n+1) y(n)=x(n-1)+y(n-1) y(n)=x(n+1)+y(n-1) Hint 196). Which one is an example of a non-recursive system? y(n)=x(n)+y(n-1) y(n)=x(n)+x(n-1) y(n)=x(n-1)+y(n-1) y(n)=x(n+1)+y(n-1) Hint Time's up