WorksheetsECEA114x Practice Exit Exam
Total questions: 100
Worksheet time: 50mins
Name
Class
Date
1.
1. Is a signal in which each value of the signal is fixed, being determined by a mathematical expression, rule or table.
a)
Random Signal
b)
Deterministic Signal
c)
Periodic Signal
d)
Digital Signal
e)
Aperiodic Signal
2.
2. Are signals that are zero for all negative time.
a)
Causal Signal
b)
Non-causal Signal
c)
Random Signal
d)
Deterministic Signal
e)
Analog Signal
3.
3. For a band limited signal with maximum frequency fmax the Nyquist rate of signal is ___
a)
fmax/2
b)
1/fmax
c)
Fmax
d)
2fmax
e)
fmax/4
4.
4. Which of the following is true when the sampling time becomes less than Nyquist interval?
a)
The original signal can be recreated
b)
The bandwidth decreases
c)
The bandwidth increases
d)
The channel capacity decreases
e)
The channel capacity increases
5.
5. What is the duration of the unit sample response of a digital filter?
a)
Finite
b)
Infinite
c)
Impulse (very small)
d)
Zero
e)
None of the choices
6.
6. What happens if all the coefficients in the difference equation of an FIR filter are set to zero except for the first coefficient?
a)
The filter becomes IIR filter
b)
The filter becomes a moving average filter
c)
The filter becomes unstable
d)
The filter’s frequency response changes
e)
None of the choices
7.
7. Which of the following methods are used to convert analog filter into digital filter?
a)
Approximation of Derivatives
b)
Bilinear transformation
c)
Impulse Invariance
d)
All of the mentioned
e)
None of the choices
8.
8. Consider a continuous time system which represented using a differential equation dy(t)dt+ 0.1y(t) = x(t). The digital filter is obtained using the first forward difference method with the derivative part replaced with (y[n+1]-y[n])/T. The values of T, for which the digital filter is stable are:
a)
T < 10
b)
All positive values of T
c)
T > 20
d)
0 < T < 20
e)
All negative values of T
9.
9. The output of a linear time invariant system can be obtained from its unit impulse response function and the input function by
a)
Addition
b)
Multiplication
c)
Convolution
d)
Correlation
e)
Autocorrelation
10.
10. Which of the following parameters are required to calculate the correlation between the signals x(n) and y(n)?
a)
Time delay
b)
Attenuation Factor
c)
Noise signal
d)
All of the mentioned
e)
None of the choices
11.
11. A complete communication system should include
a)
A transmitter, a receiver and a spectrum analyzer
b)
A multiplexer, a demultiplexer and a channel
c)
A transmitter and a receiver
d)
A transmitter, a receiver and a channel
e)
A transducer, modulator and demodulator
12.
12. A simultaneous two-way communication is called
a)
Simplex
b)
Full-full duplex
c)
Full duplex
d)
Half duplex
e)
None of the choices
13.
13. Recovering the originally transmitted signal is called
a)
Modulation
b)
Demodulation
c)
Multiplexing
d)
Duplexing
e)
retransmission
14.
14. Which of the following is a disadvantage of analog communication systems compared to digital communication systems?
a)
Higher bandwidth requirements
b)
Greater susceptibility to noise
c)
Limited data transmission rates
d)
Reduced signal clarity
e)
All of the mentioned
15.
15. A noise figure is a measure of
a)
How much noise is in the channel
b)
How much noise does an amplifier adds to a signal
c)
How much noise is in a communications system
d)
Signal-to-noise ratio in dB
16.
16. The ideal noise figure is
a)
1 dB
b)
0 dB
c)
Infinite
d)
0
e)
None of the choices
17.
17. What is the total noise power in dBm for a bandwidth of 1Hz?
a)
174 dBm
b)
74 dBm
c)
-174 dBm
d)
-74 dBm
e)
147 dBm
18.
18. If an amplifier has a bandwidth B = 20kHz and a total noise power N = 2x10-17 W, determine the total noise power in dBμ if the bandwidth increases to 80kHz.
a)
-101 dBμ
b)
101 dBμ
c)
100 dBμ
d)
-100 dBμ
e)
110 dBμ
19.
19. The total noise power present in a 1-Hz bandwidth
a)
Noise figure
b)
Noise factor
c)
Noise limit
d)
Noise intensity
e)
Noise density
20.
20. An AM transmitter is modulated by two sine waves at 1kHz and 2.5 kHz, with modulations of 25% and 50%, respectively, What is the effective modulation index?
a)
0.56
b)
0.65
c)
0.25
d)
0.75
e)
0.45
21.
21. An AM wave has a total transmitted power of 4kW when modulated 85%. What is the total transmitted power if J3E was used instead?
a)
1061.5 W
b)
530.76 W
c)
2123.4 W
d)
2938.5 W
e)
265.38 W
22.
22. Is a technique used in electronic communication, works by varying the strength of the transmitted signal in relation to the information that is being sent.
a)
Angle Modulation
b)
Phase Modulation
c)
Frequency Modulation
d)
Amplitude Modulation
e)
Digital Modulation
23.
23. Maximum frequency deviation of a phase modulated (PM) signal occurs at
a)
Positive peak points
b)
Negative peak points
c)
Zero crossing points
d)
All of the mentioned
e)
None of the choices
24.
24. The maximum deviation of an FM carrier is 2kHz by a maximum modulation signal of 400Hz. The deviation ratio is
a)
0.5
b)
2
c)
5
d)
80
e)
100
25.
25. A 100MHz carrier is deviated 50kHz by a 4kHz signal. The modulation index is
a)
100
b)
250
c)
25
d)
12.5
e)
7.5
26.
26. It uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF), which can be more conveniently processed than the original radio carrier frequency.
a)
Tuned-radio frequency receiver
b)
Superheterodyne receiver
c)
Coherent BFO
d)
Non-coherent BFO
e)
None of the choices
27.
27. For an AM receiver tuned to a station at 590kHz, with IF=455kHz. Calculate the image frequency rejection in dB. Assume that the input filter consists of one tuned circuit with a Q of 40.
a)
36.98 dB
b)
39.86 dB
c)
36.89 dB
d)
38.96 dB
e)
38.69 dB
28.
28. A signal other than the desired RF which when mixed with the oscillator frequency will produce the same IF.
a)
Intermediate Frequency
b)
Image Frequency
c)
Oscillator Frequency
d)
Source Frequency
e)
Beat Frequency
29.
29. An analog pulse modulation scheme in which the amplitude of each resulting pulse is made proportional to the amplitude of the modulation signal at the instant at which it is sampled.
a)
Pulse Width Modulation
b)
Pulse Position Modulation
c)
Pulse Code Modulation
d)
Pulse Frequency Modulation
e)
Pulse Amplitude Modulation
30.
30. What is the key characteristic of pulse modulation techniques?
a)
Continuous waveform transmission
b)
Analog signal representation
c)
Discrete signal representation
d)
High-frequency carrier waves
e)
Audio frequency signal
31.
31. ASK, PSK, FSK, and QAM are examples of
a)
Digital-to-Digital
b)
Digital-to-Analog
c)
Analog-to-Analog
d)
Analog-to-Digital
e)
None of the choices
32.
32. Which of the following is most affected by noise?
a)
ASK
b)
FSK
c)
PSK
d)
QAM
e)
None of the choices
33.
33. In broadband communication, what is the purpose of frequency division multiplexing (FDM)?
a)
To reduce signal distortion
b)
To increase data security
c)
To transmit multiple signal simultaneously
d)
To minimize signal delay
e)
None of the choices
34.
34. Which modulation technique is commonly used in broadband digital communication systems like cable television?
a)
Pulse Code Modulation (PCM)
b)
Quadrature Amplitude Modulation (QAM)
c)
Pulse Amplitude Modulation (PAM)
d)
Frequency Shift Keying (PSK)
e)
None of the choices
35.
35. If the frequency spectrum of a signal has a bandwidth of 500Hz with the highest frequency at 600Hz, what should be the sampling rate according to Nyquist theorem?
a)
200 samples/sec
b)
500 samples/sec
c)
1000 samples/sec
d)
1200 samples/sec
e)
1500 samples/sec
36.
36. The factors affecting the successful interpreting of signal are:
a)
Signal level, bit rate, data rate
b)
SNR, data rate, bandwidth
c)
Baud rate, data rate, bandwidth
d)
SNR, data rate, baud rate
e)
Signal level, SNR, bandwidth
37.
37. Which of the following is the idea of modulating the carrier wave with data?
a)
AM
b)
FM
c)
PSK
d)
PCM
e)
QAM
38.
38. Which of the following encoding methods does not provide synchronization?
a)
RZ
b)
NRZ-L
c)
NRZ-I
d)
Manchester
e)
None of the choices
39.
39. How many bits are required to encode 64 level PCM
a)
8
b)
7
c)
6
d)
5
e)
4
40.
40. In what technique the signal’s energy is distributed in the form of pulses?
a)
Pulse Amplitude Modulation
b)
Angular Modulation
c)
Continuous Wave Modulation
d)
Pulse Code Modulation
e)
Pulse Width Modulation
41.
41. Most commonly used modulation system for telegraphy is
a)
Multitone modulation
b)
Single tone modulation
c)
PCM
d)
FSK
e)
ASK
42.
42. A 2000 bps binary information data signal is required to be transmitted in half-duplex mode using BFSK digital modulation technique. If the separation between two carrier frequency is 4000Hz, then the minimum bandwidth of the BPSK signal is
a)
2 kHz
b)
4 kHz
c)
6 kHz
d)
8 kHz
e)
12 kHz
43.
43. Calculate the baud rate of ASK signal having a bit rate of 400 bps.
a)
400 baud/s
b)
600 baud/s
c)
800 baud/s
d)
200 baud/s
e)
100 baud/s
44.
44. In Phase Shift Keying (PSK), how is digital information typically represented?
a)
By varying the amplitude of the carrier signal.
b)
By varying the frequency of the carrier signal
c)
By varying the width of the pulses
d)
By varying the phase of the carrier signal
e)
By varying the information
45.
45. The channel capacity is measured in terms of:
a)
Bits per channel
b)
Number of input channels connected
c)
Call per channel
d)
Number of output channels connected
e)
Bits per minute
46.
46. If the probability of a message is ¼, then the information in bits is
a)
1 bit
b)
2 bits
c)
3 bits
d)
4 bits
e)
8 bits
47.
47. Calculate the system bandwidth capacity in an FDM system having 200 users with individual bandwidth of 3MHz.
a)
1200 MHz
b)
800 MHz
c)
400 MHz
d)
1000 MHz
e)
600 MHz
48.
48. CDMA stands for
a)
Code-Division Multiple Access
b)
Carrier Division Multiple Access
c)
Compact Digital Multiplex Arrangement
d)
All that is mentioned
e)
None of the choices
49.
49. TDMA is used instead of TDM when:
a)
All the signal come from the same source
b)
The signals come from different sources
c)
TDM is used in RF communications
d)
They mean the same thing
e)
None of the choices
50.
50. To resolve and combine multipath components in CDMA system, which of the following is/are used
a)
Equalizer
b)
Registers
c)
Rake receiver
d)
Frequency divider
e)
Modulator
51.
51. What causes the characteristic impedance of a transmission line to change?
a)
Altering the cross-sectional area of the line
b)
Lengthening the transmission line
c)
Changing the frequency of the signal
d)
Varying the temperature of the transmission line
e)
None of the choices
52.
52. In a transmission line the velocity of the line is 2.5 x 108 m/sec. Capacitance of the line is 30pF/m, find the inductance per meter of the line.
a)
533 nH/m
b)
5.33 mH/m
c)
3.3 nH/m
d)
533 mH/m
e)
53.33 nH/m
53.
53. A transmission line of 0.4𝜆 length has a characteristic impedance of 100Ω and is terminated by a load impedance of 200 + j180Ω. Find the input impedance of the line.
a)
40 + j62Ω
b)
40 + j52Ω
c)
40 + j72Ω
d)
40 + j82Ω
e)
40 + j42Ω
54.
54. Determine the characteristic impedance of an air-filled concentric transmission line with a D/d ratio of 6.
a)
107.064 Ω
b)
106.704 Ω
c)
104.607 Ω
d)
100.764 Ω
e)
107.460 Ω
55.
55. What graphical tool is commonly used to analyze and design transmission line circuits?
a)
Bode plot
b)
Nyquist plot
c)
Smith chart
d)
Polar plot
e)
Solar plot
56.
56. Effective earth radius to true earth radius ratio
a)
Index of refraction
b)
K factor
c)
Fresnel zone
d)
Path profile
e)
Velocity factor
57.
57. What is the highest frequency that can be straight upward and be returned to earth?
a)
MUF
b)
Skip frequency
c)
Critical frequency
d)
Gyro frequency
e)
LUF
58.
58. What is the effective radiated power of a repeater with 200W transmitter power output, 4dB feedline loss, 4dB duplexer and circulator loss, and 10 dB feedline antenna gain?
a)
2000 W
b)
126 W
c)
317 W
d)
260 W
e)
371 W
59.
59. In radio wave propagation, what is ground wave propagation most influenced by?
a)
Ionization of the atmosphere
b)
Atmospheric refraction
c)
Earth’s magnetic field
d)
Tropospheric ducting
e)
None of the choices
60.
60. In what frequency range does ground wave propagation typically occur?
a)
Very High Frequency (VHF)
b)
Ultra-High Frequency (UHF)
c)
Medium Frequency (MF)
d)
High Frequency (HF)
e)
Super High Frequency (SHF)
61.
61. What is the Free Space Loss (FSL) in dB at 300 MHz between the earth station and a satellite at 30,000 km?
a)
173.42 dB
b)
139.02 dB
c)
147.12 dB
d)
162.53 dB
e)
129.20 dB
62.
62. Atmospheric condition is controlled by
a)
Humidity
b)
Pressure
c)
Temperature
d)
All of the mentioned
e)
None of the choices
63.
63. A measure of distribution of radiated power over a given area is called
a)
Field Strength
b)
Polarization
c)
Power Density
d)
Attenuation
e)
Interference
64.
64. The capture area of an antenna is directly proportional to the
a)
Frequency of the received signal
b)
Distance between transmitter and receiver
c)
Gain of the antenna
d)
Power density of the signal
e)
None of the choices
65.
65. What is the purpose of a director in a Yagi-Uda antenna?
a)
To receive signals from multiple directions
b)
To reflect signal towards the driven element
c)
To focus signals in a specific direction
d)
To increase the antenna’s gain
e)
All of the mentioned
66.
66. The standard reference antenna for the directive gain is ___
a)
Elementary doublet
b)
Isotropic antenna
c)
Half-wave dipole
d)
Infinitesimal dipole
e)
monopole
67.
67. Which type of antenna is known for its circular polarization?
a)
Yagi-Uda
b)
Log-periodic
c)
Helical
d)
Dipole
e)
Turnstile
68.
68. Determine the power density at a point 20km, from an antenna that has input power Pin = 40W, efficiency ɳ = 85%, and directivity D = 16dB.
a)
269. 283 nW/m2
b)
268.293 nW/m2
c)
263.289 nW/m2
d)
262.983 nW/m2
e)
264.293 nW/m2
69.
69. What is the ERP if the output of a transmitter is 5 kW, the coax line loss is 25W, and antenna power gain is 3 dB?
a)
10.263 kW
b)
10.026 kW
c)
10.623 kW
d)
10.362 kW
e)
10.620 kW
70.
70. What is the primary function of a waveguide in the context of electromagnetic waves?
a)
To generate electromagnetic waves
b)
To guide and direct electromagnetic waves
c)
To absorb electromagnetic waves
d)
To amplify electromagnetic waves
e)
None of the choices
71.
71. What is the core of an optical fiber primarily made of?
a)
Glass or plastic with a lower refractive index
b)
Glass or plastic with a higher refractive index
c)
Metal with a low conductivity
d)
Metal with high conductivity
e)
None of the choices
72.
72. What is the cut-off wavelength of a 6cm x 3cm waveguide? Assume the dominant mode of operation.
a)
3 cm
b)
6 cm
c)
8 cm
d)
9 cm
e)
12 cm
73.
73. Calculate the numerical aperture and the maximum angle of acceptance for a fiber with core and cladding refraction indices of 1.6 and 1.4 respectively.
a)
0.775, 50.768°
b)
0.577, 50.768°
c)
0.757, 57.078°
d)
0.757, 50.678°
e)
0.777, 57.078°
74.
74. The color of light emitted by an LED depends on
a)
Forward bias voltage
b)
Reverse bias voltage
c)
Value of series resistance in the circuit
d)
Type of semiconductor material
e)
None of the choices
75.
75. What is the material used in making photovoltaic cells?
a)
Silicon
b)
Arsenic
c)
Antimony
d)
Germanium
e)
Carbon
76.
76. What is the part of the PLC called where inputs and outputs are connected?
a)
Memory
b)
Processor
c)
Input/output interface
d)
Power supply
e)
Load
77.
77. Which of the following is a PLC input device?
a)
Fan
b)
Motor
c)
Sensor
d)
Light
e)
None of the choices
78.
78. Which type of sensor is commonly used in HVAC systems to measure air temperature?
a)
Thermocouple
b)
Pyroelectric sensor
c)
Thermistor
d)
Photodiode
e)
None of the choices
79.
79. In a security and surveillance control system, what does CCTV stand for?
a)
Closed Circuit Television
b)
Centralized Control and Tracking
c)
Covert Communication Technology
d)
Camera and Video Transmission
e)
None of the choices
80.
80. What is the purpose of an access control system in building security?
a)
To regulate HVAC systems
b)
To control lighting and audio systems
c)
To monitor and control entry to secure areas
d)
To manage fire safety systems
e)
None of the choices
81.
81. What is the primary purpose of data communications?
a)
To transmit electrical power
b)
To exchange information between devices
c)
To control mechanical systems
d)
To generate heat
e)
None of the choices
82.
82. Which of the following is an example of analog data?
a)
Text document
b)
Audio signal
c)
Image file
d)
Binary code
e)
None of the choices
83.
83. In data communication, what is the primary function of the physical layer?
a)
Error detection and correction
b)
Routing and addressing
c)
Transmission of raw bitstream over a physical medium
d)
Compression and decompression of data
e)
None of the choices
84.
84. Which category of data communication protocols is responsible for ensuring reliable and error-free delivery of data?
a)
Transport layer protocols
b)
Network layer protocols
c)
Data link layer protocols
d)
Physical layer protocols
e)
Application layer protocols
85.
85. What is the purpose of a hub in a network configuration?
a)
To connect devices in a star topology
b)
To route data between different networks
c)
To regulate data flow in a bus topology
d)
To amplify signals in a ring topology
e)
None of the choices
86.
86. In a telephone system, which transmission mode is commonly used for voice communication between two users?
a)
Simplex
b)
Half- duplex
c)
Full-duplex
d)
Multiplex
e)
None of the choices
87.
87. What type of circuit is commonly used for long-distance communication, such as in telecommunication networks?
a)
Two-wire circuit
b)
Four-wire circuit
c)
Simplex circuit
d)
Duplex circuit
e)
None of the choices
88.
88. In a conference call scenario, which transmission mode is most suitable for multiple participants to communicate simultaneously?
a)
Simplex
b)
Half-duplex
c)
Full-duplex
d)
Multiplex
e)
None of the choices
89.
89. What is the primary disadvantage of using two-wire circuits in communication systems?
a)
Limited bandwidth
b)
High cost
c)
Susceptibility to noise and interference
d)
Complex circuitry
e)
None of the choices
90.
90. What is the purpose of synchronization in data communication?
a)
To increase data transmission speed
b)
To align data frames at the receiver
c)
To encrypt data for secure transmission
d)
To reduce signal distortion
e)
None of the choices
91.
91. In synchronous data transmission, how is timing maintained between sender and receiver?
a)
Start and stop bits
b)
Clock signals
c)
Checksums
d)
Error correction codes
e)
None of the choices
92.
92. What is the primary function of a terminal in a data communication network?
a)
To provide a centralized data storage
b)
To act as a bridge between different networks
c)
To enable user interaction with the network
d)
To amplify data signals
e)
None of the choices
93.
93. In the OSI model, which layer is responsible for ensuring end-to-end communication and error recovery?
a)
Physical later
b)
Data Link layer
c)
Transport layer
d)
Network layer
e)
Application layer
94.
94. What is the primary function of the Presentation layer in the OSI model?
a)
Ensuring reliable data transfer
b)
Formatting and encrypting data
c)
Managing network routing
d)
Establishing and terminating connections
e)
None of the choices
95.
95. What organization developed the System Network Architecture (SNA) for IBM mainframe systems?
a)
Microsoft
b)
IBM
c)
Cisco
d)
Apple
e)
Huawei
96.
96. In System Network Architecture (SNA), what is the function of the Data Link Control (DLC) layer?
a)
Providing error detection and correction
b)
Managing logical network connections
c)
Defining physical addressing
d)
Encoding and decoding data for transmission
e)
None of the choices
97.
97. What layer of the TCP/IP model is equivalent to the OSI model’s Transport layer?
a)
Network layer
b)
Application layer
c)
Transport layer
d)
Internet layer
e)
Physical layer
98.
98. What does LAN stand for in networking?
a)
Local Area Network
b)
Longitudinal Access Node
c)
Limited Access Node
d)
Link Aggregation Network
e)
All that is mentioned
99.
99. Which type of network typically covers a larger geographic area compared to LAN but is smaller than WAN?
a)
LAN
b)
MAN
c)
WAN
d)
GAN
e)
RAN
100.
100. What is the primary advantage of GAN (Global Area Network)?
a)
High-speed data transfer within a building
b)
Connectivity across multiple cities or countries
c)
Low cost of implementation
d)
Limited coverage for local applications
e)
None of the choices
100 %
