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WorksheetsDATU PUTI
Total questions: 100
Worksheet time: 50mins
Which of the following is NOT a classification of signals?
Continuous-time
Discrete-time
Dynamic-time
Analog
What defines a periodic signal?
It has a repeating pattern over a specific interval
It has a continuous spectrum
It does not repeat its pattern
It has no fundamental frequency
What is the Nyquist rate?
Half the sampling frequency
Twice the highest frequency component in the signal
Equal to the highest frequency component in the signal
Equal to the sampling frequency
Aliasing in signal processing occurs when:
The sampling frequency is too low
The sampling frequency is too high
The signal is continuous
The signal is periodic
What differentiates a Finite Impulse Response (FIR) filter from an Infinite Impulse Response (IIR) filter?
FIR filters use feedback
IIR filters have a finite number of coefficients
IIR filters have an infinite impulse response
FIR filters have recursive difference equations
Which type of filter exhibits linear phase characteristics?
IIR Filter
FIR Filter
Both FIR and IIR
Neither FIR and IIR
Which of the following is a characteristic of Finite Impulse Response (FIR) filters?
They exhibit recursive behavior
They have an infinite impulse response
They can have feedback loops
They have a finite duration impulse response
The z-transform is used to:
Convert time-domain signals to frequency-domain signals
Convert frequency-domain signals to time-domain signals
Evaluate poles and zeros of a system
Perform convolution operations
Pole-zero-gain filters are characterized by:
Number of poles and gain
Number of zeros and gain
Number of poles, zeros, and gain
Only the gain
In signal processing, Fourier transforms are primarily used for:
Time-frequency analysis
Evaluating system poles and zeros
Modifying phase response of a filter
Converting frequency-domain signals to time-domain signals
What is the main purpose of a modulator in a communication system?
To convert digital signals into analog signals
To amplify signals for transmission
To encode data into a carrier wave
To convert analog signals into digital signals
Which of the following is NOT a characteristic of digital communication?
High noise immunity
Increased bandwidth requirement
Reduced error rate
Greater security in transmission
What does the term ‘bandwidth’ refer to in communication systems?
The frequency range of the modulated signal
The capacity of data transmission
The range of available radio frequencies
The amount of noise in the system
What component of a communication system is responsible for signal reception?
Transmitter
Modulator
Receiver
Antenna
Noise from random acoustic or electric noise that has equal per cycle over a specified frequency band.
Thermal noise
Gaussian noise
White noise
All of the choices
None of the choices
The signal in the channel is measured to be 23dB white while noise in the same channel is measured to be 9dB. The signal to noise ratio therefore___.
9/23
23/9
32dB
14dB
What factor affects thermal noise in a communication system?
Temperature
Bandwidth
Bandwidth
Antenna height
An amplifier has an output S/N that I half of its input S/N. What is its noise figure?
3dB
-3dB
2dB
-2dB
If an amplifier has a bandwidth B=20kHz and a total noise power N=2x10^-17W, determine the total noise power in dBu if the bandwidth increases to 80kHz.
100 dBu
101 dBu
-100 dBu
-101 dBu
50 dBu
Modulation is the process of
Generating constant frequency radio waves
Combining audio and radio frequency waves at the transmitting end of a communication system
Reducing distortion in the RF amplifiers
Improving the thermal stability of a transistor
What does the term ‘carrier suppression’ refer to in modulation?
Reducing the power of the carrier wave
Completely removing the carrier wave
Minimizing interference from other carriers
Amplitude reduction of the carrier wave
A transmitter supplies 10kW of a carrier power to the antenna. The total radiated power with 45% modulation is___kW.
14
10.8
1.6
25
100% modulation is produced in AM when the carrier.
Frequency equals signal frequency
Frequency exceeds signal frequency
Amplitude equals signal amplitude
Amplitude exceeds signal amplitude
Which of the following statement regarding single sideband transmission is not correct?
In such transmission, only one sideband is transmitted, leaving off the other side and the carrier
It has gained general acceptance for the use home entertainment equipment
It is generally reserved for point to point communication
The amount of power and the bandwidth necessary to be transmitted for a given amount of information are appreciably reduced
The difference between phase and frequency modulation
is purely theoretical because the same in practice
Is too great to make the two systems are compatible
Lies in the poorer audio response of the phase modulation index
Lies in the different definition of the modulation index
In superheterodyne broadcast receiver, the frequency of the local oscillator is ___ the incoming signal frequency.
Higher than
Lower than
Equal to
Cannot be determine
What is the primary function of a mixer in superheterodyne receiver?
To amplify the received signal
To convert the received signal to fixed frequency
To filter out unwanted frequencies
To detect the modulated signal
The standard intermediate frequency for the FM radio is
10.7 MHz
4.5 MHz
27 kHz
15 kHz
Which type of modulation is commonly used in digital communication systems?
Amplitude modulation (AM)
Phase modulation (PM)
Pulse width modulation (PWM)
Quadrature amplitude modulation (QAM)
What is the primary function of a modem in a communication system?
To convert digital signals into analog signals
To amplify signals for transmission
To encode data into a carrier wave
To decode modulated signals
An analog pulse modulation technique in which the duration of each resulting pulse is varied in step with the amplitude of the modulating signal at the time it is sampled and that the sampled pulses have the same amplitude.
Pulse width modulation (PWM)
Pulse duration modulation (PDM)
Pulse length modulation (PLM)
All of the choices
None of the choices
What does pulse code modulation (PCM) primarily involve?
Modulating pulse width
Converting analog signals to digital signals
Varying pulse amplitude
Modulating pulse position
What is the advantage of using differential pulse code modulation (DPCM) over pulse code modulation (PCM)?
Higher data transmission rate
Lower quantization noise
Reduced bandwidth requirement
Better resistance to channel noise
What is the primary characteristic of spread spectrum modulation techniques?
Concentrating signal energy into narrow bandwidth
Spreading signal energy over a wider bandwidth
Transmitting signals at high frequencies
Using multiple carrier frequencies for modulation
What is the main advantage of digital modulation over analog modulation?
Higher power efficiency
Greater resistance to noise
Simplicity in modulation
Wider frequency range
What is the primary advantage of digital communication over analog communication?
Higher power efficiency
Simplicity in modulation
Greater resistance to noise
Wider frequency range
Which of the following is not a component of a digital communication system?
Modulator
Demodulator
Receiver
Carrier wave generator
What is the primary difference between pulse amplitude modulation (PAM) and pulse width modulation (PWM)
PAM encodes information in pulse width, while PCM encodes in pulse amplitude
PAM uses a fixed pulse width, while PWM uses variable pulse widths
PAM is digital, while PWM is analog
PWM is used in audio applications, while PAM is used in video applications
In pulse code modulation (PCM), what does quantization refer to?
Encoding the analog signal into binary code
Sampling the analog signal at regular intervals
Modulating the amplitude of pulses
Assigning numerical values to each signal level
Which modulating technique encodes information in the timing of pulses?
Pulse amplitude modulation (PAM)
Pulse width modulation (PWM)
Pulse position modulation (PPM)
Pulse code modulation (PCM)
What is the primary advantage of quadrature amplitude modulation (QAM) over other modulation techniques?
Higher data transmission rates
Simpler demodulation process
Lower power consumption
Greater resistance to noise
What is the main advantage of frequency shift keying (FSK) over amplitude shift keying (ASK)?
Higher spectral efficiency
Simpler modulation process
Greater resistance to noise
Higher data transmission rates
In digital communications, what does ASK stand for?
Amplitude shift keying
Angle shift keying
Analog signal keying
Amplitude sampling keying
In phase shift keying (PSK), how many phase states can a signal have to encode information?
1
2
3
4
Which information theory concept measures the average amount of information produced by a source of data?
Entropy
Bit rate
Redundancy
Channel capacity
What is the primary purpose of error detection codes in digital communication?
To correct errors in transmitted data
To minimize the occurrence of errors
To identify if errors have occurred during transmission
To compress the data for efficient transmission
CDMA stands for:
Code-division multiple access
Carrier division multiple access
Compact digital multiplex arrangement
None of the choices
All of the choices
An analog multiplexing technique where the optical fiber data rate is higher than the data rate of the metallic transmission cable. It is also used to combine optical signals.
FDM
WDM
CDMA
TDM
Which of the following is not a common FDM application?
Telephone
Stereo broadcasting
Secure communications
Telemetry
It is the basic building block of the FDM hierarchy.
Voice channel
Group
Baseband channel
Message channel
None of the choices
A quarter-wave length of a line is used as a/an
Impedance transformer
Lecher line
Stub matching
Grounding
What cause the characteristic impedance of a transmission line to change?
Lengthening the transmission line
Changing the frequency of the signal
Altering the cross-sectional area of the line
Varying the temperature of the transmission line
A coaxial line with an outer diameter of 6mm has 50ohms characteristic impedance. If the dielectric constant of the insulation in 1.60, calculate the inner diameter.
2.09mm
2.90mm
2.09cm
2.90cm
Indicate the false statement. The SWR on a transmission line is infinity; the line is terminated in
A pure reactance
A short circuit
An open circuit
A complex impedance
Which parameter of a transmission line determines its ability to transfer signals without distortion?
Attenuation
Characteristic impedance
Propagation constant
Phase velocity
What factors affects the power density of transmitted signal?
Frequency of the signal
Transmitting antenna height
Atmospheric pressure
Transmitting antenna material
A microwave transmitting antenna is 550ft high. The receiving antenna is 200ft high. The minimum transmission distance is
20 mi
38.7 mi
53.2 mi
32.3 mi
Effective earth radius to true earth radius ratio
Fresnel zone
Index of refraction
Path profile
K-factor
A measure of distribution of radiated power over a given area is called
Power density
Filed strength
Attenuation
Polarization
The power density at a certain distance from a 5kW isotropic source in free space is 15.9x10^-14W/m2. How far away is the source?
50,024.36 mi
50,024.36 m
50,024.36 km
50,024.36 ft
What is the free space loss (FSL) in dB at 300MHz between the earth station and a satellite at 37,00km?
167.4 dB
173.4 dB
185.4 dB
197.4 dB
A 500-kHz transmitter produces a field strength of 100uV/m at 100mi. What is the theoretical strength at 200mi?
25uV
50uV
75uV
100uV
A space that does not interfere with the normal radiation and propagation of waves.
Free space
Space wave
Normal space
Space jam
What does the term ‘polarization’ refer to in antenna systems?
The shape of the antenna
The frequency of the transmitted signal
The orientation of the electromagnetic wave’s electric field
The distance between the antenna and the receiver
A device designed to radiate electromagnetic energy into space.
Transmission lines
Matching transformer
Antenna
Conductors
The amount of electromagnetic spectrum needed or allocated for a particular communication channel or group of channels.
Power density
Bandwidth
Beamwidth
Field strength
In a given direction, the relative gain of a transmitting antenna with respect to the maximum directivity of a half-wave dipole multiplied by the net power accepted by the antenna from the connected transmitter.
Power density
Field strength
Effective isotropic power
Effective radiated power
What is meant by antenna gain?
The final amplifier gain minus the transmission line loss (including any phasing lines present)
The ratio of the amount of power produced by the antenna compared to the output power of the transmitter
The ratio of the signal in the forward direction to the signal in the backward direction
The numeric ratio relating the radiated signal strength of an antenna to that of another antenna
What is the primary function of a directive antenna?
To radiate electromagnetic waves equally in all directions
To concentrate electromagnetic waves in one direction
To reduce the frequency of transmitted waves
To amplify received signals
What is the cut-off wavelength of a 6cmx3cm waveguide? Assume the dominant mode of operation.
6cm
9cm
12cm
15cm
What is the primary advantage of using waveguides for transmission compared to from space transmission?
Higher power losses
Limited bandwidth capacity
Lower propagation speed
Better confinement of electromagnetic waves
What is the primary reason for using fiber optics in communication systems?
Higher susceptibility to electromagnetic interference
Greater signal distortion over long distances
Higher data transmission rates
Lower bandwidth capacity
What property of optical fibers allows them to transmit data over long distances?
High attenuation
Low dispersion
Limited bandwidth
High numerical aperture
What characteristic defines a thermocouple as a temperature sensor?
It measures temperature by changes in resistance
It generates voltage proportional to temperature differences
It uses light emission to detect temperature variations
It directly measures heat flow
What is the primary function of a photodiode in an optoelectronic system?
To emit light when a current passes through it
To convert light energy into electrical current
To amplify electrical signals
To control the intensity of light emitted by an LED
What does the term ‘GPIO’ stand for concerning interfacing techniques?
Graphic process input/output
General purpose input/output
Geographical positioning in/out
Global peripheral input/output
What is the primary role of an analog-to-digital converter (ADC) in interfacing systems?
To convert digital signals into analog signals
To amplify analog signals for better reception
To convert analog signals into digital signals
To control the flow of digital data
Which component is essential in a fire and life safety control system?
Temperature sensor
Motion detectors
Access control system
Carbon monoxide detectors
What is the primary function of a supervisory control and data acquisition (SCADA) system in building management?
To control fire and life safety systems
To supervise and collect data from various sensor and equipment
To manage audio-video and lighting controls
To regulate HVAC systems
What is the primary function of an HVAC control system in a building management system?
To monitor and control the heating, ventilation, and air conditioning
To manage the security and surveillance systems
To control the lighting and audio-video systems
To supervise and acquire data from different sensors
What type of network topology uses a central node to connect all other nodes?
Bus topology
Star topology
Ring topology
Mesh topology
A ___ interconnects LAN having identical protocols at the physical data link and network layers.
Node
Router
Bridge
Gateway
Which category of data communication involves transmitting data over short distances within a building or campus?
WAN (Wide Area Network)
LAN (Local Area Network)
MAN (Metropolitan Area Network)
GAN (Global Area Network)
Wireless Local Area Network (WLAN)
What is the main advantage of a mesh network topology?
Ease of installation and maintenance
Redundancy and fault tolerance
High-speed data transmission
Centralized control of the network
In which network configuration are all devices connected to a single, continuous cable?
Mesh configuration
Ring configuration
Bus configuration
Star configuration
What distinguishes a four-wire circuit from a two-wire circuit?
Four-wire circuits use separate wires for transmission and reception, while two-wire circuits use the same wire for both
Two-wire circuits have higher bandwidth than four-wire circuits
Four-wire circuits are used for analog transmission, while two-wire circuits are used for digital transmission
Two-wire circuits are used in telephony, while four-wire circuits are used in data communication
In which transmission mode can data be transmitted in both directions but not simultaneously?
Simplex
Half-duplex
Full-duplex
Multiplex
What is the primary advantage of using a full-duplex transmission mode?
Simplicity in implementation
Higher data transmission rates
Lower error rates
Reduced of hardware
Which transmission mode allows simultaneous transmission and reception of data?
Simplex
Half-duplex
Full-duplex
Multiplex
Which network component acts as an interface between a computer and a network?
Terminal
FEP (Front-End Processor)
Serial interface
LCU (Line Control Unit)
What type of synchronization ensures that sender and receiver clocks are synchronized periodically during data transmission
Asynchronous synchronization
Synchronous synchronization
Isochronous synchronization
Plesiochronous synchronization
What network component manages multiple data streams onto single communication channel?
Terminal
Multiplexer
Concentrator
LCU (Line Control Unit)
In the OSI model, which layer ensures data integrity and provides error detection?
Data link layer (Layer 2)
Network layer (layer 3)
Physical layer (layer 1)
Transport layer (layer 4)
What character-oriented protocol is commonly used for email communication?
ASCII
Baudot
EBCDIC
Unicode
Which layer of the OSI model is responsible for establishing, managing, and terminating connections between applications?
Transport layer (layer 4)
Presentation layer (layer 6)
Application layer (layer 7)
Session layer (layer 5)
Which layer of the TCP/IP model is responsible for routing packets across different networks?
Transport layer
Network layer
Application layer
Data link layer
Which bit-oriented protocol is widely used for synchronous communication in WANs?
HDLC (high-level data link control)
BSC (binary synchronous communication)
PPP (point-to-point protocol)
LAPB (link access procedure, balanced)
What distinguishes a WAN from a LAN?
WANs cover larger geographical areas than LANs.
WANs area easier to set up than LANs
WANs have lower transmission speeds compared to LANs
WANs use wireless technology while LANs use wired technology
What does ISDN stand for in telecommunications?
Integrated switched digital network
International subscriber dialing network
Intelligent system data network
Integrated services digital network
Which network type covers a broad geographical area, such as a city or town?
LAN (Local area Network)
MAN (Metropolitan Area Network)
WAN (Wide Area Network)
GAN (Global Area Network)
