Data-Communication

Question 1
A stable multivibrator are used as
A
comparator circuit
B
squaring circuit
C
frequency to voltage converter
D
voltage to frequency converter
       Data-Communication       stable-multivibrator       Nielit Scientist-C 2016 march
Question 1 Explanation: 
● A multivibrator is a one type of electronic circuit, that is used to implement a two state system like flip-flops, timers and oscillators.
● Multivibrators are classified into three types based on the circuit operation, namely Astable multivibrators, Bistable multivibrators and Monostable multivibrators.
● The astable multivibrator is not stable and it repeatedly switches from one state to the other. In monostable multivibrator, one state is stable and remaining state is unstable.
● When the power is turned ON consider the flip flop is cleared initially, then the o/p of the inverter will be high. The charging of the capacitor will be done using two resistors R1& R2. When the voltage of the capacitor goes above 2/3 Vcc, then the output of the higher comparator will be High, it changes the control flip flop
Question 2
The astable multivibrator has
A
two quasi stable states
B
two stable states
C
one stable and one quasi-stable state
D
none of these
       Data-Communication       stable-multivibrator       Nielit Scientist-C 2016 march
Question 2 Explanation: 
A multivibrator is an electronic circuit used to implement a variety of simple two-state devices such as relaxation oscillators, timers and flip-flops. It consists of two amplifying devices (transistors, vacuum tubes or other devices) cross-coupled by resistors or capacitors.
Question 3
The process of converting the analog sample into discrete form is called
A
Modulation
B
Multiplexing
C
Quantization
D
Sampling
       Data-Communication       Sampling-Types       Nielit Scientist-B CS 22-07-2017
Question 3 Explanation: 
Sampling is the process of recording an analog signal at regular discrete moments of time.
sampling is the reduction of a continuous-time signal to a discrete-time signal. A common example is the conversion of a sound wave (a continuous signal) to a sequence of samples (a discrete-time signal).
Quantization in digital signal processing, is the process of mapping input values from a large set (often a continuous set) to output values in a (countable) smaller set, often with a finite number of elements.
The sampling rate fs is the number of samples per second.
The time interval between samples is called the sampling interval Ts=1/fs
Question 4
Which of the following is not a transceiver function?
A
Transmission and receipt of data
B
Checking of line voltages
C
Addition and subtraction of headers
D
Collision detection
       Data-Communication       Transceiver       Nielit Scientist-B CS 2016 march
Question 4 Explanation: 
A transceiver is a device comprising both a transmitter and a receiver that are combined and share common circuitry or a single housing. When no circuitry is common between transmit and receive functions, the device is a transmitter receiver.
Question 5
Vestigial sideband most commonly used in radio transmission
A
radio transmission
B
telephony
C
television transmission
D
all of the above
       Data-Communication       Radio-Transmission       NieLit STA 2016 March 2016
Question 5 Explanation: 
Limitation of single-sideband modulation being used for voice signals and not available for video/TV signals leads to the usage of vestigial sideband. A vestigial sideband (in radio communication) is a sideband that has been only partly cut off or suppressed. Television broadcasts (in analog video formats) use this method if the video is transmitted in AM, due to the large bandwidth used. It may also be used in digital transmission, such as the ATSC standardized 8VSB.
Vestigial sideband (VSB) is a type of amplitude modulation ( AM ) technique (sometimes called VSB-AM ) that encodes data by varying the amplitude of a single carrier frequency . Portions of one of the redundant sidebands are removed to form a vestigial sideband signal – so-called because a vestige of the sideband remains.
Question 6
T1 carrier system is used:
A
For delta modulation
B
Industrial moise
C
For frequency modulated signals
D
None of the above
       Data-Communication       Carrier-System       Nielit Scientist-B CS 4-12-2016
Question 6 Explanation: 
The T-carrier system, introduced by the Bell System in the U.S. in the 1960s, was the first successful system that supported digitized voice transmission. The original transmission rate (1.544 Mbps) in the T1 line is in common use today in​ Internet service provider (ISP) connections to the Internet. Another level, the T3 line, providing 44.736 Mbps, is also commonly used by Internet service providers.
The T-carrier system is entirely digital, using pulse code modulation (PCM) and time-division multiplexing (TDM). The system uses four wires and provides duplex capability (two wires for receiving and two for sending at the same time). The T1 digital stream consists of 24 64-Kbps channels that are multiplexed.
Question 7
A low pass filter is:
A
Passes the frequencies lower than the specified cutoff frequency
B
Used to recover signal from sampled signal
C
Rejects higher frequencies
D
All of the above
       Data-Communication       Pass-Filters       Nielit Scientist-B CS 4-12-2016
Question 7 Explanation: 
A low-pass filter (LPF) is a filter that passes signals with a frequency lower than a selected cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. The exact frequency response of the filter depends on the filter design.
Question 8
The sequence of operation in which PCM is done :
A
Sampling, quantizing, encoding
B
Quantizing, sampling, encoding
C
Quantizing, encoding, sampling
D
None of the above
       Data-Communication       PCM       Nielit Scientist-B CS 4-12-2016
Question 8 Explanation: 
● Pulse code modulation (PCM) is a digital scheme for transmitting analog data. The signals in PCM are binary; that is, there are only two possible states, represented by logic 1 (high) and logic 0 (low). This is true no matter how complex the analog waveform happens to be. Using PCM, it is possible to digitize all forms of analog data, including full-motion video, voices, music, telemetry, and virtual reality (VR).
● sampling is the reduction of a continuous-time signal to a discrete-time signal. A common example is the conversion of a sound wave (a continuous signal) to a sequence of samples (a discrete-time signal).
● Quantization in digital signal processing, is the process of mapping input values from a large set (often a continuous set) to output values in a (countable) smaller set, often with a finite number of elements.
● The encoder encodes the quantized samples. Each quantized sample is encoded into an 8-bit code word by using A-law in the encoding process.
Question 9
ICA(in computational intelligence) stands for__
A
Intermediate Computational Algorithms
B
Immediate Computational and Analysis
C
Independent Component Analysis
D
Independent Computational Algorithms
       Data-Communication       Independent-Component-Analysis       Nielit Scientist-D 2016 march
Question 9 Explanation: 
In signal processing, independent component analysis is a computational method for separating a multivariate signal into additive subcomponents. This is done by assuming that the subcomponents are non-Gaussian signals and that they are statistically independent from each other.
Question 10
What frequency range is used for microwave communications, satellite and radar?
A
Low frequency: 30 kHz to 300 kHz
B
Medium frequency: 300 kHz to 3 MHz
C
Medium frequency: 300 kHz to 3 MHz
D
Extremely high frequency: 30000 kHz
       Data-Communication       Satellite       ISRO CS 2015       Video-Explanation
Question 10 Explanation: 
→ Microwave signals are often divided into three categories:
1)Ultra high frequency (UHF) (0.3-3 GHz);
2)Super high frequency (SHF) (3-30 GHz); and
3)Extremely high frequency (EHF) (30-300 GHz).
→ In addition, microwave frequency bands are designated by specific letters.
→ The term “P band” is sometimes used for ultra high frequencies below the L-band. For other definitions, see Letter Designations of Microwave Bands
→ Lower Microwave frequencies are used for longer links, and regions with higher rain fade. Conversely, Higher frequencies are used for shorter links and regions with lower rain fade.
Question 11
​ An ideal op-amp is an ideal
A
Voltage controlled current source
B
voltage controlled voltage source
C
current controlled current source
D
current controlled voltage source
       Data-Communication       ideal-op-amideal-op-amp       Nielit Scientific Assistance IT 15-10-2017
Question 11 Explanation: 
An ideal op-amp lead us to an op-amp with input resistance is infinite, so no current flows into either input terminal (the “current rule”) and that the differential input offset voltage is zero (the “voltage rule”).
Ideal operational amplification will have
➝ High input impedance ( R in = ∞ ) and low output impedance ( R out = 0 )

➝ R in = ∞ , so zero input current
➝ Infinite voltage gain
➝ So, it is a voltage controlled voltage source device.
Question 12
A carrier A​ c​ Cos(w​ C​ )t is frequency modulated by a signal E​ m​ Cos(w​ m​ )t. The modulation index is m​ f​ . the expression for the resulting FM signal is
A
A​ c,​ Cos[w​ c​ t+ m​ f​ Sin(w​ m​ )t]
B
A​ c​ Cos[w​ c​ t+ m​ f​ Cos(w​ m​ )t]
C
A​ c​ Cos[w​ c​ t+ ​ π ​ m​ f​ Sin w​ m​ t]
D
A​ c​ Cos[w​ c​ t+ 2 ​ π ​ m​ f​ E​ m​ Cos(w​ m​ )t/w​ m​ ]
       Data-Communication       FM-Signal       Nielit Scientific Assistance IT 15-10-2017
Question 12 Explanation: 
Question 13
In MOSFET fabrication, the channel length is delayed during the process of
A
Isolation oxide growth
B
Channel stop implantation
C
Poly-Silicon gate patterning
D
Lithography step leading to the contact pad
       Data-Communication       MOSFET       Nielit Scientific Assistance CS 15-10-2017
Question 13 Explanation: 
In MOSFET fabrication channel length is defined during Poly-Silicon gate patterning process
Question 14
When the object making the sound is moving towards you, the frequency goes up due to he waves getting pushed more tightly together. The opposite happens when the object moves away from you and the pich goes down. This phenomenon is called
A
Band Width
B
Doppler effect
C
Sound refraction
D
Vibrations
       Data-Communication       Doppler-Effect       KVS DEC-2013
Question 14 Explanation: 
→ The Doppler effect is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source.
→ The Doppler effect is observed whenever the source of waves is moving with respect to an observer.
→ The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding.
Question 15
The closeness of the recorded version to the original sound is called
A
Fidelity
B
Digitization
C
Sampling
D
Nyquist Theorem
       Data-Communication       Fidelity       KVS DEC-2013
Question 15 Explanation: 
→ Digitization is the process of converting information into a digital format . In this format, information is organized into discrete units of data (called bit s) that can be separately addressed (usually in multiple-bit groups called bytes).
→ sampling is the reduction of a continuous-time signal to a discrete-time signal. A common example is the conversion of a sound wave (a continuous signal) to a sequence of samples (a discrete-time signal).
→ “fidelity” denotes how accurately a copy reproduces its source
Question 16
The diagram below represents
A
Moore’s law
B
Newton raphson method
C
Boyle’s law
D
Gregor law
       Data-Communication       Moore’s-law       KVS DEC-2013
Question 16 Explanation: 
Moore’s law is the observation that the number of transistors in a dense integrated circuit doubles about every two years.
Question 17
A___ multivibrator circuit is one in which both LOW and HIGH output states are stable
A
Monostable
B
Bistable
C
Multistable
D
Tristable
       Data-Communication       stable-multivibrator       KVS DEC-2013
Question 17 Explanation: 
● The Bistable Multivibrator is another type of two state device.
● Bistable Multivibrators have TWO stable states (hence the name: “Bi” meaning two) and maintain a given output state indefinitely unless an external trigger is applied forcing it to change state.
Question 18
Refer to the monostable multibrator circuit in the figure below.

The trigger terminal(pin 2 of the IC) is driven by a symmetrical pulsed waveform of 10kHz. Determine the duty cycle of the output waveform.
A
0.56
B
0.55
C
0.57
D
0.58
       Data-Communication       stable-multivibrator       KVS DEC-2013
Question 18 Explanation: 
Question 19
The percentage resolution of an eight bit D/A converter is
A
0.39%
B
0.38%
C
0.50%
D
0.51%
       Data-Communication       A/D-Converter       KVS DEC-2013
Question 19 Explanation: 
→ An eight-bit D/A converter have 2​ 8​ -1 resolvable levels which is nothing but 255 levels.
→ Percentage resolution is (1/255)×100=0.39%
Question 20
The diagram below depicts:
A
Sound in waveform
B
Wind frequency
C
Line of sight
D
Compressions on a map
       Data-Communication       Waveform       KVS DEC-2013
Question 20 Explanation: 
●The generic term waveform means a graphical representation of the shape and form of a signal moving in a gaseous, liquid, or solid medium.
●For sound, the term describes a depiction of the pattern of sound pressure variation (or amplitude) in the time domain
● The temporal frequencies of sound waves are generally expressed in terms of cycles (or kilocycles) per second. The simplest waveform is the sine wave, since it has only one frequency associated with it. The sound waves associated with, say, music, are constantly varying.
Question 21
The diagram below represents
A
Resolution
B
Vibration
C
Reverberation
D
Frequency
       Data-Communication       Reverberation       KVS DEC-2013
Question 21 Explanation: 
● Reverberation, in psychoacoustics and acoustics, is a persistence of sound after the sound is produced.
● A reverberation, or reverb, is created when a sound or signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space – which could include furniture, people, and air.
Question 22
The process of taking a snapshot of the waveform at regular intervals and representing it as a binary number is known as
A
Sampling
B
Standard Assessment
C
Sequential Formatting
D
Sound Structure
       Data-Communication       Digital-sampling       KVS DEC-2013
Question 22 Explanation: 
Digital sampling is the recording of a sound using a string of numbers to represent the sound. 1s and 0s. These numbers are called samples.
Question 23
The _____ measures the relative strengths of two signals or a signal at two different points
A
frequency
B
decibel
C
Attenuation
D
throughput
       Data-Communication       Signal       KVS 30-12-2018 Part B
Question 23 Explanation: 
Decibel (dB), unit for expressing the ratio between two physical quantities, usually amounts of acoustic or electric power, or for measuring the relative loudness of sounds. One decibel (0.1 bel) equals 10 times the common logarithm of the power ratio
Question 24
ECL is the fastest of all logic families. High speed in ECL is possible because transistors are used in difference amplifier configuration, in which they are never driven into ____.
A
Race condition
B
Saturation
C
Delay
D
High impedance
       Data-Communication       ideal-op-amp       UGC NET CS 2017 Jan -paper-2
Question 24 Explanation: 
→ ECL is the fastest of all logic families. High speed in ECL is possible because transistors are used in difference amplifier configuration, in which they are never driven into Saturation.
→ Emitter-coupled logic (ECL) is a high-speed integrated circuit bipolar transistor logic family. ECL uses an overdriven BJT differential amplifier with single-ended input and limited emitter current to avoid the saturated (fully on) region of operation and its slow turn-off behavior.
→ As the current is steered between two legs of an emitter-coupled pair, ECL is sometimes called current-steering logic (CSL), current-mode logic (CML) or current-switch emitter-follower (CSEF) logic.[
Question 25
Which of the following is/are true w.r.t. applications of mobile computing ?
(A) Travelling of salesman
(B) Location awareness services
A
(A) true; (B) false.
B
Both (A) and (B) are true.
C
Both (A) and (B) are false.
D
(A) false; (B) true.
       Data-Communication       Mobile-Computing       UGC NET CS 2017 Jan -paper-2
Question 25 Explanation: 
Mobile computing main applications:
1.Portability
2. Connectivity
3.Social Interactivity
4. Individuality
5. IMobility
Travelling of salesman applicable to mobility of application.
Location awareness services applicable to Connectivity.
Question 26
Which of the following services is not provided by wireless access point in 802.11 WLAN ?
A
Association
B
Disassociation
C
Error correction
D
Integration
       Data-Communication       WLAN       UGC NET CS 2015 Dec- paper-2
Question 26 Explanation: 
→ Wireless LANs are use high frequency radio waves instead of cables for connecting the devices in LAN. Users connected by WLANs can move around within the area of network coverage. Most WLANs are based upon the standard IEEE 802.11 or WiFi.
→ A wireless access point (WAP), or more generally just access point (AP), is a networking hardware device that allows other Wi-Fi devices to connect to a wired network.
→ Wireless access point in 802.11 WLAN services are association, association and Integration.
Question 27
Four channels are multiplexed using TDM. If each channel sends 100 bytes/second and we multiplex 1 byte per channel, then the bit rate for the link is __________.
A
400 bps
B
800 bps
C
1600 bps
D
3200 bps
       Data-Communication       Multiplexing        UGC NET CS 2015 Dec- paper-2
Question 27 Explanation: 
Given data,
— 4 channels are multiplexed using TDM
— Multiplex 1 byte per channel. So, total 4 bytes=4 channels.
— Each channel sends 100 bytes/sec
— Bit rate=?
Bit rate= 100 * 4 bytes(1 byte=8 bits)
= 100 * 4 *8 (we are converting into bits because we are finding bit rate)
= 3200 bps
Question 28
In a typical mobile phone system with hexagonal cells, it is forbidden to reuse a frequency band in adjacent cells. If 840 frequencies are available, how many can be used in a given cell?
A
280
B
110
C
140
D
120
       Data-Communication       Frequency-Band       UGC NET CS 2015 Dec- paper-2
Question 28 Explanation: 
— Mobile phone system with hexagonal( equals to 6) cells
— 840 frequencies are available.
— How many can be used in a cell?
In this we need maximum 3 unique cells are required.

Total cells used with frequency is = 840/3
= 280 frequencies
Question 29
A data cube C, has n dimensions, and each dimension has exactly p distinct values in the base cuboid. Assume that there are no concept hierarchies associated with the dimensions. What is the maximum number of cells possible in the data cube, C?
A
p​ n
B
p
C
(2​ n​ – 1)p+1
D
(p + 1)​ n
       Data-Communication       Mobile-Computing       UGC NET CS 2015 Dec- paper-2
Question 29 Explanation: 
Option-A:​ This is the maximum number of distinct tuples that you can form with p distinct values per dimensions.
Option-B:​ You need at least p tuples to contain p distinct values per dimension. In this case no tuple shares any value on any dimension.
Option-C:​ The minimum number of cells is when each cuboid contains only p cells, except for the apex, which contains a single cell.
Option-D:​ We have p+1 because in addition to the p distinct values of each dimension we can also choose ∗.
Question 30
The mechanism with which several uses can share a medium without interference is :
A
Frequency modulation
B
Amplitude modulation
C
Multiplexing
D
None of these
       Data-Communication       Multiplexing        UGC NET CS 2005 Dec-Paper-2
Question 30 Explanation: 
Multiplexing is a method by which multiple analog or digital signals are combined into one signal over a shared medium. It can share a medium without interference.
Question 31
The frequency reuse plan is divided into cell grouping using how many cells, where the number of cells equals N ?
A
3
B
10
C
7
D
21
       Data-Communication       Cellular-Networks       UGC NET CS 2005 june-paper-2
Question 31 Explanation: 
The cluster size N = 7 and the frequency reuse factor is 1/7 since each cell contains one-seventh of the total number of available channels.
Total cells=7*3
=21
Frequency reuse concept, cells with the same letter use the same set of frequencies. A cell cluster is outline in blue color and replicated over the converge area.
Question 32
Which interim standard describes inter-switching networking ?
A
IS – 54
B
IS – 95
C
DS – 45
D
ANSI – 41
       Data-Communication       Cellular-Networks       UGC NET CS 2005 june-paper-2
Question 32 Explanation: 
→ Interim Standard 95 (IS-95) was the first ever CDMA-based digital cellular technology.
→ The IS-95 standards describe an air interface, a set of protocols used between mobile units and the network.
→ IS-95 is widely described as a three-layer stack, where L1 corresponds to the physical (PHY) layer, L2 refers to the Media Access Control (MAC) and Link-Access Control (LAC) sublayers, and L3 to the call-processing state machine.
Question 33
Theoretically, how many 1.25 MHz Carriers are there in a CDMA cell ?
A
18
B
22
C
9
D
64
       Data-Communication       Cellular-Networks       UGC NET CS 2005 june-paper-2
Question 33 Explanation: 
→ In CDMA, multiple users share a 1.25 MHz channel by using orthogonal spreading codes (Walsh codes)
→ IS-95a standard designed for AMPS cellular band
→ Each cellular provider is allocated 25 MHz spectrum and ten 1.25-MHz CDMA duplex channels if A AMPS Band provider, 9 if B band provider
Question 34
The frequency band allocated for the downlink in GSM is :
A
960 – 985 MHz
B
935 – 960 MHz
C
920 – 945 MHz
D
930 – 955 MHz
       Data-Communication       Cellular-Networks       UGC NET CS 2006 Dec-paper-2
Question 34 Explanation: 
There are 2 popular GSM methods.
1. GSM-900
2. GSM-1800
GSM-900 uses 890 – 915 MHz to send information from the Mobile Station to the Base
Transceiver Station (uplink) and 935 – 960 MHz for the other direction (downlink), providing 124 RF channels (channel numbers 1 to 124) spaced at 200 kHz. Duplex spacing of 45 MHz is used.
Question 35
What is the transmission signal coding method for a T1 carrier called ?
A
Binary
B
NRZ
C
Bipolar
D
Manchester
       Data-Communication       Transmission-method       UGC NET CS 2006 June-Paper-2
Question 35 Explanation: 
The transmission signal coding method of T1 carrier is called Bipolar. Bipolar encoding is a type of return-to-zero (RZ) line code, where two nonzero values are used, so that the three values are +, −, and zero. Such a signal is called a duobinary signal.
Question 36
How much bandwidth is required to send 132 voice – grade channels by FDM on an international satellite system ?
A
500 MHz
B
10 MHz
C
1320 MHz
D
50 MHz
       Data-Communication       Multiplexing        UGC NET CS 2006 June-Paper-2
Question 36 Explanation: 
In telecommunications, frequency-division multiplexing (FDM) is a technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency bands, each of which is used to carry a separate signal. The most natural example of frequency-division multiplexing is radio and television broadcasting, in which multiple radio signals at different frequencies pass through the air at the same time.
Frequency Division Multiple Access(FDMA):
FDMA is simply another example of the familiar data and voice transmission technique called FDM. This technique is used to allocate small portions of a large bandwidth (500MHz for satellite transponders) to individual users. For instance, a telecommunications common carrier in a particular country like Brazil. It might want 132 voice grade channels for sending voice and analog coded data to various other countries. The bandwidth required on the current international satellite systems for this many channels is 10MHz. Because 1 transponder has a bandwidth of 500Mhz, it could accommodate 50 users, each requiring 132 channels. The Brazilian user might be allocated the frequency band between 5990 and 6000MHz for the uplink to the satellite and the corresponding downlink frequencies would be 3765 to 3775Mhz.
Question 37
Infrared signals can be used for short range communication in a closed area using _______ propagation.
A
ground
B
sky
C
line of sight
D
space
       Data-Communication       FM-Signal       UGC NET CS 2014 June-paper-2
Question 37 Explanation: 
Propagation methods are 3 types
1. Ground
2. Sky
3. Line of sight


Question 38
Match the following with respect to the mobile computing technologies :

 
A
a-iii, b-iv, c-ii, d-i
B
a-iv, b-i, c-ii, d-iii
C
a-ii, b-iii, c-iv, d-i
D
a-ii, b-i, c-iv, d-iii
       Data-Communication       Mobile-Computing       UGC NET CS 2014 June-paper-2
Question 38 Explanation: 
GPRS → An emerging wireless service that offers a mobile data
GSM → An integrated digital radio standard
UMTS → The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the International Telecommunications Union IMT-2000 standard set and compares with the CDMA2000 standard set for networks based on the competing cdmaOne technology. UMTS uses wideband code division multiple access (W-CDMA) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators.
EDGE → Enhanced GPRS or EGPRS. It is a data system used on top of GSM networks. It provides nearly 3 times faster speeds than the outdated GPRS system. Nine different schemes for modulation and error correction.
Question 39
The GSM network is divided into the following three major systems :
A
SS, BSS, OSS
B
BSS, BSC, MSC
C
CELL, BSC, OSS
D
SS, CELL, MSC
       Data-Communication       Cellular-Networks       UGC NET CS 2012 Dec-Paper-2
Question 39 Explanation: 
GSM Architecture:

Mobile Station (MS)
Mobile Equipment (ME)
Subscriber Identity Module (SIM)
Base Station Subsystem (BSS)
Base Transceiver Station (BTS)
Base Station Controller (BSC)
Network Switching Subsystem (NSS)
Mobile Switching Center (MSC)
Home Location Register (HLR)
Visitor Location Register (VLR)
Authentication Center (AUC)
Equipment Identity Register (EIR)
Question 40
The VLF and LF bauds use _______ propagation for communication.
A
Ground
B
Sky
C
Line of sight
D
Space
       Data-Communication       Propagation       UGC NET CS 2013 Dec-paper-2
Question 40 Explanation: 
The VLF and LF bauds use ground propagation for communication.
Propagation methods are 3 types
1. Ground
2. Sky
3. Line of sight

→ Very low frequency or VLF is for radio frequencies (RF) in the range of 3 to 30 kilohertz (kHz), corresponding to wavelengths from 100 to 10 kilometers, respectively.
→ The low-frequency signals travel in all directions from the transmitting antenna.
Question 41
______ is a satellite based tracking system that enables the determination of person’s position.
A
Bluetooth
B
WAP
C
Short Message Service
D
Global Positioning System
       Data-Communication       GPS       UGC NET CS 2012 June-Paper2
Question 41 Explanation: 
Global Positioning System(GPS) is a satellite based tracking system that enables the determination of person’s position.
Question 42
The amount of uncertainty in a system of symbol is called
A
Bandwidth
B
Entropy
C
Loss
D
Quantum
       Data-Communication       Information-theory       UGC NET CS 2011 Dec-Paper-2
Question 42 Explanation: 
→ The amount of uncertainty in a system of symbol is called entropy. → Generally we can call entropy is disorder or uncertainty.
Question 43
The cellular frequency reuse factor for the cluster size N is
A
N
B
N2
C
1/N
D
1/N2
       Data-Communication       Cellular-Networks       UGC NET CS 2011 Dec-Paper-2
Question 43 Explanation: 
The frequency reuse factor is related to cluster size then the frequency reuse factor=1/N
Question 44
Handoff is the mechanism that
A
transfer an ongoing call from one base station to another
B
initiating a new call
C
dropping an ongoing call
D
none of above
       Data-Communication       Cellular-Networks       UGC NET CS 2011 Dec-Paper-2
Question 44 Explanation: 
Handoff is the mechanism that transfer an ongoing call from one base station to another.
Hard handover (or) Hard Handoff: Early systems used hard handoff. In a hard handoff, a mobile station only communicates with one base station. When the MS moves from one cell to another, communication must first be broken with the previous base station before communication can be established with the new one.
Soft handover (or) Soft Handoff: New systems use a soft Handoff. In this case, a mobile station can communicate with base stations at the same time. This means that, during handoff, a mobile station may continue with the new base station before breaking off from the old one.
Question 45
A telephone conference call is an example of which type of communications ?
A
same time / same place
B
same time / different place
C
different time / different place
D
different time / same place
       Data-Communication       Cellular-Networks       UGC NET CS 2011 Dec-Paper-2
Question 45 Explanation: 
A telephone conference call is an example of same time / different place type of communications.
Question 46
The diffusion current is proportional to
A
applied electric field
B
concentration gradient of charge carriers
C
square of electric field
D
cube of applied electric field
       Data-Communication       Diffusion-Current       NIELIT Junior Teachnical Assistant_2016_march
Question 47
For generating 1 MHμ frequency signal, the most suitable circuit is
A
phase shift oscillator
B
weinbridge oscillator
C
colpilt’s oscillator
D
audio oscillator
       Data-Communication       Colpitt’s-oscillator       NIELIT Junior Teachnical Assistant_2016_march
Question 48
In a two stage CE amplifier circuit, the ac collector resistance of the first stage depends on
A
the input impedance of first stage
B
the input impedance of second stage
C
load resistance only
D
none of the above
       Data-Communication       A/D-Converter       NIELIT Junior Teachnical Assistant_2016_march
Question 49
Class C amplifier is suitable for
A
a narrow frequency band
B
audio frequency
C
a wide frequency band
D
all the signals
       Data-Communication       amplifier       NIELIT Junior Teachnical Assistant_2016_march
Question 50
For a BJT, α and β are related to
A
β =α/(1−α)
B
β =α/(1+α)
C
β =1/(1+α)
D
α=β/(1+β)
       Data-Communication       BJT       NIELIT Junior Teachnical Assistant_2016_march
There are 50 questions to complete.

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