This is the Multiples Choice Questions Part 10 of the Series in Fiber Optics Communications as one of the Communications Engineering topics. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize yourself with each and every question compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic Systems and Technologies, Communications Books, Journals, and other Communications References.
MCQ Topic Outline included in ECE Board Exam Syllabi
- MCQ in Principles of Light Transmission
- MCQ in Types of Light Sources, Laser, LED
- MCQ in Light Detectors
- MCQ in Modulation and Waveform
- MCQ in System Design
- MCQ in General application
- MCQ in System Bandwidth
- MCQ in Splicing Techniques
Continue Practice Exam Test Questions Part 10 of the Series
⇐ MCQ in Fiber Optics Communications Part 9 | ECE Board Exam
Choose the letter of the best answer in each questions.
451. It is a device that distributes light from a main fiber into one or more branch fibers.
A. optical fiber coupler
B. optical fiber splice
C. optical fiber connector
D. optical isolator
Answer: Option A
Explanation: nowadays, requirements to divide combined optical signals for applications are increasing. optical fiber coupler is one such device that is used for dividing and combining optical signals. it is generally used in lans, computer networks etc.
452. Optical fiber couplers are also called as
A. isolators
B. circulators
C. directional couplers
D. attenuators
Answer: Option C
Explanation: Optical fiber couplers are passive devices. The power transfer in couplers takes place either through the fiber core cross-section by butt jointing the fibers or by using some form of imaging optics between the fibers. It distributes light from one fiber to many fibers and hence it is also called as a directional coupler.
453. How many types of multiport optical fiber couplers are available at present?
A. two
B. one
C. four
D. three
Answer: Option D
Explanation: multiport optical fiber couplers are subdivided into three types. these are three and four port couplers, star couplers and wavelength division multiplexing (wdm) couplers. these couplers distribute light among the branch fibers with no scattering loss.
454. The optical power coupled from one fiber to another is limited by
A. numerical apertures of fibers
B. varying refractive index of fibers
C. angular power distribution at source
D. number of modes propagating in each fiber
Answer: Option D
Explanation: when two fibers are coupled to each other, the optical power is limited by number of modes propagating in each fiber. for example, when a fiber propagating with 500 modes is connected to a fiber that propagates only 400 modes, then at maximum, only 80% of power is coupled into the other fiber.
455. _______ couplers combine the different wavelength optical signal onto the fiber or separate the different wavelength optical signal output from the fiber.
A. 3-port
B. 2*2-star
C. wdm
D. directional
Answer: Option C
Explanation: wdm coupler is abbreviated as wavelength division multiplexing coupler. it is a category of multiport optical fiber couplers. it is designed to permit a number of different peak wavelength optical signals to be transmitted in parallel on a single fiber.
456. How many fabrication techniques are used for 3 port fiber couplers?
A. one
B. two
C. three
D. four
Answer: Option B
Explanation: there are two fabrication techniques available for three port couplers. first is a lateral offset method which relies on the overlapping of the fiber end faces and the other is the semi-transparent mirror method. using these techniques, three port couplers with both multimode and single-mode fibers can be fabricated.
457. Which is the most common method for manufacturing couplers?
A. wavelength division multiplexing
B. lateral offset method
C. semitransparent mirror method
D. fused bi-conical taper (fbt) technique
Answer: Option D
Explanation: the fbt technique is basic and simple. in this technique, the fibers are generally twisted together and then spot fused under tension such that the fused section is elongated to form a bi-conical taper structure. a three-port coupler can be obtained by removing one of the input fibers.
458. Couplers insertion loss is same as that of excess loss.
A. true
B. false
Answer: Option B
Explanation: excess loss is defined as the ratio of input power to output power. the insertion loss is defined as the loss obtained for a particular port-to-port optical path.
459. The measured output power at ports 2,3 and 4 are 0.003, 23.0 and 24.5 μW respectively. Determine the excess loss.
A. 0.22 dB
B. 0.33 dB
C. 0.45 dB
D. 0.12 dB
Answer: Option A
Explanation: excess loss is a ratio of power input to power output of the fiber and it is given by excess loss = 10log10 p1/(p3+p4) wherep1, p3, p4 = output power at ports 1,3 and 4 resp.
460. How many manufacturing methods are used for producing multimode fiber star couplers?
A. two
B. one
C. three
D. five
Answer: Option A
Explanation: the manufacturing methods of star couplers are mixer-rod technique and fbt technique. in the mixer-rod method, a thin platelet of glass is employed, which mixes light from one fiber, dividing it among the outgoing fibers. fbt method involves twisting, heating and pulling of fiber.
461. Calculate the splitting loss if a 30×30 port multimode fiber star coupler has 1 mW of optical power launched into an input port.
A. 13 dB
B. 15 dB
C. 14.77 dB
D. 16.02 dB
Answer: Option C
Explanation: The splitting loss is related to the number of output ports N of a coupler. It is given by-
Splitting loss (Star coupler) = 10log10N (dB).
462. A _________ coupler comprises a number of cascaded stages, each incorporating three or four-port FBT couplers to obtain a multiport output.
A. star
B. ladder
C. wdm
D. three-port
Answer: Option A
Explanation: a star coupler can be realized by constructing a ladder coupler. it consists of many cascaded stages. if a three-port coupler is used, then a ladder coupler does not form symmetrical star coupler. it is a useful device to achieve a multiport output with low insertion loss.
463. A number of three-port single-mode fiber couplers are used in the fabrication of a ladder coupler with 16 output ports. The three-port couplers each have an excess loss of 0.2 dB along with a splice loss of 0.1 dB at the interconnection of each stage. Determine the excess loss.
A. 1.9 dB
B. 1.4 dB
C. 0.9 dB
D. 1.1 dB
Answer: Option D
Explanation: The number of stages M within the ladder design is given by 2M=16. Hence M=4.
Thus, excess loss is given by-
Excess loss = (M×loss in each 3-port coupler) + (Number of splices×Loss in each stage)
Where number of splices = 3 (as the value of M is equal to 4).
464. A permanent joint formed between two different optical fibers in the field is known as a
A. fiber splice
B. fiber connector
C. fiber attenuator
D. fiber dispersion
Answer: Option A
Explanation: the jointing of two individual fibers is called as fiber splicing. it is used to establish long-haul optical fiber links by joining two small length fibers.
465. The insertion losses of the fiber splices are much less than the Fresnel reflection loss at a butted fiber joint.
A. true
B. false
Answer: Option A
Explanation: the fresnel reflection loss is usually more because there is no large step change in refractive index with the fusion splice as it forms a continuous fiber connection. also, some method of index matching tends to be utilized with mechanical splices.
466. What is the main requirement with the fibers that are intended for splicing?
A. smooth and oval end faces
B. smooth and square end faces
C. rough edge faces
D. large core diameter
Answer: Option B
Explanation: a curved mandrel is used which cleaves the fiber to achieve end preparation. the edges must be smooth and have square face at the end for splicing purpose.
467. In score and break process, which of the following is not used as a cutting tool?
A. diamond
B. sapphire
C. tungsten carbide
D. copper
Answer: Option D
Explanation: The score and break process is also called as scribe and break. It involves the scribing of the fiber surface under tension with a cutting tool. Copper is not used as a cutting tool.
468. The heating of the two prepared fiber ends to their fusing point with the application of required axial pressure between the two optical fibers is called as
A. mechanical splicing
B. fusion splicing
C. melting
D. diffusion
Answer: Option B
Explanation: fusion splicing is also called as welding. it refers to the welding of two fiber ends. it is essential for fusion splicing that the fiber ends are adequately positioned and aligned in order to achieve good continuity of the transmission medium at the junction point.
469. Which of the following is not used as a flame heating source in fusion splicing?
A. microprocessor torches
B. ox hydric burners
C. electric arc
D. gas burner
Answer: Option D
Explanation: micro-plasma torches uses argon and hydrogen and alcohol vapor. the most widely used heating source is an electric arc. thus, gas burner is not used in fusion splicing.
470. The rounding of the fiber ends with a low energy discharge before pressing the fibers together and fusing with a stronger arc is called as _________.
A. pre-fusion
B. diffusion
C. crystallization
D. alignment
Answer: Option A
Explanation: Pre-fusion involves rounding of fiber ends. It removes the requirement for fiber end preparation which has a distinct advantage in the field environment. It is utilized with multimode fibers giving average splice losses of 0.09 dB.
471. __________ is caused by surface tension effects between the two fiber ends during fusing.
A. pre-fusion
B. diffusion
C. self-alignment
D. splicing
Answer: Option C
Explanation: the two fiber ends are close but not aligned before fusion. during fusion, the surface tension affects the fiber ends to get aligned. after fusion, they are aligned in such a way that a transmission medium can get a good continuity.
472. Mean splice insertion losses of 0.05 dB are obtained using multimode graded index fibers with the Spring roove splice.
A. true
B. false
Answer: Option A
Explanation: spring roove utilizes a bracket containing two cylindrical pins which act as alignment guide for two fiber ends. an elastic element is used to press the fibers into a groove. the assembly is secured with a drop of epoxy resin. it provides a loss of 0.05 dB and has found a practical use in Italy.
473. _______ is the unique property of the glass fiber.
A. transmission
B. opaque property
C. ductile
D. malleable
Answer: Option A
Explanation: glass fibers have a unique property as a transmission medium which enables their use in the communication. the major transmission characteristics are dispersion and attenuation.
474. _________ limits the maximum distance between the optical fiber transmitter and receiver.
A. attenuation
B. transmission
C. equipment
D. fiber length
Answer: Option A
Explanation: attenuation along with dispersion and the conductor size are some of the factors that limit the maximum distance between the optical transmitter and the receiver. the associated constraints within the equipment also affect the distance.
475. The ________ incorporates a line receiver in order to convert the optical signal into the electrical regime.
A. attenuator
B. transmitter
C. repeater
D. designator
Answer: Option C
Explanation: Repeaters are a mediator between transmitter and receiver. The weak signal is strengthened back by the repeaters on its path to the receiver.
476. A regenerative repeater is called as
A. repetitive repeater
B. regenerator
C. attenuator
D. gyrator
Answer: Option B
Explanation: when digital transmission techniques are used, the repeater also regenerates the original digital signal in the electrical signal before it is retransmitted as an optical signal via a line transmitter.
477. How many encoding schemes are used in optical fiber communication system design requirements?
A. three
B. one
C. two
D. four
Answer: Option C
Explanation: encoding schemes are used for digital transmission of data. these are bi- phase and delay modulation codes. they are also called as Manchester and miller codes respectively.
478. In ___________ the optical channel bandwidth is divided into non-overlapping frequency bands.
A. time division multiplexing
B. frequency division multiplexing
C. code division multiplexing
D. de-multiplexing
Answer: Option B
Explanation: in fdm, the non-overlapping frequency bands are divided to the individual frequencies. these individual signals can be extracted from the combined fdm signal by electrical filtering at the receiver terminal.
479. A multiplexing technique which does not involve the application of several message signals onto a single fiber is called as
A. time division multiplexing
B. frequency division multiplexing
C. code division multiplexing
D. space division multiplexing
Answer: Option D
Explanation: in sdm, each signal channel is carried on a separate fiber within a fiber bundle or multi-fiber cable form. the cross coupling between channels is negligible.
480. Which of the following is not an optical fiber component?
A. fiber
B. connector
C. circulator
D. detector
Answer: Option C
Explanation: circulator is a device used in electromagnetic theory. all others are optical components.
481. _________ technique involves an increase in the number of components required.
A. time division multiplexing
B. space division multiplexing
C. code division multiplexing
D. frequency division multiplexing
Answer: Option B
Explanation: sdm involves good optical isolation due to the negligible cross coupling between channels. it uses separate fiber and thus requires more number of components.
482. Time division multiplexing is inverse to that of frequency division multiplexing.
A. true
B. false
Answer: Option A
Explanation: tdm involves distribution of channels in time slots whereas fdm involves bands that are run on different frequencies.
483. SONET stands for
A. synchronous optical network
B. synchronous operational network
C. stream optical network
D. shell operational network
Answer: Option A
Explanation: sonet stands for synchronous optical network. frame relay uses sonet to physically transmit data frames over a frame relay network as sonet is cheaper and provides better network reliability than other carriers.
484. In SONET, STS-1 level of electrical signalling has the data rate of
A. 51.84 mbps
B. 155.52 mbps
C. 2488.320 mbps
D. 622.080 mbps
Answer: Option A
Explanation:
explanation:-sts-1 level provides the data rate of 51.84 mbps, sts-3 provides a data rate of 155.52 mbps, sts-12 provides a data rate of 622.080 mbps and sts-48 provides a data rate of 2488.320 mbps.
485. The path layer of SONET is responsible for the movement of a signal
A. from its optical source to its optical destination
B. across a physical line
C. across a physical section
D. back to its optical source
Answer: Option B
Explanation: the path layer in sonet is responsible for finding the path of the signal across the physical line to reach the optical destination. it is ideally expected to find the shortest and the most reliable path to the destination.
486. The photonic layer of the SONET is similar to the _________ of OSI model.
A. network layer
B. data link layer
C. physical layer
D. transport layer
Answer: Option C
Explanation: the photonic layer in sonet is like the physical layer of the osi model. it is the lowest layer among the four layers of sonet namely the photonic, the section, the line, and the path layers.
487. In SONET, each synchronous transfer signal STS-n is composed of
A. 2000 frames
B. 4000 frames
C. 8000 frames
D. 16000 frames
Answer: Option C
Explanation: sonet defines the electrical signal as sts-n (synchronous transport signal level-n) and the optical signal as oc- n (optical carrier level-n). the building block of sonet is the sts-1/oc-1 signal, which is based on an 8-khz frame rate and operates at 51.84 mbps.
488. Which one of the following is not true about SONET?
A. frames of lower rate can be synchronously time-division multiplexed into a higher-rate frame
B. multiplexing is synchronous TDM
C. all clocks in the network are locked to a master clock
D. sts-1 provides the data rate of 622.080 Mbps
Answer: Option D
Explanation: in sonet, sts-n stands for synchronous transport signal level-n. sts- 1 level provides the data rate of 51.84 mbps, and sts-12 provides a data rate of 622.080 mbps.
489. A linear SONET network can be
A. point-to-point
B. multi-point
C. both point-to-point and multi-point
D. single point
Answer: Option C
Explanation: synchronous optical network (sonet) is basically an optical fiber point- to-point or ring network backbone that provides a way to accommodate additional capacity as the needs of the organization increase to multipoint networks.
490. Automatic protection switching in linear network is defined at the
A. line layer
B. section layer
C. photonic layer
D. path layer
Answer: Option A
Explanation: The Line layer in SONET operates like the data link layer in the OSI model and it is responsible for the movement of signal across a physical line. The Synchronous Transport Signal Mux/Demux and Add/Drop Mux provide the Line layer functions.
491. A unidirectional path switching ring is a network with
A. one ring
B. two rings
C. three rings
D. four rings
Answer: Option B
Explanation: one ring is used as the working ring and other as the protection ring in which each node is connected to its respective adjacent nodes by two fibers, one to transmit, and one to receive.
492. __________ is a multi-functional element of optical network.
A. hop
B. optical node
C. wavelength
D. optical attenuation
Answer: Option B
Explanation: An optical node is a multi-functional element which acts as a transceiver unit capable of receiving, transmitting and processing the optical signal. The optical nodes are interconnected with optical fiber links.
493. A signal carried on a dedicated wavelength from source to destination node is known as a
A. light path
B. light wave
C. light node
D. light source
Answer: Option A
Explanation: a light path is a dedicated path from a source to a destination. the data can be sent over the light paths as soon as connections are set up. a controlling mechanism is present to control the data flow.
494. The fundamentals of optical networking are divided into ______ areas.
A. two
B. one
C. four
D. three
Answer: Option D
Explanation: the fundamentals divided into three areas contain mainly optical network terminology. the other two areas include functions and types of optical network node and switching elements and the wavelength division multiplexed optical networks.
495. The network structure formed due to the interconnectivity patterns is known as a
A. network
B. struck
C. topology
D. d-pattern
Answer: Option C
Explanation: a topology is a combination of patterns interconnected to each other. it provides connection patterns to users at different places. it embarks on the principle of multi-usability.
496. In the _________ topology, the data generally circulates bi-directionally.
A. mesh
B. bus
C. star
D. ring
Answer: Option B
Explanation: in a bus topology, data is input via four port couplers. the couplers couples and stations the data bi-directionally and are removed from the same ports.
497. The ring and star topologies are combined in a ________ configuration.
A. mesh
B. fringe
C. data
D. singular
Answer: Option A
Explanation: the mesh configuration is a combination of ring and star topologies. it is referred to as full-mesh when each network node is interconnected with all nodes in the network.
498. The full-mesh configuration is complex.
A. false
B. true
Answer: Option B
Explanation: The full-mesh topology is a combination of two or more topologies. It is often preferred for the provision of either a logical or virtual topology due to its high flexibility and interconnectivity features.
499. How many networking modes are available to establish a transmission path?
A. three
B. one
C. two
D. four
Answer: Option C
Explanation: there are two networking modes often referred to the networking. these are connection-oriented and connectionless networking modes. these include an end-to-end and bidirectional communication environment between source and destination.
500. Packet switching is also called as
A. frame switching
B. cell switching
C. trans-switching
D. buffer switching
Answer: Option B
Explanation: in packet or cell switching, messages are sent in small packets called cells. cells from different sources are statistically multiplexed and are sent to the destinations.
- MCQ in Fiber Optics Communications Part 10 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 9 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 8 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 7 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 6 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 5 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 4 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 3 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 2 | ECE Board Exam
- MCQ in Fiber Optics Communications Part 1 | ECE Board Exam
Complete List of MCQ in Communications Engineering per topic
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