McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .
| 151. |
How many types of multiport optical fiber couplers are available at present? |
| A. | two |
| B. | one |
| C. | four |
| D. | three |
| Answer» D. three | |
| 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. | |
| 152. |
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» D. number of modes propagating in each fiber | |
| 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. | |
| 153. |
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» C. wdm | |
| 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. | |
| 154. |
How many fabrication techniques are used for 3 port fiber couplers? |
| A. | one |
| B. | two |
| C. | three |
| D. | four |
| Answer» B. two | |
| 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. | |
| 155. |
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» D. fused bi-conical taper (fbt) technique | |
| 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. | |
| 156. |
Couplers insertion loss is same as that of excess loss. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 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. | |
| 157. |
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» A. 0.22 db | |
| 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. | |
| 158. |
How many manufacturing methods are used for producing multimode fiber star couplers? |
| A. | two |
| B. | one |
| C. | three |
| D. | five |
| Answer» A. two | |
| 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. | |
| 159. |
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» C. 14.77 db | |
| Explanation: the splitting loss is related to the number of output ports n of a coupler. it is given by- | |
| 160. |
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» A. star | |
| 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. | |
| 161. |
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» D. 1.1 db | |
| Explanation: the number of stages m within the ladder design is given by 2m=16. hence m=4. | |
| 162. |
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» A. fiber splice | |
| 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. | |
| 163. |
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» A. true | |
| 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. | |
| 164. |
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» B. smooth and square end faces | |
| 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. | |
| 165. |
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» D. copper | |
| Explanation: the score and break process is also called as scribe and break. it involves the | |
| 166. |
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» B. fusion splicing | |
| 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. | |
| 167. |
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» D. gas burner | |
| 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. | |
| 168. |
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» A. pre-fusion | |
| Explanation: pre-fusion involves rounding of fiber ends. it removes the requirement for | |
| 169. |
is caused by surface tension effects between the two fiber ends during fusing. |
| A. | pre-fusion |
| B. | diffusion |
| C. | self-alignment |
| D. | splicing |
| Answer» C. self-alignment | |
| 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. | |
| 170. |
Mean splice insertion losses of 0.05 dB are obtained using multimode graded index fibers with the Springroove splice. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: springroove 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. | |
| 171. |
is the unique property of the glass fiber. |
| A. | transmission |
| B. | opaque property |
| C. | ductile |
| D. | malleable |
| Answer» A. transmission | |
| Explanation: glass fibres have a unique property as a transmission medium which enables their use in the communication. the major transmission characteristics are dispersion and attenuation. | |
| 172. |
limits the maximum distance between the optical fiber transmitter and receiver. |
| A. | attenuation |
| B. | transmission |
| C. | equipment |
| D. | fiber length |
| Answer» A. attenuation | |
| 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. | |
| 173. |
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» C. repeater | |
| Explanation: repeaters are a mediator between transmitter and receiver. the weak | |
| 174. |
A regenerative repeater is called as |
| A. | repetitive repeater |
| B. | regenerator |
| C. | attenuator |
| D. | gyrator |
| Answer» B. regenerator | |
| 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. | |
| 175. |
How many encoding schemes are used in optical fiber communication system design requirements? |
| A. | three |
| B. | one |
| C. | two |
| D. | four |
| Answer» C. two | |
| 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. | |
| 176. |
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» B. frequency division multiplexing | |
| 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. | |
| 177. |
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» D. space division multiplexing | |
| 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. | |
| 178. |
Which of the following is not an optical fiber component? |
| A. | fiber |
| B. | connector |
| C. | circulator |
| D. | detector |
| Answer» C. circulator | |
| Explanation: circulator is a device used in electromagnetic theory. all others are optical components. | |
| 179. |
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» B. space division multiplexing | |
| 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. | |
| 180. |
Time division multiplexing is inverse to that of frequency division multiplexing. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: tdm involves distribution of channels in time slots whereas fdm involves bands that are run on different frequencies. | |
| 181. |
SONET stands for |
| A. | synchronous optical network |
| B. | synchronous operational network |
| C. | stream optical network |
| D. | shell operational network |
| Answer» A. synchronous optical network | |
| 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. | |
| 182. |
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» A. 51.84 mbps | |
| 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. | |
| 183. |
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» B. across a physical line | |
| 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. | |
| 184. |
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» C. physical layer | |
| 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. | |
| 185. |
In SONET, each synchronous transfer signal STS-n is composed of |
| A. | 2000 frames |
| B. | 4000 frames |
| C. | 8000 frames |
| D. | 16000 frames |
| Answer» C. 8000 frames | |
| 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. | |
| 186. |
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 622.080mbps |
| Answer» D. sts-1 provides the data rate of 622.080mbps | |
| 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. | |
| 187. |
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» C. both point-to-point and multi-point | |
| 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. | |
| 188. |
Automatic protection switching in linear network is defined at the |
| A. | line layer |
| B. | section layer |
| C. | photonic layer |
| D. | path layer |
| Answer» A. line layer | |
| Explanation: the line layer in sonet operates like the data link layer in the osi | |
| 189. |
A unidirectional path switching ring is a network with |
| A. | one ring |
| B. | two rings |
| C. | three rings |
| D. | four rings |
| Answer» B. two rings | |
| 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. | |
| 190. |
is a multi-functional element of optical network. |
| A. | hop |
| B. | optical node |
| C. | wavelength |
| D. | optical attenuation |
| Answer» B. optical node | |
| Explanation: an optical node is a multi- functional element which acts as a transceiver unit capable of receiving, transmitting and | |
| 191. |
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» A. light path | |
| 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. | |
| 192. |
The fundamentals of optical networking are divided into areas. |
| A. | two |
| B. | one |
| C. | four |
| D. | three |
| Answer» D. three | |
| 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. | |
| 193. |
The network structure formed due to the interconnectivity patterns is known as a |
| A. | network |
| B. | struck |
| C. | topology |
| D. | d-pattern |
| Answer» C. topology | |
| 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. | |
| 194. |
In the topology, the data generally circulates bi-directionally. |
| A. | mesh |
| B. | bus |
| C. | star |
| D. | ring |
| Answer» B. bus | |
| 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. | |
| 195. |
The ring and star topologies are combined in a configuration. |
| A. | mesh |
| B. | fringe |
| C. | data |
| D. | singular |
| Answer» A. mesh | |
| 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. | |
| 196. |
The full-mesh configuration is complex. |
| A. | false |
| B. | true |
| Answer» B. true | |
| Explanation: the full-mesh topology is a | |
| 197. |
How many networking modes are available to establish a transmission path? |
| A. | three |
| B. | one |
| C. | two |
| D. | four |
| Answer» C. two | |
| 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. | |
| 198. |
Packet switching is also called as |
| A. | frame switching |
| B. | cell switching |
| C. | trans-switching |
| D. | buffer switching |
| Answer» B. cell switching | |
| 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. | |
| 199. |
mode is temporary, selective and continuous. |
| A. | cell switching |
| B. | buffer switching |
| C. | cache |
| D. | circuit switching |
| Answer» D. circuit switching | |
| Explanation: an end-to-end connection is required for a circuit switching to take place. the transmissions are continuous and are in | |
| 200. |
A is a series of logical connections between the source and destination nodes. |
| A. | cell circuit |
| B. | attenuation circuit |
| C. | virtual circuit |
| D. | switched network |
| Answer» C. virtual circuit | |
| Explanation: a virtual circuit consists of different routes which provide connections between sending and receiving devices. these routes can change at any time and the incoming return route does not have to mirror the outgoing route. | |
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