Q&A Hero

Q: The biphase codes are known as self-clocking codes.

Q: A category of encoding techniques known as multilevel binary addresses some of the deficiencies of the NRZ codes.

Q: Using two different voltage levels for the two binary digits is a difficult way to transmit digital signals.

Q: The encoding scheme is the mapping from data bits to signal elements.

Q: The most familiar use of transmitting digital data using analog signals is the public telephone network.

Q: The modulation rate of a signal is the rate, in bits per second, that data are transmitted.

Q: A digital signal is a sequence of discrete, discontinuous voltage pulses.

Q: Some transmission media, such as optical fiber and unguided media, will only propagate analog signals.

Q: In general, the equipment for encoding digital data into a digital signal is more complex and expensive than digital to analog modulation equipment.

Q: Both analog and digital information can be encoded as either analog or digital signals.

Q: Used for amateur radio, CB radio, and international broadcasts such as BBC and Voice of America, ________ propagation is a signal from an earth based antenna reflected from the ionosphere back down to earth.

Q: The ________ frequency band is used for satellite communication, radar, terrestrial microwave links, and wireless local loop.

Q: A form of attenuation known as ________ is when a transmitted signal attenuates over distance because the signal is being spread over a larger and larger area.

Q: A single orbiting satellite will operate on a number of frequency bands called ________ channels.

Q: The simplest radiation pattern is produced by the ________ antenna, which is a point in space that radiates power in all directions equally. The actual radiation pattern is a sphere with the antenna at the center.

Q: Defined as an electrical conductor, or system of conductors, used either for radiating or collecting electromagnetic energy, unguided media uses an ________ to achieve transmission and reception.

Q: Wireless transmission frequencies in the range of about 1 GHz to 40 GHz are referred to as ________ frequencies. Highly directional beams are possible at these frequencies.

Q: Often used in LANs, ________ transmission has a higher refractive index at the center which makes the light rays moving down the axis advance more slowly than those near the cladding.

Q: A thin, flexible medium capable of guiding an optical ray is an ________.

Q: The ________ standards identify a number of categories of cabling and associated components that can be used for premises and campus-wide data distribution.

Q: For ________ media the bandwidth of the signal produced by the transmitting antenna is more important than the medium in determining transmission characteristics.

Q: The least expensive and most widely used guided transmission medium for both analog and digital signals is ________.

Q: Optical fiber transmits a signal encoded beam of light by means of ________. This can occur in any transparent medium that has a higher index of refraction than the surrounding medium.

Q: In a data transmission system the ________ medium is the physical path between transmitter and receiver.

Q: Twisted pair, coaxial cable and optical fiber are examples of ________ media, which provide a physical path along which signals are propagated.

Q: ________ is a general term used to encompass frequencies in the range of 3 kHz to 300 GHz. A) Radio B) Satellite C) Terrestrial microwave D) Broadcast radio

Q: A loss between the transmitting and receiving antennas caused by water vapor and oxygen is ________. A) atmospheric absorption B) parabolic loss C) atmospheric interference D) isotropic loss

Q: A communication ________ is a microwave relay station used to link two or more ground based microwave transmitter/receivers known as earth stations. A) transmitter B) transponder C) dish D) satellite

Q: Requiring line of site transmission and fewer amplifiers or repeaters than coaxial cable over the same distance, ________ is used in long haul telecommunications. A) terrestrial microwave B) twisted pair C) UTP D) optical fiber

Q: Defined as the power output in a particular direction compared to that produced in any direction by a perfect omnidirectional antenna, ________ is a measure of the directionality of the antenna. A) effective area B) antenna gain C) parabola D) antenna wavelength

Q: Wireless transmission frequencies in the range of 30 MHz to 1 GHz are suitable for omnidirectional applications and are referred to as the ________ range. A) radio B) transponder C) terrestrial D) paraboloid

Q: When using optical fiber, the term ________ refers to the change in direction of light rays after they strike small particles or impurities in the medium. A) relay B) scattering C) parabola D) directrix

Q: The two different types of light source used in fiber optic systems are the ________. A) single mode and the multimode B) LID and the DEL C) TIR and the GIM D) light-emitting diode and the injection laser diode

Q: Typically used for long distance applications, ________ propagation provides superior performance because there is a single transmission path. A) single-mode B) direct-line mode C) step-index multimode D) graded-index multimode

Q: The transmission medium used for television distribution, long distance telephone transmission, and short run computer system links is ________. A) coaxial cable B) unshielded twisted pair C) shielded twisted pair D) optical fiber

Q: The ________ class is targeted for support of next generation applications beyond 10-Gbps Ethernet. A) Category 5e/Class D B) Category 6A/Class EA C) Category 6/Class E D) Category 7/Class F

Q: ________ twisted pair is subject to external electromagnetic interference, including interference from nearby twisted pair and from noise generated in the environment. A) Standard B) Shielded C) Unshielded D) Coaxial

Q: A ________ consists of two insulated copper wires arranged in a regular spiral pattern. A) coaxial cable B) optical fiber C) cable D) twisted pair

Q: For ________ transmission media, the transmission capacity, in terms of either data rate or bandwidth, depends critically on the distance and on whether the medium is point-to-point or multipoint. A) unguided B) guided C) terrestrial microwave D) atmospheric

Q: Wireless transmission occurring through the atmosphere, outer space or water is an example of ________. A) guided media B) bandwidth C) wavelength D) unguided media

Q: Microwave is used in cellular systems.

Q: The parabolic reflective antenna is a type of antenna used in terrestrial microwave and satellite applications.

Q: The same antenna cannot be used for both transmission and reception in two way communication.

Q: Attenuation is significantly lower for optical fiber than for coaxial cable or twisted pair and is constant over a wide range.

Q: Coaxial cable can be used over longer distances and support more stations on a shared line than twisted pair.

Q: Unshielded twisted pair provides better performance at higher data rates.

Q: The most commonly used medium in the telephone network is twisted pair.

Q: Data rate and distance are not a key concern when designing a data transmission system.

Q: Microwave is used for satellite communications.

Q: Twisted pair is much less susceptible to interference and crosstalk than coaxial cable.

Q: The characteristics and quality of a data transmission are determined both by the characteristics of the medium and the characteristics of the signal.

Q: Guided media employ an antenna for transmitting through air, vacuum, or water.

Q: Coaxial cable is used to transmit both analog and digital signals.

Q: Twisted pair may only be used to transmit analog and digital signals.

Q: The transmission media that are used to convey information can be classified as guided or unguided.

Q: Because of delay distortion some of the signal components of one bit position will spill over into other bit positions causing ________ interference, which is a major limitation to maximum bit rate over a transmission channel.

Q: ________ noise is due to thermal agitation of electrons. It is present in all electronic devices and transmission media and is a function of temperature.

Q: The ratio of the power in a signal to the power contained in the noise that is present at a particular point in the transmission is the ________ ratio.

Q: The maximum rate at which data can be transmitted over a given communication path under given conditions is referred to as the ________.

Q: ________ noise is noncontinuous, consisting of irregular pulses or noise spikes of short duration and of relatively high amplitude. It is generated from a variety of causes such as lightning and faults and flaws in the communications system.

Q: Thermal noise is also referred to as ________ noise.

Q: To achieve greater distances in digital transmissions ________ are used.

Q: A means of transmitting analog signals without regard to their content is ________ transmission.

Q: A technique known as ________ is used to provide a flicker free image without increasing the bandwidth requirement.

Q: The ________ bandwidth is the band where most of the signal energy is concentrated.

Q: The ________ bandwidth of a signal is the width of the spectrum.

Q: The simplest sort of signal is a ________ signal, in which the same signal pattern repeats over time.

Q: In a ________ guided configuration more than two devices share the same medium.

Q: Twisted pair, coaxial cable and optical fiber are examples of ________ media.

Q: The designer of a communications facility must deal with four factors: the data rate that is used for digital information, the amount of noise and other impairments, the level of error rate that is acceptable and the ________ of the signal.

Q: When signals at different frequencies share the same transmission medium the result may be ________ noise. A) crosstalk B) white C) intermodulation D) impulse

Q: The rate in bits per second at which data can be communicated is the ________. A) analog transmission B) data rate C) digital transmission D) channel capacity

Q: A reduction in strength is ________. A) delay distortion B) attenuation C) pulsing D) interlacing

Q: ________ is generated by terminals. computers, and other data processing equipment and then converted into digital voltage pulses for transmissions. A) Voice B) Audio C) Binary data D) Text

Q: An example of digital data is ________ or character strings. A) interlaced B) text C) audio D) video

Q: The communication of data by the propagation and processing of signals is ________. A) interlacing B) transmission C) signaling D) effective bandwidth

Q: A(n) ________ signal is a sequence of voltage pulses that may be transmitted over a wire medium. A) audio B) text C) digital D) analog

Q: The ________ of a signal is the range of frequencies that it contains. A) spectrum B) effective bandwidth C) bandwidth D) wavelength

Q: The ________ of a signal is the distance occupied by a single cycle. A) bandwidth B) frequency C) wavelength D) amplitude

Q: The ________ is the maximum value or strength of the signal over time; typically this value is measured in volts. A) period B) phase C) frequency D) peak amplitude