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Question
As the mobile user covers distances well in excess of a wavelength, the urban environment changes as the user passes buildings of different heights, vacant lots, and intersections. Over these longer distances, there is a change in the average received power level about which the rapid fluctuations occur. This is referred to as ________.Answer
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Related questions
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Amplitude shift keying is less susceptible to error than binary frequency shift keying.
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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.
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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
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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
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The parabolic reflective antenna is a type of antenna used in terrestrial microwave and satellite applications.
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The most commonly used medium in the telephone network is twisted pair.
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Guided media employ an antenna for transmitting through air, vacuum, or water.
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The transmission media that are used to convey information can be classified as guided or unguided.
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________ 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.
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A means of transmitting analog signals without regard to their content is ________ transmission.
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The simplest sort of signal is a ________ signal, in which the same signal pattern repeats over time.
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________ 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:
A(n) ________ signal is a continuously varying electromagnetic wave that may be propagated over a variety of media, depending on spectrum. Examples are wire media and fiber optic cable.
A) digital
B) periodic
C) aperiodic
D) analog
Q:
A guided transmission medium is ________ if it provides a direct link between two devices and those are the only two devices sharing the medium.
A) multipoint
B) simplex
C) point-to-point
D) wireless
Q:
Delay distortion occurs because the velocity of propagation of a signal through a guided medium varies with frequency.
Q:
An analog signal can be transmitted only a limited distance before attenuation, noise, and other impairments endanger the integrityof the data.
Q:
A familiar example of analog data is audio, which, in the form of acoustic sound waves, can be perceived directly by human beings.
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It is necessary to impose a layer of control in each communicating device that provides functions such as flow control, error detection, and error control.
Q:
In ________ transmission each block of data is formatted as a frame that includes a starting and an ending flag.
A) parallel
B) asynchronous
C) analog
D) synchronous
Q:
A ________ error can occur in the presence of white noise when a slight random deterioration of the signal to noise ratio is sufficient to confuse the receiver's decision of a single bit.
A) burst
B) idle
C) single-bit
D) digital
Q:
________ is one of the most fundamental requirements in the transmission of a stream of bits from one device to another.
A) Standardization
B) Digitalization
C) Synchronization
D) Configuration
Q:
The ratio of data bits to total bits is called the code rate .
Q:
In an __________ , there is a cluster of bits in which a number of errors occur, although not necessarily all of the bits in the cluster suffer an error.
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Forward error correction schemes are frequently used in __________ transmission, where retransmission schemes are highly inefficient and error rates may be high.
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The ________ is a measure of how much additional bandwidth is required to carry data at the same data rate as without the code.
Q:
In the differential ________ scheme a binary 0 is represented by sending a signal burst of the same phase as the previous signal burst sent. A binary 1 is represented by sending a signal burst of opposite phase to the preceding one.
Q:
Multiple signals, each at a different position on the spectrum, sharing the same transmission medium, is known as frequency division ________.
Q:
In ________ the phase of the carrier signal is shifted to represent data.
A) MFSK
B) ASK
C) FSK
D) PSK
Q:
Because of their simplicity and relatively low frequency response characteristics, ________ codes are commonly used for digital magnetic recording.
A) NRZ
B) AMI
C) VSES
D) B8ZS