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61 Cards in this Set
- Front
- Back
Attenuation |
excessive cable weakening |
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dispersion |
spreading of the signal so that different parts of the signal arrive at different times at the destination |
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Frequency modulation refers to the changing of the height of the sound wave. |
False- frequency is measured by number of waves per second |
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If each sample uses 16 bits and the number of samples taken each second is 8000; then the transmission speed on the circuit is? |
128 Kbps |
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Multimode fiber is capable of longer transmission distances than single mode fiber. |
False- single mode transmits a single light beam resulting in faster and longer distances
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____________ is a modulation technique that combines two different amplitude combinations with eight different phase combinations modulation to send four bits per symbol. |
Quadrature Amplitude Modulation |
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In a multipoint circuit configuration, each computer can use the circuit at the same time. |
False- Because it is shared, only one computer can use the circuit at a time |
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With nonreturn to zero signaling, the voltage alternates between zero and a positive or negative voltage. |
False- reach positive and negative values to represent on and off |
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_________ is the basic physical layout of the circuit. |
Circuit Configuration |
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Propagation delay is negligible with satellite transmission. |
False- Propagation delay is a disadvantage to satellite b/c the signal has to ravel out into space and back to earth, that is noticeable eve at the speed of light |
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____________ is used by IM and other applications that provide voice services over lower-speed digital circuits. |
adaptive differential pulse code modulation (ADPCM) |
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The predominant method of transferring information internally in a computer is via parallel mode. |
True- used to transfer binary info within computer |
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Fiber optic cable carries signals in traditional electrical form |
False- uses high-speed streams of light pulses from lasers or LEDs that carry info inside hair-thin strands of glass called optical fibers |
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With which type of digital signaling does the signal always return to zero volts after each bit? |
Return-to-zero signaling |
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The earliest type of fiber optic systems were: |
Multimode (step index then graded) |
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The type of media usually installed on homes and businesses by the telephone company is called ____________. |
Twisted Pair |
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A(n) __________ circuit is another name for a multipoint configuration. |
Shared |
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Digital transmission occurs when the signal sent over the transmission media constantly varies among an infinite number of states. |
False- only two states 0 and 1 |
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Digital transmission produces more errors than analog transmission. |
False |
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Multitasking means to break one high-speed physical communication circuit into several lower-speed logical circuits so that different devices can simultaneously use it. True |
False- Multiplexing |
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The typical range of human hearing is: |
20-14,000 Hz |
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__________ is a line-of-sight type of wireless media. |
Microwave |
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Which of the following statements is correct? |
Serial transmission is slower than parallel transmission. |
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Transmission speeds: |
differ widely among media |
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A codec converts an incoming digital signal to an analog signal for transmission over an analog network. True |
False- converts incoming analog signal to a digital |
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Which of the following media can best withstand harsh environmental conditions? |
fiber optic cable? |
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A physical circuit refers to the transmission characteristics of the connection. |
False |
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Nonreturn to zero is a type of unipolar signaling |
False- Bipolar |
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Time division multiplexing is more efficient that frequency division multiplexing because the guardbands used in the frequency division multiplexing or not needed. |
True |
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ASCII is the least popular code for data communications. |
False |
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______________ refers to the time it takes for a signal to travel from sender to recipient (highly exaggerated with satellite transmission). |
Propagation delay |
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Which is not true about point-to-point circuits? |
point-to-point circuits reduce the amount of cable required and use the circuit more efficiently than multipoint circuits. |
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The medium is the physical matter or substance that carries the voice or data transmission. |
True |
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The cabling that runs from the telecommunications closet to each LAN is called backbone cabling. |
False |
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WDM is a version of FDM used in fiber-optic cables. |
True |
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Which type of digital signaling would experience fewer errors because it has more distinct signals? |
bipolar |
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__________ refers to the transmission characteristics of the circuit |
logical circuit |
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Coding schemes are groups of bits that translate into the "alphabet" of any given system. |
True |
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Baud rate is the number of bits transmitted per second. |
False- the number of of times per second the signal on the communication circuit changes |
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Data compression can increase the throughput of a communication link. |
True |
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In full-duplex transmission, two stations can send and receive simultaneously. |
True |
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The acronym, Modem, stands for _________________. |
Modulator/demodulator |
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When all bits of a character are transferred one after another, the bits are transferred in ___________ mode. |
Serial |
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____________ refers to changing the shape of the sound wave in different ways to represent a 1 or a 0. |
modulation |
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In which type of modulation is a 1 distinguished from a 0 by shifting the direction in which the wave begins? |
phase modulation |
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The _____________ of a circuit determines a circuit's capacity. |
bandwidth |
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In general, networks designed to transmit primarily computer data are likely to be ________. |
digital |
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Frequency division multiplexing divides the circuit into a set of different time slots. |
False-divides circuit horizontally into series of separate channels |
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One form of interference with satellite transmission is called raindrop attenuation in which the transmissions are absorbed by heavy rain. |
True |
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Radio, microwave and satellite are all examples of guided media. |
False-Wireless media |
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Ethernet, a common LAN technology, uses Manchester encoding. |
True |
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Which of the following is the most secure wired media? |
Fiber Optic |
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Having a conversation with someone using a cellular phone is an example of _________ transmission. |
Full-duplex |
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When sending four bits at a time using frequency modulation, the number of different frequency levels that would be needed would be _______. |
16 |
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Microwave transmission: |
is a type of high frequency radio communication, requires a clear line-of-sight pathis typically used for long distance data transmission, does not require the laying of any cable, all of the above |
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Which of the following statements is true? |
bandwidth is constant across any wire, therefore distance is not relevant to its capacity |
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Statistical time division multiplexing does not require the capacity of the circuit to be equal to the sum of the combined circuits. |
True |
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Another term for the weakening of a signal over distance is: |
Attenuation |
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___________ is not a type of digital signaling technique. |
Data rate signaling |
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The room that contains the cable termination points and the distribution frames is referred to as |
telecommunications closet |
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_____________ refers to the difference between the original analog data and the approximation of that data using the techniques for translating from analog data to digital signals. |
quantizing error |