Data Comm Chapter 3 Quiz
If each sample uses 16 bits and the number of samples taken each second is 8000, then the transmission speed on the circuit is?
need to find the answer****
A _____ is a FDM device that splits the physical circuit into three logical circuits (phone, upstream data, downstream data).
DSL modem
Digital transmission occurs when the signal sent over the transmission media constantly varies among an infinite number of states
False
In a multipoint circuit configuration, each computer has a dedicated circuit between itself and each of the other computers in the network
False
The amount of time it takes to switch between sending and receiving in half-duplex transmission is called the propagation delay
False
Microwave transmissions require a line of sight between any two points
True
One way to reduce quantizing errors is to increase the sampling rate of the analog signal
True
WDM is a version of FDM used in fiber-optic cables
True
The ability to transmit in both directions, but only in one direction at a time is an example of _____________ transmission
half-duplex
Microwave transmission:
is a type of high-frequency radio transmission
A coding scheme that uses 10 bits to represent each character is capable of representing _________ different characters
1024
When sending four bits at a time using frequency modulation, the number of different frequency levels needed is __
16
How many bits are required to sample an incoming signal 4000 times per second using 64 different amplitude levels?
6
When converting analog voice data to digital signals, Pulse Code Modulation typically samples the incoming voice signal ________ per second?
8000
If the highest freqency of a circuit is 10KHz and the lowest frequency is 900 Hz, the circuit's bandwidth is __
9.1 khz
_________ is one of the most commonly used coding schemes used in data transmission
ASCII
Which of the following is a key advantage of digital transmission?
it is more efficient than analog transmission, it is less prone to data transmission errors than analog, it is simpler to integrate video, voice and data on the same circuit
__ refers to changing the shape of an analog wave form in different ways to represent a 1 or a 0.
modulation
When you send an e-mail from the U.S. to the E.U., it is most likely to be transmitted from one continent to another through one of the ____ that connect America and Europe.
need to find answer*
Which of the following is not a digital signalling technique?
need to find answer**
A(n) __________ circuit is another name for a multipoint configuration.
shared
Which of the following is a characteristic of electromagnetic waves that can be modulated to convert digitial data into analog signals?
amplitude
Another term for the weakening of a signal over distance is:
attenuation
Lempel-Ziv encoding enables modems to support ___
data compression
A codec converts an incoming digital signal to an analog signal for transmission over an analog network
false
Baud rate is the number of bits transmitted per second
false
One form of interference with satellite transmission is called raindrop attenuation in which the transmissions are absorbed by heavy rain
false
Which of the following is the most secure guided medium?
fiber optic cable
Which is not true about point-to-point circuits?
none; everything is true: called dedicated circuits, more expensive than multipoint, are used when the connected computers generate enough traffic to fill the capacity of the communications circuit
Which of the following is not an important factor to consider when selecting media to be used in a network?
prestige value of the type of media
_ is a widely used modulation technique that combines amplitude and phase modulation
quadrature amplitude modulation
__ 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
The room that contains the cable termination points and the distribution frames is referred to as the:
telecommunication closet
The predominant method of transferring information internally in a computer is via parallel mode
true