Chapter 3: Physical Layer
Physical
Data is physically transmitted from one computer or terminal to another in the _____ layer.
Codec
Equipment used to transform analog voice signals to digital signals and digital signals to analog signals.
Manchester Encoding
Ethernet uses:
Digital and Analog
Two fundamentally different types of data are:
Serial
When all bits of a character are transferred one after another, the bits are transferred in _____ mode.
8,000
When converting analog voice data to digital signals, Pulse Code Modulation typically samples the incoming voice signal _____ times per second.
16
When sending four bits at a time using frequency modulation, the number of different frequency levels that would be needed would be _______.
Submarine Cables
When you send an email from the US to Europe, it likely is transmitted from one continent to another through one of the _____ that connects America and Europe.
Point-to-Point Circuits reduce the amount of cable required and use the circuit more efficiently than multipoint circuits.
Which is not true about point-to-point circuits?
Phase
Which of the following is a characteristic of sound waves that can be modulated to convert digital data into analog signals?
It permits only low transmission rates.
Which of the following is not a key advantage of digital transmission?
Prestige value of the type of media
Which of the following is not an important factor to consider when selecting media to be used in a network?
Fiber-Optic Cable
Which of the following media can best withstand harsh environmental conditions?
Serial transmission is slower than parallel transmission.
Which of the following statements is correct?
Bandwidth is constant across any wire, therefore distance is not relevant to its capacity
Which of the following statements is true?
Microwave
Which of the following would be considered a type of wireless media?
Bipolar
Which type of digital signaling would experience fewer errors because it has more distinct signals?
Return-to-Zero Signaling
With which type of digital signaling does the signal always return to zero volts after each bit?
Frequency Division Multiplexing (FDM)
_____ can be thought of as dividing the circuit horizontally.
Mircowave
_____ is a line-of-sight type of wireless media.
V.44
_____ is a modem standard that uses Lempel-Ziv encoding to compress data.
Quadrature Amplitude Modulation (QAM)
_____ is a modulation technique that combines two different amplitude combinations with eight different phase combinations modulation to send four bits per symbol.
VoIP
_____ is commonly used to transmit phone conversations over digital networks.
Synchronous Time Division
_____ is not a form of modulation used to transform digital data into analog signals.
Data Rate Signaling
_____ is not a type of digital signaling technique.
ASCII (American Standard Code for Information Interchange)
_____ is one of the most commonly used coding schemes used in data transmission.
Adaptive Differential Pulse Code Modulation (ADPCM)
_____ is used by IM and other applications that provide voice services over lower-speed digital circuits.
Modulation
_____ refers to changing the shape of the sound wave in different ways to represent a 1 or a 0.
Quantizing Error
_____ 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.
Dispersion
_____ refers to the spreading of the signal that different parts of the signal arrive at different times at the destination.
Propagation Delay
_____ refers to the time it takes for a signal to travel from sender to recipient (highly exaggerated with satellite transmission).
Logical Circuit
_____ refers to the transmission characteristics of the circuit.
Circuit Configuration
is the basic physical layout of the circuit.
DSL Modem
A _____ is an FDM device that splits the physical circuit into three logical circuits (phone, upstream data, downstream data).
1024
A coding scheme that uses 10 bits to represent each character is capable of representing _____ different characters.
Shared
A(n) _____ circuit is another name for a multipoint configuration.
Multiplexer
A(n) _____ divides one high-speed communication circuit into several lower-speed circuits for the primary reason of saving communication line costs.
Attenuation
Another term for the weakening of a signal over distance is:
operates by dividing the signal into different frequencies.
Frequency division multiplexing:
Full-Duplex
Having a conversation with someone using a cellular phone is an example of _________ transmission.
6
How many bits are required to sample an incoming signal 4000 times per second using 64 different amplitude levels?
128 Kbps
If each sample uses 16 bits and the number of samples taken each second is 8000; then the transmission speed on the circuit is?
Digital
In general, networks designed to transmit primarily computer data are likely to be _____.
Analog
In general, older networks and local loops designed to transmit voice data are likely to be _____.
Phase Modulation (PM)
In which type of modulation is a 1 distinguished from a 0 by shifting the direction in which the wave begins?
All of the Above
Microwave transmission:
Bandwidth
The _____ of a circuit determines a circuit's capacity.
Half-Duplex
The ability to transmit in both directions, but only in one direction at a time is an example of _____ transmission.
Modulator/Demodulator
The acronym, Modem, stands for _____.
Phase
The direction in which the sound wave begins is known as:
Multimode
The earliest type of fiber optic systems were:
Amplitude
The height of a sound wave is called its:
Digital Coding
The representation of the character A by the group of 8 bits, 01000001, is an example of:
Telecommunications Closet
The room that contains the cable termination points and the distribution frames is referred to as _____.
Guided and Wireless (Radiated)
The two basic types of media are:
Twisted Pair
The type of media usually installed on homes and businesses by the telephone company is called _____.
Wavelength Division Multiplexer (WDM)
The type of multiplexer that divides the circuit horizontally into different light frequencies that are transmitted simultaneously across many channels is a:
20 to 14,000 Hz
The typical range of human hearing is:
Splits the communication circuit vertically (with time slots) instead of horizontally
Time (non-statistical) division multiplexing differs from frequency division multiplexing because it _____.
increase the range of frequencies available for a transmission
To get more "bandwidth" in a digital transmission, you must _____.
differ widely among media
Transmission speeds:
