Chapter 5

Question 1

The technique of transmitting multiple signals over a single medium is called..

Answer 1

multiplexing.

Question 2

For multiple signals to share one medium, the medium must be ……… somehow to give each signal a portion of the total bandwidth.

Answer 2

“divided”

Question 3

What is the assignment of non-overlapping frequency ranges to each “user” of a medium?

Answer 3

Frequency division multiplexing (FDM)

Question 4

Which multiplexing technique is the oldest and is the simplest technique.

Answer 4

Frequency division multiplexing (FDM)

Question 5

What common fields of communications is used with FDM

Answer 5

-broadcast television and radio
-cable television
-cell phones.

Question 6

To allow multiple users to share a single medium, FDM assigns each user a separate ……..

Answer 6

channel

Question 7

A ………. is an assigned set of frequencies that is used to transmit the user’s signal. In frequency division multiplexing, this signal is often analog.

Answer 7

channel

Question 8

the device that accepts input from one or more users is called the
what?

Answer 8

the multiplexor

Question 9

The device attached to the receiving end of the medium that splits off each signal to deliver it to the appropriate receiver is called the what?

Answer 9

second multiplexor, or demultiplexor.

Question 10

To keep one signal from interfering with another signal, a set of unused
frequencies called a ………. is usually inserted between the two signals to
provide a form of insulation.

Answer 10

guard band

Question 11

What allows only one user at a time to transmit, and the sharing of the medium is accomplished by dividing available transmission time among users?

Answer 11

time division multiplexing (TDM)

Question 12

What are the two kinds of TDMs?

Answer 12

• synchronous TDM
• statistical TDM

Question 13

What TDM gives each incoming source signal a turn to be transmitted, proceeding through the sources in round-robin fashion?

Answer 13

Synchronous time division multiplexing (Sync TDM)

Question 14

WHAT are two types of SynTDMs?

Answer 14

• T-1 multiplexing
• Sonet/SDH

Question 15

In ……… the frames of the T-1 multiplexor’s output stream
are divided into 24 separate digitized voice/data channels of 64 kbps each

Answer 15

T-1 multiplexing

Question 16

This service known as ……. multiplexed digital data and digitized voice onto a high-speed telephone line with a data rate of 1.544 megabits per second.

Answer 16

T-1

Question 17

The T-1 multiplexed stream is a ……….. of frames.

Answer 17

continuous repetition

Question 18

…………. and ………… are powerful standards for multiplexing data streams over a single medium.

Answer 18

• Synchronous Optical Network (SONET)

-Synchronous Digital Hierarchy(SDH)

Question 19

What are two almost identical standards for the high-bandwidth
transmission of a wide range of data types over fiber-optic cable.

Answer 19

SONET and SDH

Question 20

What are two important features of SONET/SDH

Answer 20

• They are both synchronous mutiplexing techniques
• They are able to multiplex varying speed streams of data onto on fiber connection.

Question 21

SONET defines a hierarchy of signaling
levels, or data transmission rates, called what?

Answer 21

synchronous transport signals (STS)

Question 22

Which TDM transmits data only from active users and does not transmit empty time slots?

Answer 22

statistical time division multiplexing (Stat TDM)

Question 23

The inability of a single fiber-optic line to meet users’ needs is called what?

Answer 23

fiber exhaust

Question 24

What multiplexes multiple data streams onto a single fiber-optic line?

Answer 24

Wavelength division multiplexing (WDM)

Question 25

Wave division multiplexing uses different …………… to transmit multiple signals at the same time over a single medium.

Answer 25

wavelength (frequency) lasers

Question 26

The wavelength of each differently colored laser is called the what?

Answer 26

lambda

Question 27

When WDM can support a large number of lambdas, it is often called what.

Answer 27

dense wavelength division multiplexing (DWDM).

Question 28

Dense wavelength division multiplexing is an expensive way to ……………… due to the high number of differently colored lasers required in one unit.

Answer 28

transmit signals from multiple devices

Question 29

What is a less expensive technology because it is designed for short-distance connections and has only a few lambdas, with a greater space between lambdas.

Answer 29

Coarse wavelength division multiplexing (CWDM)

Question 30

What is a multiplexing technique commonly found in DSL systems?

Answer 30

Discrete multitone (DMT)

Question 31

What is a relatively new technology that has been used extensively by both the military and cellular telephone companies.

Answer 31

code division multiplexing (CDM)

Question 32

………. is the process of taking data and somehow packing more of it into the same space,

Answer 32

compression

Question 33

With a ………. technique, no
data is lost due to compression.

Answer 33

lossless compression

Question 34

If a compression technique does lose some of the data as a result of the compression process, then it is referred to as a ……….. technique.

Answer 34

lossy compression

Question 35

What technique replaces any repetitions of the same bit or byte that occur in a sequence of data with a single occurrence of the bit/byte and a run count, or simply with a run count.

Answer 35

run-length encoding

Question 36

……….. is used to compress music.

Answer 36

perceptual encoding

Question 37

………… is a common form of audio compression.

Answer 37

MP3(MPEG)

Question 38

……… is a technique that is very commonly used to compress video images.

Answer 38

JPEG