Question 1

____ is the assignment of nonoverlapping frequency ranges to each "user" of a medium.

Accepted Answer

Frequency division multiplexing (FDM) is the assignment of nonoverlapping frequency ranges to each "user" of a medium, allowing multiple signals to be transmitted simultaneously without interference. Time division multiplexing (TDM) and transmission code multiplexing (TCM) do not involve assigning frequency ranges. Amplitude division multiplexing (ADM) is not a commonly used term in networking.

Question 2

In FDM,____ take up frequencies that might be used for other data channels,thus introducing a certain level of wastefulness.

Accepted Answer

Guard bands are used in FDM to separate channels and prevent interference between them. However, they also take up frequencies that could potentially be used for other data channels, leading to wastefulness. Therefore, guard bands introduce a certain level of inefficiency in FDM.

Question 3

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

Accepted Answer

FDM (Frequency Division Multiplexing) assigns each user a separate channel within the spectrum, allowing multiple users to share a single communication medium by dividing it into frequency bands.

Question 4

Under normal circumstances,the synchronous time division multiplexor maintains a simple ____ sampling order of the input devices.

Accepted Answer

A round-robin sampling order is the most fair and efficient method of managing input devices in a synchronous time division multiplexor. It cycles through each input device in a sequential order, ensuring that each device is given equal time slots for transmission. This method also results in minimal delay and avoids favouring any one input device over another. Therefore, A) round-robin is the best choice for maintaining a simple sampling order.

Question 5

Presently,a medium can be divided in three basic ways: a division of ____,a division of time,and a division of transmission codes.

Accepted Answer

A medium can be divided into different frequencies, which correspond to different wavelengths and determine how the information is transmitted. This division is commonly used in radio and telecommunications. Divisions based on amplitude or direction are less commonly used. A division based on time would refer to different time slots or intervals for transmitting information.

Question 6

The human ear can hear sounds only within a certain range,which for an average person is 10 Hz to 40 kHz (40,000 Hz).

Accepted Answer

The average human ear can hear sounds between 20 Hz to 20 kHz (20,000 Hz), not 10 Hz to 40 kHz.

Question 7

Since time division multiplexing was introduced,it has split into two roughly parallel but separate technologies: synchronous time division multiplexing and ____ time division multiplexing.

Accepted Answer

Statistical Time Division Multiplexing (STDM) is the correct answer because it dynamically allocates time slots based on the statistical properties of the traffic, unlike Synchronous Time Division Multiplexing (TDM) which allocates fixed time slots to each signal regardless of its activity.

Question 8

DSL is capable of achieving speeds into the millions of bits per second.

Accepted Answer

DSL (Digital Subscriber Line) is a type of internet connection technology that uses existing copper telephone lines to deliver high-speed internet access. DSL can achieve speeds into the millions of bits per second, depending on factors such as distance from the telephone exchange and the quality of the copper wiring.

Question 9

The basic way to perform compression is to look for some common pattern in the data and replace each data pattern with a symbol or symbols that will consume less space during transmission or storage.

Accepted Answer

This statement is true. Compression works by identifying patterns within data and representing them in a more efficient way, often using fewer bits or bytes to represent the same information.

Question 10

The big advantage of frequency division multiplexing over synchronous TDM is the lower noise due to the use of digital signals during transmission.

Accepted Answer

Frequency division multiplexing and synchronous TDM both use digital signals during transmission. The advantage of FDM is that it can carry more channels at once, each using a different frequency band, while synchronous TDM dynamically allocates time slots to different channels. The noise level in both techniques is affected by various factors, such as signal strength and interference, and is not inherently lower in FDM compared to synchronous TDM.

Question 11

Synchronous time division multiplexing does not require as high-speed a line as statistical time division multiplexing does.

Accepted Answer

This statement is false. Synchronous time division multiplexing requires a higher-speed line because it requires each channel to be assigned a fixed time slot, regardless of whether there is data to transmit or not. Statistical time division multiplexing, on the other hand, can dynamically allocate time slots to the channels that have data to transmit, which can result in a more efficient use of the available line bandwidth.

Question 12

First-generation cellular telephone systems allocated channels using frequency ranges within the 800 to ____ megahertz (MHz)spectrum.

Accepted Answer

First-generation cellular telephone systems allocated channels in the frequency range of 800 to 900 MHz. Among the given options, only choice B falls within this range. The frequency range was later expanded with the introduction of second and third-generation cellular systems.

Question 13

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

Accepted Answer

Sync TDM gives each incoming source signal a turn to be transmitted in a round-robin fashion. It is a method of transmitting multiple signals over a single communication link by dividing the link into time slots and allocating each slot to a specific channel. The time slots are synchronous, meaning that each source must transmit its data during its assigned time slot. This method is commonly used in telecommunications and is effective for handling multiple voice channels or data streams. FTDM and ETDM are not valid options as they are not commonly used in telecommunications and are not defined as standard TDM methods. Stat TDM is a valid TDM method, but it operates differently from Sync TDM as it allocates time slots based on demand and traffic patterns, rather than in a fixed, synchronous manner.

Question 14

Three types of synchronous time division multiplexing that are popular today are T-1 multiplexing,____ multiplexing,and SDH.

Accepted Answer

T-1 multiplexing and SDH are both examples of synchronous time division multiplexing, but IPS/SPX and RS-232 are not. The correct option is therefore C, which identifies a third popular type of synchronous TDM, namely SONET.

Question 15

Code division multiplexing is based upon a class of modulation techniques known as spread spectrum technology.

Accepted Answer

Code division multiplexing (CDM) is a form of spread spectrum technology used in telecommunications to allow multiple users to share the same communication channel by assigning unique codes to each user. Therefore, CDMA is closely related to and can be considered a form of spread spectrum technology.

Question 16

The Lempel-Ziv algorithm can be fairly effective in compressing data.

Accepted Answer

The Lempel-Ziv algorithm is a widely used lossless data compression algorithm that is effective in compressing data. It is used in various applications such as file compression, image compression, and video compression.

Question 17

A video device displays multiple (typically 30)frames per second.

Accepted Answer

This is true, as most video devices display multiple frames per second to create a smooth, continuous video playback. The exact number of frames per second may vary depending on the device and the content being displayed.

Question 18

The device that is attached to the receiving end of the medium and splits off each signal to deliver it to the appropriate receiver is called the second multiplexor,or ____.

Accepted Answer

The device that splits off each signal to deliver it to the appropriate receiver is called a demultiplexor or demux. Therefore, the best choice is D, demultiplexor. A, multiplexor, is the device that combines multiple signals into a single stream, so it is not the correct choice. B and C are not valid terms in the context of multiplexing and demultiplexing.

Question 19

The MP3 encoder produces a data stream that has a much faster data rate than that of conventional CD-quality music.

Accepted Answer

The MP3 encoder reduces the data rate compared to conventional CD-quality music by using lossy data compression to discard parts of the audio not typically heard by the human ear, resulting in a smaller file size and slower data rate.

Question 20

Code division multiplexing,while using a fairly wide bandwidth of frequencies and a complex technology,is scalable like WDM.

Accepted Answer

Code division multiplexing allows multiple users to share the same frequency band by assigning unique codes to each user's signal. This technology is scalable because adding more users to the network does not require additional frequency bandwidth, as each user can be assigned a unique code within the existing bandwidth. This makes it similar to Wavelength Division Multiplexing (WDM), which allows multiple signals to be transmitted simultaneously over different wavelengths of light in a single optical fiber.

Quiz 5: Making Connections Efficient: Multiplexing and Compression