Modems

Question 1

What does modem stand for ?

Answer 1

Modulator - demodulator

Question 2

Define my modem ?

Answer 2

A device that modulates an analogue carrier signal and encodes the information in digital format

It also demodulates the carrier signal to enable decoding of the transmitted information

Question 3

What are the two types of modem ?

Answer 3

Serial and parallel

Question 4

What is a serial modem ?

Answer 4

It is a modem that transmits and receives one bit at a time

Question 5

What is a parallel modem ?

Answer 5

It is a modem that transmits and receives data via a number of levels and more than one bit at a time

Question 6

What are the advantages of serial modems ?

Answer 6

Reduces the cable size needed and often less expensive

There is. I requirement for synchronisation between terminals - better over a long distance

Question 7

What is the disadvantage of a serial modem ?

Answer 7

They have much slower transmitter times

Question 8

What are the advantage of parallel modems ?

Answer 8

Faster transmission times

Question 9

What are the disadvantages of parallel modems?

Answer 9

They require an internal clock to maintain synchronicity

Require signalling commands to transmit data

Question 10

Where are modems employed ?

Answer 10

Computes, teleprinters, digital speech, narrow band phone dial up, broadband internet

Question 11

In narrow band/ phone dial up modems what are its two basic functional parts ?

Answer 11

An analogue section for generating signals and operating the phone

A digital section for set up and control

Question 12

What two modes can an narrow band / phone dial up modem be in while operational ?

Answer 12

Data mode- data is sent to and from the compute over the phone line

Command mode - the modem listens to data from the computer for commands, then carries them out

Question 13

What is a typical session for a narrowband/dial up modem ?

Answer 13

Powering up the modem which automatically is in command mode … command for dialling a number ….. once connection is established it will go into data mode

Question 14

What uses radio modems ?

Answer 14

Direct broadcast satellite
Wifi
Mobile phones

Question 15

Where are radio modems commonly deployed ?

Answer 15

High speed computer network links to outlying areas where the laying of fibre cable may not be economical

Question 16

Where are wireless data modems used ?

Answer 16

In wifi and WiMAX standards which operate at microwave frequencies

Question 17

Where is wifi principally used ?

Answer 17

In laptops for internet connections and in wireless application protocol

Question 18

When can a wifi enabled devices connect to the internet ?

Answer 18

When it is in range of a wireless network connected to the internet

Question 19

What is the coverage of one or more access points called ?

Answer 19

A hot spot

Question 20

What area can a hot spot comprise ?

Answer 20

As small as a few rooms to as large as many square miles

Question 21

What does WiMAX stand for ?

Answer 21

Worldwide interoperability for microwave access

Question 22

What is WiMAX ?

Answer 22

A telecommunications protocol that provides fixed and fully mobile internet access

Question 23

What is the advantage of WiMAX over wifi ?

Answer 23

WiMAX enables data transfer between nodes at greater distances and greater speeds

Question 24

What does WiMAX utilise ?

Answer 24

Orthogonal frequency division multiplexing

Question 25

What are three types of mobile/cellular modem ?

Answer 25

Gprs- general packet radio service

Umts- universal mobile telecommunications systems

Hspa- high speed packet access

Question 26

What is a benefit of a cellular router ?

Answer 26

It allows multiple people to connect to it

Question 27

What is a modem made for ?

Answer 27

One connection

Question 28

Explain broadband modems ?

Answer 28

They are more advanced than dial up modems , as they can modulate/ demodulate hundreds of channels simultaneously

Question 29

What does ITU stand for ?

Answer 29

International telecommunications union

Question 30

Expand ITU-R and describe thier focus ?

Answer 30

International telecommunications union - radio communications

Responsible for the management of international radio frequency spectrum and satellite orbit resources

Question 31

Expand and describe the focus of ITU-T

Answer 31

International telecommunications union- T standardisation

Set the standard relating to modems that utilise telephone circuitry

Question 32

Expand and describe ITU -D

Answer 32

International telecommunications union - development sector

Help spread equitable, sustainable and affordable access to information and communication technologies

Question 33

What does the ITU-T V series recommendations do ?

Answer 33

Provides recommendations for data communications over the telephone network,

Specifically protocols that given approved modem communications, standards and interfaces

Question 34

What are the v.23 recommendations ?

Answer 34

Half duplex between to analogue modems using FSK modulation.

600-1200 bands

600-1200 bits

Question 35

What are the v.90 recommendations ?

Answer 35

Modem allowing 56.4 kbits download to 33.6 kbits upload

Question 36

What three types of data do modems typically send ?

Answer 36

Digital facsimile

High speed data

Telemetary and telecontrol

Question 37

Expand gprs

Answer 37

General packet radio service

Question 38

Expand Umts

Answer 38

Universal mobile telecommunications systems

Question 39

Expand hspa

Answer 39

High speed packet access