Modems Chapter 11 Release 22/10/2010powered by dj

Modems

Chapter 11

Release 22/10/2010 powered by dj

Slide 2 of 24Chapter 11

Objectives

Identify the features of a modem Discuss the working of a modem Explain the different types of a modem Discuss about the external modem status LEDs Install and configure a modem Test a modem Troubleshoot a modem



Modem

Is a short form for Modulator/DemodulatorThe process of converting binary

information into analog signals is called modulation and process of converting analog signal back to binary information is called demodulation

Enables a computer to transfer data over the telephone or cable lines



Features of a Modem

Transmission speed – high data transmission rate can be achieved by compressing the data

Voice or Data communication - Data compression – if the modem is trying to

compress data that is already compressed, the compression will be less efficient

Auto answeringFax capability



Working of a Modem

Software in computer activates modem, which listens for dial tone on phone line

Modem dials a specified numberModem at receiving end answers call and

sends out a signalModem at sending end converts digital signals

to analog signals Modem at receiving end converts analog

signals back to digital signals



Basic Types of Modems Internal - A modem card

that you can plug into an expansion slot on the motherboard. It is advisable to remove the telephone line when not used

External - Connected to the PC through a cable, which is plugged into serial port on the back of the system unit. External Modem

Internal Modem



Types of Modems - I

Dial up Modem – Uses normal telephone lines (copper lines) to transmit analog signals.

Provides maximum theoretical data transfer speed of 40-50kbits/s.

Modern dial up modem providing maximum theoretical speed of 56kbits/s.

Phone line noise and quality of modem are the factors which affect the connection speed.



Types of Modems - II

ISDN Modem - Enables to send data, voice, and video over digital telephone lines or over an ordinary telephone wire. DTR is 64 kbps and requires ISDN adapter to perform conversion between digital and analog signal

DSL Modem - Carries both voice and data at the same time. It’s a high speed connection that allows the phone wires to transmit modulated digital content at high speed



Types of Modems - III

Cable Modem – Transfers data much faster than the regular telephone modems, ISDN modems, and DSL modems.

External cable modem is connected to either Ethernet card or USB port on the computer.

Communicates with a Cable Modem Termination System (CMTS) at the local cable TV company office



Types of Modems - IV

ADSL Modem – ADSL (Asymmetric Digital Subscriber Line) is a high speed data communication technology.

Allows you to transmit digital information at a high bandwidth using existing copper telephone lines. ADSL is an "always on" service (as long as your computer is powered on); this allows you to leave the downloading of larger files to continue without you.

Data stream speed of ADSL is from 512 kbps to 8 Mbps.



Question for GD Time Limit – 3 Mins

What are the different types of modems?


Sl. Types of Modems


Types of Modems - V

USB Data Card - It is a device used with computers or laptops to provide mobile wireless internet access.

Always comes with a SIM card and software setup CD.

User has to install the setup file for the first time to access the internet.

DTR is 3.1 Mbps and this type of service is provided mostly by Reliance. Tata, Idea and MTS ISP.



LEDs on External Modem

AA – Auto Answer CD – Carrier Detect RD – Receive Data SD – Send Data TR – Terminal Ready (Same DTR) CS – Clear to Send ARQ – Error Control OH – Off Hook MR – Modem Ready



Practical Activity Time Limit – 5 Mins

Ask the students to install the internal modem.



Practical

Perform the activity mentioned in Lab no. 1 in the text book:

• To install the internal & external modem and install the driver.

• Click on the image to run the video.



Practical Activity Time Limit – 5 Mins

Ask the students to connect laptop to the internet using data card.



Practical


• To configure the installed modem.



Practical


• To test the installed modem.



Troubleshooting Modems

To solve the problems that might arise due to modem itself or due to communication software such as auto dialer or dial up connection. Some of the problems are:• External modem is not working

• External modem is not receiving the commands

• Modem dials but does not connect

• Modem does not get a dial tone

• Modem is busy or not responding



Summary - I Modem is a communication device that enables a

computer to transfer data over the telephone or cable lines

Data transmission speed, data compression, data or voice communication, fax capability are the most common features of a modem

An internal modem is a modem card that you can plug into an expansion slot on the motherboard

An external modem is connected to the PC through a cable, which is plugged into serial port on the back of the system unit



Summary - II

Integrated Services Digital Network (ISDN) is a set of international communication standard for transmitting digital data over a telephone line

DSL needs a device called DSL modem to convert digital signals to analog signals and analog signals back to the digital signals

The distinguishing characteristic of ADSL over DSL is that ADSL offer high speed in downstream direction (from your Internet service provider (ISP) to you) and much slower speeds in upstream direction (from you to the ISP).



Summary - III

Now a days data cards are used with PCs and Laptops to provide mobile wireless Internet access and come with a SIM card.

A cable modem is a device that enables to connect a PC to the cable TV line.

Modem protocols are used to transfer data over a telephone line.

Configuring a modem helps to modify the properties of the modem

AT commands are used to communicate directly with the modem.

Troubleshooting modem enables to solve the problems



Explorative Work

Refer to Internet, reference books or magazine to get the information.

Do not copy the information provided in this text book. Consult your faculty for further guidance.


Modem

Sl. Make Speed Type Warranty Approx. Cost

1

2

3

4

5


Mind Map

Draw a mind map to summarize this chapter


Documents

Modems Chapter 11 Release 22/10/2010powered by dj