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

Slide 3 of 24Chapter 11 Modem  Is a short form for Modulator/Demodulator  The 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 Release 22/10/2010powered by dj

Slide 4 of 24Chapter 11 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 answering  Fax capability Release 22/10/2010powered by dj

Slide 5 of 24Chapter 11 Working of a Modem  Software in computer activates modem, which listens for dial tone on phone line  Modem dials a specified number  Modem at receiving end answers call and sends out a signal  Modem at sending end converts digital signals to analog signals  Modem at receiving end converts analog signals back to digital signals Release 22/10/2010powered by dj

Slide 6 of 24Chapter 11 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 Release 22/10/2010powered by dj

Slide 7 of 24Chapter 11 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. Release 22/10/2010powered by dj

Slide 8 of 24Chapter 11 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 Release 22/10/2010powered by dj

Slide 9 of 24Chapter 11 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 Release 22/10/2010powered by dj

Slide 10 of 24Chapter 11 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. Release 22/10/2010powered by dj

Slide 11 of 24Chapter 11 Question for GD Time Limit – 3 Mins  What are the different types of modems? Release 22/10/2010powered by dj Sl.Types of Modems

Slide 12 of 24Chapter 11 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. Release 22/10/2010powered by dj

Slide 13 of 24Chapter 11 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 Release 22/10/2010powered by dj

Slide 14 of 24Chapter 11 Practical Activity Time Limit – 5 Mins  Ask the students to install the internal modem. Release 22/10/2010powered by dj

Slide 15 of 24Chapter 11 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. Release 22/10/2010powered by dj

Slide 16 of 24Chapter 11 Practical Activity Time Limit – 5 Mins  Ask the students to connect laptop to the internet using data card. Release 22/10/2010powered by dj

Slide 17 of 24Chapter 11 Practical  Perform the activity mentioned in Lab no. 2 in the text book: To configure the installed modem. Release 22/10/2010powered by dj

Slide 18 of 24Chapter 11 Practical  Perform the activity mentioned in Lab no. 3 in the text book: To test the installed modem. Release 22/10/2010powered by dj

Slide 19 of 24Chapter 11 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 Release 22/10/2010powered by dj

Slide 20 of 24Chapter 11 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 Release 22/10/2010powered by dj

Slide 21 of 24Chapter 11 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). Release 22/10/2010powered by dj

Slide 22 of 24Chapter 11 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 Release 22/10/2010powered by dj

Slide 23 of 24Chapter 11 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. Release 22/10/2010powered by dj Modem Sl.MakeSpeedTypeWarrantyApprox. Cost

Slide 24 of 24Chapter 11 Mind Map  Draw a mind map to summarize this chapter Release 22/10/2010powered by dj