Modem

Department of Computer Engineering,

M.S.P.V.L.Polytechnic College,Pavoorchatram.

A PresentationOn

Modem

Introduction:

• A modem [Modulator -Demodulator] is a

device.

• Data communication means transmitting

digital information form one computer to

other computers through the

comuunication channels.

Modem

Cont.,

• Communication between computers

through the existing telephone cables.

Structure of data communication through modem

Digital data

Analog data

Working principle

• The digital data from the computer is

converted into analog data by the

modem and are transmitted over the

telephone line.

Cont.,

• The analog data received from the

telephone line is converted to digital by

the modem and is given to the computer.

RS232 interface

• This interface is used to connect

computer and modem through serial port

using standard RS232C.

• The user communicated to the modem

with the help of Hays commands through

this interface.

Memory Processor and Memory

• This unit is used to control the

operations of the modem with respect to

the Hayes commands.

• DTP - Dynamic Trunking Protocol

`switches are used to set auto

answering.

Modem

Modem data pump and signal processor• This unit receives serial data and gives it

to the modulator.

• It receives demodulated data from the

demodulator and gives it to the modem

processor.

Modulator

• This unit is used to convert the digital

data from computer into analog data.

This process is called modulation.

• This is done by adding a carrier signal to

the digital signal.

Cont.,

0 0 01 1 11 1 10 0Amplitude

modulation

Demodulator

• This unit is used to convert the analog

data from telephone system into digital

data.

• This is done by eliminating the carrier

signal from analog signal.1 1 10 0 0 0 01 1 1

Demodulation

Phone interface

• Connect modem with the phone socket.

• Dial the umber for making

communication.

• Detect the incoming ring signals.

• Connect speaker for giving voice

information , ring tone , data tone,

engaged tone etc.,

Phone Socket

Types of modems

Two types of modem.

External modem

Internal modem

External modem

• External modem is separate device and is

kept outside the computer.

Internal modem

• Internal modem is a part of the computer

and is connected inside the system.

Installing

• Switch off the computer and connect the

modem.

• The computer is switched on , it detect

the modem and displays new hardware

found dialog box.

• Insert the installation CD.

Cont.,

• After completing installation close the

windows and restart the computer.

• Test the modem by the phone dialer

option given in the accessories.

….Thank you…

The END