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![Modem
Introduction:
• A modem [Modulator -Demodulator] is a device.
• Data communication means transmitting digital
information form one computer to other computers
through the comunication channels.
• Communicate equipment used for long distance data
transfer through telephone lines.
• A pair of modems are needed to communication](https://image.slidesharecdn.com/modem-201006171017/75/Types-of-Computer-Modem-1-2048.jpg)
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Types of Computer Modem
- 1. Modem Introduction: • A modem[Modulator -Demodulator] is a device. • Data communication means transmitting digital information form one computer to other computers through the comunication channels. • Communicate equipment used for long distance data transfer through telephone lines. • A pair of modems are needed to communication
- 2.
- 3. Cont., • Communication betweencomputers through the existing telephone cables.
- 4. Structure of datacommunication through modem Analogdata Digital data
- 5. Working principle • Thedigital converted data from the computer is into analog data by the over themodem and are transmitted telephone line.
- 6. Cont., • The analogdata received from the telephone line is converted to digital by the modem and is given to thecomputer.
- 7. • This unitreceives serial data and gives it to the modulator. • It receives demodulated data from the demodulator and gives it to the modem processor. • This interface is used to connect computer and modem through serial port using standard RS232C used in external modem for bits conversion.
- 8. Modulator • This unitis 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.
- 9. Cont., 0 01 10 1 1 0 1 0 1Amplitude modulation
- 10. Demodulator • This unitis used to convert the analog data from telephone system into digital data. • This is done by eliminating the carrier signal from analog signal. 1 0 1 0 1 1 0 1 0 1 0 Demodulation
- 11. Phone interface • Connectmodem with the phone socket. • Dial the umber for making communication. • Detect the incoming ring signals. • Connect speaker information, ring for tone, giving data voice tone, engaged tone etc.,
- 12.
- 13. Types of modems Twotypes of modem. External modem Internal modem
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- 15. External modem • Externalmodem is separate device and is kept outside the computer. • A 9 pin (DB9) or 25 pin serial cable connects the PC serial port to the modem. Thus CPU need not be opened during modem installation. • External modems avoid hardware conflicts such as (conflict of I/O address lines and that of interrupt lines) the external modem setup is faster and easier than internal modems.
- 16. Internal modem • Internalmodem is a part of the computer and is connected inside the system.
- 17. Internal modem • Internalmodem that plugs directly into PCI or ISA expansion slot. • Peripheral Component Interconnect • Industry Standard Architecture • modulator converts digital data from computer into analog signal which is transmitted through RJ-11 jack. (Registered Jack) • On receiver side receive the analog signal and pass them to demodulator it converts signal and sends to UART. (Universal Asynchronous Receiver/Transmitter)
- 18. Internal modem • Itthen converts serial bit data into parallel byte • Controller is used to manage overall operation of modem • Non-volatile RAM (NVRAM) it stores modem parameters.
- 19. Installing • Switch offthe 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. • After completing installation close the windows and restart the computer. • Test the modem by the phone dialer option given in the accessories.