Network modem
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Modems allow computers to transfer data over telephone or cable lines by converting digital signals to analog and vice versa. They come in internal and external varieties and support different transmission speeds like 56kbps for X2 modems and 64kbps for ISDN. Common modem types are X2, V.90, ISDN, DSL, and cable which use different connection technologies to transmit data at varying speeds over phone lines or cable infrastructure. Proper installation and safety precautions should be followed when installing a modem.
Network modem
- 2. 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
- 3. 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
- 4. 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
- 5. 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 Internal Modem • External - Connected to the PC through a cable, which is plugged into serial port on the back of the system unit. External Modem
- 6. Types of Modems • X2 Modem – US robotics developed X2 technology to transmit data at the speed of 56 Kbps over plian old telephone service (POTS). Limitations: DTR is 40kbps from your computer to dial up server and ISP modem must support V.90 standard • V.90 Modem - Built with an assumption that one end of a modem session has a pure digital connection to the telephone line and DTR is 56 kbps
- 7. Type of Modems • 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
- 8. Types of Modems • 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 • 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
- 9. EXTRA NOTE • Best Practices – Read the modem documentation before installing a modem • Precautions – Wear an anti-static wristband – Ensure the computer is switched off and unplug the power cord from the wall socket – Disconnect all the peripheral devices attached to the computer