Modem stands for modulator-demodulator is an electronic device that convert data between the analog form used on telephone lines and the digital form used on computers.

Answered by Ashish , an ibibo Wizard, at 8:55 PM on February 27, 2008

its useing the internet purpose

Answered by viswanath1 , an ibibo Citizen, at 11:26 AM on February 24, 2008

hi yatin, [modem] modulator/demodulator, modem has become common usage. An electronic device that modulates an analog carrier, enabling digital information to be sent over analog transmission facilities.

Answered by Saurabh , an ibibo Master, at 11:44 AM on February 20, 2008

Modem (from modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from driven diodes to radio.

The most familiar example is a voiceband modem that turns the digital '1s and 0s' of a personal computer into sounds that can be transmitted over the telephone lines of Plain Old Telephone Systems (POTS), and once received on the other side, converts those 1s and 0s back into a form used by a USB, Serial, or Network connection. Modems are generally classified by the amount of data they can send in a given time, normally measured in bits per second, or "bps". They can also be classified by Baud, the number of distinct symbols transmitted per second; these numbers are directly connected, but not necessarily in linear fashion

source :
http://en.wikipedia.org/wiki/Mod em

Answered by Smarty , an ibibo Master, at 1:15 AM on February 20, 2008

well, Acronym for MODulator/DEModulator. A device that transforms digital signals from the computer into electrical impulses for transmission over telephone lines, and does the reverse in reception,modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted pair telephone line and demodulates the incoming analog signal and converts it to a digital signal for the digital device

Answered by Romi , an ibibo Master, at 9:43 PM on February 19, 2008

hi yatin well modem is a [ modulator/demodulator] A communications device that converts one form of a signal to another that is suitable for transmission over communication circuits, typically from digital to analog and then from analog to digital.

Answered by Uttam , an ibibo Master, at 12:09 PM on February 19, 2008

The word "modem" is a contraction of the words modulator-demodulator. A modem is typically used to send digital data over a phone line.

Modem modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. This enables communication between two digital networks like computers through a analogue medium like a telephone cable.

The sending modem modulates the data into a signal that is compatible with the phone line, and the receiving modem demodulates the signal back into digital data. Wireless modems convert digital data into radio signals and back.

Modems came into existence in the 1960s as a way to allow terminals to connect to computers over the phone lines.

When a terminal's modem dials a computer's modem, the terminal's modem is called the originate modem. It transmits a 1,070-hertz tone for a 0 and a 1,270-hertz tone for a 1. The computer's modem is called the answer modem, and it transmits a 2,025-hertz tone for a 0 and a 2,225-hertz tone for a 1. Because the originate and answer modems transmit different tones, they can use the line simultaneously. This is known as full-duplex operation. Modems that can transmit in only one direction at a time are known as half-duplex modems, and they are rare.

In order to create faster modems, modem designers had to use techniques far more sophisticated than frequency-shift keying. First they moved to phase-shift keying (PSK), and then quadrature amplitude modulation (QAM). These techniques allow an incredible amount of information to be crammed into the 3,000 hertz of bandwidth available on a normal voice-grade phone line. 56K modems, which actually connect at something like 48 Kbps on anything but absolutely perfect lines.

The next step in the evolution of the modem was asymmetric digital subscriber line (ADSL) modems. The word asymmetric is used because these modems send data faster in one direction than they do in another. An ADSL modem takes advantage of the fact that any normal home, apartment or office has a dedicated copper wire running between it and phone company's nearest mux or central office. This dedicated copper wire can carry far more data than the 3,000-hertz signal needed for your phone's voice channel. If both the phone company's central office and your house are equipped with an ADSL modem on your line, then the section of copper wire between your house and the phone company can act as a purely digital high-speed transmission channel. The capacity is something like 1 million bits per second (Mbps) between the home and the phone company (upstream) and 8 Mbps between the phone company and the home (downstream) under ideal conditions. The same line can transmit both a phone conversation and the digital data.

The approach an ADSL modem takes is very simple in principle. The phone line's bandwidth between 24,000 hertz and 1,100,000 hertz is divided into 4,000-hertz bands, and a virtual modem is assigned to each band. Each of these 249 virtual modems tests its band and does the best it can with the slice of bandwidth it is allocated. The aggregate of the 249 virtual modems is the total speed of the pipe.

Today we use our modems to connect to an Internet service provider (ISP), and the ISP connects us into the Internet. The Internet lets us connect to any machine in the world (see How Web Servers and the Internet Work for details). Because of the relationship between your computer, the ISP and the Internet, it is no longer appropriate to send individual characters. Instead, your modem is routing TCP/IP packets between you and your ISP.

The standard technique for routing these packets through your modem is called the Point-to-Point Protocol (PPP). The basic idea is simple -- your computer's TCP/IP stack forms its TCP/IP datagrams normally, but then the datagrams are handed to the modem for transmissio

Answered by Kannan , an ibibo Specialist, at 11:13 AM on February 19, 2008

"Modem" is an acronym that stands for "MOdulator/DEModulator". These are the technical terms for the way your modem converts information you send from your computer into sounds (the MOdulator part) which a modem on the other end of the phone line can translate back into information (the DEModulator part).

Answered by Nirmal C , an ibibo Advisor, at 12:05 AM on February 19, 2008

this is the device which is used to connect to Internet.
it is device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data.

Answered by Rahul , an ibibo Citizen, at 10:33 PM on February 18, 2008

A modem is a device that converts digital signals from a computer's serial port to the analog signals required for transmission over traditional telephone lines, and vice versa. Modem stands for modulator/demodulator. Conversion is necessary because telephone lines were initially designed to handle the analog nature of the human voice, not data.
The speed at which a modem transmits data is measured in units called bits per second or bps. The first modems ran at even less than 300 bps. Now 1200, 2400, and 9600 bps modems are considered slow. The faster models reach speeds of 14,400 and 28,800 bps. The faster the modem, the faster the data appear. Even a 28,800 bps modem, however, cannot compare to the several million bps speed that a campus Ethernet connection gives you.
Modem (from modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from driven diodes to radio.
The most familiar example is a voiceband modem that turns the digital '1s and 0s' of a personal computer into sounds that can be transmitted over the telephone lines of Plain Old Telephone Systems (POTS), and once received on the other side, converts those 1s and 0s back into a form used by a USB, Serial, or Network connection. Modems are generally classified by the amount of data they can send in a given time, normally measured in bits per second, or "bps". They can also be classified by Baud, the number of distinct symbols transmitted per second; these numbers are directly connected, but not necessarily in linear fashion (as discussed under Baud.)

Faster modems are used by Internet users every day, notably cable modems and ADSL modems. In telecommunications, "radio modems" transmit repeating frames of data at very high data rates over microwave radio links. Some microwave modems transmit more than a hundred million bits per second. Optical modems transmit data over optical fibers. Most intercontinental data links now use optical modems transmitting over undersea optical fibers. Optical modems routinely have data rates in excess of a billion (1x109) bits per second. One kilobit per second (kbit/s or kb/s or kbps) as used in this article means 1000 bits per second and not 1024 bits per second. For example, a 56k modem can transfer data at up to 56,000 bits per second over the phone line.

Answered by sanjiv dhir , an ibibo Specialist, at 10:01 PM on February 18, 2008