explain tasks performed by modem
Answers
Explanation:
Telephones are amazing: they can carry the sound of your voice from one side of the world to the other in a matter of seconds by making electricity flow down a wire. Telephones are also the power behind the Internet—without them, it would be almost impossible for most of us to go online.
The marriage of the telephone (a 19th-century technology) with the computer (a 20th-century innovation) was something of a shotgun wedding. Computer technology is largely digital: it involves storing, processing, and transmitting information in the form of numbers. But telephone technology is still partly analog: information is transmitted down phone lines as continuously varying electrical signals. How, then, do digital computers communicate across analog telephone lines designed to carry speech? Simple: they use modems, devices that turn digital information into analog sound signals for the telephone journey and then turn it back again at the other end. Think of modems as translators. Computers speak digital, and telephones speak analog, so you need modems to translate between the two.
HSDPA mobile broadband modem or dongle made by ZTE
Photo (above): A state-of-the-art HSDPA broadband wireless modem (sometimes called a "dongle") made by ZTE. You need one of these to surf the Net on a cellphone network.
Suppose you want to connect your computer to an Internet Service Provider (ISP) using an ordinary phone line. The computer at your end needs a modem to modulate its digital signals (add them on top of an analog telephone signal) so they can travel down the phone line just like the sound of your voice. Once the signals have reached the other end, they have to pass through a second modem, which demodulates them (separates them out from the telephone signal and turns them back into digital form) so the ISP computer can understand them. When the ISP computer replies, it sends its signals through a modulator back down the line to you. Then a demodulator at your end turns the signals back into digital form that your computer can understand.
A box that we call a modem thus contains two different kinds of translators. There's a modulator (for transmitting digital signals out down the phone line in analog form) and a demodulator (for receiving analog signals from the phone line and turning them back into digital form)—and that's why it's called a modem.
Modulation is simply a fancy name for transmitting information by changing the shape of a waveform. If you send information by making the peaks of a wave bigger or smaller, that's called amplitude modulation or AM (because the amplitude is the size of the wave peaks); if you send information by changing how often the peaks travel, that's frequency modulation or FM (because the frequency is the number of peaks that travel per second). You may have heard the terms AM and FM before, because they describe how radio signals travel. (You can read a slightly longer explanation of modulation in our article on radio.) please mark me as brainliest