Ever have a secret decoder ring when you were a kid? First you received a secret message from someone. Then you used your decoder ring to look up the secret message's numbers, letters or symbols and find their corresponding letters to "decode" the secret message. Finally, you had the secret message back in its original form so you could read it. So the secret message might come in looking like this: * Xyz gera9sor oe piue fjk owlp And after you pass it through the decoder ring, it might look like this: * The treasure is under the boat You could even do the opposite - make your own secret message by using the decoder ring to turn a normal sentence into its secret version, and then send it off to someone else with a decoder ring. And the more you used the ring, the faster you got so you could read and/or send your messages in less time. That's what a modem is like. Modem is short for MODulator/DEmodulator. Modulating is like taking the normal message and making it secret. Demodulating is like taking the secret message and making it normal again. For example, when you type in a URL address in your browser to view a webpage, the webpage already exists on another computer called a server. But before the server sends the webpage information to you, it gets modulated into a different version that can be sent over the phone lines used by the Internet to your computer. (It's really not about keeping anything secret. Rather, phone lines were designed to carry human voice signals, not digital computer info.) The same is true if you're sending something from your computer to another computer on the Internet (e.g., sending an email). Before the info gets sent, your modem changes it so it can go over the phone lines. Then the modem on the other end changes it back so the receiving computer can read it. And the faster the modem, the faster you can receive and send info over the Internet. And that's why a modem is like a secret decoder ring. |
