Modems

  
Computers 
Internet 
Telephones 

 
How Things Work: Computers 
Answers to common questions by University of Virginia Physics Professor Louis A. Bloomfield. 
Complete Guide to the Internet 
A fellow ThinkQuest '97 project, offers extensive information.

Analog-Digital 
Telephones run on analog signals. The electronic pulses that travel from your phone through the phone network vary as you speak softer and stronger. But computers don’t use this analog process. They have an exact method of transmitting information: off and on. To make your computer communicate over phone lines, you’ll need a device to interpret these digital pulses into analog tones. This device is called a modem, short for MOdulator-DEModulator. 

How it works 
To connect to another computer, your modem, which is linked between your computer and phone line, calls another modem (just like a telephone would; the other modem is connected between a computer and phone line too.), and they exchange information about their capabilities, settling on a specific speed that both are capable of. Once connected, information from your computer sent to the other modem gets translated from digital to analog, runs across the phone line, and gets transferred back to digital so the computer on the other end can understand it. If you are connecting to the Internet, the modem you "dial into", will pass your information on to other computers until it reaches its destination. Whenever you want to get something from the Internet, such as an e-mail message or a web page, the modem finds the server (computer that sends out Internet information), lets it know what you want, and the server sends it back to you. This process of getting the information is called downloading. 

Modems for PCs are available as external peripherals  that connect to a "port" connector on the back of your system unit, or an internal card that rests in a slot inside the unit. When modems first became widely used, they operated at 300 to 2 400 bits per second. When first launched, the only thing computers needed to transmit was basic text, which doesn’t take much bandwidth (capacity to transmit information). Today, you’ll find the World Wide Web: filled with graphics, sounds, animations, and more. If you tried to download this page on a 300bps modem, it could take 45 minutes! To keep up with the demand of today’s Internet, most people have a 28 000 bps modem, or 28.8kpbs (kilobits per second). More recently, modem speeds have increased to 36.6kpbs, and even 56kpbs. 

Bandwidth 
A common Internet buzzword is Bandwidth, the amount of information that can travel down the wire simultaneously. Standard modems have very little bandwidth, and this is becoming more apparent every day. The World Wide Web using a normal POTS modem (POTS stands for Plain Old Telephone Service) has often been dubbed the World Wide Wait. But newer technologies are solving the problem. Some phone companies offer ISDN service, a mildly faster alternative to POTS. Other technologies are even better: Most ISP’s (Internet Service Providers, who provide you with Internet access) connect their servers using T-1 or T-3 lines, which run several MB/per second. While reliable, these servers are unrealistically expensive for home users. To compensate, Internet companies are offering highspeed consumer solutions using cable modems, which access information on the same wires as you get your cable TV. Similar technology is available from Mini-dish satellites like DirecTV. But the best consumer connection technologies aren’t modified from existing technologies. Telephone Company NBTel in New Brunswick, Canada, is wiring it's province for Vibe, capable of unparalled high speed consumer access. Once more services such as this are in place, the Internet will become a very exciting place.