modems
A modem is used to translate information transfered through telephone lines or cable.
The term stands for modulate and demodulate which changes the signal from digital, which computers use, to analog, which telephones use and then back again. A high speed connection
also requires a modem but because the information is transfered digitally it isn't required to change the signal from digital to analog but is used to creat the connection between your computer and the computer you are connecting with.
- Modems are mearsured by the speed that the information is transfered. The measuring tool is called the baud rate. Originary modems work at speeds below 2400 baud but today analog speeds of 56,000 are common. Cable, wireless or digital subscriber lines (DSL) modems can transfer information much faster with rates of 300,000 baud and up.
- Modems also use Error Correction which corrects for transmission errors by constantly checking whether the information was recieved properly or not and Compression which allows for faster data transfer rates. Information is transfered in packets. Each packet is checked for errors and is re-sent if there is an error.
Anyone who has used the Internet has noticed that at times the information travels at different speeds. Depending on the amount of information that is being transferred the information will arrive at it's destination at different times. The amount of information that can travel through a line is limited. This limit is called bandwidth.
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