A broadband modem is a device that connects a computer to both the Internet and to other computers on a network. The broadband modem gets its name by sending and receiving large amounts of data over a wide band of frequencies, typically via a fiber optic cable or telephone line. This data is altered by the modem when it reaches the computer to become digital signals, and converted back to frequencies when sent out. Broadband modems have replaced the older and slower technology of the dial-up modem, which required exclusive use of a phone line.
The computer modem, which is actually a combination of the words modulator and demodulator, is capable of modulating outgoing digital data into frequencies that can travel over phone or cable lines, and also demodulating the data back into digital signals when it arrives from another source. Modems originally were able to reach only very limited speeds of data transfer, and dial-up modems, which used the same frequencies as a telephone line, reached their peak at 53,000 bits per second. Asymmetrical digital subscriber lines (ADSL) as well as cable connections are able to offer a much faster data transfer rate by utilizing the upper range of telephone line frequencies in the case of ADSL, and fiber optics in the case of cable.
These methods of data transfer allow a wider range of frequencies to be used, thus making more space in which the data can travel. For example, a T1 broadband line can reach transfer rates of up 1,544,000 bits per second. Broadband is actually a relative term, and can really only be applied when comparing one method to another. Data transfer over a fiber optic line, for example, can be considered broadband when compared to a dial-up modem because of the wide array of frequencies it uses. There currently is no international standard which denotes how broad a frequency band must be before it can be defined as broad, although both fiber optic cable and ADSL are considered to fall into this category.
One important thing to note about any broadband modem is that the data transfer mechanism is asymmetrical, which means that the modem is able to download information far quicker than it can upload, typically in the area of ten times as much. A broadband modem can be either internal or external to the computer, and its size and placement make no difference to its transmission capabilities. As well, many devices such as mobile phones and laptops are now able to connect to the Internet using a wireless broadband system that functions over cell phone carrier waves. Most Internet providers will offer a broadband modem as part of a start-up package for a consumer, and it is typically available for either rental or purchase.