Tuesday, October 11, 2005

What is broadband?

Broadband in general refers to data transmission where multiple pieces of data are sent simultaneously to increase the effective rate of transmission. In network engineering this term is used for methods where two or more signals share a medium.Analog modems above 600 bit/s, are broadband, broadband has been more closely associated with higher data rate forms of broadband data transmission such as T-carrier and Digital Subscriber Lines while narrowband refers to a signal which occupies only a small amount of space on the radio spectrum.Example narrowband is an FM broadcast station takes up 150~200kHz on the FM band, whereas a TV station's audio is narrowband, taking up only 25kHz, and weatheradio broadcasts are even narrower than that. Therefore, the word broadband has also come to mean a relatively high rate, while the term narrowband is used to mean a relatively low rate. It is now quite common to hear a broadband method such as a 9600 bit/s modem described as narrowband, while a high rate baseband transmission such as 10BASE-T is described as broadband. The International Telecommunication Union Standardization Sector (ITU-T) recommendation I.113 has defined broadband as a transmission capacity that is faster than primary rate ISDN, at 1.5 to 2 Mbit/s. However speeds of 256 kbit/s and greater are commonly marketed as broadband and this convention is held to by policy makers and ISPs alike.The term narrowband is also used to mean the opposite of wideband instead of the opposite of broadband.

Disediakan Oleh : Wong How Ling (A108917)

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