The term “Broadband” is ambiguous and is often confused in telecommunication field. Often people use the word broadband without thinking or knowing the real interpretation of broadband. Different criteria for “broad” have been applied in different contexts and at different times. Broadband has changed its status from being merely a technical word to a word in marketing internet business.
The Broadband Integrated Services Digital Network (B-ISDN) used the term in 1980s to refer to a broad range of bit rates, independent of physical modulation details. Broad means Wide and Band means channels in telecom world. Broadband has Its origin in physics, acoustics, and radio systems engineering. The term Broadband had been used with a meaning similar to “wideband”. After the introduction of digital telecommunications, the term was mainly used for transmission over multiple channels. 1990s witnessed a kind of evolution in telecommunications field with the internet demanding more data carrying transmission technologies. Internet was depending on Dialup access technology until the introduction of Broadband technology.
The predecessor of Broadband signal, that is Passband signal is also modulated so that it occupies higher frequencies, but passband still occupies a single channel. The key difference is that what is typically considered a broadband signal in this sense is a signal that occupies multiple (non-masking, orthogonal) passbands, thus allowing for much higher throughput over a single medium.
Broadband became popularized through the 1990s as a marketing term for Internet access that was faster than dialup access, the original Internet access technology, which was limited to 56 kbit/s.
In telecommunications, a broadband signaling method is one that handles a wide band of frequencies. “Broadband” is a relative term, understood according to its context. The wider the bandwidth of a channel, the greater the information-carrying capacity, given the same channel quality.
In radio, a very narrow band will carry Morse code, a broader band will carry speech, and a still broader band will carry music without losing the high audio frequencies required for realistic sound reproduction. This broad band is often divided into channels or “frequency bins” using passband techniques to allow frequency-division multiplexing instead of sending a higher-quality signal.
A television antenna may be described as “broadband” because it is capable of receiving a wide range of channels, while a single-frequency or Lo-VHF antenna is “narrowband” since it receives only 1 to 5 channels. The U.S. federal standard FS-1037C defines “broadband” as a synonym for wideband.
In data communications a 56k modem will transmit a data rate of 56 kilobits per second (kbit/s) over a 4-kilohertz-wide telephone line (narrowband or voiceband). The various forms of digital subscriber line (DSL) services are broadband in the sense that digital information is sent over multiple channels. Each channel is at higher frequency than the baseband voice channel, so it can support plain old telephone service on a single pair of wires at the same time. However, when that same line is converted to a non-loaded twisted-pair wire (no telephone filters), it becomes hundreds of kilohertz wide (broadband) and can carry up to 60 megabits per second usingvery-high-bitrate digital subscriber line techniques.