A short history of bandwidth

Since the 1920s scientists have been researching bandwidth, paying particular attention to increasing the possible loads on communication channels. Today, corporate wars are being fought over the humble copper wire of the telephone, and the race to improve infrastructure, including installing fibre optics and even electrical power lines, is on.

Types of bandwidth

Bandwidth itself is a measurement of a cable’s capacity to relay data – whether it is the sine waves of an alalog signal, the digital data of a computer or television signals.

Television

The coaxial cable and microwave transmissions used in television are considered to be a “broadband” – that is, the method has a wide bandwidth which enables the transmission of large amounts of data. Coaxial cable has a bandwidth of 500,000,000 hertz, or 500 mega hertz, and microwave transmissions are 10,000 hertz.

Recently, the change to digital television (and laying of fibre optic cables) has increased the possible bandwidth, which in turn increases the quality of the signal. Likewise, there is an increasing need for broadband in other communications, such as the Internet.

The telephone line

Because of its ubiquity, the telephone line has been a relatively cheap and simple way for communications companies to hook many people up to the Internet.

Taking advantage of the fact that voice calls use only a small amount of the available bandwidth on the Plain Old Telephone Lines (POTs), ADSL opened up the remaining bandwidth for Internet use. ADSL (Asymetric Digital Subscriber Lines) are becoming increasingly popular, as ADSL doesn’t interfere with a user’s phone line and technology developments are rapidly increasing possible transmission speeds.

Digital data

Just about anything these days can be converted into digital data and transmitted as long as the bandwidth is wide enough. Everything from music to movies, books to photographs, are now commonly exchanged over the Internet as packages of digital data.

The Internet itself is a global network of inter-connected computers. The original concept, some suggest, began as a US military experiment back in the 1960s. The ever-widening use of the Internet came about with the invention of the World Wide Web, introduced by Time Burners-Lee in 1990-91. Burners-Lee devised a way for information to be stored on servers anywhere in the world, and, using an agreed set of protocols and standards, this data could be called upon by any computer in the world.

Of course, since this time, use of the World Wide Web has exploded and with it the desire for greater bandwidth.

Pioneers of bandwidth research

So who are the inventors? While research into bandwidth had been undertaken for nearly a decade before Harry Nyquist’s name became synonymous with the term, it was his discovery in 1933 of the fundamental relationship between the bandwidth of the transmission system and the amount of data in bits that can be transmitted each second that made his name famous.

He developed the Nyquist Intersymbol Interference Theorem, which could allow a calculation of the theoretical maximum rate of data that could be sent. The introduction of this theorum enabled communications specialists to develop coding that could increase the bandwidth of a communications system.

Claude Shannon from Bells Labs recognised that Nyquist’s Theorum only established theoretical maximums, which were often not achieved in reality. In 1948, he refined the Theorum so that inherent noise could be accounted for. This became known as Shannon’s Theorum.