Spread spectrum in the context of "Chirp"

The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 KHz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU).

Different parts of the radio spectrum are allocated by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum). Because it is a fixed resource which is in demand by an increasing number of users, the radio spectrum has become increasingly congested in recent decades, and the need to utilize it more effectively is driving modern telecommunications innovations such as trunked radio systems, spread spectrum, ultra-wideband, frequency reuse, dynamic spectrum management, frequency pooling, and cognitive radio.

Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. This allows several users to share a band of frequencies (see bandwidth). To permit this without undue interference between the users, CDMA employs spread spectrum technology and a special coding scheme (where each transmitter is assigned a code).

CDMA optimizes the use of available bandwidth as it transmits over the entire frequency range and does not limit the user's frequency range.

George Johann Carl Antheil (/ˈæntaɪl/ AN-tyle; July 8, 1900 – February 12, 1959) was an American avant-garde composer, pianist, author, and inventor whose modernist musical compositions explored the sounds – musical, industrial, and mechanical – of the early 20th century. Spending much of the 1920s in Europe, Antheil returned to the United States in the 1930s, and thereafter composed music for films, and eventually, television. As a result of this work, his style became more tonal. A man of diverse interests and talents, Antheil was constantly reinventing himself. He wrote magazine articles, an autobiography, a mystery novel, and newspaper and music columns.

In 1941, Antheil and the actress Hedy Lamarr developed a radio guidance system for Allied torpedoes that used a code (stored on a punched paper tape) to synchronize frequency changes, referred to as frequency hopping, between the transmitter and receiver. It is one of the spread spectrum techniques that became widely used in modern telecommunications. This work led to their induction into the National Inventors Hall of Fame in 2014.