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In the US, FCC part 15 on unlicensed spread spectrum systems in the 902–928 MHz and 2.4 GHz bands permits more power than is allowed for non-spread-spectrum systems. Both FHSS and direct-sequence spread-spectrum (DSSS) systems can transmit at 1 watt, a thousandfold increase from the 1 milliwatt limit on non-spread-spectrum systems.
In telecommunications, especially radio communication, spread spectrum are techniques by which a signal (e.g., an electrical, electromagnetic, or acoustic) generated with a particular bandwidth is deliberately spread in the frequency domain over a wider frequency band. Spread-spectrum techniques are used for the establishment of secure ...
Hedy Lamarr, U.S. patent 2,292,387 — with co-inventor George Antheil, frequency hopping spread spectrum radio for jam-proof remote control of torpedoes. This work led to their induction into the National Inventors Hall of Fame in 2014. [3] Abraham Lincoln, [2] U.S. patent 6,469 — [method for] Buoying vessels over shoals. George Lucas [2]
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 ...
Frequency-hopping spread spectrum [498] 2014 Hedy Lamarr: 1914 Frequency-hopping spread spectrum [499] 2014 Howard Aiken: 1900 Automatic sequence controlled calculator (Harvard Mark I) [500] 2014 Mildred Dresselhaus: 1930 Lattice structure [501] 2014 Otis Boykin: 1920 Electrical resistor [502] 2014 Richard DiMarchi: 1952 Insulin Lispro [503 ...
Direct-sequence spread-spectrum transmissions multiply the symbol sequence being transmitted with a spreading sequence that has a higher rate than the original message rate. Usually, sequences are chosen such that the resulting spectrum is spectrally white. Knowledge of the same sequence is used to reconstruct the original data at the receiving ...
TRANSEC includes the use of frequency hopping, spread spectrum and the physical protection of communication links to obscure the patterns of transmission. It is particularly vital in military and government communication systems, where the security of transmitted data is critical to prevent adversaries from gathering intelligence or disrupting ...
CDMA is a spread-spectrum multiple-access technique. A spread-spectrum technique spreads the bandwidth of the data uniformly for the same transmitted power. A spreading code is a pseudo-random code in the time domain that has a narrow ambiguity function in the frequency domain, unlike other narrow pulse codes. In CDMA a locally generated code ...