In telecommunications, direct-sequence spread spectrum (DSSS) is a spread spectrum modulation technique. Spread spectrum systems are such that they transmit the message bearing signals using a bandwidth that is in excess of the bandwidth that is actually needed by the message signal. This spreading of the transmitted signal over a large bandwidth make the resulting wideband signal appear as a noise signal which allows greater resistance to intentional and unintentional interference with the transmitted signal.
Gustav Guanella (June 21, 1909 – January 12, 1982) was a Swiss inventor,Guanella had a strong interest in electronics, especially high-frequency (HF) techniques. While he did consulting work for various companies such as Philips, AEG and BBC, he came up with inventions resulting in 40 patent application before entering employment at BBC. Some of these early inventions related to locating and radio direction-finding solutions as predecessors to radar before and during the first years of World War II.
His most important inventions were conceived while working for BBC from 1941 onwards. It is less known that BBC had a rapidly growing electronics division besides electrical equipment manufacturing. Guanella and other outstanding engineers positioned the company in the fields of radio transmitters, power line communications, microwave links and encryption techniques.In particular, Guanella is credited as one of the inventors of the Direct Sequence Spread Spectrum (DSSS) transmission technique. The patent filing date in Switzerland was January 29, 1942. The corresponding US Patent 2405500 Means for and method of secret signaling was granted in 1946.DSSS is of considerable importance for mobile radio up to now.
Guanella is best known for the Guanella Balun,a high-frequency impedance adapter. The term balun in an abbreviation of balanced-unbalanced signals, referring to a suitable coupling at such interfaces. Patents were granted in many countries, such as US Patent 2470307 and GB 617870.Widespread use led to considerable royalty income.
In his lifetime, Guanella was inventor or co-inventor of more than 200 patents.He was not only a brilliant Swiss inventor but also a successful department manager bringing various HF products to the market.