Back الطيف المنثور بالسلسلة المباشرة Arabic Espectre eixamplat per seqüència directa Catalan Direct Sequence Spread Spectrum Czech Direct Sequence Spread Spectrum German Espectro ensanchado por secuencia directa Spanish Otsejadaga hajaspektermodulatsioon ET DSSS Finnish Direct-sequence spread spectrum French DSSS Croatian Direct Sequence Spread Spectrum Italian
| Passband modulation |
|---|
 |
| Analog modulation |
| Digital modulation |
| Hierarchical modulation |
| Spread spectrum |
| See also |
| Multiplexing |
|---|
 |
| Analog modulation |
| Related topics |
In telecommunications, direct-sequence spread spectrum (DSSS) is a spread-spectrum modulation technique primarily used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. After the despreading or removal of the direct-sequence modulation in the receiver, the information bandwidth is restored, while the unintentional and intentional interference is substantially reduced.[1]
Swiss inventor, Gustav Guanella proposed a "means for and method of secret signals".[2] With DSSS, the message symbols are modulated by a sequence of complex values known as spreading sequence. Each element of the spreading sequence, a so-called chip, has a shorter duration than the original message symbols. The modulation of the message symbols scrambles and spreads the signal in the spectrum, and thereby results in a bandwidth of the spreading sequence. The smaller the chip duration, the larger the bandwidth of the resulting DSSS signal; more bandwidth multiplexed to the message signal results in better resistance against narrowband interference.[1][3]
Some practical and effective uses of DSSS include the code-division multiple access (CDMA) method, the IEEE 802.11b specification used in Wi-Fi networks, and the Global Positioning System.[4][5]
- ^ a b Torrieri, Don (2018). Principles of Spread-Spectrum Communication Systems, 4th ed.
- ^ "Espacenet - Bibliographic data". worldwide.espacenet.com. Retrieved December 2, 2020.
- ^ Stuber, Gordon L. (2017). Principles of Mobile Communication, 4th ed.
- ^ Rappaport, Theodore (2002). Wireless Communications Principles and Practice, 2nd ed.
- ^ Pratep, Misra; Enge, Per (2012). Global Positioning System: Signals, Measurements, and Performance, rev. 2nd ed.