How does direct sequence spread spectrum (DSSS) differ from frequency hopping spread spectrum (FHSS)?
Direct sequence spread spectrum (DSSS) and frequency hopping spread spectrum (FHSS) are the two most popular types of radios that the FCC permits to operate in the ISM (Industrial, Scientific and Medical) bands. A DSSS radio spreads its power across a very wide portion of the ISM band. As a result, it has the capability of sending high-speed data across this extended bandwidth. Wireless LAN (WLAN) radios utilizing IEEE Ethernet 802.11a/b/g standards use DSSS because of this capability. The drawback is that a DSSS radio has very short range and low interference immunity. DSSS radios attempt to surmount this by using a feature called processing gain to overcome a limited amount of interference. Processing gain is the equivalent to a software filter – however, even the best processing gain will net only 10 to 20dB of interference suppression. FHSS radios constantly change frequency – 50 times or more per second. They concentrate all their energy on a very narrow bandwidth as their transmi
Related Questions
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- How does direct sequence spread spectrum (DSSS) differ from frequency hopping spread spectrum (FHSS)?
