A Peek Into Pandora’s Box: Direct Sequence vs. Frequency Hopped Spread Spectrum

Spread spectrum signaling has properties that make it useful for hiding and encrypting signals, reducing interference to (and from) other radio transmissions, accurate ranging, multiple access, and multipath mitigation. Direct sequence (DS) and frequency hopped (FH) systems each have their strengths and weaknesses with respect to the above criteria, and these are often manifested in different ways. There is no universal agreement on whether DS or FH systems have inherently the simplest, and hence least expensive, design. DS and FH implementations in satellite systems, CDMA cellular systems, and low power unlicensed applications are discussed. FH has advantages in certain situations, but DS systems appear to be superior in most realizations.