Spread Spectrum is a family of transmission techniques in which a Signal’s energy is deliberately spread across a Bandwidth much wider than the minimum required for the data rate. This provides resistance to narrowband interference and jamming, and allows multiple users to share the same band.
DSSS
Direct Sequence Spread Spectrum
Direct Sequence Spread Spectrum (DSSS) is a Spread Spectrum technique in which a narrowband Signal is spread over a wide Bandwidth by multiplying it with a high-rate PN sequence. Each data bit is replaced by an entire PN sequence, producing a wideband signal whose bandwidth is determined by the Chip rate rather than the data rate.
At the Receiver, correlating against the same PN sequence despreads the signal, recovering the original data while suppressing interference and noise that are uncorrelated with the sequence.
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FHSS
Frequency-Hopping Spread Spectrum
Frequency-Hopping Spread Spectrum (FHSS) is a Spread Spectrum technique in which the carrier frequency is rapidly switched among many frequencies according to a PN sequence known to both transmitter and receiver. This spreads the signal’s energy across a wide Bandwidth over time, providing resistance to narrowband interference and jamming.
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