Which spread spectrum method uses spreading with a pseudo-random code to spread the spectrum?

• A. Direct Sequence Spread Spectrum
• B. Frequency Hopping
• C. Both
• D. None

Answer: (A)

Spreading the spectrum with a pseudo-random code is characteristic of Direct Sequence Spread Spectrum. In this approach, the data signal is multiplied by a high-rate pseudo-random chip sequence, which broadens the signal’s bandwidth. At the receiver, the same chip sequence is used to correlate and despread, recovering the original data while providing processing gain and resistance to interference.

Frequency hopping, on the other hand, changes the carrier frequency according to a pseudo-random hopping sequence. This spreads energy over different frequencies but does so by hopping, not by multiplying the data with a spreading code. So the spreading with a pseudo-random code to widen the spectrum points to Direct Sequence Spread Spectrum.