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Chapter 3 - Self Encoded Spread Spectrum

3.1 Introduction to Spread Spectrum Systems

Figure 3 Conventional Spread Spectrum System

A conventional spread spectrum system, like in Figure 3 above, employs Pseudorandom

Noise (PN) code generators (or similar methods like m-sequence, Gold, Walsh codes, etc.) to

spread the signal across a wider bandwidth. A visual on how the PN codes are used to spread a

signal can be seen in Figure 4 on the next page. They present a practical implementation

problem because data recovery by the intended receiver requires prior knowledge of the codes

for signal detection. So, the PN codes have to be pre-assigned or be transmitted through the

channel to the receiver. This brings up security issues as the PN codes may have pseudo-random

properties; they also possess spectral lines and can be duplicated, thus potentially compromising

the transmission security.

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