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1

CHAPTER 1 Introduction

1.1 History of Spread Spectrum Communications

Spread spectrum communications refer to any modulation scheme that creates a much wider

bandwidth for the transmitted signal than the information bandwidth. At first glance, it would

appear spread spectrum systems are wasteful as they require more bandwidth to transmit a

signal. However, there are several benefits to spread spectrum systems including:

1

Rejects hostile jamming, as well as unintentional interference.

2

Lowers probability of intercept because its spread over larger bandwidth, making

detection harder because signal is likely below the noise level.

3

Provides message privacy because any unauthorized listener who lacks prior knowledge

of the system and the timing cannot demodulate the signal.

4

Provides a good resistance from multipath signals.

5

Offers a high degree for accuracy for measuring distance.

6

Like in Code Division Multiple Access (CDMA), it allows simultaneous signaling on the

same frequency.

Although there is no real clear inventor of spread spectrum communication, all sources agree

that the majority of advancement and research came from efforts during World War II to provide

secure means of communication in hostile environments [1]. One of the most interesting and

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