11. spread spectrum communications: intro

11.1 a brief history

• SS from its origin area, military applications, has two major goal

reduce the communicator's detectability, low probability of intercept (LPI) communication system
combat the enemy-introduced interference, antijam (AJ) communication system

• SS for peacetime use, commercial applications

SS techniques is useful in the commercial applications, especially in the area of cellular mobile communications.

11.2 why spread spectrum?


11.3 basic concepts and terminology

 is modulating signal.

 is spreading signal.

 is called complex envelope.
if the complex envelope,

 is a function of the modulating signal

, then it is

.
if the complex envelope,

 is a function of the modulating signal

, then it is

.
the complex envelope for spread spectrum, in most cases, a product function is used,

.

 is the spread spectrum signal.^[각주:1]

1. 여기서 사용되는 각종 notation은 digital and analog communication systems, chapter 4, http://worthatry.tistory.com/179 와 chapter 5, http://worthatry.tistory.com/200 의 내용을 따른다. [본문으로]