onally Blank Chapter Chapter 1 PSEUDONOISE CODE ACQUISITION IN IDIRECT-SEQUENCE RECEIVERS One of the primary functions of a direct-sequence (DS) spread-spectrum (SS) receiver is to despread the received pseudonoise (PN) code. This is accomplished by generating a local replica of the PN code in the receiver and then synchronizing this local PN signal to the one which is superimposed on the incoming (received) waveform. Multiplication or remodulation of the incoming signal by the synchronized local PN code replica then produces the desired despreading process. The process of synchronizing the local and received PN signals is ordi- narily accomplished in two stages. Initially, a coarse alignment of the two PN signals is produced to within a small (typically less than a fraction of a chip) residual relative timing offset. The process of bringing the two codes into coarse alignment is referred to as PN acquisition. Once the incoming PN code has been acquired, a fine synchronization system takes over and con- tinuously maintains the best possible waveform alignment by means of a closed loop operation. The process of maintaining the two codes in fine syn- chronism is referred to as PN tracking. In this chapter, we focus our atten- tion on techniques and their performance for accomplishing PN acquisition. Chapter 2 deals with the companion problem of PN tracking. 1.1 HISTORICAL SURVEY If one searches through the literature which discusses PN acquisition tech- niques, the common denominator among almost all the methods is that the received and local PN signals are first multiplied1 to produce a measure of correlation between the two. This correlation measure is then processed by a suitable detector/decision rule and search strategy to decide whether the two codes are in synchronism and what to do if they're not. The The word "multiplied" is used here in the broadest sense allowing for the possibilities of active or passive, analog or digital, time continuous or time discrete correlation operations. The spe- cific differen