improvement results for a three-dwell system (N = 3) analogous to those given in Figures 1.19 and 1.20, respectively, for the two-dwell system. Once again as the detection probability PD approaches unity, the performance improvement ratio Td/G(3) approaches unity. A Unified Approach to Serial Search Acquisition with Fixed Dwell Times 1.4 A UNIFIED APPROACH TO SERIAL SEARCH ACQUISITION WITH FIXED DWELL TIMES We now present a unified approach [14] to predicting the performance of serial search acquisition systems which employ fixed dwell time detector structures. Included as special cases in this generalized approach are the sin- gle dwell time system and the multiple dwell time system discussed in Sections 1.2 and 1.3, respectively, as well as a fast decision-rate matched fil- ter acquisition system, which will be discussed in detail in Section 1.5. The restriction of the approach to systems with predetermined and fixed dwell times25 is based upon the desire to utilize the discrete Markov nature of the imbedded process in such systems to allow application of the flow graph techniques previously demonstrated. We begin our discussion with a descrip- tion and analysis of a generalized flow graph technique suitable for pre- dicting the acquisition performance of serial search fixed dwell time systems. 1.4.1 The Flow Graph Technique Consider a generalized serial search system of the type mentioned above where H denotes the hypothesis that the received and local codes are mis- aligned by less than a code chip (previously designated as a "hit") and H the alternate hypothesis, i.e., the relative alignment is greater than or equal to a chip. The discrete Markovian nature of the underlying process of such a system allows it to be represented by a V + 2-state flow graph, where V - 1 of the states belong to the cells corresponding to H, and one state (the v- th) corresponds to H. Since, depending on the actual value of the relative offset (misalignment) between the codes, up to either 2q/Nu or (2q/Nu) - 1 cells correspond to 