sofar as our discussion is concerned to perform a fur- ther classification of detectors for PN acquisition schemes depending upon whether they are of the fixed or variable integration time type. Within the category of fixed integration time detectors, one can further subdivide them into single dwell [1], [6] and multiple dwell types [7], [8] depending, respec- tively, upon whether the detector's decision is made on the basis of a sin- gle (suitably processed) fixed time observation of received signal plus noise or many such observations (not necessarily independent of one another). Depending upon the duration of the observation, or equiva- lently, the time allotted to make a decision, relative to the PN code period, single dwell time detectors can be further differentiated according to whether they utilize partial or full period code correlation. The multiple Much of the ensuing discussion on classification, as well as the unified approach presented in Sections 1.4 through 1.6, is based on the theory as formulated by Polydoros [38], Polydoros and Weber [14], and Polydoros and Simon [39]. Superscript(3)An envelope detector followed by a square-law device. Historical Survey dwell detectors differ from one another in the way in which the additional observations are used to verify the temporary decision made based on the first observation alone. More specifically, since all of the detector structures of interest make deci- sions based on a threshold comparison test of one form or another, fol- lowing a threshold exceedance of the first dwell (integration) output, the additional dwells in combination with threshold testing are used in accor- dance with a specified verification algorithm to produce a final decision on whether the code phase position under test corresponds to true synchro- nization. This verification mode of operation of the detector structure typ- ically falls into one of two categories. In the type of multiple dwell acquisition system discussed by DiCarlo [7], [8], a code phase position is immediately