m [30]). Figure 1.56 illustrates the false alarm probability as a function of nor- malized test truncation time (time-out) BTo for several different values of normalized lower detection threshold n2/NoB and normalized bias b/N B. The bias values are computed from (1.263) and as such correspond to pre- detection signal-to-noise ratios y = -17.5, - 15.0, and - 12.5 dB. For suffi- ciently large BT o we observe that PEA decreases exponentially with an exponent whose magnitude increases with increasing bias but is essentially independent of lower threshold. Qualitatively this behavior is analogous to that previously discussed for the two-threshold system with regard to the behavior of false alarm probability versus normalized upper threshold and bias. Figure 1.57 illustrates the corresponding results for the average sample number Nd. Again the behavior here is qualitatively similar to that of the Pseudonoise Code Acquisition in Direct-Sequence Receivers 72 INOB=-0.3 b/No4 B = 1.009 bINO B = 1.016 b/NOB=1.028 = Figure 1.56. False alarm probability versus normalized test truncation time with normalized lower detection threshold and normalized bias as parameters. two-threshold system in that the average sample number decreases with increasing bias and increasing lower threshold (decreasing /n2/NoB). Finally, Figure 1.58 illustrates the detection probability versus normalized test trun- cation time for the same values of normalized lower detection threshold as in Figure 1.56. Here, we observe that detection probability decreases with increasing bias as expected. Furthermore, for small values of BTo, detection probability at first decreases but eventually levels off for sufficiently large values of BTo. Because of this behavior, it is reasonable to choose the trun- cation time To to satisfy the requirement on false alarm probability. Search / Lock Strategies b/N, B = 1.009 721NOB=-0.3 b/N B = 1.028 Figure 1.57. Average sample number versus normalized test truncation time with normalized lower detection threshold and normal