s into those that cause a cell dismissal without entering the lock mode and those that do likewise by passing through the lock mode. In the case of the former, we observe from Figure 1.65 that there are only two appropriate Pseudonoise Code Acquisition in Direct-Sequence Receivers events, namely, miss and hit-miss. Thus, the corresponding component of the mean dwell time is (1.305) where PFA1 and PFA2 are, respectively, the false alarm probabilities for search states 1 and 2. For the latter case, we have already observed that only two successive hits cause an entering of the lock mode, which is accompanied by a penalty of Tp sec before rejecting the cell. Thus, this corresponding com- ponent of the mean dwell time is (1.306) Finally, adding (1.305) and (1.306) gives the mean dwell time as (1.307) Note that by letting Tp = KTd2 and substituting (1.304) and (1.307) in (1.288) and (1.289), we obtain the results for the mean and variance of the acquisi- tion time given in [1], which have also been modified as per our previous discussions to include the effects of code Doppler. Using the actual lock mode of the SLS in Figure 1.65, Tp would in reality be given by (1.300) with, in general, P FA2 replaced by P FA3 and Td2 by Td3. We conclude our discussion of this strategy by pointing out that measured values of acquisition time taken on an actual implementation of Figure 1.65 in the code acquisition portion of the Space Shuttle Orbiter system were accurate to within 1 dB of the theoretical results as predicted by the above equations. 1.9 FURTHER DISCUSSION Throughout this chapter our discussion has focused on rapid acquisition ser- ial search techniques wherein a single code phase at a time is examined for possible alignment. A natural extension of these techniques would be to use two or more paths to simultaneously search more than one code phase at a time with the hope that by increasing complexity, the acquisition time might decrease in direct relation to the number of paths used. To this end we pre- sent here a brie