ized bias as parameters. 1.8 SEARCH / LOCK STRATEGIES In this final section, we discuss the behavior and performance of the receiver's search/lock strategy (SLS) whose primary function is to logically control the transition from the search mode of operation (coarse PN acqui- sition) to the lock mode of operation (PN tracking). The intermediate state as represented by the above transition from coarse acquisition to tracking is often referred to as fine PN acquisition. In effect, it yields a verification of the validity of a "hit" produced by the search algorithm before turning control over to the tracking loop. A secondary function of the SLS is to con- tinuously monitor the receiver while in its lock mode of operation SO as to determine when a loss of synchronization has occurred thereby requiring reinitiation of the search mode. In selecting an SLS, conflicting requirements on the dwell time per test of a code phase cell must be compromised. Since rapid acquisition is desirable, Pseudonoise Code Acquisition in Direct-Sequence Receivers 10-3/L Figure 1.58. Detection probability versus normalized test truncation time with nor- malized lower detection threshold as a parameter. the dwell time Td per test cell in the search mode should be as small as prac- tical; however, a large Td is required to ensure a high probability of detect- ing the correct cell once it is found. In the lock mode, a very high probability of detection is required to ensure that the detector will not prematurely declare a loss of lock and reinitiate the search, thereby disrupting synchro- nization. However, since in the lock mode search time is no longer a strong consideration, advantage of this fact can be taken by increasing the post- Search / Lock Strategies detection integration (dwell) time to meet the requirement on detection probability. Unfortunately, since the probability of entering the lock mode due to a false alarm is non-zero, the time spent on a false lock while in the lock mode will be substantially increased by the longer integ