| 摘要 |
<p>PURPOSE: To accelerate the retrieval of a code phase and to improve the estima tion accuracy of an output from a detector in respect to a radio telephone to be operated based on a spread spectrum procedure. CONSTITUTION: In an acquisition system 10 based on double dwell which are given as functions of maximum likelihood value, and are maximum likelihood, serial sliding, there are employed two thresholds different from a previously defined optimum threshold, are adopted. The two thresholds have signal dependent values and are obtained in real time by correlating a PN signal received in acquiring process with a locally generated PN sequence. In the acquisition method, the reliability of the detected signal is always monitored, decision making process is always executed, and at the time of determining the existence of reliability of the detected signal, the acquiring process is immediately stopped. In the acquisition method, a principle is employed that the optimum threshold level in a power domain is lower than the threshold level of a maximum likelihood signal by 6 dB.</p> |
