Such key technologies are introduced as weak signal frequency acquisition,ultra-narrow phase-locked loop,side-band aided residual carrier loop,windowed loop technology,weighted IDF,SSME signal-to-noise estimation technology,varying loop bandwidth and varying window technique are emphasized.

Algorithm for weak signal acquisition in GPS software receiver;

The input clock can be automatic detected and divided into three segment,fulfilled the high frequency capture range,thus can supports d.

For pulsed pseudolite signal acquisition,the traditional method is saturated receiving.

The factors which affect GPS signal acquisition sensitivity were analyzed.

In order to test the effectiveness of these modules,actual collection results of signal acquisition,tracking and positioning precision were performed.

Direct-sequence Spread-spectrum Signal Acquisition Using Iterative Message-passing Techniques;

The High Dynamic of system,namely the radial distance and rate between the navigation satellite and receiver,makes phase delay and Doppler-frequency,so the problem makes signal acquiring more difficult.