Tracking Loop Algorithm Design of GPS Softwarre Receiver
Date Issued
2006
Date
2006
Author(s)
Ho, Ping-Tao
DOI
en-US
Abstract
GPS system combines CDMA technology and trilateration method to get the precise positions of the receivers. Most function of a GPS receiver could be implemented in software. This thesis outlines the main topics of a GPS software receiver which makes the system highly flexible when different algorithms should be tested.
The main intention here is in design and analysis of the tracking algorithms in GPS software receiver. In the beginning, a software parallel correlation is presented to enhance the speed of signal processing which can reduce the execution time. Also, efforts on the carrier tracking loops are derived including a new ATAN approximation of the carrier loop discriminator and some algorithms applied in the carrier tracking loop to track the larger Doppler frequency offset.
A loop controller design method for digital phase locked loop (DPLL) is presented. DPLL with dynamic gain control technique is implemented such that a better performance of transient response is acquired. Additionally, Gear-shifting algorithm is also applied to make the speed of the carrier tracking much faster in about 26% in comparison with the conventional one. Finally, the thorough system simulations are performed so as to accomplish the job of verification.
Subjects
衛星定位
軟體接收機
追蹤迴路
鎖相迴路
GPS
Software Receiver
Tracking
PLL
Type
thesis
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