Research And Implementation Of Development Platform Of GPS Software Receiver Based On C#

GPS (Global Positioning System), referred to as GPS, is a radio-based positioning, navigation and timing system developed by the United States, and has a wide range of applications in the military and the civilian market. Following the Internet and mobile communication, GPS is one of pillar industries of the fastest growing information society. As the U.S. E911act promulgated and GPS modernization, location-based service (LBS) is more and more popular. LBS refers that through radio communication networks or external positioning method (such as GPS) to get the position information of a mobile terminal user, which make the GPS satellite positioning services face great challenges.This paper solved the problem that we are not capable of completing the baseband signal processing of software GPS by the use of a common CPU.Without relying on any external hardware-assisted acceleration component case, we optimized baseband signal processing algorithms, made use of multi-threading and parallel computing technology and CPU multi-core processing ability, solved the problem of large computation consuming in signal acquisition and tracking of software GPS receiver baseband signal processing.A software defined GPS receiver can compatible with multi-system and has better flexibility and adaptability.This paper mainly studies the realization algorithm of the GPS software receiver based on c#, research results are divided into the following three points:(1) A software GPS receiver platform based on C#has been built to complete baseband signal processing, including software GPS receiver system architecture, signal acquisition and tracking and positioning solver algorithms. The developing platform is based on software radio frame and flexible software interface had been adopted which enable the modules can be upgraded or substituted easily. A lot of simulations and field tests show that the platform can verify the developed algorithms and resolve the longitude and latitude accurately which surpass the traditional hardware receiver. At the same time,the base band processing messages and processing states can also be exported simultaneously.(2) In order to study the relationship between the error rate and Fault-tolerant code element number and frame synchronization performance in harsh environments, we have studied the frame synchronization algorithm basing on autocorrelation function, and found that the increasing bit error rate can affect the frame synchronization performance. Therefore, it discussed the relationship between the frame synchronization performance and the number of fault-tolerant code element number. All of these factors had been validated though real GPS intermediate frequency signals. All the satellite signals that SNR is-28dB can be synchronized by increasing a certain number of fault-tolerant code element in the frame synchronization algorithm, which means that sensitivity has been improved nearly9dB relative to conventional-19dB SNR threshold.(3)A detailed discussion is involved about signal acquisition, tracking and positioning algorithm.To cope with the conflict between no any specialized hardware acceleration and a large number of correlation calculation in the GPS baseband signal processing.In order to reduce time to first fix (TTFF), our algorithms take a full consideration the CPU efficient, memory allocation efficiency, while using the parallelization of software architecture and relying on general CPU multi-core processing power. Finally, we also discuss the parallel acceleration algorithm of tracking module.