Research And Realization Of GNSS Software Receiver

For its good flexibility, portability and expandability, the GPS software receiver has attracted more and more attentions, and becomes a hotspot. In this paper, an RF front end is designed with MAX2769, which is a high-performance and highly integrated GPS receiver chip made by MAXIM company. Using the RF front end, the real GPS satellite data are collected and converted to IF signal. The receiver configuration is flexible, and it can work in a variety of modes. After the actual test, the design is verified for effectiveness. By means of acquisition to identify all satellites visible to the user, and get a rough estimate value of the carrier frequency and code phase. Then through carrier and code tracking, adjusting the carrier frequency and code phase continuously to refine the coarse values. Once acquisition and tracking is achieved, the code phase, Doppler shift and navigation message can be obtained. The output will be converted into navigation data through bit synchronization, subframe matching and parity checking. According to these data the instantaneous position of the satellite and the pseudorange between the satellite and the receiver can be calculated, and then the GPS receiver’s position can be got.