Research And Implementation On Processing Algorithm For New Satellite Navigation Signal Receiver

With the constant progress of satellite navigation technology and the development ofnavigation system in many countries, new kinds of modulation mode of navigation signalincreasingly appears. BOC navigation signals are developed on the basis of the traditionalBPSK signals. BOC (m, n) modulation is typical in the new BOC navigation system. On thebasis of original traditional modulation method, the subcarrier modulation components areadded. Compared with the traditional navigation signals, the novel BOC (m, n) navigationsignals not only can exploit the limited frequency spectrum resource, but also improve thecode tracking accuracy and reduce multipath interference performance. Because of itsnarrower and multiple correlation peaks, the receiver may acquire or track the signal faultily.Hence, it is of significance and has application values to research the methods of how toreceive and process the BOC navigation signals.Firstly, on the basis of traditional BPSK signals, the modulation mode and the signalcharacteristics of BOC (m, n) are specifically introduced. Then, the modulating schematicdiagram, the correlation function and the spectrum are provided in this paper. In addition tothis, the influence to the acquisition, due to the autocorrelation ambiguity, is kindly analyzed.Secondly, the thesis introduces some common acquisition algorithms, and an acquisitionalgorithm of combination of FFT and matched filter is presented. On the basis of the principleof the algorithm, the overall design and the specific sub-modules design, and simulationresults on the FPGA are provided in the paper. Meanwhile, its logic function is tested as well.In the design of tracking, according to the navigation signal tracking theory and the classicaltwo tracking loop structure method, the new method, which is named three tracking loopstructure, is designed for the new BOC (m, n) navigation signals. In the hardware design progress, the specific design and its implementation of the correlators are mainly discussed. Inthe last part, the decoding unit module, which could decode the convolutional coding, isdesigned by the IP core in FPGA.Finally, the BOC (14,2) signal, which is generated by the analog signal source, is testedfor many times on the FPGA+DSP hardware platform. As a result, it illustrates that theadopted algorithm and hardware implementation can quickly acquire the navigation signal.Likewise, based on this, a stable tracking and decoding could be achieved at the same time.Last but not least, no abnormal situation (such as faultily acquisition etc.) occurs in the wholeprocesses.