Study And Realization Of Interference Suppression In Indoor And Outdoor Positioning Receiver

As the development of society and the advancement of technology and increasement of demand for location-based services, location services links the most dynamic three industries-satellite navigation, mobile communication and Internet in IT industry today naturally and forms a unique emerging industries that have infinitely broad prospects. In addition, as there are urgent needs for high-precision positioning service in the field of public safety emergency rescue, it has a great significance to research on the technology of indoor and outdoor high-precision positioning.However, it’s difficult to work well in complex indoor environment with satellite navigation systems,so it’s necessary to develop indoor and outdoor seamless positioning systems integrated satellite navigation and positioning system. In support of this project, this thesis is mainly studying the interference suppression technology of TC-OFDM positioning receiver from near-far effect and multipath,aimed at improving the weak signal acquisition and tracking capability and positioning signal demodulation capability of positioning receiver under the complex indoor and outdoor environment and providing protection for the indoor and outdoor high-precision positioning.Near-far effect suppression:first, this thesis proposes a cross-correlation interference mitigation algorithm that captures progressively.The idea is that the strong signal is stripped from the middle strong signal,and then the middle strong signal is stripped from the weak signal, so the strong signal,middle strong signal and weak signal can be captured by three-level demodulation.Each of the two signal strength difference is less than 24dB. After this algorithm is realized in FPGA baseband, combined base station IPDL advertised,the receiver can capture the weak signal effectively that the strength difference is 27dB matched the IPDL broadcast base station signal.Second,this thesis proposes a partial replacement code program from the spreading code parameter optimization of signal system.It’s proved that it can better inhibit near-far effect after experiment under Near-far effect inhibition platform.Multipath suppression:this thesis proposes a narrow correlation based on variable integration time from the angle of code loop adjustment. According to the multi-path model,We can generate different parameters multipath data by using matlab.And we use them to simulate capture and tracking in these methods such as MET,ahead less lag amplitude Law, narrow correlator and narrow correlator based on variable integration time.We can get a conclusion that the capability of narrow correlator based on variable integration time is best after analysis code loop phase error simulation data. It guarantees the ability of capture and tracking of the receiver baseband and improves the positioning accuracy.