Design And Relization Of Baseband In CMMB+ Positioning Receiver

As the rapid increase of location based service(LBS)application and urgent need 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.For this reason,program of positioning based on enhanced China Mobile Multimedia Broadcasting signal(CMMB+)is proposed,and this paper's main work is studying on the key technologies of CMMB+ receiver baseband,and making the baseband implemented on FPGA,by which the important parameters can for positioning be obtained finally.The baseband on CMMB+ signal mainly includes three parts:acquisition on Non-Continuous signal,tracking with Superimposed Pseudo Code,and near-far effect inhibitory based on T-PIC.The folded correlator and parallel frequency search module is designed for CMMB+signal acquisition,and the low-precision parameter,like code-phase and residual carrier frequency,is gotten to initial the next tacking module.The tracking is used to strip pseudo-code and carrier from IF signal by carrier ring and code ring to keep on tracking on the CMMB+ signal,and,in the same time,the high-precision parameters are obtained,and navigation message is demodulated,which can be sent to next machine for position solution.For solve the strong signal' interference on the weak signal while acquisition,the near-far effect inhibitory module based on T-PIC is proposed here,and the correlation peak of weak signal can be strengthened by subtracting the copy of strong signal from the blended IF signal.The three module above is proved perfect performance by simulation.The design of baseband is finally realized on FPGA.Not only it keeps on stable tracking for practical CMMB+ signal in normal situation,but can the weak signal be detected,even lower 26dB than strong signal.The design is also optimized in the resource and timing sequence parts,and has the advantages of high-speed,stable,low-power,etc.