The Research Of New Direct Acquisition Technology Based On BOC Modulaion

The satellite navigation technology is developing continuously in recent years, theapplication of this technology has covered in each domain of people’s life, which has becomean indispensable part of our lives. At present, there are four main global navigation staellitesystem (GNSS) in the world, that are American GPS (U.S.A.), European GALILEO, RussianGLONASS and Chinese COMPASS. There are many increasingly serious problems, such asmutual interference between signals, frequency band crowded and signal confidentiality fellsharply with the GPS technology widely used in military and civil field. It has becomeinevitable to develop a new modulation considering the significance of the satellite navigationsystem.Because the BOC (Binary Offset Carrier) modulation signal has a good performance ofthe autocorrelation function and the spectrum splitting characteristics, which can effectivelysolve the problems and possess the more excellent multi-path discrimination capability andhigher code tracking accuracy. Now the traditional PSK modulation signals have beenreplaced by BOC modulation signals in most of the navigation systems, such as the UnitedStates GPS military M code signal, the European GALILEO system E1, E5a, E5b and E6frequency channel signals, China Beidou satellite signal (COMPASS) etc. With the goodcharacteristics of the BOC modulation signal have been constantly discovered, the research ofthe BOC modulated signal synchronization acquisition technology has also become the mostconcerned problems all around the world at present.Firstly, the thesis has launched in-depth research on the BOC modulation signal, andelaborated the principle of the BOC modulation, the structure and the generation process ofthe BOC modulation signal, analyzed the BOC modulation spectrum and autocorrelationcharacteristics. In addition, this thesis has also focused on studying the generation andcharacteristic of the MBOC and AltBOC modulation signals on this basis, and the relatedMATLAB simulation was studied.Secondly, some acquisition methods of BOC modulation signals proposed by domesticand foreign studies have been launched in-depth research in the thesis, such as sidebandalgorithm, BPSK-like acquisition algorithm, three-way parallel algorithm, the subcarrierphase cancellation algorithm, the ASPeCT (Autocorrelation Side-Peak CancellationTechnique) algorithm etc. However, those algorithms had shortcoming for acquisitionmulti-peaks, hardware resources required higher, signal energy loss greatly, range of application narrow etc. The thesis has proposed a subcarrier phase cancellation algorithmbased on the thought of the average sampling and fast FFT by comparing the advantages anddisadvantages of the above algorithms. Simulation and analysis have shown that the improvedacquisition algorithm has smaller account of calculation, shorter acquisition time, and broaderapplication bound. It has shown that the algorithm is effective and reasonable. The thesisadopts the Tong algorithm as the acquisition decision strategy, which has improved thedetection probability and reduced the false-alarm probability of the system.In the end, Various key sub-modules of the BOC modulation signal acquisition algorithmhave been designed and implemented through FPGA approach, the acquisition algorithm ofBOC modulation signals has been debugged, tested and validated by FPGA through hardwareand software platforms in EP1S80B956C6chip of the Altera company.