Research On Simulation Technology For Changhe Ⅱ Navigation Signal

The Chang he Ⅱ navigation signal analog source is the Chang he Ⅱ signalgenerator equipment, which occupies an important position in the Chang he Ⅱsystem construction and receiver applications, can provide the excitation signalsimulation while its receiver development and debugging can also be used forregular inspection and testing Chang he Ⅱ receiver operational status andperformance indicators. Therefore, in consideration of China’s internationalenvironment and comprehensive strength, considering our country existing Chang heⅡ resources, taking into account national security, to carry out the Chang he Ⅱnavigation signal analog technology research, the development of the Chang he Ⅱnavigation signals analog source has important practical significance and theapplication background.Based on a detailed study of the large-scale programmable gate array (FPGA,Field Programmable Gate Array) and direct digital synthesis (DDS, Direct DigitalSynthesizer) technology, to build the whole system signal generator platform, andmakes the design and implementation of the Chang he Ⅱ navigation signal simulator.First, briefly review the history of Chang he Ⅱ system development history and itscurrent application situation, and introduced the status and research significance ofLoran-C radio navigation system at home and abroad, and then focuses on thecomposition of the system and signal system in the signal transmission process,Analysis of the signal propagation process, the traditional great-circle distancecalculation method for signal propagation delay factor, on this basis, the calculationformula was improved and the preparation of the C++program for the great circledistance, and described in detail for the DDS technology principle and technicalcharacteristics, in view of the overall system design requirements, the design schemeof FPGA+DSP system hardware platform. The FPGA as the signal generator of thesystem of Chang he Ⅱ navigation signal simulator, control reconfiguration completesignal waveform and the corresponding chain, DSP as the main controller system,complete code Chang he Ⅱ chain signal format and transmits it to the FPGA work. Inthe concrete realization of the process, the factors that affect the system signal and itsmain modules have been optimized, design and simulation waveforms to verify the correctness of the system design, and finally summarize the advantages of thisdesign method and its design process inadequate.Finally, in the build system signal generation platform, by means of the methodof combining FPGA+DSP and MATLAB，according to the principle of waveformChang he Ⅱ navigation pulse signal based on direct digital frequency synthesis (DDS)technology to design and implement a master pulse signal is located in the ShandongRongcheng generation module and standard of a head of Chang he Ⅱ navigationsignal.