The Research & Implementation Of VHF Navigation Signal Generation Method Based On SDR

The basic concept of the SDR is that the radio can be totally configured or defined by the software so that a common standard modular hardware platform can be used to achieve different functions, freed the radio design from hardware based and application oriented. The avionics test needs to use limited resources to build a multifunctional automatic test system(ATS). Because the signal of airborne electronic equipment are so variety and complex, including the low and high frequency signals,continuous and discrete signals, but also including some non-electrical signal, the demand of flexibility and comprehensibility is so high that general signal generator can hardly adapt it. In contrast, because its flexibility, openness and so on, generator based on software-defined radio has highlighted advantages and more responsive to needs. At the same time, it will also facilitate the teaching and research related.Compared and researched the ways of signal generation based on SDR with the character of VHF navigation signal and the requirement of avionic equipment, chose the DDWS as a plan of the VHF signal generator for the ATS. Studied and researched theory about signal sorting and modeling in ATLAS and IEEE1641, refers to the SDR`s principle, completed the signal modeling. Studied and research the ideology of LabVIEW programming, use it to program to calculated and use the waveform data. The different human-computer interface has been designed for the different purpose.The generator can provide VOR, LOC/GS, MB and IDENT signal with the changeable modulation index, carrier frequency and power, and the composite signal include the information about location. Because of its expansibility, the more signal required can be generated in the same hardware, with some necessary change in software. Through the many testing and debugging, error analysis of the measurement data has been done, and the instrument accuracy researching. Added the correcting factor about the frequency and the power which got by the curve fitting, the accuracy of the generator has been improved effectively. According to measurement results, the main performance parameters has achieved the expected targets.