A Study Of Signal Emulator For Airborne Multi-Mode Navigation System

The Multi-Mode Navigation System, consists of the Instrumental Landing System, the Microwave Landing System and Distance Measuring Equipment/Precision, starts to work when airplanes are within the distance of 200 Km and guides airplanes to safe landings. It plays a significant role in takeoff and landing, especially under atrocious weather such as rainstorms and haze, so regular detections and maintenances are necessary. Both in a military and civil aviation, the core of the system is how to generate a multi-mode navigation signal emulator, thus developing an accurate and efficient signal emulator has extraordinary effects.According to technical and applied problems existing in current studies, this paper improves the architecture of multi-mode signal emulator and makes a simulation combined with characters of multi-mode navigation baseband and radio signals. The main study are on the following.The importance of the study of multi-mode navigation emulator and domestic research situations are illustrated firstly.Secondly, relative formulations regarding on rationales of multi-mode navigation system are derived, which builds a foundation of subsequent FPGA designs.Thirdly, through simulating features of ILS, MLS and DME/P, preparations of MATLAB files Look-up Table research and references to verify the correctness of simulating waveforms are made.Fourthly, this paper analyzes signal emulator FPGA design and obtains a baseband signal waveform generation method based on importing simulating waveform files to ROM Look-up Table.Fifthly, this paper demonstrates the feasibility of a signal emulator hardware circuit and designs a selective RF channel by using radio frequency matrix chips and elliptic filters, realizing the output signals of instrument landing, microwave landing and precise ranging all from one port.Sixthly, the relationship between upper computer software and hardware realization is concluded, A kind of upper computer software based on Lab VIEW is designed and its efficiency is enhanced due to hierarchical design. Meanwhile, the important idea of design is elaborated as well.Finally, by comparing waveforms produced by signal emulator with simulating waveforms, the availability and effectiveness of signal emulator are confirmed.