The Study Of Realizing The Interface And Low-Level Control Of Electrimagnetic Interference Fault Diagnosis Based On Labwindows/CVI

Security is the eternal theme of aircraft operation. With the development and the application of avionics technology, high-tech has been widely applied to aircraft, which continuously improves its automation, concentration, digitalization, and power. Its self-test capability is also strengthened. But at the same time, the electromagnetic interference on airborne equipment and system becomes increasingly significant. The problem of electromagnetic interference is more and more serious, because the electromagnetic interference not only affects the proper operation of the system, but also may result in flying accidents. When electromagnetic interference malfunction occurs, the aircraft needs to be test in operation. Thus, there is a serious need for a non-standard test measurement which can diagnose the specific location of the fault, and provide the evidence for taking electromagnetic compatibility measures.This paper begins with the introduction of foreign advanced testing equipment from aspects of the development and requirements of electromagnetic interference testing. And then, it discusses its system hardware structure, based on the relating theories of analysis testing system, and sets up a fault diagnosis system of electromagnetic interference which can be used for nonstandard test in Lab Windows or CVI environment.This paper focuses on the practical study of system's interface and underlying control. The system has adopted GPIB card to control system hardware, and data acquisition card to optimize the spectrum analyzer, which aims to complete the data acquisition of radiation signal, processing and storage, and then displays testing results in terms of intuitive graphical data. According to the design requirements of software system, this paper gives flow chart to complete the function of electromagnetic interference fault diagnosis system, and realizes the system's interface and underlying control, by methods of multi-threading applications. This system has many functions such as the transformation of test unit, the self-calibration of instrument, the correction of antenna factor, the conversion of test unit, the spectral scanning and the spatial scanning. The study has proved that the system can be used in an ordinary environment, which is free from the site constraints of electromagnetic interference testing, and has substantially increased the system testing efficiency with use of external trigger, which is of great value.