Electromagnetic Emission Characteristic Research Of A Beidou Vehicle Satellite Navigation Equipment

With the construction and improvement of Beidou satellite navigation system, a large number of Beidou navigation terminal arises at the historic moment. Beidou vehicle navigation equipment is one of them, and it has become a common electronic equipment installed on cars. For the electronic equipments inside the car are numerous, to make sure that Beidou navigation terminal does not affect them and to guarantee the normal work of them, we should consider its electromagnetic emission characteristics. If the electromagnetic emission of the vehicle navigation terminal is over high, on the lighter side it will impact or interfere with other electronic equipments in the car, and make them not work properly, on the sever side it may damage the corresponding electric components, thus causes instability of the system, or even could threaten the safety of driving. So to test and research the electromagnetic emission characteristics of Beidou vehicle navigation terminal is particularly important.This paper revolves around electromagnetic emission-conducted and radiated emission characteristics of a certain type of Beidou vehicle navigation terminal. In view of conducted emission, this paper expounds the experiment principle and key equipment LISN-line impedance stabilization network, which plays an important role in the test, then the test setup is given. Base on discussion and analysis of conducted emission test results of a certain type of Beidou vehicle navigation terminal, measures to suppress the conduction interference was presented. In addition, by adopting the method of time-frequency analysis -STFFT (short time fast Fourier transform),the conduction interference is further analyzed. Conducted emission of navigation terminal in different states, under different signal strength were compared.For radiated emission, the electromagnetic radiation mechanism of DC/DC converter was elaborated at first. By using equivalent model of radiation source, radiation of cable conductor was analyzed. Radiation characteristics of waveguide slot was discussed based on the theory of waveguide slot. Electric radiated emission test method was analyzed and the relationship between the beam width of one receiving antenna and the test results was discussed. The influence of different test configurations on the radiation of different polarized wave was discussed, too. Based on the phenomenon that radiated emission of a Beidou vehicle navigation terminal exceed the limit, the probable causes that lead to surpassing the limit in low and high frequency were discussed respectively, solutions were put forward and was verified through experiment. The improvement ideas against radiated emission in high frequency can provide certain reference to related researchers. Scattering parameter transfer functions and optimized method-multiple segment transfer functions were introduced to estimate the radiation field, these methods can reduce the testing fee of products under development. By analyzing the sources of uncertainty, the uncertainty of conducted emission and radiated emission were both analyzed and evaluated.