Design And Implementation Of RF Front-end Of Multi-channel Anti-interference ADS-B Receiver

As a new generation of air traffic monitoring technology,Automatic Dependent Surveillance-Broadcast(ADS-B)has the advantages of strong terrain adaptability,high monitoring efficiency,convenient construction and maintenance.As the low-level interference signals become more and more complex,ADS-B information is publicly exposed and is susceptible to interference signals.At present,most of the ADS-B receivers on the market are single-channel and do not have interference suppression capability.For the development of anti-interference ADS-B receiver,this thesis designs a RF front-end of multi-channel anti-interference ADS-B receiver.The RF end has the characteristics of channel consistency,high gain,high dynamic range and low noise figure,which lays a certain technical foundation for the development of anti-interference ADS-B receiver.Firstly,the thesis introduces the components of the anti-interference ADS-B receiver.Combined with the requirements of the project design,the performance indicators of RF front-end of the multi-channel anti-interference ADS-B receiver are analyzed.By comparing the different receiver schemes,the structure of the superheterodyne receiver is determined,and the indicators are assigned to each module in the RF end.Secondly,the thesis select the appropriate chip according to the design index.The performance of the chip is simulated and verified by ADS RF software.In the design of the amplifier,The amplifier was designed with impedance matching and bias circuit design.In the design of the filter,Three different bandwidth Butterworth bandpass filters are designed.A section of ADS-B is generated in MATLAB to test,compare and analyze three different bandwidth filters.In the design of the local oscillator,this paper chooses the phase-locked loop scheme.Using ADS RF software to simulate the open-loop and closed-loop phase-locked loop environment,a loop filter with a bandwidth of 10 KHz and a phase margin of 45 degrees is designed.The emitter-coupled differential amplifying circuit and the power divider are used to keep the phase difference of the local oscillator signal stable and the amplitude consistent.Add an attenuator to each channel on the RF side to keep the amplitude of each channel consistent.In the design of the mixer,a balun transformer is added to reduce the influence of channel noise.The touch screen is used to adjust the local oscillator frequency of the phase-locked loop and the attenuation of the attenuator,so that the performance parameters of each channel are consistent.Then,the performance and verification of the whole circuit are carried out in the ADS RF software,and the feasibility of the RF front-end is theoretically analyzed.Finally,the RF front-end is made into a physical object.Set up a test environment and test the modules and systems of the designed RF end.The RF front-end and the interference suppression platform are tested in joint debugging.The test results show that the indicators of the RF end are better than the design requirements.The RF end have good performance and practical value.