Research On Interference Cognition And Cognitive Adaptive Beamforming

With the development of electronic information countermeasures and interference technology,the suppression of interference signals is of great significance to effective information transmission in the electromagnetic battlefield,and the detection and identification of enemy targets.It can even become a decisive factor in the victory of the electromagnetic battlefield.Based on the actual project requirements of a certain institute,this thesis studies the interference cognition and adaptive beamforming in the case of cognition,and focuses on the interference cognition method based on the received signal and the hardware implementation of the interference cognition.Combining with the hardware processing flow of interference cognition,the digital down-conversion based on CORDIC,the channelization of polyphase filters and the interference detection algorithm based on energy detection as well as parameter measurement are studied,which simplifies the complexity of related processing and saves the resources required for implementation.At the same time,the main interference cognitive processing algorithm was implemented on NI’s FPGA platform.The thesis also studied the beamforming based on interference recognition,completed the spatial parameter and frequency domain parameter recognition,and compared the beamforming performance in situations of interference recognition or non-interference cognitive under ideal conditions,as well as non-ideal cognitive conditions.In the case of spatial parameter cognition,the pattern can be applied to a higher signal-to-noise ratio without distortion than in the case of no cognition.Similarly,the adaptive beamforming pattern based on frequency domain cognition has better suppression of interference direction than without frequency domain cognition.Finally,the interference cognitive system was tested.Based on the X310,the interference signal required for the test is generated.The interference signal is received by USRP-2955 and preprocessed,and then transmitted to the LABVIEW host computer and the FPGA processing platform of PXIe-7976 through PCIe.At the same time,the digital processing and cognition of the interference signal is completed in PXIe-7976,and the cognition processing result is transmitted to the upper computer through PCIe,and the calculation and display of the relevant index parameters are completed in the upper computer.After the final test,the various indicators have reached the expected requirements of the project.