Research And Application Of Weak Signal Detection System Based On Correlation Theory

Weak signal detection technology is widely used in many fields,and it is a new technology to extract useful signal from noise.With the development of modern science and technology,the human search for the unknown field has become more and more in-depth,which makes the signal detection become more urgent,and the lower limit of signal detection put forward higher requirements at the same time.Weak signal detection in strong noise background has been a difficult problem in the field of engineering application.It is necessary to solve this problem to meet the needs of modern scientific research and technology application.Therefore,it has important theoretical significance and practical value to study the technology of weak signal detection.According to the requirement of weak signal detection,this paper make an experimental research,and study a digital weak signal detection system with high performance and high precision based on FPGA which make orthogonal vector lock-in amplifier as the core.First,this paper introduces the significance and several common detection methods of the weak signal detection,and emphatically describes lock-in amplifier with superior performance based on correlation detection.By analyzing the basic working principle of the related amplification technology and making theoretical research on the implementation algorithm,a design scheme of digital lock-in amplifier based on correlation principle is presented.And then the validity and feasibility of the method are proved by Simulink modeling and simulation analysis.Then,the hardware circuit and FPGA software programming have been done for the system.The hardware circuit includes pre amplifier and filter circuit of the signal pretreatment,FPGA digital realization circuit,signal acquisition circuit,serial port control circuit,key circuit,LCD display circuit,etc.The software part includes reference signal generation,multiplier design,FIR low-pass filter design,CORDIC rotation algorithm for amplitude / phase etc.Finally,the test and application of the system are studied.(1)A number of weak signals are made to detected,and the detection results show that the system detection error rate is less than 3%,which can be widely used in weak signal detection.(2)Take battery internal resistance detection as an example to have a test,the test results with the results of battery internal resistance tester are compared and analyzed,which shows that the system is accurate,the error rate is small,and the repeatability is good.