Application Of FIR Digital Filter In Electromagnetic Nondestructive Testing System

Filtering technology is one of important branches in signal analysis and processing technology, which is an important technology to control electromagnetism noise and guarantee electromagnetism compatibility, and improve stability and privacy of the equipment.Due to sensitive reactions to multiple parameters, all kinds of interfering factors should be eliminated in the process of testing, and testing system demands signal processing must be real-time and flexible. However, some of the current detection systems do not have filtering systems, and some of those have only simple filter circuits, which is difficult to meet the two demands above. Along with the development of PLD device and EDA technology, using FPGA to actualize FIR filter, which meets the real-time, precision and flexibility requirement. The work mainly as follows:1.According to digital FIR filtering theory, analyze and compare the methods of designing FIR filter;2.The paper discusses the serial, parallel FIR filters deeply, and proposes the improved serial, parallel FIR filters gradually;3.In view of the improvements above are insufficient, the paper studied in-depth distributed algorithm theory. FPGA has Look-Up-Table structure itself, which is ideal for using distributed algorithm, based on the FIR filter design of the structure, pivotal multiplication in FIR filter are changed into the process of a Look-Up-Table and the process of adder computing. In the design process, giving full consideration to the contradictions of the resources and speed, FIR filter based on our final design of the cutting table DA algorithm.4.The paper uses the Matlab to simulate FIR filter based on Cutting-LUT DA algorithmic and gets the correct result. The FIR filter module is added into testing system finally. The result proved that this system is real-time, accurate and flexible.