Design Of Pipeline Magnetic Flux Leakage Inspection System With FPGA

In order to enhance the measure precision and expand the using area of the existing oil pipeline MFL (Magnetic Flux Leakage) detecting system to natural gas pipeline testing, detailed information of flux obtained by decreasing sampling time and space interval is needed. The huge amount of data produced by this will exceed the processing ability. So existing systems must be improved.FPGA (Field-Programmable Gate Array) is super large-scale, ultrafast programmable logic device that use extensively in recent years, Because it has merit of high integrated level (the single chip of system gate number integrated reaches up to ten million gates) , the high speed (200 MHz and more than) , programmable in system etc, has brought the breakthrough change for the digital system design, greatly driving the single chip and automation of the digital system design, has shortened single digital system design cycle, improved design flexibility and dependability. In the ultrafast signal progress and in measure and control in real time has very extensive application.We regard FPGA as control's core of new-type pipeline magnetic flux leakage detecting system, research and design control's core of pipeline magnetic flux leakage detecting system based on FPGA. The project includes two parts. One is the hardware. The other is the software. There are many circuits in the hardware design. The circuit of data collected by the multi channel A/D, the IDE interface circuit of data stored, the circuit of configurable program, the RS232 interface circuit of serial communication etc. The software design includes three modules of data collecting, processing, storing, which complete the multi channel A/D control, data compression, data store control function in hard disk.The module of multi channel A/D data collecting may accomplish 150 channels' data collecting, the collecting rate arrives at 500KHz; the module of data processing accomplish data compression, which exactly completes the subtract of border upon groups data and codes the data by Huffman's Encode, thecompressing rate arrives at 5:1 and relaxes the bottle-neck problem of between great capacity for liquor collecting and storing; the module of data storing, which adopts the PIO mode to transfer data, accomplishs the data stored in the disk. Experiments validate the validity of system's functions, which accord to the requirements of design. All the program fountainhead codes are writed by the VHDL language.