A/D Acquistion System Based On The PC104

As the oil transportation piping is widely used in every part of the world,the safety detection for piping has been paid more and more attention.Because accidents frequently happen in the later stage of its operation,it becomes very important to conduct a reseach on the technology of piping detection.The reseach on the methods of signal collection, conversion,processing and compression is one of the most important design and development of piping leak detection system and it will directly affect the detection efficiency of equipmentSince the features of the pipe structure decide that the detection equipment will be sure to be subjected to the limitation of hardware,the problem of high-speed large data storage should be solved.This requires that we should not only save the maximum space in hardware design but also carry on the optimum processing to all kinds of different signals in software design.This paper mainly discusses the method of hardware system design and software compression of piping leak detection signal.By way of the judgment of leakage signal threshold and the features of the signal,indefective and defective signal can be figured out. Huffman arithmetic can be used to defective data to carry on lossless compression of low compression ratio,while wavelet transform can be used to indefective data and noise data to carry on the compression of high compression ratio.Through analog test,the compressed data can reflect the message of the original data after restoration.In hardware design,it adopts the industrial computer of PC104 and store its collected data in the industrial disk.Considering the volume of hardware is limited,AD conversion adopts 10 bit precision AD conversion chip and achieve the 100 route data conversion through controlling one AD chip by using 25-group switch to increase the rate of space utility to the utmost. The combination of Huffman and wavelet has higher compression ratio compared with the single compression arithmetic and more advantages in retaining the original data.