Research And Development The Rail Detecting System With Ultrasonic Technology Based On Digital Signal Processing

Railage takes a very important role in the system of traffic, so regularly testing therail is one of main methods to guarantee the safe of railage. A portable instrumentwith ultrasonic to detect the rail is the main means used for testing the railroad inChina nowadays. This type of instrument is based on analog technology. It can onlyprocess the collected ultrasonic signal simplely and is not easy to use. The incorrectresult is easily got because operators can only estimate the flaw in the rail by watchingthe ultrasonic waveform on the screen. Moreover the function of processing the dataof this instrument is not very good.This dissertation brings forward a new project to resolve the disadvantages of theold type of instrument. Its main idea is to develop a new type of instrument based onsignal processing technology. It will have many advantages contrast to the old ones,such as detection is more precision, can give an alarm automatically when find theflaw and can prevent the mistake made by operators, the data can be recorded tocomputer or other memory for future analyse, can realize the more complicatedfunction when detect the rail, use LCD to enrich the content displayed, so it is easy touse and raise the efficiency of detection.Main works having been achieved are following:1. In this dissertation the theory and technology of detection used ultrasonic wasdetail studied, and a kind of digital Portable Rail Detector mainly based on DSP andMCU was developed. The system was made up of analog circuit and digital circuit.The function of analog circuit was to emit and receive the ultrasonic, adjust thereceived signal;the function of digital circuit was to process the received signal anddisplay waveform.2. The interaction between ultrasonic and flaw in rail was researched, the ultrasonicecho was analyzed. The model of echo restraining and gain compensation wasdesigned;the software on the basis of this model was programmed. This model wasproved very effective for accurate detecting the flaw in the rail with experiments.3. A new kind of collect and compress algorithm was designed combining collectwith compress. Up to six times compressing ratio was realized when the collectionratio was 14M. The ability of capturing the effective signal and the accuracy ofdetection was raised.4. The basic functions of the Digital Flaw Detector with ultrasonic was verified byexperiments, the result of experiments and error were analyzed.