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Research And Realization On The Auto-spectral Method For Airborne Gamma-ray Spectrometry System

Posted on:2011-10-26Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y LuoFull Text:PDF
GTID:2120360308959339Subject:Nuclear technology and applications
Abstract/Summary:PDF Full Text Request
Airborne gamma-ray spectrometry has be used in many fields such as mineral exploration, environmental investigation, basic geological research, nuclear accident emergency radiation monitoring, environmental radiation monitoring and radioactive source search applications. And it has made the significant progress. With the development of China's economic construction, the applications study of airborne gamma-ray spectrometric will play a more important role, and will be more and more in-depth.This thesis has got financial support by National―863‖high-tech research project:―Research of airborne gamma-ray spectrometry exploration system‖(Serial number of the project: 2006AA06A207),Major research aviationγspectrometry method in the auto-spectrum. Focusing on the data of airborne gamma-ray spectrometry, the peaks which is not easy to be affected were selected as reference peak. The system which was applied the digital control gain amplifier and the digital spectroscopy technology to ensure stability. And the method combined with the search the peak and the advanced algorithms and to adjust the gain was used. In this paper three methods to achieve goals, which based on the kalman filter application and the successive approximation was adopted and multi-peak position with the PID to realize auto spectrum stabilization in airborne spectrum.At first the paper analyzes the characteristics of airborne gamma-ray spectral data. The mainly reason and methods for spectrum stabilization were summed up. On the model of non-stable we analyses relationship on spectral drift related with working time and temperature of the crystals. There were several parts to describe accordance with the choice of reference peak, the calculation of spectral drift, calibration parameters. There were several key technology to be introduced in this paper which were contain the digital control gain amplifier designed by AD734 and the digital spectroscopy technology designed by high speed ADC and CPLD and the principal controller comprised by STM32.On the part of software, the peaks position of potassium,thorium and uranium were selected. We designed the method which used the differential value between the peak which established on the form and the peak location of spectrum data to adjust the gain of the digital control gain amplifier. In this paper, kalman filter algorithm was adopted to smooth the noise based on the single peak position within the airborne spectrum.The method adopted by successive approximation was enacted to solving is existent of shortage on Previous method. To obtained good results, the method with digital PID algorithm and multi-peak position to adjust the system parameters Airborne gamma-ray spectrometry system was completed. The method under the various environments for test the airborne gamma-ray spectrometry and the correspond result were describe.The main production and innovation are:(1) The experiment for airborne gamma-ray spectrometry system was carried on. Under the model of non-stabilize, the relationship between work time and spectral drift was obtain to lay the foundation for the correction of the spectral drift on airborne gamma-ray spectrometry.(2) The method to realize auto spectrum stabilization was divided into several parts in airborne spectrum. The methods to realize auto spectrum stabilization was summed and the advantages and disadvantages in these method ware compare.(3) In order to satisfy the requirements of airborne gamma-ray spectrometry system, the structure under "software + hardware + characteristic peaks" was designed. The digital control gain amplifier and the digital spectroscopy technology were designed to reduce the influence come from the parameter change the electronic components(4) On the foundation of the good hardware, three algorithms were designed to regulate the parameter of system. It showed good effect by using the method which applied the kalman filter to smooth the noise. The result is: spectrum drift less than±2channel when resolution is 1024 channels under the static conditions in the laboratory environment that taken the Cs-137 as reference peak . But the result is not good when the system work in vehicle. When the adopted the method which using the peak area to search the peak position, using successive approximation algorithm to adjusting parameters and in-vehicle experiments. The result is: spectrum drift less than±1channel when resolution is 256 channels. To Improve the speed of the adjustment, the method which were used multiple reference peaks and the PID regulator. The result is: spectrum drift less than±1channel when resolution is 256 channels.After tests and improvement, the method had been applied to AGS-863 Airborne gamma-ray spectrometry system. It show that AGS-863 airborne gamma-ray spectrometry system is more better than The same kind product from the foreign.
Keywords/Search Tags:Airborne gamma-ray spectrometry, Auto spectrum, Spectral drift
PDF Full Text Request
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