Design Of Nuclear Spectrum Measurement System Based On DSP Technology

Nuclear spectrum measurement is one of the important methods for material composition analysis and radioactivity measurements.With the development of electronic and communication technology, nuclear spectrum measurement is also gradually penetrate into other areas of industrial measurement. Such as the spectrum measurement was used to measure the rock lithology density of the oil well logging .This paper bases on the project of "Modular Dynamic Formation Test System and EILog accessory equipment", which comprehensively description the nuclear spectrum measurement system based on DSP. This paper prominent nuclear spectrum measurement technology application in oil well logging, and has a good application prospect and popularize value.In the nuclear spectrum measurement technique, based on the spectrum of the objects of acquisition and analysis can be obtained directly or indirectly structure and composition of the substance elements and many other important information. Its working principle is nuclides in the process of decay, the releases of particles or ray energy is different. Detector output electrical pulse signal amplitude is proportional to the energy of incident particle or ray, by measuring the pulse amplitude, get the energy of incident particles or rays.The system uses Texas Instruments TMS320F2809 DSP as core processor, it uses high-speed 12bit ADC of internal integration as a multi-channel pulse amplitude analyzer ADC part, geting the external input nuclear signals for A/D convertion, and finally forming the multi-channel spectrum. In this system, USB communication method is used, the multi-channel spectrum data which is collected by the processor ,through the USB upload to the PC. Using VC6.0 complete the PC spectrum analysis software design, and under the spectrum analysis software system control ,the system complete the energy spectrum measurement, data transmission and other functions.In the system hardware design, this paper highlights a new TMS320F2809 DSP core processor for the nuclear spectrum measurement system, the system including probe selection, the main amplifier circuit, multi-channel analyzer, TMS320F2809 processor circuit and the USB interface circuit .In the system software design, introduced the nuclear spectrum acquisition software based on the DSP processor and the nuclear spectrum analysis software based on computer. In the nuclear spectrum acquisition software compilation process, using C language completed system initialization, A/D conversion control, DSP graphical window display, Flash program download and USB communication module. This not only improves the speed of software development, but also increase the software maintenance and expansion. In nuclear spectrum analysis software establishment process, using VC + +6.0 language achieved the nuclear spectrum real-time display, analysis processing and document manipulation treatment.After the completion of the system hardware and software design, the system was actually tested. From the test results, the system realizes 500KHz sine wave, 1MHz triangular wave and 137Cs spectrum of acquisition, real-time display and analysis, the system design was achieved to the expected goal. Meanwhile, the system is completed the initial testing which intergrated by the EILog system of Petrochina Logging Technology Company.The testing results show that the system can correctly complete spectrum data acquisition and the spectrum data will be uploaded to the monitoring software real-time. The system runs correctly and transmission reliablely.