The Research Of Odor Signal Acquisition System Based On Photoelectric Detection Technology

With the intensification of urbanization and the improvement of people’s living standards. The waste produced during the production and living process also increases rapidly,and its stench seriously influences the health of human beings.In addition,The disgusting and suffocating gas from the Industrial and pharmaceutical companies is also not optimistic. So malodorous gases has become a key monitoring object. However,domestic stench pollution control is far from perfect, and there is no proven detection system.Therefore,developing a high cost-effective stench detection system is imminent.Through the research on the domestic and foreign odor measurement methods, combined with the photoelectric detection technology so far, this paper has desgined an odor signal acquisition system based on light absorption. The system which is based on photoelectric colorimetry method uses two optical path that is, each acquisition circuit module has two optical paths:one is reference light path,the other is signal path.Both signal acquisition circuits uses double-sideband amplitude modulation technology.The two signals after phase-sensitive demodulation goes into the differential amplifier to make the difference.And then,we use a wide range programmable gain amplifier to get the desired AD value. The system is suitable for a wide range of concentrations of malodorous acquisition signals, especially for measuring the faint stench signal. The system is suitable for malodorous signals acquisition which needs a wide range, especially for measuring the faint stench signal. The design can resist interference, noise, and improve the sensitivity of the acquisition, and also can increase the measuring range.Through the research and analysis, combined with the characteristics of the system,we finally determine the embedded system architecture. In order to prevent subsequent operation of complex issues,we set aside a PC interface. By comparison with other chips, we finally choose STM32F103VET6 as the main chip which makes us effectively reduce the cost and increase the flexibility of the system. This topic transplanted μC / OS-Ⅲ operating system to ensure the real-time collection of the stench gas. Because there was no graphical interface in the operating system,we transplanted STemWin graphical interface and optimized its bottom layer interface. Then we wrote module drivers in each part, and completed the signal acquisition, display, save, and human-computer interaction tasks.After the system design, we take many machine tests.The experimental results show that the high sensitivity of the system, the large-scale range, good repeatability, high stability, reliability and real-time performance can meet the requirements of this topic. The system has an important practical value and broad application prospects. In addition, because of using embedded system, There are many advantages sucn as design of low cost, small size and interface humanization.