Ultrasound Application Of Oxygen Concentration Measurement

Oxygen is combustion supporting gas in industrial fuel production process and gas for human survival.The testing of oxygen concentration is also one of the means of energy-saving and emission-reduction as well as biochemical control.Ultrasonic measurement technology is a new measurement technology which is developed in the modern times.The principle of this technology is to measure the transmission carrier by using the information carried by ultrasonic wave in the process of transmission.For the traditional oxygen sensor.although there are a number of advantages,it is not very suitable for accurate analysis of gases.For example.by using electrochemical oxygen concentration sensor.the concentration of oxygen cannot be measured accurately when the environmental pressure changed.Besides,when the oxygen concentration is relative high,some potential risks will exist if there is immediate contact between traditional oxygen sensor and oxygen.With the development of ultrasonic technology.testing oxygen concentration by ultrasonic technology will cover the shortage of traditional oxygen sensor.Based on the difference of measurement principle,ultrasonic measurement technology can be divided into Time-Difference method and Frequency-Difference method,etc.This dissertation will use Time-difference method to detect the concentration of gas oxygen.Using this method,the flight time of along or reverse the transmission direction of ultrasonic can be calculated.Through the information of forward flight and reverse flight time,the velocity of ultrasonic wave propagation in the medium can be calculated.The velocity of ultrasonic wave is different in different mediums.Using this principle,the corresponding oxygen concentration can be calculated by different propagation speed.Ultrasonic wave propagation in gas,due to the change of air pressure,receiving waveform produce jitter.excitation Combined with amplitLude and phase debugging.It can increase the received signal stability.Through software filtering algorithm(In a job,saving three groups of flight time,choose one of them as the time of flight),Improving the accuracy of detection.Experiments show that it can increase the accuracy of ultrasonic time of flight testing.Combined with the requirements of the actual application market.on the one hand,we should optimize design and simplify the circuit;on the other hand,a variety of filtering algorithm such as delay receiving technology.This dissertation uses Stm32 as a micro controller of the designed circuit.Stm32 adopts the ARM Cortex-M3 kernel,which is characterized by high performance,low-cost,and low power consumptionExcitation Combined with amplitude and phase debugging.Software combined with filtering algorithm.completed the prototype.Because of the experimental environment.I can only use oxygen generator to test the prototype,tests show that the prototype work well.