Research On Signal Processing And System Realization Of Microwave Solid Flowmeter

People have raised the requirements of higher accuracy,faster speed,lower cost,and more convenient use for the measurement of solids flow in industrial production.The microwave sensor transmits a 24 GHz microwave signal to the test pipeline,and receives the echo signal,which is mixed with the transmitted one.Then,the Doppler signal is obtained.And the flow value is calculated through signal acquisition and signal processing of the Doppler signal.The main contributions of the thesis are:1.The related background knowledge of the microwave solid flowmeter was explained correspondingly.The measurement principle and system composition of microwave solid flowmeter were discussed based on microwave method.Some key technologies applied in the system were also expounded,including the Doppler effect,velocity-concentration measurement,fitting algorithm,power spectrum estimation,parameter determination methods,echo signal analysis and so on.2.The hardware design scheme of microwave solid flowmeter was given,including signal processor hardware design and signal converter hardware design,the central controllers of which were both FPGA.The hardware design of the signal converter was similar to the signal processor.The design of the hardware of the FPGA circuit was presented separately.3.A communication protocol for data transmission between the three systems of the host computer,the signal processor and the signal converter was set.The FPGA program design for the signal processor and the signal converter was proposed.And a detailed description of the transmission protocol and program design between each subsystem was made.The ISE and ModelSim were used to simulate the key function modules such as AD acquisition,FIR,FFT,sliding window filtering,etc.The simulation verified the correctness of the timing.4.Conducting data analysis.First of all,the physical system and its components were introduced,including the microwave sensor,signal processor,signal converter,host computer and LCD display.A single microwave sensor flowmeter system was tested for feasibility.Then single microwave sensor and three microwave sensors were used to measure the soybean respectively.The measurement results were analyzed.The results showed that the three microwave sensors wre better than the single channel in terms of stability and accuracy.Different mass flow were measured multiple times.And the mean square error was calculated.Finally,the causes of the error was analyzed.From the measurement results,it showed that the mean squared error was generally distributed between 0.2 and 0.5,which was less than the estimated value of 1.The microwave solid flowmeter system had high measurement accuracy and was relatively stable.