Research And Implementation Of Portable Acoustic Analyzer

The portable acoustic analyzer is widely applied in the industrial practices.As the continuous development of the industrialization, there is an increasingdemand for the fault monitoring equipment with the upsizing and complicateddevelopment of the industrial equipment. For the actual demand of the portablefault monitoring instrument, a set of embedded high commonality portableacoustic analyzer, which analyzes the sound signal during the equipmentoperation to detect any facilities which are not easy to link the signals ofvibrate directly, is analyzed in this paper. As a part of the field failuremonitoring, the portable acoustic analyzer can be used cooperatively with thelarge fault diagnosis system.This thesis analyzes the sound signal with the Fast Fourier Transformtheory. Both FPGA and ARM skills are used to not only speed up the runningrate but also cut down the volume and power. The portable acoustic analyzeralso creates both sound meter and spectral analysis function with the EDAhardware design method and the advantage of simulation.On the basis of the analysis of design principles and functional requirements of the system, the paper designs the hardware architecture of thesystem. The selected function of the sensor is excellent. It is not necessaryelectrets condenser microphone which supply the additional power forcapacitance plate. Amplifier circuit is designed for two kinds of benefits: bothapplied to sound pressure level and to spectral analysis. Choosing theanti-aliasing filter16-bit A/D chip in the design of precision A/D conversioncircuit is in order to avoid aliasing phenomenon caused by the high frequencysignal in the process of signal sampling. A variety of voltage power supply isdesigned to make each chip stable at the nominal voltage working condition.Default5kinds of peripheral interface circuit, including the JTAG downloadinterface circuit, the AS download interface circuit, USB interface circuit, SDcard slot and RS232interface circuit, is for providing a variety of connecter forsystem debugging, upgrade and maintenance, data storage, and functionextension.Based on the methodology of EDA technology and frequency spectrumanalysis method, the paper made the selection of hardware and designed thecircuit with hardware description language. It realized the control of A/Dtransformation frequency in FPGA. Due to the low frequency A/D conversionand a higher frequency required by other operation module in data processing,PLL is used for providing the abundant clock frequency signal for the system,aiming at the different clock frequency. Because the A/D conversion moduleand other operations data processing speed is different, FIFO is used for the input/output data cache.Papers used FPGA to provide rich resources of IP core, design and realizethe function of sound level meter, used the DSP Builder to aid the design oflookup table, and made the window treatments for FTT. Coding by FFT trillionnuclear functions can realize the function of fast Fourier transform. Thecombination of Modelsim and Matlab software is for simulation andverification. In order to realize the data communication of the FPGA and ARM,ARM is used to control the show part, by displaying the output spectrum charton the LCD.In the design of each module, simulation software and logic analyzer areboth used for simulating, debugging auxiliary function and verifying thecorrectness of the result and finally completing the design of the whole system.Experiments proved that the portable acoustic analyzer had the function ofcommutating sound pressure level, analyzing and real-time displaying theacoustic signal spectrum. It complies with the design requirements, and isextensible.