Research And Design On Digital Filter For Audio Data Acquisition System

Digital audio signal processing is one of the hot issues in digital signal processing. Thecommunication manufactures’ research focuses on how to minimize both external distractionsand transmission loss in the process of signal acquisition and transmission. Digital audiosignal processing is a process in which audio signals is filtered to eliminate or attenuate theunwanted signals. With the continuous development of microelectronics technology. Thescientific community and industry lay much emphasis on audio filtering technology and hasworked out the implementation structures and methods of various rejectors. Striving to meetthe technical requirements of the filter as well as to reduces the development cycle and capitalinvestments. With the development of FPGA. Filters, centered on FPGA, has became amainstream design that can achieve a variety of filters simultaneously with high realibility,strong versatility, easy implementation.In the design process of the system, XC6SLX45chip in Xilinx Spartan-6seriesfunctions as the control CPU. Under the control of XC6SLX45, LM4550(AC972.1) willconvert speech signal collected by microphone into digital signal in real time, then transferthe date to the main control chip XC6SLX45to filter the audio signal and eliminate theunwanted signals. This paper introduced an audio filtering system carrying out realtime voicesignal gathering, filtering and playback. Furthermore, this multi-functional system solved theproblem of speech filter reconfiguration by making full use of the advantages of FPGA asprogramming, erasure and being used repeatedly.The filter hardware design in the audio signal acquisition system selected XC6SLX45chip in Xilinx Spartan-6series as the main control chip which realizes system control, theacquisition, playback and filtering of audio signal through programming. Audio signal filtercan be divided into three parts, namely, low-pass, high-pass and band-pass filter. Peripheralcomponents are composed of audio decoder LM4500chip, crystal oscillator, buttons, switches,LED, JTAG port, audio input and output interfaces ect. The filter hardware in the audio signalacquisition system mainly conducts the acquisition, transmission, processing and playback ofaudio signal. In the design process, FPGA programming and testing are realized throughJTAG interface and test interface.The filter software design in the audio signal acquisition system is a joint-design withFPGA associated software development platform ISE Foundation14.3, System Generatortoolkit, available from Xilinx and MATLAB, available from Math Works as its developmenttool. System Generator and MATLA are used for modular design, the acquisition, processingand playback of audio signal. While ISE Foundation undertakes the task of timing simulation,program debugging, online logic simulation and hardware test of the whole system.