Design And Implementation Of Digital Spectrum Analyzer Based On FPGA

In recent years, with the development of science and technology, spectrum analysis as a modern method of analyzing signal,which is an important basis for development, production and testing of electronic products, has been widely used in various discipline. Algorithm and implementation technology of high-resolution, real-time broadband digital spectrum analysis are constantly developed, and they have been a focus in design of circuits and system.With the development of microelectronics and signal processing, the design of electronic system is no longer use a variety of general-purpose IC to design PCB board, but use large-scale FPGA(Field Programmable Gate Array) or ASIC(Application Specific Integrated Circuits) as the physical carrier to design system chip SOPC(System On Programmable Chip) or SOC(System On a Chip). With the rapid development of EDA tools, it is easy to achieve the whole design of system in FPGA from behavior algorithm level (system level) to physical structure level. In particular, the software of Quartus II and Nios II IDE from Altera Corporation provide a great convenience for achieving SOPC system based on FPGA embedded IP cores. So, there are many advantages to use digital signal processing methods to achieve the signal frequency analysis. First of all, a digital programming system has the flexibility to reconfigure the signal processing operations by changing the program, while the analog system needs to be re-produced to reconfigure the circuit. Secondly, the digital system can easily control the precision of signal processing by specifying the system word length and using floating-point operations, while the analog circuit can not allow designers to control accuracy because of the fault tolerance of the device. Finally, it is easy to store and implement complex signal processing algorithm with the digital signal.In view of the various points mentioned above, this paper puts forward an implementation scheme of digital spectrum analyzer based on FPGA embedded Nios II soft-core processor.Taking full advantage of the strong computing power of Nios II and the easy features of system integration in FPGA, the small hardware spending, real-time strong and high-resolution spectrum analyzer is realized. With the help of analog/ digital converter (ADC) to sample the input signal using digital methods,then by Fast Fourier Transform(FFT) to decompose the measured signal to independent frequency components, and further to the spectrum distribution. The system has achieved to dual-channel display the spectrum by LCD 12864 module and VGA interface. The 8-point FFT is realized in LCD 12864 module, while VGA interface implements the 256-point FFT on a computer monitor. Compared the eventually achieved spectrum with the analysis results of the common data with Matlab, the result is satisfactory. Using NiosⅡsoft-core processor to achieve Fast Fourier Transform in FPGA, which also shows the superiority of SOPC solution raised by Altera Corporation.