The Research Of Time-frequency Analysis Method Of Signal Based On FPGA

The Fourier transform is a global transformation, which is powerless for thenon-stationary signal processing, for this, the time-frequency joint distribution has been usedto describe and analysis the non-stationary signal. At present, a lot of time-frequency analysismethods has been proposed, it is widely used in many fields such as mechanics, electronic,biology, medicine and so on. With the further study as well as practical engineering need oftime-frequency analysis, it is of great necessity to develop the time-frequency analysisinstrument. The most common method is to realize in the PC with software, or to use the dataacquisition card so as to develop virtual time-frequency analysis instrument. In addition, it ispossible for the real-time signal analysis with the development of the semi-conductortechnology, especially DSP and FPGA, and other high-speed device.This paper introduces several typical time-frequency analysis methods, at the same time,it studies the FPGA realization of signal frequency analysis with the combination of thecurrent rapidly developed FPGA technology. It also projects the time-frequency analysissystem of non-stationary signal based on the Fourier transform. This major work done in thispaper is listed as following:A good method of subframe and windowing has been found; It is able to realize frameoffset and windows function parameters in an adjustable way, according to using the threeport RAM and two port ROM in the FPGA chip design, it is a great flexibility fortime-frequency analysis.The radix4DIT (decimation in time) FFT (fast fourier transform) processor is designed;The processor can deal with1024points,16bits, fixed point type, real numbers and complexnumbers, including serial structure and parallel structure, one structure can be chosen betweenserial and parallel for the meet of the signal processing speed requirements.Image gray transformation based on FPGA realizing is presented; The transformationstructure of spectrum is to signal for design prototype, using curve approach to get. It cancomplete the spectrum image enhancement processing prevailed without solving logarithm.Simple and easy, it takes up fewer resources of the FPGA.The time-frequency analysis system scheme based on FPGA realization is proposed;This scheme can analysis non-stationary signal, such as the linear frequency modulationsignal, the frequency-hopped signal, speech signal. It can examine the parameters at differentframe and time-frequency spectrogram under different frame offset. The realization of thesystem provides a feasible scheme for the hardware realization time-frequency analysisinstrument.