Principle And Application Of High-Precision Receiver Algorithm Based On All-Phase Fft

With the development of science and technology,digital signal processing technology is becoming more and more mature.In the 1980 s,a digital receiver with a digital signal processing circuit as its main feature was derived from the receiver system.Due to the good sensitivity,high precision,strong anti-interference ability and good stability of the digital receiver,this technology is widely used in the fields of communications,radar,navigation systems,electronic countermeasure systems,digital TV sets,cell-phone and so on.The key technology of digital receiver is to realize the measurement of signal frequency and phase.Many digital receivers use FFT algorithm for frequency and phase measurement.In order to obtain higher measurement accuracy,this article aims to use the all-phase FFT algorithm as the theoretical basis to realize the measurement of the frequency and phase of the signal.The main contents of this article are as follows:(1)This article first analyzes the traditional FFT and all-phase FFT algorithms.Through derivation of the two algorithm principles and modeling and simulation.The shortcomings of the FFT algorithm in measuring frequency and phase are pointed out.In the measurement process of the FFT algorithm,there are spectrum leaks and the measurement phase will cause error "diffusion".To get the measurement result of the signal phase in FFT,you must first find the frequency of the signal,and the frequency of the signal can only be obtained by estimation,which may lead to the expansion of the error.At the same time,the use of all-phase FFT algorithm as the core algorithm of digital receiver is proposed.The all-phase FFT can well suppress the spectrum leakage.Through the theoretical derivation of the all-phase FFT,its spectrum amplitude is the square of the traditional FFT,and this square relationship exists for each spectrum line,and the signal energy can be more focused on the main score.It is found in the MATLAB simulation results that the all-phase FFT can suppress spectrum leakage better than the traditional FFT.All-phase FFT can also directly obtain the phase of the signal through spectral peak search.(2)Whether it is an all-phase FFT or a traditional FFT,frequency correction is required to measure the frequency of the signal,so the spectrum correction method required for frequency measurement is explored.Finally,the FFT / all-phase FFT integrated phase difference method is selected as the correction method for frequency measurement.For the ratio method and the energy correction method,their correction algorithms rely on the side spectral lines.Once the signal contains multiple frequency components,the measurement results will show great errors,which is not suitable for the frequency correction of this paper.The correction accuracy of the full-phase FFT phase difference method is the highest,but the calculation amount is much larger than the traditional FFT and FFT / all-phase FFT phase difference method.The accuracy of the FFT / all-phase FFT integrated phase difference method is only slightly lower than that of the all-phase FFT phase difference method,but the amount of calculation is much smaller.Through MATLAB simulation analysis,when measuring the same signal,the FFT / all-phase FFT method requires 30% less correction time than the all-phase method.(3)This paper designs an implementation of a measurement system based on allphase FFT algorithm,and builds an experimental platform based on Xilinx's VIRTEX 7 development board.VIRTEX 7 development board and ADC sampling module complete data collection and sampling.Then send the sampled data to the PC through the PCIE interface.Complete the data processing in MATLAB,and finally get the frequency and phase of the signal.When the number of sampling points N is 1024,the continuous signal and pulse signal with a frequency of 100 MHz to 1.2 GHz are tested with this platform,and the final measurement error does not exceed 1 MHz.