The Improment Of High Dynamic Carrier Capture Technology Based On Discrete Match Fourier Transform

Synchronous technology is a challenging problem in digital communication. It is the premise of communication system. High dynamic environment will make the carrier frequency shift of dozens of KHz or even hundreds of KHz,Frequency variation will dozens of KHz/s, or even a second frequency variation rate (in this paper only consider frequency variation rate).It increases the difficulty of signal capture greatly. Although receiver can have some prior knowledge to receive signals and can preset local carrier center frequency. But hundreds of initial frequency variation still can cause carrier capture a long time or even cannot capture。First, characteristic of several typical Time-frequency analyses are given. Putting forward that Matching Fourier Transform is a linear transformation of no influence of cross signal by analyzing. It can detect signal in low SNR and the resolution is high.It is an efficient parameter estimation method about linear frequency-modulated signals.Then, giving several high dynamic frequency measurement algorithms and tracking algorithms. Pointting out the main emphasis of our research is to solve the problem of large Doppler frequency shift, high frequency rate and low signal-to-noise ratio (SNR).Finally, pointting out high dynamic signal can be seen as linear frequency modulation signal (LFM). Putting forward improving methods of high dynamic carrier capture based on Discrete Match Fourier Transform (DMFT). Rough capture of delay self-correlation combined with FFT provides priori knowledge for DMFT before the high precision capture of DMFT. And Discrete Match Fourier Transform enables efficient computation using FFT through transform. It is proved that this algorithm not only can reduce the amount of computation but improve accuracy of capture through the simulation. Further introduce Modified Discrete Chirp Fourier Transform to overcome the constraint condition of Discrete Match Fourier Transform. Alternative Discrete Match Fourier Transform by Modified Discrete Chirp Fourier Transform. The simulation results are analyzed and the superiority of the algorithm is proved. Giving a parameter estimation method of many components of LFM signals based on MDCFT combining with CLEAN. Proving the effectiveness of the algorithm proposed through the simulation in MATLAB.