The Fractional Fourier Transform And Its Applications In Microwave Interferometer

Microwave interferometer can be used to measure the moving parameter of the projectile in the life-weary taker, and is the important ensure of improving the performance of the artillery and the projectile. The doppler signal that is mixed and exported by microwave interferometer is a non-stationary signal, its instantaneous frequency is changing time variant. The traditional fourier transform can't describes the time domain and frequence domain information of the signal at the same time, is not suitable to process the non-stationary signal. As the generalized form of the fourier transform, the fractional fourier transform(FRFT) is a new method of time-frequence analysis, and is possessed of good performance of time-frequence to non-statioary LFM signal. This paper mainly reaserches the fractional fourier transform and its applications in the signal processing system of microwave interferometer.First of all, this paper introduces the development, the definition, the property, the speculative knowledge in the fractional convolution and the fractional correlation, and the relation with other Time-Frequency Analysis methods, and discusses numerical algorithm method of discrete fractional fourier transform. Secondly, this paper researches the adaptive narrowband Time-Frequence filtering of the chirp signal based on the domain of the fractional fourier transform and dislodges the baseline drift, and the results of simulation experiment proves the availability of this algorithm. In the end, this paper researches the detection and parameter estimation of the chirp signal, and adopts the algorithm changing step to optimize and improve original algorithm; The detection and parameter estimation of multi-component chirp signal based the fractional fourier transform and the"CLEAN"thought in the domain of the fractional fourier transform; The detection and parameter estimation of nolinear FM signal based on the short fractional fourier transform. The results that the data measured is processed show that the time-frequence method based on the fractional fourier transform can estimate the instantaneous frequency of the FM signal all-right under low signal-noise ratio.