Broadband Receiver In The Signal Separation Technique

As receiving the wide band radar signals by a wide band digital receiver, it has great probability of receiving the narrow band radar signals at the same time. The technologies of signal separation and parameter estimation are the most important technologies of the wide band digital receiver. Therefore, it is widely concerned on separating signals from the aliasing signals and estimating the parameters of the signals in the various complicated electromagnetic circumstance. In this dissertation, it is focused on the LFM (Liner Frequency Modulated) signals, and the technology of separating the wide band signal from the narrow band signal in time domain, frequency domain and the time-frequency domain respectively are researched. The main works of this dissertation are included:1.The signal characteristics under modern electronic reconnaissance environment are analyzed. It's pointed out that wideband digital receiver must satisfy wide monitoring band. The types and characters of aliasing signals are given and researched in time domain, frequency domain and the time-frequency domain respectively.2.Based on the fractional Fourier Transform (FrFT), a method, which separates and estimates parameters under the signals sub-sampled condition, is presented. After modulation rate roughly estimated using the signal with its delay version production and Newton's iterative method,signals are filtered and separated in the fractional Fourier Transform domain. Finally, the initial frequencies of the sub-sampled LFM signal are estimated unambiguously. It is solved the problem of the two-dimensional searches in separating signals using FrFT.3.Based on the auto-correlation theory, a method, utilized to separate the wide band signals from the narrow band signals and to estimate the parameters is researched. The envelopment characters of LFM signals correlated in time domain are analyzed. Using the leap character of the envelopment, the aliasing signals are processed in subsection and the original signals are reconstructed by data fitting.4.A method based on the CLEAN algorithm is researched. In this method, the...