Advanced Materials Research Vols. 989-994

Abstract: Image edge detection is easily affected by noise. Wavelet algorithm can divide the image into low frequency and high frequency. By the processing of high frequency signal and the reconstruction of wavelet coefficients, the purpose of removing noise can be achieved. In the environment of VC++6.0, an image de-noising algorithm based on the wavelet combined with the Canny edge detection is proposed, which obtains a good result. The above algorithms are implemented based on OpenCV, which is more efficient, providing the conditions for subsequent image analysis and recognition. Experiments are carried out and the results show that the proposed algorithm is available and has a good performance.

Abstract: This paper presents a multi-component chirp signal detection with new methods of parameter estimation. The method using spatial characteristics of the antenna array. By array average fractional Fourier domain weighting function is introduced to reduce noise and suppress mutual interference between the signals from different sources. And compared to a single array element method. The proposed method greatly improves the multi-component chirp signal detection and parameter estimation performance. Simulation results show the effectiveness of the method.

Abstract: According to the characteristics of PCM / FM signal demodulation method is proposed based on virtual radio platform. This paper discusses in detail the basic principles of this demodulation method and implementation process, analyze the demodulation performance and complexity of the method. Simulation results show that the method for actually received PCM / FM demodulation signal has better performance.

Abstract: Presents a IIR adaptive frequency estimator to achieve multi-frequency estimation algorithm. More traditional phase locked loop algorithm, which has no mixing components, to achieve the advantages of full-band frequency estimation, frequency estimation accuracy under the same environment and phase locked loop fairly.

Abstract: Based on the relationship between the Radon-Wigner transform and fractional Fourier transform and the time frequency distribution, using the property that Radon-Wigner transform has better performance in time and frequency domain, detection and parameter estimation of Chirp signal have been done by Radon-Wigner transform or fractiona1 Fourier transform. The theoretica1 analysis and simulation prove that two techniques are better than generic time-frequency transform, such as Wigner-Ville transform.

Abstract: The fractional Fourier transform (FRFT) is a generalization of the Fourier transform. The article first introduces the definition of FRFT transformation; then analyzed FRFT Chirp signal based on this humble proposed restoration Chirp signal in a noisy background in two ways: one is based on parameter estimation, and the other is based on the scores Fourier domain filtering to achieve signal reconstruction; Finally, simulation verify the feasibility of the above analysis.

Abstract: According instantaneous frequency measurement theory, we propose a new PCM / FM telemetry signal demodulation method. This paper introduces the basic principles of this demodulation method and implementation process, the influence of instantaneous frequency measurement accuracy and the impact of factors on the Doppler frequency demodulation performance is proposed to improve the accuracy and instantaneous frequency measurement method demodulation performance .

Abstract: As a generalization of Fourier transform, the fractional Fourier Transform (FRFT) contains simultaneity the time-frequency information of the signal, and it is considered a new tool for time-frequency analysis. This paper discusses some steps of FRFT in signal detection based on the decomposition of FRFT. With the help of the property that a LFM signal can produce a strong impulse in the FRFT domain, the signal can be detected conveniently. Experimental analysis shows that the proposed method is effective in detecting LFM signals.

Abstract: This paper focuses on the weak signal reception and atmospheric noise suppression in VLF Chirp spread spectrum communication system. Due to interference of atmospheric noise generated by lightning phenomena, it makes the chirp signal detection under low SNR condition becoming more difficult. Therefore, we select alpha stable distribution noise model to generate noise to simulate the real atmospheric noise. Then, we introduced a new technique of Chirp Spread Spectrum (CSS) communication based on Fractional Fourier Transform (FRFT). Finally, we study a nonlinear processing interference suppression method of clipping in time domain. Simulation results verified its feasibility.

Abstract: Faced with complex electromagnetic environment and varieties of adaptive radar waveforms, radar signal analysis and identification becomes more and more complex. Considering two important physical quantities - time and frequency in modern signal processing methods, this paper proposes that the joint time-frequency analysis (JTFA) method based on fractional Fourier transform (FrFT) and short-time Fourier transform (STFT) is applied to adaptive radar signal processing. The simulation results show that the joint time-frequency analysis method is superior to single short-time Fourier transform, getting a better analysis of results. The joint time-frequency analysis method provides the joint distribution of the time domain and frequency domain for adaptive radar signal analysis and describes the relationship between signal frequency and time.