Advanced Materials Research Vols. 989-994

Abstract: Same-beam interferometry (SBI) has a wide range of applications and prospects in collocate geostationary satellites, space rendezvous and docking, landers and rovers positioning. The paper introduces the basic principles, underlying processing algorithms, ambiguity resolution solving, process flow comprehensively and systematically. Then use FX-related processing algorithms and integer ambiguity solution method step by step to process signals, draw process flowchart.

Abstract: Utilizing power line to transmit information speedily and safely is very important and significant. Whereas, the communication environment and construction of power grid are complex and hostile. The paper introduces the application, common modulation technology—OFDM and noise characteristics of PLC. The paper builds an OFDM input and output system and adds the power line noise into the channel, then compares and analyzes the difference between the OFDM output signals in common channel and PLC channel.

Abstract: According to the characteristics of PCM / FM signals, we propose a new software-based STFT Demodulation algorithm. This paper discusses in detail the basic principles of this demodulation algorithm and implementation process, analyze the complexity of the algorithm, proposed a new method for the extraction and correction code synchronization. Simulation results show that the algorithm not only can effectively suppress the influence of various disturbances in the actual signal synchronization accuracy of the code, with better demodulation performance, and realization of the principle is simple, high efficiency, easy to implement software-oriented real-time treatment.

Abstract: In order to identify the Zherong Radix Pseudostellariae, a geographical indication products, diffuse reflectance spectroscopy of came from ten different origins were collected by the Fourier near-infrared spectrometer. The spectroscopy was analyzed with Chemometrics method,and the spectroscopy was pretreated by the second derivative, first derivation and minus a straight line condition. The range of spectra was 3996.1-7282.5 cm^-1. The Calibration models of Radix Pseudostellariae were established by the qualification testing, principal component analysis, and cluster analysis respectively, and each model was verified. The results show that the optimal model established by the qualification testing, principal component analysis and cluster analysis can effectively identify authentic Zherong Radix Pseudostellariae , and accuracy rate was more than 97.5%. In conclusion, Zherong Radix Pseudostellariae can be identified accurately and quickly by the near-infrared spectroscopy technique.

Abstract: GrowCut algorithm is not only an interactive algorithm on the basis of cell automata, but also a multi-label algorithm based on seeds point. Aiming at the GrowCut algorithm usually asks users to partition foreground and background manually and mark a lot more initial seeds. This paper presents an automatic object segmentation method which combining secondary watershed and GrowCut algorithm, here in the following paper refers it to as SWGC algorithm. It firstly using the twice used watershed algorithm to partition the input image, the segmented regions are labeled using Mahalanobis distance, and merged according to the image color and space information, thereafter applying the GrowCut algorithm to perform globally optimized segmentation. The main contribution focuses on performing automatic segmentation which consist of obtain the foreground and background region and generate the seed template of GrowCut algorithm automatically. Thus not only leave out the constraints of user interaction operation, but also avoid the subjectivity and uncertainty. The proposed method reduces the runtime significantly as well as improves the segmentation accuracy and robustness of GrowCut algorithm. Experimental results show SWGC algorithm has superior performance compared to the other related methods.

Abstract: Comparing with the traditional fixed carrier frequency signal, using FH (Frequency-Hopped) signals improved the performance of anti-interference of the TT&C system when bring the low signal tracking accuracy. In order to solve this problem, this paper proposed a loop structure of using wiener filter, the filter coefficient was deduced. Simulation results show that the loop tracking precision was increased after the optimization, and the improvement has relations with the filter order n. When, the speed measuring precision reached 30cm/s which was increased about 3 times than did not use wiener filter.

Abstract: Based on fractional Fourier transformation (FRFT), the feature of the signals which vary smoothly from time domain to frequency domain is given. The FRFT method is applied to the estimation and detection of nonlinear frequency modulated signals to which piecewise linearly approach. Wigner-Ville time frequency distribution of the signals is used after approaching and the masking results of the original signal accumulate energy as detecting statistic. A signal detector based on energy accumulation from time frequency domain in the angle of analysis of both time and frequency is proposed. Finally, a comparison with traditional non-coherent energy accumulation methods is made, which shows the proposed method has superior performance.

Abstract: The general method time-varying amplitude linear FM signal parameter estimation, the proposed parameter fractional Fourier transform for time-varying estimates of the magnitude of the chirp signal, and the related issues of a more in-depth research. Study the time-varying amplitude of the initial phase chirp signal, the initial angular frequency, modulation frequency and amplitude information extraction and estimation methods, and the magnitude of the Gaussian function varies with the magnitude of random variation and chirp signal for the object properties (parameters on parameter estimation estimate the mean square error) were simulated.

Abstract: The measurement performance with the interference is presented with the new DS/FH hybrid spread spectrum signal system. The DS/FH system model is established. The change of the SNR ratio is obtained by analyzing the characteristics of three kinds of interference signal such as partial-band noise jamming (PBNJ), wide-band noise jamming (WBNJ) and additive white Gaussian noise (AWGN). Then the ranging and velocity measurement performance is got through the simulation.

Abstract: Because wavelet transform has good time-frequency characteristics, and its application in image denoising has been promising. Firstly, use the threshold method of the wavelet transform is used in removing image noise, and then the denoised image is smoothed using neighborhood average filtering with Gauss template. And wavelet denoising process and domain threshold selection principle are discussed. Simulation results show that this method can effectively reduce the noise and can remain most of image details better.