Applied Mechanics and Materials Vols. 543-547

Abstract: In LTE system, random access plays an important role in both uplink time adjustment and initial access of UE. This paper analyzes the theory of the related signal detection and the correlation calculation, and proposes a method to detect the received sequence in the receiver. And at last, it presents the implementation on DSP including the baseband signal processing module, Local frequency domain ZC sequence generation module and Correlation calculation module. In a word, it provides a solution for implement the PRACH receiver on hardware.

Abstract: This paper describes a testing method about handover conformance and testing framework based on TTCN-3. In addition, the handover conformance testing process between the LTE and TD-SCDMA system is designed, and the testing flow chart and reports are generated by the TTWORKBENCH platform, finally this test system is verified. The results accord with the requirement of the 3GPP conformance testing.

Abstract: Influenced by Wi-Fi signal interference, Shenzhen subway is forced to stop frequently, which has caused enormous safety hazard. This paper proposes a method to test the interference transferred from Wi-Fi signals to the Communication Based Train Control (CBTC) systems, then the testing data are collected and analysed. The test is aim to two signal transmission modes: free wave and leaky cable. The test result shows that the signal transmission mode of leaky cable is more reliable, while the transmission mode of free wave has the worse anti-interference capability to Wi-Fi signals. Particularly, it is an effective way to apply for specific frequency bands, which will make a contribution to reducing the interference effect on the CBTC systems caused by Wi-Fi signals.

Abstract: To solve the problem that traditional automatic image clipping method is on the basic of simple principles, such as fixed size and fixed location, an improved arithmetic based on face recognition is proposed. Firstly, the face region is located by face detecting.Then according to the proportion of face area in the selected region on the template image,the clipping region size of the image to cut is matched.At last,through the relative position of the face center in the template image,the cutting position can be got. The experimental results show that this algorithm can achieve better clipping effect.

Abstract: In this paper, we propose a new secure communication synchronization system which exploits the combination of the fourth-order hyper-chaotic system and the synchronization theory. We study the fast encryption and decryption methods of the images and the performance analysis of the secure communication based on the hyper-chaotic system. The simulation results show that the proposed hyper-chaotic secure communication generates the unpredicted pseudorandom sequences which have greater complexity and better randomness characteristics comparing to the traditional chaotic encryption schemes. Furthermore, it has larger key space and higher safety performance. Since the proposed system provides a new thought for the synchronization problems of the hyper-chaotic system, it is regarded as a potential scheme for resisting the popular attack means.

Abstract: Emotion recognition is an important part in affective computing. It is the basis of building a harmonious man-machine environment. Respiratory (RSP) signal and electrocardiogram (ECG) signal are one of the main study objects in the emotion recognition based on physiological signal. The variations of the RSP signal and the ECG signal is one of the true performances of the human emotions. Through the analyses of the RSP signal and the ECG signal, we can recognize the inner emotion variations of human beings. This lays the foundation for the system modeling of emotion recognition. In this paper, we study the approximate entropy extraction of the physiological signals and analyze the chaotic characteristics and frequency domain characteristics of the approximate entropy under different emotions. The study results show that the different emotion status is corresponding to different approximate entropy and different variations in the frequency domain.

Abstract: Studying of image enhancement shows that the quality of image heavily relies on human visual system. In this paper, we apply this fact to design a new image enhancement method for medical images that improves the detail regions. First, the eye region of interest (ROI) is segmented; then the Un-sharp Masking (USM) is used to enhance the detail regions. Experiments show that the proposed method can effectively improve the accuracy of medical image enhancement and has a significant effect.

Abstract: Thinning is widely used in image processing and pattern recognition, it reduces redundancy of the original image and for easily extracting features. By a lot of experiments, a new improved thinning algorithm is proposed in this paper. A flow process diagram is given too. In the new algorithm, thinking about some details. For example, thing of P1 cant be deleted, thing of how to wipe off burr. The experiments show that these algorithms achieve anticipate results.

Abstract: In recent decades, Hybrid Spread Spectrum (DS/FH) signals has been rapidly developed and extensively used in the field of both military communications and aerospace monitoring. Through the study of hybrid spread spectrum signal, firstly use time-frequency analysis to get the time-frequency diagram of hybrid spread spectrum signal, and then wipe off the DS pseudo-code, lastly use the high-resolution frequency to estimate the parameters of hopping frequency signal, in order to provide a kind of ideas and reference to test hopping frequency parameter of hybrid spread spectrum signal.

Abstract: PCM/FM system is one of the most widely used in the missile and rocket telemetry system. For the problem that the breakthrough tradition demodulation method of demodulation threshold leaded by the telemetry signals low signal noise ratio (SNR) of target spacecraft reentry telemetry environment, a baseband complex rotating orthogonal MSD based soft PCM/FM signal demodulation method is studied combined with the PCM/FM signal phase characteristic. The corresponding synchronization algorithm is applied to ensure the smooth operation of the demodulation. The simulation and test results verify the soft demodulation algorithm can make reduce the demodulation threshold effectively.