Applied Mechanics and Materials Vols. 716-717

Abstract: Cooperative spectrum sensing technology has been identified as an effective approach to mitigate the interference generated by cognitive radio users on primary networks. In this paper, based on the rigorous mathematical derivation, we proposed an interference model of cooperative cognitive radio networks on the licensed user over Rayleigh fading wireless channel. In the case of the cognitive radio users independently and cooperatively sensing the existence of the licensed user, the proposed model analyzes the effect of some key parameters on the interference such as the missing detection probability of spectrum sensing scheme, spatial density of cognitive radio users etc. This model not only is a theoretical expression but also can be put into applications. The numerical results are given to verify the proposed model.

Abstract: This paper introduced the structure and special property with type device, analyzed how to realized programmable analogue function module with digital potentiometer. This paper gave a design example of programmable second-order active low pass filter by using digital potentiometer. The programmable filter can be application to the signal filter processing of data acquisition systems. This paper has reference value of theory and practice on the application of digital potentiometer

Abstract: This paper presents a method to suppress narrowband interference in the direct sequence spread spectrum communication based frequency domain adaptive algorithm. The method determines the interference threshold by N-sigma algorithm and calculates the cut-off condition by separating the signal. The method suppresses the narrowband interference by frequency domain batch algorithm. This paper gives a detailed design method and simulation results, and makes a performance comparison with other methods. The results show that, the method in this paper has better performance than other methods. It is suitable for narrowband interference suppression in broadband systems.

Abstract: In the digital baseband transmission system, the intersymbol interference is one of the main factors affecting the performance. Therefore, how to overcome its influence, making the system error rate reduction must study and solve the problems in the digital baseband system. This paper designs a new mobile communication non intersymbol interference filtering system based on MATLAB numerical simulation, the system is the integration of the Calman filter theory, and combining the genetic algorithm and PID control algorithm to achieve the rapidity and stability of the system filter. The filter design and validation simulation can be seen that the filter can effectively eliminate the measurement and observation error in the mobile communication process, to avoid the signal fluctuation caused by intersymbol interference. Through the system response curve, it can be seen that the system does not appear overshoot, fast convergence speed, and good response stability will provide the technical reference for the research of mobile communication system.

Abstract: In the digital mobile communication signal transmission system, the inter-symbol interference is one of the main factors affecting the performance. In order to make the error rate reducing to a minimum, this paper designs a new Calman digital equalization filter. It is based on Calman filter principle, and establishes the control mathematical model of observation equation and state equation, and uses MATLAB programming to realize the algorithm. In order to verify the effectiveness and reliability of this filter, this paper uses filter toolbox of MATAB to do numerical simulation on the filtering effect. Through comparing with normal digital equalization filter effect, after adding the Calman digital equalizer filter, the feedback signal is conformed to the reference signal. The duty ratio of SPWM follows the basic changing law, so as to maximize the elimination of crosstalk inter-symbol. It provides reference data for the research on mobile communication inter-symbol interference.

Abstract: Intersymbol Interference (ISI) problem is one of the main factors affecting the baseband transmission performance of mobile communication’s digital signal which can not only reduce the transmission quality of the information but also can result in misinformation and false pass of information and provide troubles to the user and communications. In order to minimize the error rate, we propose a new digital equalization filter and establish the basic model of the digital filter and introduce non-linear Kalman observation equation and the state equation into the model and design partial differential mathematical model of the Kalman filter and develop MATLAB solver based on the mathematical model. In order to verify the validity and reliability of Kalman filter algorithms and mathematical procedures designed in this paper, it uses MATLAB toolbox to simulate the filter of mobile crosstalk signal and obtains amplitude-frequency characteristics and time-domain characteristics before and after filtering. By comparison, we can see that the filter can eliminate the high frequency crosstalk signal which provides technical reference for the study of the problem of crosstalk between the mobile communication codes.

Abstract: With the development of computer technology and information technology, voice interaction has become a necessary means of human-computer interaction, and voice signal acquisition and processing is the precondition and foundation of human-computer interaction. This paper introduces the MATLAB visualization method into voice signal acquisition system, and uses MATLAB programming method to drive sound card directly, which realizes the identification and acquisition of voice signal and designs a new voice signal visualization acquisition system. In order to optimize the system, this paper introduces the variance analysis algorithm into the design of visualization system, which realizes the optimization of voice signal recognition model with different level parameters. At the end this paper does numerical simulation on the speech signal acquisition system; through signal acquisition 2D and 3D visualization voice signals are obtained. It extracts single signal characteristics, which provides a theoretical reference for the design of signal acquisition system.

Abstract: This paper proposes a design of powered device interface chip compatible with communication protocol IEEE 802.at standard, for Ethernet control of power supply. This design has all the features IEEE 802.at standard requires, including the detection, classification, under-voltage lockout and inrush current control, support of not less than 25.5W of power. The circuit of the chip is designed with Hangzhou Silan BCD process technique. Specific features of the design are 140mA inrush-current-limiting, complementary-output-enable-signal, under-voltage, overvoltage, over temperature protection, an optional external power adapter input, IEEE 802.3at type2 display signals by new electrical equipment, as well as two-event classification logic implementation.

Abstract: To reduce the mutual coupling effects among the collocated electromagnetic vector sensor and enhance the performance of the joint space-polarization filtering, an improved adaptive beamforming method is proposed for non-collocated vector sensor array in this paper. First, the distributed array geometry composed of the crossed dipole pair and the signal model are introduced. Second, theoretical derivation of the improved method is discussed. By projecting the weight vector of the joint space-polarization minimum variance distortionless response (SPMVDR) onto a signal subspace, the optimal weight vector of the improved method is obtained. The projection operation generates a lower power of the output noise and improves the signal to interference plus noise power ratio (SINR) compared with the conventional SPMVDR. Computer simulation results indicate that the improved algorithm can achieve a good joint filtering performance and enhance the robustness to array pointing error.

Abstract: This paper studies a new type of power transmission network and power communication transmission technology. First, the working principle and network topology form of power optical transmission network have been presented in this paper, the power budget of the optical transmission model has been given through the loss of optical system and dispersion limit theory. Then the power transmission network and power communication transmission have been simulated through EPOCHS software simulation software, which based on the design aspects of CP transport port, transport protocol and transmission signal, the simulation parameters has been set according to the transmission mathematical model, and the security and efficiency of power transmission network has been proved through the fault signal diagnosis and signal characteristics of delay and jitter. The result of simulation shows that power transmission network power transmission have shorter delay and less jitter, which provides the reliable theory basis for the development of electric power communication network and complex network.