Advanced Materials Research Vols. 945-949

Abstract: Includes the establishment of the spontaneous radiation of vertical cavity semiconductor optical amplifier (VCSOA) bistable model, numerical analysis and comparison of VCSOA and traditional SOA bistable characteristics of amplified spontaneous emission (ASE) sensitivity.

Abstract: We know that Inter-satellites communica-tion is a very important to us.However, real global coverage can only be achieved by satellite systems. Satellites communication is the most important mean of the communication network. The traditional satellites communication and inter-satellites links are built by microwave. Recent years, laser links for inter-satellites communication are becoming more and more important.

Abstract: Based on UDP protocol in Visual Basic Winsock control, this paper designed third-party software to send and receive data. Wireless data transmission module used CM3160EP module. In order to decrease wireless data loss rate, four kinds of packets format is designed. The results show the stable data transmission and verify the send-receive and display of hexadecimal data on server-side.

Abstract: Since fixed Forward Error Correction cannot show a better performance in solving error problems for transmission in wireless network, this paper proposed an AFEC strategy in active network. Simulation and analysis prove that it can not only prompt the redundancy that change adaptively with the network condition, but also not rely on the constancy of the network environment any more and enhance the adaptability and robustness of the FEC algorithm, so that more adapt to the changing wireless environment.

Abstract: This paper presents an all digital delay-locked loop (DLL) to achieve wide range operation, fast lock and process immunity. To keep track of any potential phase problem caused by environmental variations, a delay compensation mechanism is employed. Utilizing the delay compensation controller (DCC), the proposed DLL can overcome the false-lock problem in conventional designs. It is fast locking because the DLL’s initial state can be detected by the delay compensation controller and the initial large phase difference can be eliminated. The proposed DLL is implemented in a 0.13μm CMOS process. The experimental result shows that the chip could work in a wide frequency range from 10 MHz to 1 GHz, with less than 20 cycles lock-in time, 10-ps delay resolution, and 6.4 mW at 1 GHz power dissipation.

Abstract: Along with the gradual increase of intelligent and information equipment on the battlefield, the fierce electronic warfare between the enemy and us makes the electromagnetic environment of the battlefield more and more severe. The anti-jamming capability of conventional frequency-hopping communication system is inadequate such as anti-dynamic interference, anti-intercept, etc., thus posing a serious threat to normal military communication. Moreover, currently the data transmission rate of frequency-hopping system is fairly lower, and cannot meet the increasing large-capacity real-time data transmission requirements. This article deeply researches self-adaptive MIMO-OFDM technology and frequency-hopping communication technology, and introduces the research on frequency-hopping communication technology based on self-adaptive MIMO-OFDM system. The research shows that self-adaptive MIMO-OFDM-based technology can effectively enhance the frequency-hopping communication system’s anti-jamming and anti-intercepting capability, and improve the data transmission rate.

Abstract: This article describes the SCM combined with A/D converter and wireless digital transmission module which is used for building a DC voltage measurement system based on LabVIEW. The system uses AT89C52 as controller, ICL7135 as precision, double integral A/D converter circuit as voltage data collection, PTR2000 as a wireless transmission module and the LCD display module as the measured voltage. The collected data can be transmitted to a PC. The hardware system design of the DC digital voltmeter is introduced exhaustively. It also gives some details of the hardware circuit design.

Abstract: This paper deals with application of Non-dominated Sorting Genetic Algorithm with elitism (NSGA-II) to solve multi-objective optimization problems of designing a vehicle-borne radar antenna pedestal. Five technical improvements are proposed due to the disadvantages of NSGA-II. They are as follow: (1) presenting a new method to calculate the fitness of individuals in population; (2) renewing the definition of crowding distance; (3) introducing a threshold for choosing elitist; (4) reducing some redundant sorting process; (5) developing a self-adaptive arithmetic cross and mutation probability. The modified algorithm can lead to better population diversity than the original NSGA-II. Simulation results prove rationality and validity of the modified NSGA-II. A uniformly distributed Pareto front can be obtained by using the modified NSGA-II. Finally, a multi-objective problem of designing a vehicle-borne radar antenna pedestal is settled with the modified algorithm.

Abstract: For measurement and communication interrupt between earth station and reentry vehicle in blackout area, we analyze electromagnetic environment characteristic of plasma sheath. Methods of changing electrical characteristic of plasma medium or changing measurement and communication equipments are researched based on the analysis. Also technology of trajectory reconstruction is presented by using limited measurement data of target. The paper introduces technology status of measurement and communication for blackout area reentry vehicle. Also we analyze properties of common methods and propose key questions to research. It provides reference for related researchers.

Abstract: First, briefly introduced the theory of electromagnetic shielding; second, analyzed electromagnetic shielding technology in practical and applied perspective, at the same time, pointed out the key points of electromagnetic shielding cabin design; at last, proposed improvement for the follow-up study.