Applied Mechanics and Materials Vols. 411-414

Abstract: In order to recognize the modulation type of common communication signals, an automatic recognition algorithm based on decision theory is designed and introduced. Combined with engineering realization, an adjustment is made to the algorithm. Then, a recognition scheme is proposed and realized on Digital Signal Processor (DSP), which is the key module in monitoring receiver. When the signal-to-noise ratio is not less than 12 dB, the experimental results show that the right recognition rates of eight common communication signals are above 90%. The algorithm proposed can result in a good case, and the smaller calculated complexity compared with its counterparts makes it could better reach the real-time requirement of engineering realization.

Abstract: TDOA is a predominant localization algorithm. In this paper, we propose a TDOA localization algorithm called NLLS, using the nonlinear least square estimation. We first get the initial location utilizing the LCLS algorithm, which could achieve the global optimal solution to the ordinary constraint linear least square estimation, and based on the initial location, we make use of nonlinear least square estimation to improve the localization precision. Simulation results show that compared with the CTLS algorithm, its performance is superior especially when the measurement noise is larger.

Abstract: This paper presents a fuzzy anti-interference transfer alignment method for airborne strapdown inertial navigation system (SINS). This fuzzy anti-interference transfer alignment method takes the influence of systematic error into account for SINS transfer alignment. The fuzzy rules are constructed and incorporated in the filtering process to estimate the covariance matrices of observation vector and predicted state vector with random weight method. The experimental results demonstrate that the proposed method can resist the interferences caused by the airborne maneuvering process, thus improving the accuracy for SINS transfer alignment.

Abstract: Strap-down INS is composed of fiber gyroscope. Position error propagation equation and position update algorithm of dead reckoning is deduced in this paper. The Kalman filter is proposed for compensation error of integrated system. The difference of velocity between INS and DR is used as the input of Kalman filter, attitude error, velocity error, position error and scale factor error are to be estimated which compensate and rectify the errors of integrated navigation system. By carrying out experiment upon vehicular navigation system in use of Kalman filter, the errors of integrated navigation system are estimated accurately. Experiment result show that the method not only can effectively improve precision of the system, but also is simple and convenient, so it is more suitable for practical application.

Abstract: There is no effectual navigation method to deep space aerocraft until now. Global Navigation Satellite System (GNSS) is a candidate. Its feasibility was analyzed according to the deep space geometry coverage characteristics. The antenna elevation was optimally designed to maximum the signal coverage performance in deep space. Simulation Results show that the best antenna elevation is 50-90 degrees. At the height of geosynchronous orbit, the average PDOP is 8.63, and at the height of lunar orbit, the positioning accuracy can only be achieved by km level.

Abstract: A parameter measuring system is introduced in this paper, which is used for recording the temperature and humidity, atmospheric pressure, rotation speed and acceleration, etc. The system uses a 32-bit RISC microprocessor of STM32F103ZET6 based on the core of ARM Coretex-M3 as master chip. And it writes the data recorded to NAND FLASH. After it finishes, it copies the data to host-computer through SD card.

Abstract: User range error (URE) is widely used to measure the effects of satellite orbit error and clock error on user positioning. A detailed calculation method of URE was brought forward including the partitions of the ground coverage of the MEO satellites and the calculation methods of the projection parameters of URE. The different URE performance of multiple Satellite navigation system was analyzed. Simulation results show that the radial direction projection parameters are basically the same, but the horizontal direction projection parameters are different among GPS, Galileo and BDS. The higher the satellite orbit, the smaller the horizontal direction projection parameters.

Abstract: This paper analyzes the defects of satellite navigation systems that exist in positioning and precision-guided weapons and pointes out the advantages and military needs of pseudolite. The autonomous navigation nonlinear mathematical model of Near Space Pseudolite SINS/CNS/SAR autonomous navigation system is established. Based on the merits of fading filter, robust adaptive filtering and particle filter, we propose a fading adaptive Unscented Particle Filtering algorithm. The proposed filtering algorithm is applied to SINS/CNS/SAR autonomous navigation system and conducted simulation calculation with the Unscented Kalman filter and particle filter comparison. The results show that the new algorithm that is proposed meets the needs of pseudolite autonomous navigation, and the navigation accuracy is significantly higher than the Unscented Kalman filter and particle filter algorithm.

Abstract: When the topology of data network in power grid was destroy, the system still need to provide intrusion tolerance service. The trust values relationship of the nodes in data network need be calculated. The trust value of the upper and lower limit can be deduced and adjusted to eliminate the problem of over-reliance on threshold. And the introduction of confidence values to assess the quality of the trust value. A recursive algorithm is used to obtain the average of the trust data to compute confidence values. The experimental result proves the veracity and validity of the method.

Abstract: The streaming media technology can effectively break the bandwidth bottleneck and make video/audio streaming pass through the internet smoothly. A video network platform based on the streaming media technology can well satisfy the user's requirements. This paper gives an introduction of the streaming media content type and streaming protocols. It also designs a video network platform based on B/S mode using the streaming media technology with the background management function.