A parallel tracking algorithm based on GPU computing is presented for GNSS signals. The experiments show that the speedup of the new method based on GPU is up to tens times than traditional algorithm based on CPU and it goes up with the increase of the number of tracking channels. The research shows that the multi-mode GNSS SDR receiver is becoming possible.

In order to improve the spectral efficiency of M-ary position and random-polar modified extended binary phase shift keying with continuous phase(MCP-EBPSK) modulation further,both the position and polarity of phase changes are used to carry M-ary information,then an M-ary position and three-valued MCP-EBPSK modulation is proposed.The principle of M-ary position and three-valued MCP-EBPSK is demonstrated,and the demodulator model based on multi-classifier as BP neural network,and support vector machine is also given.Comparisons and analysis on power spectrum,the-60 dB bandwidth,the spectral efficiency,and demodulation performance among the random-polar MCP-EBPSK,the three-valued MCP-EBPSK,the M-ary position and random-polar MCP-EBPSK,and the M-ary poison and three-valued MCP-EBPSK,are implemented.Simulation results show that on the premise of remaining same power spectrum structure,the new modulation method not only multiplies the bit rate and spectral efficiency,but also has better demodulation performance.

In order to solve the problem of cooperative issue in single frequency network (SFN) positioning system, in this paper, a cooperative positioning scheme using the fundamental characteristic of SFN is proposed. Some different signal levels are described for cooperative signal selection. According to the difference between the cooperative signal levels, the proper signal can be selected for cooperative positioning in different scenarios. The cooperative positioning strategies for different cooperative signal levels are also proposed to improve the positioning performance. These methods can be considered as a feasible solution for actual applications.

The training mode of innovative talents requests that the teachers should develop the students' creative talents as well as the professional knowledge and skills in their teaching program.For this purpose,focusing on the teaching process of the Basis of Computer Science course,this paper probes to a teaching mode combining what to do it with how to do it.That is to say,it is of great importance for teachers to prompt students to think for themselves how to do it,rather than tell students what to do it all along.The teaching practices have verified that the proposed teaching mode is effective and practical.

本文介绍了以连续相位载波形式构建导航卫星信号,将测距码的随机性承载在相位变化率上,在具备很高的频谱利用率的同时,更利于锁相环结构捕获与跟踪信号。使下一代GNSS具备多频段和多频点灵活部署能力,并可实现导航数据与其他信息的高速率数据传输。

Construction of a continuous phase carrier in the form of satellite navigation signals, random ranging code will be hosted on the rate of change in phase, with very high spectral efficiency at the same time more conducive to the signal acquisition and tracking using phase-locked loop structure. When employing this class of signal waveforms, the next generation of GNSS will be have multi-frequency multi-band and flexible deployment capabilities, and can transmit navigation data and other information at a high speed.

The spectrum resource in the air becomes more occupied, so it is necessary to increase spectrum efficiency with our purpose to relax more resource. Traditionally, we increase the data rate in the unit frequency band through higher order modulation, orthogonal frequency division multiplexing (OFDM) and pulse shaping. However, another way for improving spectrum efficiency is to reduce the transmitting bandwidth required for unit data rate. From this point of view, the ultra narrow band (UNB) modulation was proposed. UNB modulation is a sort of transmission technique with efficient bandwidth and high data rate. This patent review will highlight recent patents on UNB modulations, and briefly explain their theoretic foundation and key technology. Keywords: Ultra narrow band (UNB), high efficient modulations, high speed communications, special filters, modulator and demodulator (MODEM), channel coding, wireless communications, orthogonal frequency division multiplexing, Bandwidth, Sinusoidal Carrier, Carrier Energy, Waveform Manipulation Technologies, amplitude modulation, signal bandwidth, Geometric Feature Filters, Wavelet Pass Filters

The teaching of numerical integration implementation leads to four questions that guide students in programming courses at different stages of learning through self-heuristic to get satisfactory answers. For students not only mastered the basic process-oriented programming methods, but also has the global initial object-oriented programming concepts and advanced programming ideas, completed the programming model from the templates to the design patterns. The teachers make for the teaching from process-oriented to object-oriented seamlessly. Throughout a concrete example of C++ teaching practice, course of study will be linked together different knowledge to the organic way of receiving good teaching.

In this paper a throughput efficient modulation method based on the idea of continuous phase is devised, namely the continuous phase extended binary phase shift keying (CPEBPSK), which satisfies increasingly greater demand for the performance of communication systems. The detailed analysis of the corresponding power spectrum is derived by a universal way that is suitable for the binary modulation of ultra narrow band (UNB) communications. Simulation results illustrate the validity of theoretical spectrum analysis, which prove that this UNB system having high spectral efficiency. On this basis, the bandwidth is studied that indicates the CP-EBPSK technology belongs to the category of the UNB throughput-efficient communications.

Digital broadcasting signal has the unique advantages for wireless location.In this paper,the pseudo-range measurement method based on OFDM signals is introduced.A mathematical model for wireless location and tracking is presented,which exploits the feature of continuous signal transmission at a fixed rate in digital broadcasting systems.After analyzing the disadvantage of classical particle filter,i.e.the sequential important sampling(SIR) filter,a new particle filtering method using important sampling function based on EKF bank is proposed.Simulation showed that compared with the EKF and SIR filter,the new algorithm can improve the estimation precision,and converge faster.

By using OpenGL technology and Qt software in Linux,the trajectory simulation of NC code was studied.By extracting,explaining and processing the NC code,the information for simulating was got,and the graph of trajectory simulation was drawn using OpenGL.It can verify the correctness of NC code real time,fast and intuitively.The Qt software and OpenGL can run in many platforms,which makes it possible to study the trajectory simulation of NC code in embedded system.

In order to enhance the location estimation performance of mobile station (MS) tracking and positioning, a new method of mobile location optimal estimation based on the federated filtering structure and the simplified unscented Kalman filter (UKF) is presented. The proposed algorithm uses the Singer mobile statement model as the reference system, and the simplified UKF as the subfilters. The subfilters receive the two groups of independently detected time difference of arrival (TDOA) measurement inputs and Doppler measurement inputs, and produce local estimation outputs to the main estimator. Then the main estimator performs the optimal fusion of the local estimation outputs according to the scalar weighted rule, and a global optimal or suboptimal estimation result is achieved. Finally the main estimator gives feedback and reset information to the subfilters and the reference system for next step estimation. In the simulations, the estimation performance of the proposed algorithm is evaluated and compared with the simplified UKF method with TDOA or Doppler measurement alone. The simulation results demonstrate that the proposed algorithm can effectively reduce the location estimation error and variance of the MS, and has favorable performance in both root mean square error (RMSE) and mean error cumulative distribution function (CDF).

In this paper the geometry of DTV-based passive radar is studied, with the form of the ambiguity function (AF) of the system given to get TDOA and Doppler parameters, and the state and measurement models established. Then the unscented Kalman filter (UKF) method with TDOA/Doppler measurements is presented for target tracking. The simulation results show that the proposed algorithm can effectively locate and track target, and has better location and velocity estimation accuracy compared with EKF method.

For the purpose of reducing the effect of non-line-of-sight (NLOS) error that inhibits accurate location of mobile stations (MS), a novel approach based on the method of joint variance matching algorithm (JVMA) [1] is presented in our research. In order to improve location accuracy, scattering models are used to classify propagation environments and model the NLOS error effect to be incorporated into a location algorithm. By matching the statistics of the measured time-of-arrivals (TOAs) of several multipath arrivals with those produced by the scattering models, the location estimation of the MS can be obtained.

Micro-doppler effect induced by non-uniform motion of mobile receiver via faraway DTV transmit station was analyzed based on multipath channel propagation characteristics. To accurately separate and extract micro-Doppler values of multiple signal components in DTV received signals,the support vector clustering (SVC) algorithm was applied. By using FRFT transform results of the received signal,clustering analysis was conducted,and synchronous detection and accurate estimation of multiple micro-doppler components was realized. The simulation results showed that the method proposed can separate,extract and estimate micro-doppler values of multiple signal components from different paths and different DTV transmit stations under single frequency network.

In next generation mobile multimedia communications, different wireless access networks are expected to cooperate. However, it is a challenging task to choose an optimal transmission path in this scenario. This paper focuses on the problem of selecting the optimal access network for multicast services in the cooperative mobile and broadcasting networks. An algorithm is proposed. which considers multiple decision factors and multiple optimization objectives. An analytic hierarchy process (AHP) method is applied to schedule the service queue and an artiticial neural network (ANN) is used to improve the flexibility of the algorithm. Simulation results show that by applying the AHP method, a group of weight ratios can be obtained to improve the performance of multiple objectives. And ANN method is effective to adaptively adjust weight ratios when users' new waiting threshold is generated.

With the methods of theoretical analysis,this paper reveals and researches the result of frequency offset and dynamic bandwidth of a filter network in its amplitude-frequency characteristic.And through digital simulation,it proves the theoretical analysis and reveals the relationship between the rate of swept and the value of frequency offset and the broadening of dynamic bandwidth.It will be beneficial to deviation analysis of swept measurement and special design of communication filters.

The requirement and feasibility of the positioning system using digital television (DTV) broadcasting signals are analyzed. The principle of DTV positioning on the basis of frame synchronization is brought forward and the ranging characteristic is studied that the observables are asynchronously measured during the same epoch interval. The models of the pseudo-range observation and Doppler carrier phase integral are researched. The system observation and state equations are presented on the basis of the above models. The simulation results showed that DTV positioning technology could remarkably improve the precision of system state estimates using smoothing methods for positioning systems or integrated navigation systems. The DTV positioning that has a sub-meter level ranging error and meter level positioning accuracy can parallel with and even taken as a beneficial substitute for the tradition positioning technology.

Orthogonal frequency-division multiplexing(OFDM) is a bandwidth-efficient modulation technology for wideband digital communications. Because of better synchronization performance than conventional single-carrier modulation schemes,a novel positioning technology can be established on highly precise timing measurements of OFDM ranging.We focus on the signal models of OFDM ranging and analysis the lower bound of ranging measurement errors.In Part I of this paper firstly the ranging principle based on OFDM frame synchronization and the basic system model are studied;and then the system time models including signal transmission and reception,the reference time and the pseudo-range observation equation are researched;finally the transmission model and channel model for OFDM ranging signals are set up.The reception model for OFDM ranging signals and the observation performance evaluating are detailedly presented in Part II.

Orthogonal frequency division multiplexing (OFDM) modulation needs better synchronization performance than conventional single carrier modulation schemes since the former is very sensitive to time and frequency variations. So a ranging technology can be established on highly precise timing measurements of OFDM synchronization. The principles of ranging based on frame synchronization is studied that can be applied into OFDM broadcasting systems. The timing models for OFDM ranging are set up and the observational models are presented. Then the ranging performance is analyzed by calculating the Cramer-Rao lower bound of the symbol offset that is relative to the pseudo-range accuracy in OFDM ranging systems.