This PDF file contains the front matter associated with volume 6795, including the Title page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

Successful data sharing is important to integrating information between the Earth Science and geographic information communities for knowledge discovery. The Open-source Project for a Network Data Access Protocol (OPeNDAP) is a data transport architecture and protocol widely used by earth scientists. However, because the DAP and OGC protocols are incompatible. OPeNDAP lacks effective tools to access the OGC data. To solve this problem, middleware between the OGC and DAP protocols, must perform two functions--data discovery and data access. This paper discusses implementation of the data discovery component. This data discovery component first converts an OGC catalog to a THREDDS catalog encoded in XML, and then provides the XML file to the OPeNDAP client. By developing a catalog component of the middleware, the implementation enables OPeNDAP clients to discover data cataloged in OGC data catalogs.

Correcting scintillation for a slant path with adaptive optics (AO) has been studied. However, the models for solving this problem are all to treat the ray track as a straight line. Based on the engineering practical environment, in a low-earth-orbit (LEO) satellite-to-ground laser communication link, the properties of laser beam bending in the slant path will be studied in this paper, and the novel amendatory model of correcting the scintillation with AO will be presented.

LEO(Low Earth Orbit) satellite network is more suitable for multimedia communication than GEO(Geosynchronous Earth Orbit) and MEO(Medium Earth Orbit) satellite network because of short propagation delay. Routing computation in communication network with several constraint factors has been proved to be a NP-C problem. Ant colony algorithm as a bionics algorithm has good performances on solving NP-C problem. Existing research about ant colony algorithm mainly concentrates on Ad hoc network, and application in satellite network is not completely developed. According to the characteristics of LEO satellite network, this paper presents a new routing method based on ant colony algorithm with forecast strategy and elitist strategy. Generally each satellite establishes two intra-ISLs with forward and backward neighbors in the same orbit, and two inter-ISLs with left and right neighbors in the adjacent orbits. Thus the topology of satellite network consists of many grids. According to the specific topology, forecast strategy is introduced to reduce redundant information. On the other hand, pheromone is updated continuously to ensure elitist path chosen. Assuming a reference satellite network model is given, the simulation results show that the improved algorithm converges more quickly than basic ant colony algorithm.

Satellite-ground laser communication system based on Turbo code is put forward and analyzed. Firstly, this paper analyzes channel character, then simulates the characteristic of the system based on Turbo code. The result shows that Turbo code can well compensate and conquer all kinds of attenuations and noises. So the bit error rate is reduced. In addition, anti-jamming ability, stability and reliability are improved.

A new approximate time domain reflection coefficient, the relationship between the reflection and refraction on slab surfaces, and expression for propagation loss term within the slab in time domain are deduced in this paper. By using time domain convolution of the three terms, a simplified analytic solution for UWB impulse signal transmitting through a finitely conducting slab is proposed. This solution takes into account the frequency range from 3.1 to 10.6 GHz and is suitable for most common building construction materials within indoor environment. The simulations of incident monocycle transmitting through slabs of different materials and thickness are presented by applying the simplified time domain analytic solution to illustrate the characteristics of transmission and give some results in simplification of transmission field analysis in indoor channel modeling.

Due to the fast beam-steering and adaptive interference suppression performance, adaptive digital beamforming (ADBF) technique is widely used in the multi-antenna radar systems, such as phased array radar and MIMO radar, which are important measurements of space target surveillance system. However, the use of adaptive digital beamforming techniques in multiple beamforming (MBF) system is restricted by the computational requirement as the number of beam increases, especially in the spaced-based system. A fast MBF algorithm is presented in this paper. The algorithm rearranges the process of beamforming, which reduces the computational complexity by the utilization of FFT and the fast chirp z-transform (CZT) method while remaining the same performance of conventional methods. The computational cost analysis and simulation results show that the algorithm needs less computational requirement than that of direct approach without harming the adaptive interference suppression performance.

A novel multiple access model of satellite formation flying is brought forward, which has the advantages of shared signal bandwidth, asynchronous access etc, at the same time it overcomes the problems of difficulty of constructing the addressing codes in the optical code division multiple access and that of hardware implementing in wavelength division multiple access. The model makes use of delay difference between two arms of Mach-Zender interferometer (MZI) to encode and decode at the end of transmitter and receiver respectively, that's to say when the delay difference of receiving end is close to that of transmitting end, the received optical power would be maximum. Frequency shift keying modulation is adopted to achieve the coherent multiplexing multiple access. Then when the micro-satellite beam is transmitted in atmosphere condition of weak turbulence, the receiving optical field is described by the Rytov model based on the premise of independent optical field interference, the formula of SNR and BER is deduced. The simulation results show that given the turbulence amplitude, 1/SNR ascends along with increasing of satellite number, furthermore the larger turbulence amplitude, the more quickly 1/SNR rises, this proves number of satellites and turbulence amplitude are the dominating parameters which affect the system performance.

In this paper, the characteristic of satellite network is analyzed, and based on perturbation analysis, a dynamic bandwidth allocation model is put forward. Based on this model, the bandwidth event path is established, the process of the perturbation spread is analyzed and the bandwidth sensitivity about average transport delay of the space network is given. The paper lays a foundation of decrease of average transport delay and enhancement of performance of the space network.

Recently, free space optical communication has attracted a considerable amount of interest as an alternative medium to radio for wireless transmission. It has many advantages such as a huge unregulated bandwidth, high data rates, and resistance to multi-path fading relative security against eavesdropping. The work presented in this thesis focuses on modulation schemes. Concerns of eye safety and power consumption limit the average transmitter power, which suggests that modulation techniques possessing a high peak-to-mean power ratio are favorable. This is generally achieved by trading off power efficiency against bandwidth efficiency. A novel dual-header pulse interval modulation (DH-PIM) for optical wireless communications is proposed in this paper. The symbol structure, the spectral properties, and the expression for bandwidth requirement and optical power requirement of DH-PIM in the absence of and in the presence of multi-path dispersion is presented in this paper.

In recent years, high-altitude/long-endurance (HALE) airship platforms have generated great interest as a means to provide communications and surveillance capabilities using a relatively inexpensive flight platform. One of the challenges of HALE airship design is the development of flight control system. Modeling, flight control law design and real-time simulation platform construction for a conceptual high altitude long endurance airship are studied in this paper. The nonlinear six degree-of-freedom (DOF) dynamic equations of the airship with added mass and inertia are developed using Matlab, and linear models are extracted from it. Flight control laws are designed for geostationary positioning. A real-time open architecture flight simulation system was developed using commercial-off-the-shelf hardware and popular software. By using automatic code generate technique, the system drastically reduced expenses for high-fidelity simulations without abandoning quality. The simulation system is flexible enough to allow expansion and reconfiguration and later can accomplish hardware-in-the-loop (HIL) simulation.

This paper presents a selection and grouping algorithm based on proposed network coded cooperative strategy in aeronautical communications. In such a practical scenarios, communications between high-speed mobile nodes are troubled with high reliability and capacity demands of the emerging aeronautical applications. The idea of network coded cooperative strategy is combining information at the relay and joint decoding at the destination, which could improve reliability and capacity without much loss of throughput of the whole networks. Then, we consider the selection and grouping algorithms in this context. An adjacency matrix is defined to describe the connection of the nodes in one radio contact disk, so that, the selection and grouping algorithm is equal to construct this adjacency matrix avoiding girth 4 and minimize the system outage probability. At the end of the paper, simulations and results will be given to demonstrate the algorithms.

In the space laser communication, the link of communication is builded in atmospheric random channel. the laser transmission is affected by the atmospheric turbulence seriously. The communication laser is modulated to circular polarized light in order to reduce the influence of the atmospheric turbulence. A several experiments are designed to validate that the circular polarized laser is available to reduce the communication noise in the space optical communication. The methods of the laser spot detection and spot parameter analysis is put forward in this paper: Firstly the subtraction of the background is used in image preprocessing in order to eliminate the influence of static background, then a series of methods such as the local dynamic threshold segmentation, edge extraction are used to detect and recognize the spot. Finally the parameters of the spot are calculated such as spot's average brightness, background's average brightness and the contrast gradient, and the characteristic of the laser communication is analyzed. The experiment results show that the circular polarized laser can enhance the contrast and improve the communication quality in the spatial optical communication. This method satisfies the request of real-time processing in communication, and is also effective and practical. practical.

First this paper describes the principals of stereo vision, the application in spacecraft formation flying and deduces the formulations for the observation. Then a kalman filter enhanced vision system for spacecraft formation flying relative navigation is discussed. At last some virtual evaluations for proposed measurement is presented which showed the better stability and precision.

Energy-efficient should not be the only design goal in MAC protocols for wireless sensor networks, which involve the use of battery-operated computing and sensing devices. Low-latency operation becomes the same important as energy-efficient in the case that the traffic load is very heavy or the real-time constrain is used in applications like tracking or locating. This paper introduces some causes of traditional time delays which are inherent in a multi-hops network using existing WSN MAC protocols, illuminates the importance of low-latency MAC design for wireless sensor networks, and presents three MACs as examples of low-latency protocols designed specially for sleep delay, wait delay and wakeup delay in wireless sensor networks, respectively. The paper also discusses design trade-offs with emphasis on low-latency and points out their advantages and disadvantages, together with some design considerations and suggestions for MAC protocols for future applications and researches.

The Bandwidth request algorithm which intervenes in the bandwidth-on-demand (BoD) access mechanism plays an important role in DVB-RCS satellite systems to optimize bandwidth utilization. In this paper, a memory cost improved bandwidth request algorithm (MCI-BRA) is proposed. The MCI-BRA deals mainly with the memory cost which is measured as the queue size at the terminal while offers a controllable trade-off between delay and efficiency. A traffic plane model for a satellite system using DVB-RCS is also described. Several assumptions are discussed, followed by detailed description of the MCI-BRA. Comparisons between the proposed algorithm and existing ones are also presented and analyzed. The simulating results show that MCI-BRA proposed in this work performs better than existing algorithms on controlling memory cost while handles the delay and efficiency issues as well as the existing ones.

The emerging technology of ultra wide-band (UWB) high-speed indoor wireless communication has attracted worldwide attention. With the merits of high data rate, low system power cost and mufti-path immunity, compared with general narrow band wireless communication systems, UWB has became one of the most competitive and promising technologies in the near future. Theoretical researches and simulation experiments are done in this paper about a few of key problems in UWB wireless communication of channel measurements and modeling indoor wireless channel and performance evaluation of space hopping UWB Impulse Radio (SH-UWB-IR) System.

A new practical free space quantum communication system is proposed, it is based on the principle of quantum secure direct communication. Quantum cryptography is a practical method to realize free space optical communication. Different from the existing free space quantum key distribution communication system, the free space quantum secure direct communication is deterministic and the system is more simple. In this paper, a new structure of four transmitting channels is prensented, this structure could increase the security and capacity of system. The setup of transmitter and receiver of each transmitting channel is discussed in detail, and the communication process is analyzed. The result shows that this free space quantum system could be realized and can work over long distance.

On-board processing (OBP) is one of significant satellite communication technologies, and the Asynchronous Transfer Mode (ATM) is widely used in the OBP which can guarantee the QoS. This article presents the CAC (Call Admission Control) algorithm and Congestion Control algorithm. We combine with B-CAC algorithm, Bahadur-Rao's theory, Weiss theory, to improve the old method, and the simulation results show that when the PDR/LR is small the burst is high, the chain utilization and statistic multiplexing gain get a big advantage. Besides, concerning TCP congestion control, the article compared five strategies: Tahoe, Reno, Newreno, Sack and Vegas. The simulation results show that the Vegas can be used to predict congestion conditions correctly; its congestion window (cwnd) control is smoother and is superior to other algorithms in average RTT.

Modularized design takes great advantage to micro-small satellites. Many modules and subsystems are manufactured individually, needs a distributed on-board data system. A kind of distributed OBDS is carried out, all the modules and subsystems connect to data bus network by ESN. Many kinds of bus can be used in satellite, and CAN, UART and 802.11 represents three typical different kind. The ESN structure is given. Take CAN bus for example, the paper details the process of bus initialization, noting some facts for PnP function.

The method of correcting angle-of-arrival fluctuations with adaptive optics (AO) is presented in this article. Numerical simulation is used for analyzing and studying the effect of AO correction and its influence factors. The simulative results indicate that AO can correct angle-of-arrival fluctuations induced by atmosphere turbulence effectively and the effect of AO correction is related with wavelength and aperture.

European GALILEO different from GPS will have more excellent positioning performance in accuracy for that a new modulation technique which is called the Binary Offset Carrier (BOC) modulation will be adopted in GALILEO. BOC modulation has a direct high efficiency in frequency occupation and in mitigation of interference. In the pseudo range measurement for high precision application, code tracking multipath error is one of the main error sources that can not be eliminated by Differential Global Positioning System(DGPS), and many testing and measuring results have shown that code tracking multipath error has become a dominating error source in the future Global Navigation Satellite System (GNSS) applications. This paper presents the code tracking multipath error of BOC signals in GALILEO and of L1 signal in GPS after analysis of several characteristics in time and frequency domain such as AutoCorrelation Function (ACF) and Power Spectral Density (PSD). The conventional ACF of GPS signals is expressed by the triangle shaped function, but the BOC signals have ACF with multiple peaks that result in the complexity of ACF expression in many intervals. This paper presents another expression with the ceil function to compute the theoretical code tracking multipath error for sine typed and cosine typed BOC signals. Compared with the traditional algorithm, the new algorithm can speed up the numerical solution of the tracking bias in simulation. The simulation results indicate that the antimultipatherror performance of cosine BOC signals is much better than that of sine BOC signals.

It is necessary to build spatial index in order to managing complex spatial data in peer-to-peer (P2P) environments. This paper analysis and summarizes the related studies, designs a new spatial index model named P2PQR-tree which uses the distributed Quad-tree and the local R*-tree. P2PQR-tree applies Quad-tree techniques into P2P environments and uses replication strategy to improve the system's load balance. This paper includes gives the models definitions, the model's architecture design, the model's performance analysis results. P2PQR-tree has some advantages to the old methods, for example, its data management is more reasonable, it can support metadata management better, implement rights control easier, reduce changes of distributed index, and adapt to dynamic character of P2P network better.

A New Approach based on ant colony algorithm for the automatic modulation recognition of communications signals is presented. This approach can discriminate between continuous wave (CW), Amplitude Modulation (AM), Frequency Modulation (FM), Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK) and Quaternary Phase Shift Keying (QPSK) modulations. Requirements for a priori knowledge of the signals are minimized by the inclusion of an efficient carrier frequency estimator and low sensitivity to variations in the sampling epochs. Computer simulations indicate good performance on an AWGN channel, even at signal-to-noise ratios as low as 5 dB. This compares favorably with the performance obtained with most algorithms based on pattern recognition techniques.

Ad hoc space networks (ASNs) are implemented using flexible, distributed architecture consisting of constellations of dynamically deployed space, airborne and mobile platforms. The nodes within ASNs operate both as communication end-points as well as routers, enabling multi-hop wireless communication and dynamic network topology. Secure and efficient key agreement scheme is the crucial mechanism to construct secure ASNs. Previous ID-based cryptosystem is not feasible in ASNs because of the interaction process in key agreement. A novel non-interactive and efficient ID-based two-party key agreement protocol is proposed for ASNs. Based on the security analysis of IDNIKS proposed by Tso et al., the feasibility of adopting non-interactive key agreement for multi-party in ASNs is analyzed and a conclusion is given.

This paper discusses a layout of bus-on-chip core referring to SoC thinking which is composed of six sections based on a physical chip of FPGA: multi-Processor cache coherence unit, external bus control module, TT&C module, Ethernet Mac interface, EDAC/DMA module, and AMBA bridges. Multi-processor cache coherence unit, as a key part of the bus core, is used to serve the rapid parallel computing by means of the breakthrough of write/read speed of EMS memory and enhances the reliability of OBC with the service of supporting the hot standby of redundancy and the reconfiguration of fault-tolerance. External bus control module is made to support the PnP of external components applying varieties of buses, which is designed by means of soft-core in order to adapt the variation of macro-design and improve the flexibility of external application. TT&C module is the interface of subsystems of telemetry, telecommand and communication, which involves the protocols of HDLC. Ethernet Mac interface based on TCP/IP acts as the access of ISL for formation flying, constellation, etc. EDAC/DMA module mainly manages the data exchange between AMBA bus and RAM, and assigns DMA for the payloads.

Space-time coding based on transmit diversity have recently proposed as a design art of signals for transmit diversity in satellite-data communications. The paper mainly discusses the performance of some STCs applied to the forward link of a WCDMA multi-satellite UMTS environment. MRC, STBC, SDT and STTC have been firstly considered. Furthermore, outer convolutional encoder have been considered to concatenate with MRC, STBC and STD, while for STTC, a convolutional encoder plus an iterative decoding has been used to perform a STTCM. Simulation results show that STD outperforms all the other schemes in terms of BER and FER for lower values of SNR. While the SNR is increasing, STTC and STTCM have shown the best performances in terms of FER. Performance results with various modulation methods for the serially concatenated convolutional STBC system are also presented here.

It is required that an ADC for sampling broadband signal directly has high sampling rate, and this will make the sampling accuracy decrease and difficult to be realized. This paper introduces an idea that using multi-channel and low rate ADCs performs sampling broadband signal, then presents a novel method of utilizing adaptive beam forming technique to recover complete bandwidth of the broadband signal. Application of this method can implement both low rate sampling and high accuracy; in addition, it is robust to channel delay and other errors. The result of processing the simulated data has verified the effectiveness of this method.

In this paper, a broadcast channel model is set up to analyze and validate the real-time performance of the spread spectrum ALOHA used in satellite formation flying. A three-satellite formation flying system model is the concretion of the model. In the model, a frame definition referenced CCSDS recommended standard is imported. According the three-satellite model, this paper deducts the delay probability, the probability of collision and the mean time of communication to estimate the performance of spread spectrum ALOHA. By simulation, it validates that spread spectrum ALOHA has a good real-time performance in the model of satellite formation flying, which could satisfy milliseconds order requirement in distance of several hundred kilometers.

The Satellite Mission Scheduling problem (SMS) involves scheduling tasks to be performed by a satellite, where new task requests can arrive at any time, non-deterministically, and must be scheduled in real-time. This paper describes a new Satellite Mission Scheduling problem based on Genetic Algorithm (SMSGA). In this paper, it investigates algorithmic approaches for determining an optimal or near-optimal sequence of tasks, allocated to a satellite payload over time, with dynamic tasking considerations. The simulation results show that the proposed approach is effective and efficient in applications to the real problems.

A utility oriented radio resource management algorithm is proposed for broadband nongeostationary satellite network which works in the heterogeneous network environment and provides access services for various customers on the ground. Based on the game theory, the problem for optimizing the network's performance is turned into the problem for maximizing the network's long term utility in the proposed algorithm. With evaluation to the traffic condition and dimensions of Qos for the network at the moment while the access service requirements changing, the influence of this service requirement to the long term utility of the satellite network is audited and then the resource assignment decision can be made according to the rule for maximizing the satellite network's long term utility. The process directed by game theory guaranteed both that the benefit of the network and the requirements of the customers could be considered synthetically. The simulation results demonstrate the effectiveness of the proposed algorithm.

In air-ground tactical data link system, a kind of primary anti jamming technology adopted is direct sequence - frequency hopping spread spectrum (DS-FHSS) technology. However, how to implement the quick synchronization of DS-FHSS is an important technology problem, which could influence the whole communication capability of system. Thinking of the application demand of anti jamming technology in actual, a kind of cascade connection serial parallel hybrid acquisition synchronization method is given for the DS-FHSS system. The synchronization consists of two stages. The synchronization of FH communication is adopted at the first stage, and the serial parallel hybrid structure is adopted for the DS PN code synchronization at the secondary stage. Through calculating the detect probability of the FH synchronization acquisition and the acquisition time of DS code chip synchronization, the contribution to the synchronization capability of system by this method in this paper is analyzed. Finally, through simulating on computer, the performance estimate about this cascade connection serial parallel hybrid acquisition synchronization method is given.

In this work a Bluetooth-based wireless sensor network is proposed. In this bluetooth-based wireless sensor networks, information-driven star topology and energy-saved mode are used, through which a blue master node can control more than seven slave node, the energy of each sensor node is reduced and secure management of each sensor node is improved.

A piecewise linear control allocation approach was presented for the solution of the non-linear control allocation problem for flying wing Unmanned Aerial Vehicle (UAV). The presented approach utilizes the piecewise linear assumption for the control effector moment data. This assumption allows the non-linear control allocation problem to be cast as a piecewise linear program. In order to solve the piecewise linear program, it was re-formulated as a mixed-integer linear program. The discussed mixed-integer linear programs were implemented in a nonlinear Simulink simulation of a flying wing UAV landing phase. The analysis of the simulation results showed that the piecewise linear program approach results in improved tracking performance when compared to a more traditional control allocation approach that uses a linear approximation of the control moments, especially when the aircraft is subjected to control effector failures.

Autonomous navigation of spacecrafts is of a difficulty task, however which is a must in future deep space exploration. With multiple spacecrafts flying in space, this aim can be achieved by formation flying spacecrafts utilizing ITDOA and IDD methods, which can locate the position of earth-station from one-way uplink signals in the FFS coordinate, and by way of conversion of coordinates, the position of FFS is achieved in ECEF coordinate. The ability of neural network filter in navigation to extract position of spacecrafts from random measuring noise of signal arrival time and Doppler shift is studied with different radius of FFS and surveying parameters. The NN filter used by spacecraft group is new way of unidirectional autonomous navigation and is of highly precision of hybrid navigation.

Radio spectra in space are close-packed more and more, so its impact of frequency as a valuable resource is increasingly prominent. Based on reviews of those classical methods a communication engineer accustomed to, this paper will interpret the theoretic foundation and key technology of the Ultra Narrow Band (UNB) modulation and demodulation, and gives a system scheme for UNB transmissions. This UNB scheme includes a unitive expression for extending of binary phase modulations, a realization of its modulator and demodulator (MODEM), and especially an important UNB filter. Applications to space communication of the proposed high data rate UNB MODEM are discussed.

Space Internet technology is the Internet that refers to technology which is widely used in the terrestrial network, improved under the space communications feature, thus using the improved Internet protocols and technology, to meet the needs of future space mission technology. In protocol engineering area, conformance testing is a very important step. The purpose of conformance testing is to determine to what extent a single implementation of a particular standard conforms to the individual requirements of that standard. Conformance testing can increase the confidence level of implementation complying with the protocol specification, and enhance the probability of interoperability between different implementation. The ISO/IEC9646 standard described by ISO is the maturest theory in protocol conformance testing theories. Space communication network test framework is proposed, in which the test architecture is defined for conformance testing to space communication network. In this paper, the ISO9646 standard is improved, in order to meet the requirements of conformance testing of space communication network. The contribution of this paper is the proposition of a complete method to the design of conformance testing against space communication network. The simulation results have shown that the method has better test results, to meet the space communications network testing needs. With the testing of the space communications network protocol implementation, we discovered the problems of the protocol implementation. It has verified the theory and method.

By analyzing all kinds of address configuration algorithms, this paper provides a new pseudo-random dynamic address configuration (PRDAC) algorithm for mobile ad hoc networks. Based on PRDAC, the first node that initials this network randomly chooses a nonlinear shift register that can generates an m-sequence. When another node joins this network, the initial node will act as an IP address configuration sever to compute an IP address according to this nonlinear shift register, and then allocates this address and tell the generator polynomial of this shift register to this new node. By this means, when other node joins this network, any node that has obtained an IP address can act as a server to allocate address to this new node. PRDAC can also efficiently avoid IP conflicts and deal with network partition and merge as same as prophet address (PA) allocation and dynamic configuration and distribution protocol (DCDP). Furthermore, PRDAC has less algorithm complexity, less computational complexity and more sufficient assumption than PA. In addition, PRDAC radically avoids address conflicts and maximizes the utilization rate of IP addresses. Analysis and simulation results show that PRDAC has rapid convergence, low overhead and immune from topological structures.

Interplanetary (IPN) Internet is a communication infrastructure providing communication services for scientific data delivery and navigation services for the explorer spacecrafts and orbiters of the future deep space missions. The interplanetary backbone network has the unique characteristics hence routing through the backbone network present many challenges that are not presented in traditional networks. Some routing algorithms have been proposed, in which, LPDB integrates the shortest path algorithm and the directional broadcast method to guarantee fast and reliable message delivery. Through this mutipath routing strategy, unpredictable link failures is addressed, but additional network overhead is introduced. In this paper, we propose an improvement of the LPDB named ALPDB in which the source could adaptively decide the next-hop nodes according to the link condition, hence reduce the network overhead. We model this algorithm on the network simulation platform of OPNET and compare it with other applicable algorithms in data passing ratio, data delay and network overhead. The result indicates that the ALPDB algorithm could not only guarantee reliable message delivery, but also decrease the cost significantly.

Nowadays, there are some works with free-space laser communication system, but security issues of this network are always neglected. We present an efficient online/offline routing based on identity-based signature for ad hoc networks with Free-Space-Optics (FSO). The protocol is especially suitable for ad hoc networks with FSO because the major computational overhead is shifted to the offline phase, whereas the online phase requires only a very low computational overhead to achieve a full scale of authentication. In addition, since the signature scheme uses an identity-based cryptosystem, it does not need to maintain a public key directory and to exchange any certificate. The effectiveness of our protocol is simulated using QualNet tools.

Effect factors on sky radiance were analyzed based on the transfer theory of light in the random medium. In fact, these factors mainly include: 1) absorbed and scattered extinction of solar radiance by atmosphere; 2) single scattering process of solar radiance by atmosphere along viewing direction; 3) multiple scattering process of solar radiance by atmosphere along viewing direction; 4) thermal radiation of atmosphere. The latter three ones among these factors increase sky radiance. After this analysis, derivative process of the Radiative Transfer Equation was studied thoroughly from the law of conservation of energy and the transmission of solar radiance in the earth-atmosphere system, and some methods of dealing with the multiple scattering are analyzed and used in calculating sky radiation. Finally, an approximate model was developed for sky radiance of sunshiny and cloudless sky to make full use of the RTE, an analytical express of sky radiance is gave out for single scattering and quasi-multiple scattering effects. Sky spectral radiance was calculated for some representative case of clear sky, and results have been compared with those of MODTRAN. The results show that the present model is efficient under the sunny and cloudless condition.

In this paper, a channel aware HARQ (CA-HARQ) scheme based on data punctured rate compatible LDPC (DP-LDPC) codes, which might satisfy the demand for bandwidth and rate in land mobile communication system, is proposed. The scheme is based on type II HARQ technique cooperated with a DP- LDPC code. In the proposed scheme, the effective rate of the LDPC code is adapted according to the channel quality information (CQI) estimated at the receiver, so as to decrease the redundancy when the channel is good and vice versa, the retransmitted blocks are combined with the previous information transmitted to achieve high probability of successful decoding. In this paper, we use a 2-bit CQI feedback scheme. Simulation results, which based on a land mobile satellite channel, show that the proposed channel aware H-ARQ scheme based on DP-LDPC codes improved the throughput by 0.4dB at low SNR compared to a pure DP-LDPC type II HARQ, and it can also be an effective solution to compensate rain attenuation and multipath fading in land mobile satellite systems.

We consider the estimation of Doppler shift of the data-modulated signal in the direct sequence spread spectrum (DS/SS) communication system. A new open-loop Doppler shift estimation algorithm is developed by taking advantage of the priori knowledge that correlation peak is Sinc-function of Doppler shift in the DS/SS receiver. The proposed algorithm samples correlation peaks on different Doppler shifts and fits these samples to the correlation peak curve using a nonlinear least squares method. Performance of the proposed method is demonstrated by statistical analysis and numerical simulation. And a comparison with the four-quadrant frequency discriminator algorithm (FQFD) is given.

In order to offer a potential for extending the life of satellites and reducing the launch and operating costs, satellite servicing including conducting repairs, upgrading and refueling spacecraft on-orbit become much more frequently. Future space operations can be more economically and reliably executed using machine vision systems, which can meet real time and tracking reliability requirements for image tracking of space surveillance system. Machine vision was applied to the research of relative pose for spacecrafts, the feature extraction algorithm was the basis of relative pose. In this paper fractal geometry based edge extraction algorithm which can be used in determining and tracking the relative pose of an observed satellite during proximity operations in machine vision system was presented. The method gets the gray-level image distributed by fractal dimension used the Differential Box-Counting (DBC) approach of the fractal theory to restrain the noise. After this, we detect the consecutive edge using Mathematical Morphology. The validity of the proposed method is examined by processing and analyzing images of space targets. The edge extraction method not only extracts the outline of the target, but also keeps the inner details. Meanwhile, edge extraction is only processed in moving area to reduce computation greatly. Simulation results compared edge detection using the method which presented by us with other detection methods. The results indicate that the presented algorithm is a valid method to solve the problems of relative pose for spacecrafts.

Free-space laser communication is a research direction in wireless communication domain. The image transmission, compression coding and storage are ones of most important techniques in the free space laser communication. In order to improve error resilient capability and transmission efficiency for image transmission over noisy and varying channels in the free space laser communication (FLSC) , we contrive a joint source and channel coding (JSCC) scheme, in which extended set partitioning in hierarchical trees (ESPIHT) and rate compatible punctured convolutional code (RCPC) are used. Specifically, ESPIHT segments an image into different sizes of blocks whilst determining different levels of source significance; RCPC code is then used to provide unequal error protection for individual blocks. Various simulations show that this scheme can support robust and efficient image transmission in a very effective way. Experiments demonstrate that the proposed method can obviously improve the image quality compared to that of the classical approach of separate source and channel coding. The peak SNR for reconstruction image also has some improvement. It is an effective fast image compression method.

After analyzing the existing problems in real-time mission scheduling of satellite TT&C ground station, the live communication function of real-time scheduling speech fit for mission scheduling system in ground station is developed, using the IP multicast technology and multimedia speech processing technology, then the reliability of multicast is improved, and a network simulation test is made.

In this paper, we present an analytic model for evaluating the average end-to-end delay and per-node throughput in an IEEE802.11MAC DCF based wireless network. By virtue of QNA and probability generation function, we model ad hoc network as open M/G/1 queuing networks and obtain the closed form expressions for average end-to-end delay. Simulations based on NS2 validate the accuracy of our model.

In this paper, the Bluetooth wireless data transmission technology is applied in on-board computer system, to realize wireless data transmission between peripherals of the micro-satellite integrating electronic system, and in view of the high demand of reliability of a micro-satellite, a design of Bluetooth wireless network based on fault-tolerant technology is introduced. The reliability of two fault-tolerant systems is estimated firstly using Markov model, then the structural design of this fault-tolerant system is introduced; several protocols are established to make the system operate correctly, some related problems are listed and analyzed, with emphasis on Fault Auto-diagnosis System, Active-standby switch design and Data-Integrity process.

A novel nonlinear geometric feature equalizer based on minimum bit error rate is proposed in this paper for the filtering of noise and interference whose frequency band overlaps with the desired signal in extended binary phase shifting keying communications. Considering that the desired signal and the interference have different stochastic characters in feature space, the proposed equalization algorithm recovers the desired signal by neural network. Simulation results show that when extended binary phase shifting keying signals are contaminated by relatively strong interference, geometric feature equalizers can provide very low bit error rate. This will provide an alternate filter used for extended binary phase shifting keying communications and also for deep-space communications etc.

The resource planning and scheduling technology of payload is a key technology to realize an automated control for earth observing satellite with limited resources on satellite, which is implemented to arrange the works states of various payloads to carry out missions by optimizing the scheme of the resources. The scheduling task is a difficult constraint optimization problem with various and mutative requests and constraints. Based on the analysis of the satellite's functions and the payload's resource constraints, a proactive planning and scheduling strategy based on the availability of consumable and replenishable resources in time-order is introduced along with dividing the planning and scheduling period to several pieces. A particle swarm optimization algorithm is proposed to address the problem with an adaptive mutation operator selection, where the swarm is divided into groups with different probabilities to employ various mutation operators viz., differential evolution, Gaussian and random mutation operators. The probabilities are adjusted adaptively by comparing the effectiveness of the groups to select a proper operator. The simulation results have shown the feasibility and effectiveness of the method.

The images obtained by different sensors differ from each other in terms of resolution and spectrum. Image fusion is a very useful technique which focuses on forming a new image by combining the unique and complementary information provided by different images. A new image fusion method based on multi-resolution analysis and directional gradient is described in this paper. The key idea is to use different fusion strategies along different directions, in order to take into account the anisotropy of the images. The directional gradient is used in describing directional property. Experimental results show that the proposed method is effective and promising to enhance visualization in the fused image.

Impulse systems do not undergo the multipath destructive interference that manifests itself as Rayleigh fading prevalent in continuous wave systems, but rather show up as delayed replicants of the direct impulse. In this paper, the path loss characteristics for impulse signals propagation over a plane earth are proposed. The condition for direct pulse and its replicant overlapping with each other is investigated. The polarization of the transmission signals, which was always neglected by previous approaches, is taken into account here. Moreover, a new time domain reflection coefficient, which is simple and accurate in comparing with conventional results, is adopted in developing the reflected pulsed field. The simulation result shows that the path loss can be characterized as 3 zones with different path loss exponent as distance between transmitter and receiver (T-R) increasing.

LS-SVM (Least Squares-Support Vector Machines) are applied to seismic prospecting signals denoising so as to suppress the stochastic noise in this paper. Firstly, we propose and prove a new admissible support vector kernel-Ricker wavelet kernel, which is superior to the popular RBF (radial basis function) kernel in terms of the waveform retrieved and SNR (Signal to Noise Ratio) gained when applied to the noise reduction of seismic prospecting signals. LS-SVM embed two tuning parameters which may diminish the overall performance of LS-SVM if not well chosen, so we investigate the selection of LS-SVM parameters including kernel parameter and regularization parameter, respectively. We can conclude that Ricker wavelet kernel parameter should be set as the predominant frequency of seismic signal and regularization parameter γ can be accepted in a wide range. Our denoising experimental results show that the performance of Ricker wavelet LS-SVM using the aforementioned parameters setting outperforms Wiener filtering, median filtering and LS-SVM based on RBF kernel in terms of the definition of seismic prospecting event retrieved and SNR gained.

Aiming at the characteristics of acoustic transient signal emitted from antisubmarine weapon which is being dropped into water (torpedo, aerial sonobuoy and rocket assisted depth charge etc.), such as short duration, low SNR, abruptness and instability, based on traditional power-law detector, a new method to detect acoustic transient signal is proposed. Firstly wavelet transform is used to de-noise signal, removes random spectrum components and improves SNR. Then Power- Law detector is adopted to detect transient signal. The simulation results show the method can effectively extract envelop characteristic of transient signal on the condition of low SNR. The performance of WT-Power-Law markedly outgoes that of traditional Power-Law detection method.

A mobile ad hoc network is characterized by multi-hop wireless links, absence of a fixed infrastructure, and frequent host mobility. The instability of the topology in this type of networks makes multipath routing difficult for the available alternative paths are inherently unreliable. So far, much of the effort of multipath routing has been focused on using the predefined alternate path when a relay on the primary path has failed despite the alternate path is out of use. Accordingly, this reactive route handoff can decrease the overall network performance with increasing routing overhead. In this paper, we propose a feedback-based multiple paths route scheme and provide its analytical evaluation. Our scheme is based on utilizing an alternative path as a feedback channel to carry path state information for primary path. In this regard, it can proactively give up the primary path and use the current candidate path as primary path before it breaks. In this paper, we consider the problem of routing data over multiple disjoint paths via an analytic modeling framework to determine the frequency of routing discovery procedure. The results show that a significantly better performance than the single path routing and traditional multipath routing can be achieved.

Cold-test characteristics including dispersion and coupling impedance of a coupled-cavity slow-wave structure for space TWT working in millimeter band have been simulated by self-designed software. The slow-wave structure has been modeled and cold-test characteristics data were obtained. The interaction between electromagnetic wave and electron beam has also been analyzed qualitatively. The study in the paper can provide some references for the design of coupled-cavity slow-wave structure for space TWT.

Satellite remote sensing image compression system is expected high compressing rate, real time dealing and high fidelity. Based on lapped biorthogonal transform (LBT) and its integer algorithm, this paper describes a fixed-point lapped transform algorithm using approximation to trigonometric function, studies the structure of LBT coefficients and presents a modified zerotree coding algorithm. Also, this paper studies the implementation in TMS320C6000 DSP of the algorithm, the processing speed is improved through task combining, complier options, software pipelining, loop unrolling and complex instruction. This algorithm has been used in a prototype of data compression equipment. Image coding experiments show that the algorithm's memory requirement is low and its coding performance is very competitive with SPIHT when its complexity is far lower than SHIHT.

P2P applications for file-sharing and video streaming have become tremendously popular in recent years, and it is now accounting for a significant share of the total network traffic. As P2P applications nowadays tend to use arbitrary ports to camouflage their communications, traditional methods like port-based identification have become highly inaccurate. In this paper, we propose a measurement system to detect and measure the real-time P2P traffic more reliably. The measurement methodology is based on using application level signatures implemented by netfilter extension as well as packet classifier. We further present the results from a P2P traffic analysis at a campus network, which show that this P2P traffic measurement system can provide the performance and scalability required for practical applications.

This paper addresses the problem of rejecting fixed star background in star-background image. For most sensors with a fine spatial resolution, phenomenological effects, such as background, and system effects, such as noise, contribute significant numbers of spurious points to each frame. In star-background images, fixed stars are uppermost source of spurious points. Since background and noise do not behave like targets, a good tracking algorithm would eventually reject the spurious points as non-targets. However, the computation required to consider which points appearing in a frame are from the target grows geometrically with the number of points to be considered. Simply considering each of these points as a candidate target point unnecessarily burdens the tracking algorithm and in many cases would require computational resources that cannot be provided to the mission. In this paper, we proposed a new method for rejecting fixed stars based on star-point matching in star-background image. We decide the fixed stars using point matching between points in actual image and points in ideal image which relies on the catalog. This work extends applied domain of Hausdorff Distance (HD) which is one of commonly used measures for object matching. In our experiments, Least Trimmed Square HD (LTS-HD) was used in point matching, and the result is effective.

This paper demonstrates a method for three-dimensional (3D) reconstruction and visualization of large scale multidimensional surficial, geological and mine planning data with the programmable visualization environment OpenGL. A simulation system developed by the authors is presented for importing, filtering and visualizing of multidimensional geologically related data. The approach for the visual simulation of complicated mining engineering environment implemented in the system is described in detail. Aspects like presentations of multidimensional data with spatial dependence, navigation in the surficial and geological frame of reference and in time, interaction techniques are presented. The system supports real 3D landscape representations. Furthermore, the system provides many visualization methods for rendering multidimensional data within virtual 3D scenes and combines them with several navigation techniques. Real data derived from an iron mine in Wuhan City of China demonstrates the effectiveness and efficiency of the system. A case study with the results and benefits achieved by using real 3D representations and navigations of the system is given.

Methods of measuring a RVD (rendezvous and docking) cooperative object's pose from monocular and binocular images respectively are presented. The methods solve the initial values first and optimize the object pose parameters by bundle adjustment. In the disturbance-rejecting binocular method, chosen measurement system parameters of one camera's exterior parameters are modified simultaneously. The methods need three or more cooperative target points to measure the object's pose accurately. Experimental data show that the methods converge quickly and stably, provide accurate results and do not need accurate initial values. Even when the chosen measurement system parameters are subjected to some amount of disturbance, the binocular method manages to provide fairly accurate results.

The thesis introduces the on-board computer (OBC) software of Chuangxin-1 micro-satellite which developed by shanghai micro-satellite engineering department of Chinese Academy of Science, and illustrates the reliable design for on-board data handling (OBDH) software. The OBDH software adopted some new techniques to improve the reliability. The micro-satellite employed dual-computer, and the standby OBC will take over the management of micro-satellite as soon as the host is failure. The OBC is the core of micro-satellite, and all sub-system of satellite and payload are managed by OBC. To ensure the reliability of OBC, there are some special methods for OBDH software. For standby OBC can take over control of micro-satellite smoothly and resume normal running when the host is failure, some important on-orbit running information of satellite is transferred to standby OBC. These measurements assured the micro-satellite can be resumed to normal running.

The attributed scattering center model is based on the solutions from both physical optics and the geometric theory of diffraction. In this paper, the attributed scattering center model and the method of extracting the feature of attributed scattering centers from high resolution SAR image are discussed. The method includes four steps: image segmentation, the selection of the model type, the estimate of initial value and the parameter optimization. Seven parameters of one scattering center can be obtained through the above four steps. Then we can get the parameters of all the scattering centers in the imagery by the recurrence procession. The validity of this method can be proved by the results of simulation.

The purpose of this paper is to introduce the application of scannerless range imaging (SRI) laser radar in the dynamic and real-time surveillance for cooperative and uncooperative space objects. Scannerless range imaging technique enables the capture of a full scene 3D range image in one acquisition with faster image acquisition speed. Small size, lighter weight, reduced mechanically complex and faster acquisition speed make it more fit for space borne scenario. Laser radar is based on frequency-modulated (FM) ranging principle that belongs to the time-of-flight (TOF) measurement category. In this case, the time-of-flight is converted to a beat frequency proportional to the range to be measured. This conversion is realized with intensity modulation of the laser power by a linear FM continuous wave. A summary of FM ranging theory and its application in range imaging are introduced. The system architecture and theory of operation are described. The key technologies of this type of scannerless range imaging laser radar in the application of surveillance for space objects are discussed.

This paper presents a technology to deals with the tracking performance of a timing recovery loop for dynamic circumstance GPS receiver. Based on Lagrange interpolation theory authors propose a data interpolation control method suitable for software radio. In our scheme, traditional code fast acquisition algorithm was employed to estimate timing error which has high estimate accuracy. The timing correction is performed by the interpolating filter, which is derived from the timing error detector. The carrier phase tracking can be adjusted precisely by selecting interpolating filter orders such as linear or non-linear. The simulation shows that the timing error recovery has high tracking precision, fast acquisition and keep track performance under high dynamic circumstance.

In the decade of information, with the increment of the data rate and capacity in communication, free space optical communication (FSO) has been paid much attention by many countries since it integrates the advantages of fiber communication and other traditional wireless communication technologies, such as large capacity, low cost, convenient deployment and flexibility. This paper concerns with the research on the signal tracking technology of FSO. Considering that suppressing vibration is a difficulty of FSO, so suppressing methods are discussed in the paper. As a base, the ATP (Acquisition, Tracking, Pointing) technology of FSO communication system is analyzed in this paper. And a new signal tracking system for FSO communication is described. The main structure, integral parts and detailed work process of this signal tracking system are introduced in detail.

At present, owing to the advanced remote sensing technology, a great lot of marine raster data has been acquired. With the marine data's keep-rising, it turns out more and more necessary to be organized, managed and displayed data effectively so as to serve people's daily life and production. The current methods are difficult to storage and management of the massive data efficient. And there are lots of problems with the raster data publication on the network because of its features such as massiveness, real-time and variety. In this paper, after analyzing the related technologies of raster spatial database engine, WebGIS and J2EE, a three-tier-structured real-time publication system of massive marine remote sensing data is put forward. This system has been made available to users to browse, query, analyze, download, and manage of marine remote sensing data efficiently. It was used throughout the marine water quality real-time inspecting project on Zhejiang Province of China.

COSMIC is a constellation mission to study the climate, ionosphere and geodesy. The main geodetic mission of COSMIC is to determine the global gravity field model and its temporal variations, which need the precise geometric orbit of COSMIC. GPS observations onboard COSMIC are simulated using the GPS precise final orbit and high-rate clock of CODE, the designed orbit of COSMIC and the GPS antennae for precise orbit determination (POD). The precise geometric orbits of COSMIC are determined with the kinematic method from the space-borne simulated observations to test the POD capability of GPS antennae. There are two POD GPS antennae onboard COSMIC, named as POD +X and -X. The orbit from POD -X antenna has the approximately same precision as that from POD +X antenna, and the errors of both are greater than the given random error while simulating GPS data. The main reason is that the designed positions of POD antennae are not good. There are the different angels between the boresight vector and zenith direction of two antennae. Another reason is that POD +X antenna is in the flying direction and POD -X antenna is in the inverse direction. In order to get the high precision of POD, a virtual antenna is constructed from POD +X and -X, whose center is the center of mass of COSMIC. Observations from POD +X and -X then are reduced to the virtual antenna. Comparing with the referenced orbit and the kinematic orbit from the virtual antenna, the precision of orbit is consistent to the given random error when simulating GPS data, up to centimeter level.

One of the fairest mechanisms of Electronic Toll Collection (ETC) would be distance-based charging, where vehicles would pay fees at a pre-specified rate per kilometer throughout the trip. The vehicle positioning system (VPS) based on GPS (Global Positioning System) has become the main ETC technology worldwide recently. One of the key algorithms for VPS is how to provide accurate distance calculation data. Therefore, a digital mileage calculating program utilizing the position information from a commercial GPS receiver to filter out noises should be developed to accumulate the total distance of a voyage incrementally. Due to environmental climates and built-up in a metropolitan area such as high buildings, bridges, radio stations, tunnels and traffic subways, signals of GPS satellites are easily susceptible to noises or even totally blocked. In such cases, the GPS position information loses fidelity. This paper presents a procedural program, incorporating an algorithmic software filter adaptive to different situations, is an answer to the above problems and is capable of providing the mileage of a voyage in real-time base with high accuracy compared to a mechanic mileage meter.

This paper investigates sub-image cancellation for ground moving target indication (GMTI) with a single-antenna airborne synthetic aperture radar (SAR). First the paper points out how to choose the sub-image from the whole image. After the generation of the sub-image, the imaging difference of stationary object and moving object in the sub-image based on the frequency division is analyzed. Once the detection is completed, the moving target is still dispersed and the FrFT(Fractional Fourier Transformation) algorithm is chosen to focus it. Using FrFT algorithm, the doppler modulation rate can be obtained so that the azimuth velocity of the moving target is estimated in this way. The theoretical analysis and simulation results demonstrate that the method is effective and can not only detect the moving targets but also estimate their motion parameters precisely.

The function of Near Space Vehicle (NSV) in aerospace information system is analyzed in this paper firstly. Then the architecture of area information confrontation system based on NSV is presented aiming at achieving superiority in area information confrontation and the possible information confrontation mode is discussed. Finally the design of NSV information confrontation simulation system is put forward. This paper is of guiding significance for the effective utilize of near space as well as the development of NSV and its payload.

Differential Interferometric Synthetic Aperture Radar (D-InSAR) is a new technology which is capable of detecting the tiny ground deformation and extracting Digital Elevation Model (DEM). This paper introduces the basic principle of D-InSAR. Using of two pass model and SRTM DEM, acquired Kunlun Mountains region surface deformation of Ms8.1 in 2001. The result provides an important reference for Qinghai-Tibet Railway Disaster Prevention.

Star sensors and computer vision systems are generally used for spacecraft navigation in deep space, both of which make use of image sensors. To mitigate the payload of the spacecraft, a new star sensor prototype with extending use as a rendezvous and docking positioning system is described in this paper. An adaptive processing element is used to control the process of image acquiring, image pre-processing and image recognition, which makes the sharing of the image sensor feasible. The software is discussed about how to realize the two applications. The earth based experiments verify the feasibility and validity of the design, which may make a little contribution on the deep space explorations.

In recent years, spaceborne/airborne hybrid bi-static synthetic aperture radar (SA-BSAR) has been proposed as a new kind of microwave remote sensor. The SA-BSAR system combines the invulnerability of the spaceborne SAR with high resolution and flexibility of the airborne SAR. To decrease the cost for developing a new system, a suitable flexible and powerful simulation tool is essential. Nevertheless, the currently available SAR simulators, which were developed for other SAR constellation, are not sufficient for SA-BSAR. This paper presents a new simulation architecture. To improve the flexibility and the suitability of the architecture, both the requirement of SA-BSAR and the requirements of other kinds of bi- and multi-static SAR are all fulfilled in designing the architecture. Modular configuration is the key for the flexibility. The requirements, the framework and the steps in performing the simulator are discussed in detail.

Bistatic configuration is an attractive concept for synthetic aperture radar (SAR) missions, which benefit from use of separated transmitter and receiver flying on different platforms. The processing of radar data stands out as a fundamental issue to facilitate bistatic SAR research and application in remote sensing. A bistatic processing algorithm based on Loffeld's bistatic formula (LBF) is proposed. The approach involved bistatic term compensation and quasi monostatic processing, and the latter part derived from a chirp z transform algorithm for monostatic case. As steps to a bistatic SAR processor for space configuration, this paper presents an approximation of transmitter/receiver slat range depending on individual incidence angle, and modifies range CZT parameter and azimuth compression operator. First results of this algorithm on simulated raw data are included.

Recently many applications like fire simulation and tsunami monitoring bring more interests in the extents of moving objects. Present research usually focuses on the positions of moving objects. As a result, tracking the continuously changing extents of spatial objects is becoming increasingly necessary. This paper proposes a novel model to represent the irregular shape of moving objects that may have parts and support the querying of the predicated near future extents. The method is capable of representing objects evolving in one-, two- and three-dimensional space. We also provide user-defined precision level to decide the quality of modeling. Our experimental results performed on stimulation dataset show that the model is effective for representing and querying the extents of moving spatial objects.

A simplified method is presented for the problem of electromagnetic scattering of a time-harmonic plane wave from a non-planar sinusoidal periodic surface of lossy media. Assume that the heights of the rough surface are much smaller than the wavelength of the incidence and the space periodic of rough surface. The diffraction of the incidence can be described by using the elementary Huygens principle. The reflected and the transmitted field approximated by a linear combination of plane waves having different wave vectors. Based the method, we can deduce the simple formulation of the reflected field at far suitable for engineering application.

Nowadays, huge volumes of geospatial data and services are available and accessible to people all over the world. However, they are searched mostly based on keyword, which is inherently restricted by the ambiguities of natural language, which can lead to low precision and recall. In this paper, semantic share of geospatial data and services are studied based on ebXML registry. But ebXML registry specification doesn't take into account the registration of the semantic information. So we define how OWL DL constructs are mapped to ebXML registry information model (ebRIM) constructs without causing any changes in the core ebXML registry specification. After that, predefined stored procedures are provided in the ebXML registry for semantic search, which provide necessary means to exploit the enhanced semantics stored in the Registry. Then, geospatial ontologies in change detection application of remote sensing based on Global Change Master Directory, ISO19119 and ISO19115 are established. Finally, a prototype system is developed based on an open source-ebxmlrr to demonstrate the proposed model and approach.

The new generation Chinese Geostationary Meteorological Satellite (CGMS) adopts three-axis stabilized attitude control mode, using many payloads, such as spaceborne imaging radiometer and atmospheric vertical sounder, etc, implements all weather and real-time observation to the atmospheric environment of the Earth. The deviation of the orbit results in the optical axis of the payloads to deviate its normal direction and then the image quality becomes lower. To acquire high quality image, an algorithm of image motion compensation (IMC) is designed. Simulation results demonstrate that the proposed algorithm can effectively compensate the deviation of the optical axis from the motion of the satellite orbit.

This paper presents a digital modulation recognition algorithm for classifying digital signals. The algorithm is based on high order cumulants, signal square spectrum and spectrum envelope. The advantages of this methods lies on no need for prior knowledge of the signal. We can even estimate its code rate and SNR. Simulation results demonstrate the efficiency of this method.

Up to now, TERCOM hasn't been used in the gravity matching aided navigation, because of its disability in precise positioning. So does ICCP, which needs precise initial values, whereas the initial values provided by INS are not accurate enough. This paper starts from the introduction of the basic principles of TERCOM and ICCP, and compares their advantages and disadvantages, then incorporates these two methods into a new algorithm in which TERCOM provides the initial position and ICCP does the precise positioning. At last simulation data is used in the experiments, with the purpose to shed light on the effect of this new algorithm in gravity matching aided navigation. It is proved that the new method is precise and needs no initial values. It is very fit for gravity matching aided navigation.

Nowadays increasing attention has been paid to reasonable organization and effective management of vast amounts of remotely sensed data for the goal of quick browse, convenient query and Retrieval-on-Demand service. In this paper, in order to reach compromise among precision, efficiency and storage and to realize ROI coding, data partition based on Nona-tree data structure and data compression based on JPEG2000 are adopted to organize and manage original remotely sensed images. Afterwards, a prototype system in three-tier B/S mode is developed to test the validity of our data organization and management strategy for content-based retrieval mentioned above. In this system, texture-based and shape-based feature extraction algorithms based on wavelet transformation, math morphology and other relative theory are applied. Corresponding feature descriptor and similarity calculation are also given. At last, experimental results are given to show that the strategy proposed in this paper is valid, followed by brief conclusions and future directions. The work of this paper is useful to push the development of geo-spatial information services and promote content-based retrieval of remotely sensed images from experimentation to practicality.

Because the satellite comes under influences from all kinds of disturbance and some of them can not be absorbed by flywheel control system during the circulation, attitude of satellite is disturbed, which results in pixel excursion of the scan mirror image, and image quality is affected. It is necessary to be compensated. Spacecraft motion compensation means that the influences of attitude disturbance are eliminated through producing scan mirror motion control compensation signal according to compensation arithmetic. It can be realized by using real-time compensation method and model predictor method. This paper studies real-time spacecraft motion compensation method. The valid arithmetic of spacecraft motion compensation and practicable technology project are proved through simulation. The research provides theoretical principles and practicable references to develop the new generation Chinese geostationary meteorological satellite.

This paper describes an algorithm framework for fusion airborne based laser scanning data (LIDAR) and optical images. A efficient and reliable intensity-based registration framework has been used to determining the spatial transform form LIDAR to optical images. On the basis of segmented airborne images, the paper raises the arithmetic and process of merging multi-data sources to carry through classification by using multi-echo, point's space discrete characteristics, and the statistic spectrum characteristics. In addition to the theoretical method, the paper presents a experimental analysis the sensitivity and robustness of this approach to assess effectiveness the proposed arithmetic.

An adaptive algorithm of relative radiometric normalization for multi-temporal remote sensing images based on feature corner was introduced in this paper. The main purpose of this research was to explore an automatic and robust algorithm of relative radiometric normalization to minimize imaging differences of multi-temporal satellite images. The main idea was to construct statistical regression model of relative radiometric normalization by extracting steady ground point correspondences. The algorithm's detailed processes were as follows: First, a method of image matching was applied to recognize steady ground point correspondences of multi-temporal remote sensing images. Second, a statistical regression model of relative radiometric normalization was constructed to calibrate imaging difference of multi-temporal remote sensing images. By the experiments, we could see that the total RSME of reference image and corrected image was reduced apparently in comparison with the total RSME of reference image and uncalibrated image, and the hue of corrected image was looked more like that of reference image. We could conclude that this modified algorithm was more accurate and efficient than traditional algorithm, its adaptive characteristic made it easy to be integrated, and it had more feasibility and applicable value.

This paper discusses the problem of modeling sensor grid (SG). Firstly, the SG's structure is analyzed, and the interconnection and interoperation relationships of sensors are described. Secondly, the definition of SG's directed graph is presented and a SG's modeling method based on graph theory is proposed. Finally, as an example, the STSS system is analyzed based on directed graph model.

This paper examines moving targets detection using single channel Synthetic aperture radar (SAR) in spaceborne platform. Building on previous work moving targets can be retrieved from multi-look images via magnitude subtraction or phase interferometry. A more effective method is proposed which mainly consists of signal subspace processing- based data equilibrium and change detection in multi-look covariance matrix. Also different baseline is checked and weak targets may be found. Test results show that precise calibration of multi-look images are essential and short baseline is preferred when the interesting targets are weak. Therefore, the proposed method leads to improved detection performance and provides ways of GMTI in single channel SAR.

Now, more and more technology innovation and evolution have been used on the small satellite for remote measurement, target searching and tracking missions being performed in space. To achieve the formation flying relative navigation, and the formation flying relative control intelligently, or to implement some important missions, the inter-satellite relative position must be known. In this paper, the measurement procedures of small satellite relative position are given. To get precise result of inter-satellite relative position under general conditions and some specific conditions, laser ranging method is one of the most valuable methods which should be considered. Although the laser ranging method is well known, its application on small satellites in space is challenge to the typical conception. Through discussion of the principles of laser ranging and characters in different conditions, the relations of the measurement reliability, the measurement precision and the measurement condition are presented. The difference of the measurement in space and that in general condition is mentioned. Because of the laser ranging specific characters in small satellites formation-flying, some conclusion of laser ranging method will not be suitable for usage in space. The details of the causation are discussed. The use of near frequencies scale to resolve distance measurement, which is widely used in most project applications, is the major causation of that some conclusion of laser ranging method will not be suitable for usage in space. And use of separate frequencies scale to resolve distance measurement in space still has its own restriction. Then the modified laser ranging method using code modulation is designed. The parts of this method and the solve arithmetic are presented. While, this laser ranging method may require help of other means to achieve the continuous measurement of relative position in some specific missions. Finally, the outlook of the inter-satellite relative position measurement technologies and the applications of inter-satellite relative position measurement are represented.

A star-based two-dimensional (2-D) torus inter-chip network on electro-optical printed circuit board (EOPCB) is proposed to provide a simple and effective interconnection solution for such a real-time distributed parallel systems as satellite image processing, which is characterized with locally intensive communication. The proposed hybrid interconnection network has a hierarchical structure where the higher level is a 2-D torus network of 8×8 optical cross-connects (OXCs) and the lower level is a cluster of processors connected in star topology using4×4OXCs. EOPCB is used to eliminate the electrical bottleneck of high speed interconnection on board. OXCs are used to eliminate the expensive E/O/E conversion of electrical routers and provide a transparent optical channel between processors. A new approach based on combination network is proposed to construct 4×4 and 8×8OXCs with 2×2optical crossbars.

A new algorithm based on directional cumulation is presented to detect the trajectory of moving point target from image sequences in low SNR environments. First, single frame detection is performed, and then the logical "or" operation of multiple frames are used to obtain a binary planar projective image. With that based on the continuity of the moving trajectory of the point target, the second detection using directional cumulation is performed to acquire the trajectory of the target and its parameters. The result of experiments shows that the proposed method is effective to detect and track targets moving along linear or curvilinear trajectory with unrestricted velocity in low SNR, and it is of low complexity.

A new method named Landmark-based Qualitative Reference System (LBQRS) is introduced to express qualitative positional information in this paper. LBQRS provides a dynamical positional framework. Under LBQRS, Qualitative Coordinates (QC) is defined based on cardinal directional relations between target objects and one or several landmarks adjacent to it. Formal model of LBQRS based on cognitive view of landmark position are presented. Formal description and representation method are provided.

A new method of global optimal matching theory based on linear drawing of geomagnetic filed is proposed and researched. Navigation system based on the geomagnetic field has no accumulated error, and it is not influenced by weather, terrain and other factors as it is passive. Thus, geomagnetic navigation has good potentials to be an assistant method for other navigation systems such as inertial navigation system. The matching navigation method avoids the disadvantages of Kalman filter because it makes use of a set of relative information. In the literatures, the forming principle of linear drawing is discussed. A necessary global optimal matching technique is researched because matching a linear drawing with a standard planar chart results in infinite instances and the previous mismatch will affect the following process. Correlation method is applied in the matching process for its simpleness. Genetic simulated annealing algorithm is applied in the optimal researching process for its rapid convergence and global optimization. Mathematical simulations are carried out to verify the correctness and efficiency of the new solution. The results are listed in the end, which prove the rightness of the methods proposed in this paper.

Beijing-1 small satellite carries a 4m panchromatic sensor and a 32m multi-spectral sensor, with both the features of the high resolution of SPOT and the multi-spectrum of Landsat. However, its resolution and the wavelength range of the corresponding band are significantly different from the existing satellites. Meanwhile, the difference of the wavelength ranges between the panchromatic image and the multi-spectral image is rather large, especially in the NIR band where the difference reaches 80%. Thus, low correlation means that the traditional image fusion methods are not ideal to date. Aimed at the spectral features of Beijing-1 small satellite high-resolution imagery and multi-spectral imagery, the paper proposes an image fusion method based on Imagesharp. First, linear functions are used to fit the low-resolution image into the high-resolution image, and then the fitted high-resolution multi-spectral image and the high-resolution panchromatic image are fused, which can improve the spatial resolution and keep the original multi-spectral information well at the same time. At last, in comparison to the traditional HIS and Brovey fusion method, Imagesharp method can maintain the color saturation and the spectral information better. A large amount of experiments prove that Imagesharp algorithm is suitable for the Beijing-1 image fusion and it is already specially applied in the Beijing-1 small satellite data deep processing software.

Feature extraction and selection play an important role in radar target recognition. This paper focuses on evaluating feature separability for SAR ATR and selecting the best subset of features. In details, fifteen features extracted from T72, BTR70 and BMP2 in MSTAR standard public dataset are examined, which are divided into seven categories: standard deviation, fractal dimension, weighted-rank fill ratio, size-related features, contrast-based features, count feature, projection feature, and moment features. Since the number of samples is small, a new separability criterion based on the overlap degree of each two class regions is proposed to assess the separability of these features. Here the class region is described by support vector data description (SVDD) method for good generalization. Based on the proposed criterion, a forward feature selection method is adopted to choose the best subset of features. Because of the strong variability of the feature against aspect, the features are analyzed under different aspect sectors within 360°angle range stepped by 15°, 30 °, and 60°, respectively. Experiments using MSTAR dataset validate the criterion, and the best subset of features is determined.

Multicarrier spread spectrum (MC-SS) system employs frequency diversity, hence obtains the ability combating band-limited interference. In this paper, we consider a multicarrier direct sequence spread spectrum (MC-DS-SS) system, in which every sub-channel is spread by a pseudo number (PN) code respectively, making each sub-channel's bandwidth larger than jammer's. The system has the advantages of large processing gain, low interception probability, and robustness against partial band interference. We analyze bit-error ratio (BER) properties of MC-DS-SS system under partial band interference, and compare it with single carrier DS system. It is shown by the comparisons that whenever the diversity gain is observed, MC-DS-SS system always outperforms single carrier DS system under the same interference environment. When jammer spreads its bandwidth over the entire frequency range of desired signal, MC-DS-SS still outperforms single carrier DS-SS.

Cat-eye effect of opto-electric system plays a important role in the active detection, which was studied by many researchers based on the geometric methods. But in practical application of it on the war field, the laser beam must be affected by the atmospheric turbulence, which make the conventional method invalid. The main subject of this paper is to study the properties of the laser beam propagation through the atmospheric turbulence and cat-eye system. A procedure is outlined to numerically simulate the propagation of beam through them. The effects of cat-eye system on the wave field disturbed by the atmospheric turbulence are analyzed.

This paper, starting with the time and spectrum domain characteristics of the LFM pulse and its matched filter, analyzes the ranging error generated by the Doppler frequency shift in the received signal, and presents a range error correction model for the LFM pulse compression radar, which is proved applicable through further computer simulation and tracking data analysis. Cautions are also proposed as to the practical engineering application of the correction equation.

This paper utilizes ontology to define and organize the information objects, data elements and their relations in the domain of earth observation task of satellite. In this paper, we proposes a new method for building domain ontology of earth observation task, it includes five steps: task definition, task disassembly, relation analysis, describing ontology and ontology instantiation. The ontology-based method is effective and reliable for standardization and semantization of earth observation task.

The modernization of GPS and the Galileo system adopt the Interplex modulation to transmit multiple signals on one carrier, Interplex modulation is a particular constant envelope phase modulation through induce the intermodulation (IM) term. The main objective of this paper is to analyze the IM term effect degrees of interference that GPS and Galileo signals are expected to have in the L1 band. This paper extends the interference assessing methodologies to be applicable in the situation that accounting for IM term effects, and applies to analyze the impacts of Galileo IM term and the impacts of three versions IM term signal of GPS. Numerical results show that different nonlinear mechanism of Interplex modulation induce different degrees of interference, and the desired signals having different modulation models exhibit different degrees of sensitivities to the IM term interference effects.

Low-cost MEMS sensors often suffer from inaccuracy and are influenced greatly by temperature variation, and the orientation error is cumulate with time. The GPS can provide long term stability with high accuracy, but it has its insufficiencies, such as disturbed easy, lower data updating rate and so on, it is hard to meet the demand of real-time measuring. The micro-magnetic sensors, an independence precision tool, can offer real-time yaw attitude angle, and this can correct the orientation cumulate error, and it increase the independence in flight of the UAV. Based on analyzing the selection principles of testing sensor, comparing 3 kinds micro-magnetic sensors, the GMI magnetic sensor is best to test geomagnetic field. The Regional model of geomagnetic field is built, and a GMI-magnetic sensor navigation method is put forward. Three-axis magnetic sensor measure the geomagnetic field, and it is matching with the geomagnetic map, then the geomagnetic elements on currently position are knew, combining with the information of accelerometer, the position information can be gotten by matching algorithm.

Scale is an important factor when people acquire laws of geographical phenomena and processes. Generalized scale includes not only spatial scale and time scale but also semantic scale in geographic information science. Semantic scale describes semantic change amplitude and hierarchy of attribute contents of geographic entities. Semantic change amplitude represents attribute character changes in the unit time, the while hierarchy means classification and rank of attribute description. Scale is in inverse proportion to detailed degree of geographic entities when GIS displays multi-scale geographical spatial data. It is difficult that existing GIS display features of different semantic scale. As for the classified or ranked geographical spatial data the optimal solution is the hierarchy or rank of geographic entities displayed is higher when scale becomes small, so the generalization degree of detailed feature is higher. Ontology is a kind of modeling tool of concept model that is able to represent information system at the semantics and knowledge level. Geoontology is a kind of domain ontology and offers glossaries and relationships among concepts in the geographic spatial information domain. As far as the geographical hierarchy and classification system is concerned the relationships among the geographical concepts is hierarchy relationship, namely the relationship between the parent concepts and the child concepts or between hypernyms and hyponyms. Geoontology can represent formally this hierarchy relationship. A geographical concept can be navigated to its parent concept or child concept, and implements the automatic generalization of geographic spatial data by merging the features in the geographical feature classes corresponding to all child concepts of the some geographical concept in geoontology. However the automatic generalization method based on the geoontology cannot smooth the linear features and the boundary of polygon features, which should be implemented by resorting to other automatic generalization algorithms.

The quasi-dynamic wide-band scattering characteristic modeling method of space object in orbit is given in this paper, the dynamic wide-band electromagnetic scattering characteristic of a satellite is simulated significantly and we acquire procedural image of scattering centers by accumulating high-resolution range profiles of satellite in flight. And we have an idea that we can judge the structural information of satellite by the procedural image of scattering centers which formed in flight. The simulation result show that the procedural image of scattering centers of satellite target is connected with target's structure and it can be used to extract the structural information of satellite targets.

Missile borne Synthetic Aperture Radar can effectively improve the guidance accuracy of the Inertial Guidance System of long-range missile. The basic principle of the missile geo-location is described at first. According to the range equations and Doppler equations, the analytical mathematical expressions of the missile's position are deduced without complicated and unstable iterations, and the detailed flow of the missile position solving is described. Based on simulation, the effects of digital image matching, altitude and velocity errors on the geo-location accuracy are compared.

The lateral inhibition mechanism of biologic vision is introduced and applied on edge extraction of images. With the method, the image's original characters are unchanged. Furthermore, the edge extraction and image enhancement can be done effectively when the gray changes caused by varying illumination. For increasing the matching ability of resistance to geometric distortion, a new matching algorithm is established. The edges of the real-time and reference maps are extracted with the above-mentioned method based on lateral inhibition. Then the concentric circle characteristic vector of image is defined and the method of vector extraction is proposed. The concentric circle characteristic vectors of the real-time and reference maps are extracted. Finally they are matched according to the vectors. The resistance of geometric distortion is improved. A map of roadway in a city obtained by satellite is simulated. The results show that the influence of gray and geometric distortion on scene matching is effectively overcome. The algorithm is easily implemented with hardware. The operation speed of the algorithm is also fast. It's worth for the design of real-time scene matching system.

Celestial navigation is one kind of autonomous navigation technology which is suitable for navigation of deep space rovers. Autonomous navigation technology based on X-ray pulsars is under development. It could provide an essential backup navigation capability for missions that normally rely on GPS but have a need for continuity of operations in the event of loss or denial of GPS. Radiation from X-ray pulsars is relatively easy to be detected and recognized. X-ray pulsars provide with the potential to define a new time scale and frequency standard, they are nature reference constellation for deep space navigation. This paper introduces the principle of navigation based on X-ray pulsar timing. We also discuss the prospect of navigation application using China radio telescopes.

This paper presents the difference between object recognition for satellite image and general object recognition. To overcome the difficulties of object recognition for satellite image, two methods are proposed in this paper. First, it is shown that traditional moment invariants are no longer invariant while object shape is distorted or contour is blurry. This paper proposes an improved invariable moment algorithm, which reconstructs seven invariants moment formulas, and weakens the sensitivity on distorted border. Moreover, a 3D model database including all interested target's 3D model can be established. When starting to recognize the target in satellite image, several 2D projection images can be retrieved from the model database, using these images as recognition templates will be more accurate than using a single target image. Experimental results show that the methods presented in this paper are effective on satellite image recognition.

According to the character of Lidar data in rural area, this paper presents a new algorithm to generate DEM in rural area. The algorithm has fusion the distance information and intensity information to deal with the Lidar points. This paper comes to a conclusion that it is theoretical and practical significant that this method is used to generate the DEM from the Lidar data in rural area.

One new method was brought forward to solve the algebraic solution to the double-system satellite navigation equations. We established two binary quadratic equations about two satellite-station reference ranges and the matrix equations about these ranges and receiver position, where two ranges were chosen from two systems respectively. Thus the original problem is replaced by an approximate problem and for it two binary quadratic equations are obtained. Geometric and clock information is used to discard the unwanted solutions. The reference ranges, system time biases and receiver position were produced by solving these equations. Simulation indicates that our solution can solve the problem of initial position when receiver cold starts in the situations of earth-bounded and deep space. Especially in deep space where the conventional algorithm, which performs based on range-direction-cosine matrix, will probably converge to the wrong solution, our solution is still correct. In earth-bounded situation, our solution has the same precision as the conventional.

Method for navigation control of mobile robots under unknown environment is a important field of robotics. As few transcendental knowledge is known, navigation control of mobile robots has many problem to be solved. In this paper, we introduce the mechanism of a fly's vision and analyze the possibility of apply to robots navigation control. Then a navigation method based on compound eyes is given. In the end, we give expectation and advices for future research.

In high-resolution synthetic aperture radar (SAR) images, the target size may be much larger than the resolution of SAR and the background clutter statistics are generally not Gaussian-distributed. But traditional constant false alarm rate (CFAR) detection algorithm, which based on the Gaussian-distributed model, performs only one test cell at a time and ignores the mutuality information with other cells in the target, so the performance of the CFAR detection algorithm can be substantially degraded. In the paper, an extend target detection method based on the generalized compound model is proposed. Unlike traditional CFAR detection method which distinguish test cell from the background only on the basis of energy contrast, the extend target detection is sensitive to both the contrast and the distribution of the target. We demonstrate the improved performance using the extend target detection method in the real high-resolution SAR images.

Analyzing air attacking environment countermeasures is the base of constructing near space vehicle information platform. The study is significative to the development and application of near space vehicle information platform. The main content of this paper is on information war measures and feasibility using near space vehicle.

Nowadays, the edge detecting technology based on Brillouin scattering signal has became the most advanced research of lidar. This technology is widely applied to the areas of detecting atmosphere wind, space environment, and space objects and so on. In this lidar system based on edge detecting technology, it is important to analyze measuring error. In order to research measuring error, the space atmosphere channels are analyzed and the measuring error formula of detecting Brillouin scattering frequency shift is educed. At the same time, Brillouin scattering echo signal received by the edge detecting technology is estimated. A program is designed to simulate measuring error of detecting Brillouin scattering frequency shift at different altitudes and with different Brillouin scattering frequency shift. From the simulation results, we can find that in the ideal atmosphere conditions, the measuring error of Brillouin scattering frequency shift is less than 20MHz at 100km height and less than 5MHz at 30km height in the atmosphere. Based on the results above, we can draw a final conclusion: the edge detecting technology holds high signal-to-noise ratio and small measuring error.

When three satellites for passive location are used, if the height of terrain where the target locate changes greatly and the height is assumed constant the height error will be increased. So the Least-square estimation method is presented, at the same time in the process of algorithm iteration the target height can be inquired in the geography information system and be corrected continuously, and the localization error is analyzed and simulated, the result indicates that the corrected height error can improve the height precision, then improve the level precision, the improved the level precision will improve the height precision, then the integral localization precision can be improved.

To deal with the contravention between the reversibility of the point spread function of scanned pattern interferometric radar and the improvement of the azimuth resolution of the radar system, the paper presents a new method of cluster optimization design. The method bases on the variability of the maximum spatial frequency number of the theoretical formula of the array factor. By selecting an appropriate maximum spatial frequency number, we get a new aperture array. The array designed by this method not only can get the desirable azimuth resolution but also can guarantee the reversibility of the point spread function. Simulations validate the correctness of the method. At last, we also discuss the applicability of the method.

At present, integrated navigation systems are frequently used for the navigation in the space. Compared with single navigation, integrated navigation is improved in the functions, but the sensors in the system are more, the scale of the system is enlarged, and the probability of failure in the system is increased. Once the fault appears, the loss is more or less. So to ensure the liability of the system, some necessary effective steps are made for fault toleration. In other words, the fault toleration scheme is very important for high precision and liability of the navigation system. Fault detection and identification is the premise of fault toleration. Therefore a new integrated navigation system with a new fault detection and identification method called GPS(Global Positioning System)/3DR system is proposed in the paper. In terms of the characteristics and the most familiar fault types of navigation sensors, data of sensors at normal and fault are simulated in the paper. Based on the traditional navigation system, a new integrated navigation with a new fault detection and identification method is designed, and the system is verified by simulation. Finally by the comparison of the typical integrated navigation system and the new integrated navigation system, the conclusion that the new integrated navigation system is better than the typical one in three sides is achieved.

This paper deals with several key points including parameter estimation such as frequency of arrival (FOA), time of arrival (TOA) estimation algorithm and signal processing techniques in Medium-altitude Earth Orbit Local User Terminals (MEOLUT) based on Cospas-Sarsat Medium-altitude Earth Orbit Search and Rescue system (MEOSAR). Based on an analytical description of distress beacon, improved TOA and FOA estimation methods have been proposed. An improved FOA estimation method which integrates bi-FOA measurement, FFT method, Rife algorithm and Gaussian window is proposed to improve the accuracy of FOA estimation. In addition, TPD algorithm and signal correlation techniques are used to achieve a high performance of TOA estimation. Parameter estimation problems are solved by proposed FOA/TOA methods under quite poor Carrier-to-Noise (C/N0). A number of simulations are done to show the improvements. FOA and TOA estimation error are lower than 0.1Hz and 11μs respectively which is very high system requirement for MEOSAR system MEOLUT.

Laser Radar (LADAR) achieves more applications on aerial aided-navigation in mountainous areas for its good performance. But plain areas encounter terrain elevation's slow variation and occasional unavailability of Digital Feature Analysis Database (DFAD), which as necessary reference. Looking for replaceable map source and extracting common characters for matching, are the fundamental circles of imaging LADAR aided navigation research. In this paper aerial high-resolution remote sensing (RS) images are applied as substitute for DFAD, and the edge factor is chosen out by synthetically analyzing RS images' and imaging LADAR point cloud'scharacters. Then edge extraction algorithm based on multi-scale wavelet is explored to reflect their common features, and weighted Hausdorff distance method is applied to match for positioning. At last the high-resolution RS images and imaging LADAR data of the same area are assumed for simulation experiment, which testifies the validity of the methods proposed above.

Image matching is one of the most important issues in object localization algorithms, while stable feature detection and representation is a fundamental component of many image matching algorithms. SIFT algorithm has been identified as the most resistant feature extraction method to common image deformations. In this paper, we use SSIFT (Simplified Scale Invariant Feature Transform) to solve the problem of image matching in non-structured underwater environments. Like SIFT, we construct a Gaussian pyramid and search for local peaks in a series of difference-of-Gaussian (DOG) images; however, instead of using local square image patch to assign orientation and build 128-element vector, we apply local circle image region and build only 12-element vector for each keypoint. The experiments have shown that SSIFT are more robust to image rotation, and more compact than the standard SIFT representation. We also present fast matching results using such descriptors for non-structured underwater objects.

Non-coplanar circular orbital transfers based on the invariability of descending nodical local time is studied in this paper. Based on minimum principle, both of the thrust direction and magnitude are optimized, regarding minimum total impulse and final position and velocity constraints as the performance index on the assumption of fixed transfer time and continuous thrust. The optimal transfer orbit is then obtained using conjugate gradient method. As transfer time is given, a special initial condition for orbital transfers is determined, which ensures the invariability of descending nodical local time. The validity of orbital transfer strategy adopted has been verified by simulation results.

Landform skeleton are lines that indicate significant topographic features of the terrain. It is widely used in mapping and surveying, hydrology simulation, topography representation and engineering designing. In order to derive the landform skeleton, many kinds of data source have been used, including digitized contour lines, Grid-DEMs and TIN. As time goes by, more and more unorganized points have been acquired, created, maintained and disseminated in many fields. Those unorganized points are the most original and important information which is vital for mapping and surveying. How to extract the feature lines from unorganized points has been the hot-pot in computer design and reverse-engineering. Methods used to extract landform features in existence have shown dependence on data types and thresholds more or less. In the paper, the view sheds principle used to extract the feature points has been put forward and then those points have been organized into feature lines according to related rules. The result has shown that the view sheds principle can extract the features and give the levels of feature points.

A new high-accuracy pure rotational Raman (PRR) lidar system at a laser wavelength of 532.25 nm, based on a technique of wavelength division multiplexing (WDM), has been designed for profiling the atmospheric temperature of the low troposphere. A special WDM, which was usually used in fiber communication field, is designed to separate two PRR signals of N₂ and O₂ for temperature retrieval, and to simultaneously block Mie- and Rayleigh-scattering signals with a rejection rate of large than 10⁷. A numerical calculation is simulated to verify the feasibility of the lidar system, and the results showed that the PRR lidar based on spectroscopic characteristic of the WDM is capable of measuring the atmospheric temperature vertical profiles in the low troposphere, and a statistical temperature error less then 1K was achieved up to a height of 3.3 km and 5 km for daytime and nighttime measurement, respectively, under conditions of 300 mJ laser energy, 25-cm-diameter telescope, 10 min observation time, solar radiance of 3×10⁸ Wm^-2sr^-1nm^-1 and atmospheric backscattering ratio less then 3.4.

As an important part of operational effectiveness analysis of space-based system, the research on operational effectiveness of electro-optical imaging reconnaissance satellite has great academic and realistic significance. In this paper, we consider a certain scenario, in which a missile aided with an electro-optical imaging reconnaissance satellite attacks a ground-based target. The operational effectiveness analysis and evaluating model of electro-optical imaging reconnaissance satellite is built. The results of simulation demonstrate that operational effectiveness analysis and evaluating model of electro-optical imaging reconnaissance satellite is feasible and reasonable. The models can be used to analysis design, evaluating and development of space-based.

The X-ray pulsar is a special celestial source which possesses of the lighthouse effect in space. And its unique, stable and predictable pulse can be utilized for satellite navigation and attitude determination. In this paper, the pulsar description is presented to explain the properties conducive to satellite navigation. With the pulse phases detected at the satellite and predicted at the initial reference location, the range measurements about the satellite can be generated. The Kalman filter technology is used to combine the satellite dynamics and the range measurements. The simulation is provided to demonstrate the expected performance of the satellite position and velocity determination using the observed phase message within the Kalman filter.

In this paper, the schemes which perform blind MUD, also called blind interference suppression, based on independent component analysis (ICA) is proposed to be applied to GPS receivers. The ICA model is utilized mainly in blind separation of unknown source signals from their linear mixtures. In CDMA navigation application only the source signals which correspond to the coefficients of the ICA expansion are of interest. Simulation shows the method is more effective than those usually used in GPS/Galileo and, thus, it has the potential of increasing the acquisition speed.

Estimating debris population is of great significance for assessing impact risk to spacecrafts, predicting the long-term growth potential and validating space debris models. A method of estimating the confidence interval for debris population using radar beam fence is proposed. The problem whether a debris object that may cross the beam fence, i.e. has large enough inclination and radar cross section, is actually detected is modeled as a (0-1) distribution. Using orbital altitudes measured, the average probability of crossing the beam fence is obtained. The confidence interval for debris population is estimated by the Central Limitation Theorem. Experimental results show the validity of the method.

In order to overcome the azimuth spectrum folding occurrence in the spotlight imaging mode of the high resolution spaceborne Synthetic Aperture Radar (SAR), we presented a new subaperture chirp scaling algorithm (CSA) in this paper. Several phase functions of the extended CSA were modified according to the properties of subaperture processing. These modifications make the new algorithm realize the precise recombination of the phase history data of each subaperture without any additional computation load, making the subaperture overlapping and azimuth time extension unnecessary. The validity of this new algorithm is proved through point target simulations by adopting TerraSAR-X system parameters in the spotlight mode with 1m resolution and a swath of 10Km both in the range and azimuth.

Aiming at the characters of weak and small targets in infrared images, an algorithm based on Least Squares Support Vector Machines (LS-SVM) is presented to fuse long-wave and mid-wave infrared images and detect targets. Image intensity surfaces for the neighborhood of every pixel of the original long-wave infrared image and mid-wave infrared are well-fitted by mapped LS-SVM respectively. And long-wave and mid-wave infrared image gradient images are obtained by LS-SVM based on radial basis kernels function. Fusion rule is set up according to the features of gradient images. At last, segment fused image and targets can be detected with contrast threshold. Compared with wavelet fusion detection algorithm and morphological fusion detection algorithm, when a target is affected by baits, the experimental results demonstrate that the proposed approach in the paper based on LS-SVM to fuse and detect weak and small target is reliable and efficient.

Celestial Navigation System (CNS), Inertial Navigation System (INS), Global Navigation Satellite System (GNSS), such as GPS, GLONASS, GALILEO and Compass etc, and the integrations of them are some methods of autonomous navigation for space. But these methods must be depended on the high speed links of the communications network. Moreover, the precision of CNS is always worse, and can not meet the rigorous requirement of the space activities. INS can not be used for long-term space navigation applications for its errors being accumulated. High accuracy can be met by Carrier Differential Global Positioning System (CDGPS), but it is difficult to calculate the ambiguities of CDGPS. Fortunately, autonomous relative navigation based on machine vision is a direction all over the world currently, and is very suitable for autonomous spacecraft navigation because it has some advantages, such as low-cost, high precision, autonomous ability, easy practicality etc. In this paper, on the basis of the attitude dynamics of spacecrafts and the theory of machine vision, an autonomous relative navigation algorithm for spacecrafts based on dual quaternion and EKF is proposed. The basis transform unit of this algorithm is feature line. Moreover, this algorithm is used to calculate both relative position and attitude organically, and the disadvantages of those algorithms, in which, relative position and attitude must be deal with separately, are overcome. Finally, the simulations show that this algorithm is an accurate valid method for space navigation applications.

Land cover/land use has become one of the crucial but basic tasks in carrying out a series of important work. With the development of remote sensing techniques and Geo analysis model, using remotely sensed data to monitor the status and dynamical change of land cover/land use has become one of the most rapid, credible and effectual approaches. To improve the accuracy of change detection from remote sensing image, this paper introduces a new method of change detection from remote sensing image based on support vector machine (SVM), using multi-spectral remote sensing data. We choose Hengshui city in China as a typical studying sample. The result shows that it is competitive with other recently developed methods for change detection when applied to the same data sets and yield good performance with very limited training data.

This paper presents a precise expression to describe the RMS code tracking error of navigation receivers, which is deduced under the following assumptions: the receiver code discriminator use coherent early-late algorithm or early-late power algorithm; the additive noise with arbitrary spectrum is gauss distributed and is independent of signal; the code tracking error is small enough to use the linear model. The theory is not restricted by bandwidth or ripple of receiver front end. The simplified expressions are also presented in case of white noise only. Comparison between theoretically predicted RMS code tracking error and simulation results are illustrated and validate the theoretical analysis result.

This paper puts forward a new type of landing system based on decimeter wave, in-depth analysis on the forming of navigation information under this system, indicates the characteristics of the landing system, and defines the main technologies; provides the approach to realize the landing system with the application of decimeter wave instruments, puts forward the methods and the simulation of the generation of navigation signal and the establishment of antenna array radiation pattern, providing the theoretical gist for the development of decimeter wave instruments landing system.

Time-Frequency Distribution Series (TFDS), which achieves an effective balance between the time-frequency resolution and the cross-term interference, can effectively reconstruct complicated maneuver targets' instantaneous ISAR images. However, original algorithm is quite inefficient, and the approach to fast computation proposed in some literature cannot be directly applied to engineering. In this correspondence, a straightforward realizable two-dimensional filter is derived. Meanwhile, FTFDS, as the fast implementation of TFDS, is proposed based on the formula, and computational burden of FTFDS is analyzed theoretically and experimentally in detail. The analysis of FTFDS indicates that FTFDS makes a great advance of efficiency. As FTFDS fits parallel process, time-frequency analysis by FTFDS can be approximately carried out in real-time. Simulated data processing has shown that FTFDS is practical and valid in fast reconstruction of instantaneous ISAR imaging.

This paper is to take the advantage of the imagery produced from QuickBird for damage identification in urban areas. The buildings collapsed following the Bam earthquake. We present our study results in remote sensing image fusion of identification of earthquake-caused building harm with HIS transform and intensity modulation. Commencing with the inventory of buildings as objects within high resolution QuickBird satellite imagery captured before the event. The number of collapsed buildings is computed based on the unique statistical characteristics of these buildings within the 'after' scene. The promising results from this analysis prove that improving spatial detail and spectral information could be used as a potential methodology for automated identification of building damage.

To satisfy navigation demands for lunar rover operation in rough, unstructured terrain of lunar surface, a new strapdown relative inertial navigation system (SRINS) is proposed in the paper. Inertial measurements data are generated based on true trajectory of lunar rover and error models of inertial sensors (gyro and accelerometer), which are used to perform high-fidelity simulations to validate the performance of SRINS and conventional SINS (strapdown inertial navigation system) algorithms. Simulation results indicate that SRINS possesses the advantages like better accuracy, more simplicity and feasibility than the latter for lunar navigation. Moreover, the effects of inertial sensors' measurement errors on SINS precision are evaluated.

Ship detection is an important application of SAR imagery. In this paper, a new discrimination method based on morphological filter and the co-pol phase difference of the plarimetric SAR is provided. The parameter of co-pol phase difference does not only indicate targets mechanism, but also can be extracted easily from HH channel and VV channel of plarimetric SAR. The application based on the AIRSAR data shows that the new method is effective to discriminate the false alarms in ship detection.

To acquire high quality image, the control system of the new generation Geostationary Meteorological Satellite in China (GMSC) must have high pointing precision and degree of attitude stability, besides image navigation and registration (INR) must be proceeded. This paper studies scan mirror motion compensation in image registration by using model predictor method. In the study of model predictor method, the total technical case of scan mirror motion compensation is designed; the analysis of the scan mirror motion disturbances is proceeded; and the compensated objects are ensured through analysis of simulation; the model predictor mathematical model in scan mirror motion compensation model is founded; the model predictor method compensated arithmetic is designed; the valid arithmetic of model predictor method is proved through simulation. The research provides theoretical principles and practicable references to develop the new generation GMSC.

By analysis the model for wheat yield, the information sources of the wheat yield were obtained. Based on the discussion for the relationship between electromagnetism information sources and yield factors of wheat, the methods to calculate each yield factor of wheat are given and then provided the implementation and calculating procedures of yield model for wheat. The most contribution of this paper is to present a novel theory---matter Electromagnetism Information Source which has widely applications in both theory and practice.

A SAR-GMTI algorithm based on space-time adaptive processing (STAP) in frequency domain by multi-channel SAR is proposed. The paper deduces the theoretical formula of the clutter suppression in-depth based on frequency STAP and finds that the output is a chirp signal and similar to the input signal of the moving targets before suppressed, so FrFT is chosen to detect them and estimate their moving parameters. The analyses in theory and simulator results show that our new algorithm is effective.

Image matching algorithm is the core of image matching aided navigation system. This paper has given a quick and effective image matching algorithm based on Fourier-Mellin transform. It solves relative translation of two images by calculating their peak value's position coordinates through inverse Fourier transform of power spectrum. A great deal of experiments indicates that this matching algorithm has high precision and strong robustness. At last, a proposal was advanced to image matching aided navigation system.

During the flyover of large-scale terrain, in order to eliminate the popping effect of switching among levels of detail and to increase the frame rates with high image quality, a new bottom-up modeling strategy is put forward, which constructs simplified terrain triangle mesh globally and updates mesh nodes dynamically. Hybrid culling technique based on blocks and triangle faces and simplified computing method for screen-space errors are employed to select appropriate terrain nodes rapidly. Then the Delaunay terrain mesh is updated by adding nodes, deleting nodes and modifying locally. At the same time self-adaptive control for screen-space error tolerance is achieved during the terrain flyover. Results of simulation experiments demonstrate that the algorithm eliminates popping effect effectively, and has a higher frame rate compared with other algorithms. So it is particularly suitable for close-distance flyover simulation of large-scale terrain.

With the development of hydrographical work and information techniques, digital charts are more and more popular in maritime applications, and an embedded product--PDA (personal digital assistant) is widely used in navigation for its smallness and portability. However, there is lack of PDA-based product which can provide integrated data management, real-time alternate display and ship auto-track application based on traditional paper chart and s-57 ENC. Aiming at this, some new techniques and algorithms including integrated spatial data management and display mode for ENC and paper chart, multi-scale data organization, embedded chart navigation method based on GPS are presented. And the integrated electronic chart pocket navigator system (PNS) based on PDA was developed.

A method of ship formation recognition is proposed based on the information fusion of spaceborne IMINT (image intelligence) and ELINT (electronic intelligence) in this paper. Firstly, the composition and the battle array of the observed ship formation are derived from the spaceborne IMINT information of each individual ship. The beliefs about the composition and the battle array of the observed formation are calculated separately. A synthetic evaluation method is used to get the BPAF (basic probability assignment function) from IMINT information using the aforementioned two beliefs. Secondly, by computing the matching measure between the observed emitter set and that of the typical formation entity, the BPAF based on ELINT information is obtained. Thirdly, the two BPAFs based on the information of spaceborne IMINT and ELINT are combined with DS (Dempster-Shafer) evidence theory. Finally, a decision is made according to the combined BPAF. The experiment indicates that our proposed methods to obtain the BPAFs are practicable and the formation recognition accuracy is greatly improved compared to the results which use only one of the two sources.

One of critical requirement for distributed small satellite SAR is the trigger time precision when all satellites turning on radar loads. This trigger operation is controlled by a dedicated communication tool or GPS system. In this paper a hardware platform is proposed which has integrated navigation, attitude control, and data handling system together. Based on it, a probabilistic synchronization method is proposed for SAR time precision requirement with ring architecture. To simplify design of transceiver, half-duplex communication way is used in this method. Research shows that time precision is relevant to relative frequency drift rate, satellite number, retry times, read error and round delay length. Installed with crystal oscillator short-term stability 10^-11 magnitude, this platform can achieve and maintain nanosecond order time error with a typical three satellites formation experiment during whole operating process.

The realization of spaceborne SAR imaging on-board is a necessary trend for digital avionics in speedily advancing SAR remote sensors. Powerful and efficient application-specific instruction-set processors (ASIPs) play a leading role in this solution to keep data processing system functioning real-time. A few improving methodologies, technologies and advanced EDA tools in microelectronics make it possible to design such a SAR imaging processor easier and faster. Some evident and important delegates of them, including system-level modeling and simulation for SAR imaging algorithm, available IP library designed by experts, ideas of designing domain-specific SoC with multiple processors and the microelectronic ways to ruggedize avionics applied in space radiation-active environment, are presented heuristically in this paper.

Hyperspectral remote sensing, as a new remote sensing technology, provides a powerful measure to object identification and classification accurately due to its acuminous ability of spectrum detection. This paper addresses the problem of the classification of hyperspectral remote-sensing images, and studies a novel spectral matching method based on the popular Empirical Mode Decomposition (EMD) technique. EMD is a new data analysis method by which any complicated signal can be decomposed into a set of Intrinsic Mode Functions (IMFs). The IMFs express the tendency of signals at different scales. In this method, spectral curves are decomposed with EMD, the IMFs are extracted and taken as the comparing features for spectral matching and the minimum distance classifier is used to classify ground-objects. The reason to take the IMFs as the comparing components is that the IMFs represent the intrinsic and stable component of a signal. On the other hand, using IMF as comparing element is helpful to remove the effect of noise. Furthermore, to improve the classification accuracy efficiently, similarity measure method and band selection scheme are introduced. The experimental analysis has been carried out by using hyperspectral image acquired by the AVIRIS sensor on the Washington DC Mall. The obtained results confirm the effectiveness of EMD in hyperspectral image classification with respect to conventional classifications.

This paper describes a new method utilizing dual-frequency GPS data to improve the accuracy of Ground-based Augmentation System (GBAS). With this so called ionosphere-isolating method, two dual frequency carrier-smoothing filters are used to estimate differential correction and ionosphere refraction separately. By dual frequency filtering, the filter in ground and airborne can be decoupled. By utilizing both of the two estimations, dual-frequency airborne user can eliminate residual differential correction error imposed by ionosphere spatial gradient. A new GBAS architecture that exploits ionosphere-isolating method to improve the accuracy of code differential systems is presented.