This PDF file contains the front matter associated with SPIE Proceedings Volume 7651, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

To solve the conflict between TCP accelerating technology based on PEP middle node and IPSec protocol used in the Satellite Network, NASA and the Hughes Research Laboratory (HRL) each independently proposed a solution named Multilayer IPsec protocol which can integrate IPSec with TCP PEPs. The problem is: Traditional IKE protocol can't work with Multilayer IPSec protocol. In this study, the traditional IKE main mode and quick mode are enhanced for layered IPSec protocol, and an improved layered key distribution protocol: ML-IKE is proposed. This key distribution protocol is used for key exchange between peers and middle node, so that different nodes have different security associations (SA), and different security associations correspond to different IP packet fields, so different SA nodes have different authorization to different IP packet fields. ML-IKE protocol is suitable for layered IPSec, thus layered IPSec can be used for automatic key distribution and update.

Traditional land management system based on PC has some shortages, such as bad openness and bad timeliness. And, it is hard to unify the criteria of data norm and database construction, easy to result in data redundancy. As a new development stage of GIS, WebGIS has perfectly solved the above-mentioned problems, so it is greatly meaningful to study digital land WebGIS. The system adopts GeoBeans6.5 as the platform which is developed by institute of remote sensing applications, CAS (Chinese Academy of Sciences). In addition, using ncgmec.jar component supplied by GeoBeans6.5, the system which is called "A WebGIS system on the base of spatial data processing system for land application" is developed under the support of IIS5.1 and java virtual machine. In the end, the main function of this system is demoed.

Vector maps are valuable asset of data producers. How to protect copyright of vector maps effectively using digital watermarking is a hot research issue. In this paper, we propose a new robust and blind watermarking algorithm resilient to simplification attack. We proof that spatial topological relation between map objects bears an important property of approximate simplification invariance. We choose spatial topological relations as watermark feature domain and embed watermarks by slightly modifying spatial topological relation between map objects. Experiment shows that our algorithm has good performance to resist simplification attack and tradeoff of the robustness and data fidelity is acquired.

China had been successfully launched the first two small optical satellites (HJ-1-A/B) of the Small Satellite Constellation for Environment and Disaster Monitoring and Forecasting (SSCEDMF) on September 6, 2008. SSCEDMF boards two main kinds of sensors, Wide Coverage CCD Cameras (CCD) and Infrared Camera (IRS) which can be used in fire monitoring and assessment because of relative high spatial resolution. On February 6, 2009, an extremely serious forest fire happened in south eastern Australian. As the data and service center in China, National Disaster Reduction Center of China (NDRCC) timely provided the SSCEDMF and other satellites data to Australia. Furthermore, we use CCD and the middle infrared band to obtain fire spot, fire burned and damaged area, fire tendency and risk analysis products which were also provided to Australian government and institutions. The results showed that SSCEDMF images could be very useful to fire monitoring and assessment.

The imaging algorithm of target detection based on BD ( Bei Dou ) signals is studied. The constitutes and principles of detecting system space target are firstly discussed, then the imaging algorithm of target detection based on BD signals are deduced, finally according to some models of detection system working, a correspondence detection imaging are simulated, it is expected to lay some reference values for the application of BD signals in scopes of target detection.

Interference imaging spectroscopy is an advanced subject of high resolution remote sensing, and has become an important technique to acquire more spectrum information. The digital processing process of spectrum reconstruction must be executed to get spectrum because the raw data can't be used directly. In this paper, take the SMIFTS, a new payload of the HJ-1A satellite, as an example. The principle of SMIFTS and its data cube characters are introduced. The spectrum reconstruction processing process is studied. A method of relative radiometric calibration is provided to generate the CCD models of detectors in this paper, which based on statistics method, and using real data of HJ-1A satellite to verify. The results indicate that this method can correct the differences of CCD response and imported light filed. It is also beneficial to reduce the nonlinear phase offset of interfere data, and can improve the precision of spectrum reconstruction.

Gravity field measurement for the interested planets and their moos in solar system, such as Luna and Mars, is one important task in the next step of deep-space mission. In this paper, Similar to GRACE mission, LLSST and DOWR technology of common-orbit master-slave satellites around task planet is inherited in this scheme. Furthermore, by intersatellite 2-way UQPSK-DSSS link, time synchronization and data processing are implemented autonomously by masterslave satellites instead of GPS and ground facilities supporting system. Conclusion is derived that the ISL DOWR based on 2-way incoherent time synchronization has the same precise level to GRACE DOWR based on GPS time synchronization. Moreover, because of inter-satellite link, the proposed scheme is rather autonomous for gravity field measurement of the task planet in deep-space mission.

Fractal image coding algorithm is a promising technique to improve the storage efficiency for satellite applications, and it can obtain good reconstructed quality with very high compression ratio in contrast with other image compression methods. In this paper, a fractal coding algorithm for satellite image compression is proposed. The framework of this algorithm is simple, so that it can be designed for hardware and applied on satellite conveniently. In addition, some improved methods are also introduced in this paper.

Low-orbit satellite ambiguity fixing is the import factor affecting GPS network difference reliability. In this paper, the satellite will be selected as reference satellite by elevation angle of satellite and barycenter of triangle to construct weight matrix. Quickly resolving double difference wide ambiguity based on wide-lane combination, fixing ambiguity of L1/L2 by LAMBDA algorithm, estimating troposphere error in non-ionosphere combination by HOPFIELD model, improving 0.3cycle float ambiguity accuracy of low elevation angle satellite, applying this method to develop network differential systems by our own intellectual property rights. The actual tests show that: accessing to the system the actual mobile station position plane accuracy is better than 5cm.

Through the analysis of the laser scattering and absorption properties in the atmosphere and ocean with suspended particles, and the analysis of the refractional characteristics to laser in the atmosphere to ocean interface, the probability density distribution characteristics and physical properties of the laser beam in detail, which transport through the atmosphere-ocean channel, are proposed. Using the physical characteristics of light and the probability density distribution, we deduced a suitable mathematic expression model of Monte Carlo method, and then accomplished the simulation of laser channel. From the simulation, we presented the spatial distribution characteristics of photons in laser communication downlink channel throughout the atmosphere-ocean system.

Studying the space-based optical surveillance system and target identification algorithm utilizing simulation technology has been one of the hottest problems currently. The simulation principle and method of space object visible images which can embody the range and system performance of actual space-based optical surveillance systems based on STK and OpenGL is put forward. The target reflection radiation model, as well as the relationship between OpenGL imaging model and the pinhole imaging model of real imaging system, are both researched. Imaging simulation process includes 3D target modeling, orbital analysis based on STK, imaging simulation based on OpenGL, noise and blur effects modeling. At last the serial visible images of moving space object are simulated. It can provide data base for the research of space-based target identification technology.

Imaging simulation is desired to provide reference for the design and optimization of active detection system and to expand the amount of training data for image processing and target identification algorithms. However it is difficult to model and simulate the real image effect well and perfectly. Our own idea and feasible simulation method are put forward, and the content includes system performance model, space object characteristic analysis and imaging simulating. The system performance is analyzed first, and by using BRDF for describing target reflectance, the simulation model fidelity is improved. Then the flow of simulating active illumination imaging effects process is described and the illuminated target images of different attitude parameters are generated. It has been proven that the method of simulation is rational and efficient.

Precise point positioning (PPP) has been demonstrated to be a powerful sensor to monitor tropospheric zenith delay (TZD). In the PPP, some unmodelled biases still remain in the GPS observables and will inevitably degrade the precision of tropospheric zenith delay estimation. The researches show that the precision of PPP-derived TZD can be obviously improved through a suitable stochastic model for GPS measurements. Previous stochastic models assume that the accuracy of high-elevation GPS measurements is higher than that of low-elevation GPS measurements. A new stochastic model based on satellite elevation angel cosine is used in the presented paper. It examines the quality of the PPP-derived TZD calculated at shanghai GPS stations through comparison with those of nearby radiosonde soundings. It is found that the PPP-derived TZD have good agreement with results of radiosonde soundings. It is feasible to monitor tropospheric zenith delay by the singular GPS station in PPP.

As the key and fundamental technology of China Lunar Exploration Project, Sample Return Capsule will return to earth from lunar for the first time. This paper introduces the contrast to typical foreign deep space Sample Return Capsule's key performance such as Aerodynamic configuration, overload factor, entry range, stagnation point peak heating base on investigating a great deal of typical deep space sample return missions. Finally, it gives the future development direction of the deep space sample return mission, and offers some proposal for China Lunar Exploration Project.

Because of the environment conditions of the ground targets have been changing when the remote sensing images are acquired, so it is known that labeled samples from one remote sensing image is almost imposable to be used in another image classification, because the spectral signatures are various. But once it can be done successfully it will lead to great resource preserving and high work efficiency. This article proposes a classification samples spatial-time domain expanding method to address this issue. In this method, we choose training samples from a reference image, then classify the images in space and time neighborhood of the reference image by the classifier which is trained with these labeled samples. Before classifying, the relative radio-correcting (or to say radiometric normalization) of the images to be classified need be done, and it is the key step. Three classification experiments, which were the reference image and the image need be classified have only different acquisition time, only different cover region, and both the different acquisition time and different cover region, are successfully carried out. The results prove that our method has done well in classification samples expanding application in time domain, in space domain and both in the two domains.

Multi-temporal remote sensing image registration is the key step of change detection, and because of the remarkable difference and the probably unknown of sensor parameters, the automatic registration of different temporal remote sensing images is very difficult. Image registration based on Fourier-Mellin transform(FMT) is a global and phase correlation method, which is based on Fourier and Log-polar transform. This method finds the transformation parameters for registration of the images while working in the frequency-domain and it is resilient to noise, occlusions and so on. In this paper, an improved approach based on Fourier-Mellin algorithm is proposed for the registration. Spectrum aliasing and resampling interpolation will bring errors during Fourier-Mellin transform. To get a better registration result, we have improved it by adding window function and filtering to reduce spectrum aliasing and increase the robustness.

The purpose of image fusion is to merge the redundant and complementary information of multi-sensor to get a new image which is more propitious to image processing. A novel image fusion method based on wavelet transform and intersecting cortical model (ICM) is proposed in this paper. The original image is decomposed into high-frequency subimage and low-frequency subimage firstly. A region-based method is applied to high-frequency subimage to get the fused high-frequency subimage. For the low-frequency subimage, the edge metric is computed firstly, then the edge metric is used as the input of ICM and we can get the firing map of two subimage. By comparing the firing times of each nerve cell, the fused low-frequency subimage is obtained. The fused image is then obtained by inverse wavelet transform. The effectiveness of the proposed algorithm is verified by the experimental results.

Due to disadvantages of complex working procedure, long field survey and low efficiency of the traditional cadastral survey methods exist, a modified system based on GPS(Global Position System) /PDA(Personal Digital Assist) combined with TS(Total Station) is proposed. The system emphasizes the design of TS free setting station for detail survey without GPS, to realize simultaneously processing control survey and detail survey. The system also applies digital drafting method based on PDA instead of cartographical sketching, to realize fully-digitalized cadastral survey. The application in Beijing shows that the modified cadastral survey system based on GPS/PDA performs high efficiency, and the accuracy of this system can meet the requirement of 1:500 large scale cadastral survey.

Studying on the GPS height transformation algorithm to improve the accuracy of GPS height conversion has always been a hotspot in the field of geodesy. At present, there are many methods of converses GPS height into normal height, the most common of which is the method of numerical approximation, and its algorithm is mostly confined to how to choose a suitable function model or statistical model to numerical approximation. Aiming at the singularity of GPS height conversion methods, this article presents a comprehensive approximation algorithm, which combine the functional approximation models with statistical approximation models in order to take full advantage of the regularity of function approximation model and the flexibility of the statistical approximation model. Based on the analysis of the actual engineering data, the results show that the accuracy of GPS height transformation based on the algorithm of integrated approximation approach is superior to the single function transformation model or a single statistical model. At the same time, it also relaxes the selection requirements of function model and statistical model.

A dynamic inversion control method based on neural network compensation for UAV automatic landing is introduced. Aimed at the nonlinear characteristic of automatic landing procedure, the dynamic inversion method is used for feedback linearization. The on-line neural network is introduced to compensation dynamic inversion error caused by the disturbance factors during automatic landing and improves the controller performance. Numerical simulation presents that the control method can make the UAV follow the expected trace properly and have good dynamic performance and robust performance.

Owing to the global coupling and pulse synchronization characteristic of pulse coupled neural networks (PCNN), it has been proved to be suitable for image processing and successfully employed in image fusion. However, in almost all the literatures of image processing about PCNN, linking strength of each neuron is assigned the same value which is chosen by experiments. This is not consistent with the human vision system in which the responses to the region with notable features are stronger than that to the region with nonnotable features. It is more reasonable that notable features, rather than the same value, are employed to linking strength of each neuron. As notable feature, energy of Laplacian (EOL) is used to obtain the value of linking strength in PCNN in this paper. Experimental results demonstrate that the proposed algorithm outperforms Laplacian-based, wavelet-based, PCNN -based fusion algorithms.

This paper presents a novel algorithm named Ensemble Distance Metric Tracking (EDMT) for target tracking in infrared imagery. Obtaining an appropriate distance metric function can significantly improve the performance of tracking algorithms. There are two problems in distance metric choosing for object tracking. First, we can't find the data model distribution beforehand for most tracking application. Second, the data model will change as both foreground and background appearance undergoes complex changes with the target object moving from place to place. So the distance metric function also needs to adapt dynamically during the tracking procedure. Most tracking applications are conducted using a fixed distance metric function, which is determined beforehand. We propose a new algorithm that can learn and update the distance metric dynamically, which is different from the conventional methods that use the predefined metric. In our new EDMT algorithm, the ensemble distance metric function is learnt by weighted training with different distance metrics on each feature element iteratively using the boosting learning method. The new distance metric function is adopted in particle filter to compute the weights of each particle. The experimental results demonstrate the effectiveness and robustness of our tracking algorithm in challenging infrared video sequences.

Phase difference change rate has been put forward recently, which attracts wide attention as a measuring parameter in the rapid passive positioning system. In the measurement of passive location, positioning accuracy is greatly influenced by the measurement accuracy of corresponding observed quantity and the follow-up effects of wave filtering. A method of phase estimation based on correlation algorithm for sinusoid signal is presented in this paper, which can be used in the design of digital phase interferometer. Using the correlation algorithm method, it is possible to effectively separate part of noise from the useful signal, and also to improve the resistibility to random disturbance and the accuracy of measuring system. The explicit formula explanation in this paper demonstrates that as the most important characteristic of the method, the frequency for received sinusoid signal is not required in advance. The Monte Carlo simulation demonstrates that the phase estimation by this method can be achieved within 1°, which is more accurate than that with the traditional analog phase interferometer; Compared with the other method by FFT in the digital interferometer, the accuracy of this method is better in the low SNR situation.

One of the promising and relatively new directions for space exploration is research of two-level network, i.e., space network and ground network. The paper proposes a two-level network monitoring system model and implements the model based on SNMP (Simple Network Management Protocol). The management mechanism of this system is that the priority of ground part is higher than that of the space part so that the ground part could manage the space network. Encrypted configuration files are used to realize the two-level network configuration management. In order to decrease the expense resulted from the loss of the data caused by the rupture of the link, two policies are needed to compensate the loss data. One is to transmit based on request; the other one is detected periodically. The model is supportive to space exploration.

In deep space exploration, image compression plays an important role in maximizing returned scientific data. CCSDS adopts the methods based on Discrete Wavelet Transformation as the image compression standards because of its high compression ratio, progressive transmission and supporting lossless compressing. According to its feature, a new image compression scheme - Region of Interest encoding is presented for balancing the initial image acquiring rate, buffer size and data transmission rate on spacecraft in deep space communication. It is performed by which ROI is assigned with lower compression ratio, more storage space, and higher transmission priority. Thus it could be attained the goal of acquired image in deep space communication-maximizing information returning to the ground. And an optimized bit allocation method between ROI and Non-ROI is proposed according to rate-distortion model that is fit for progressive wavelet coding rate and distortion. Based on taking 2-level priority as an example, an optimized bit allocation method between ROI and Non-ROI is discussed. Simulation results show that the performance of the scheme is satisfying.

The paper mainly studies the development of assistant and decision-making system of site selection for supermarket, including development environment, overall design, design and realization of every function module, etc. The system adopts MapX5.0 and VB6.0 as the development platform, uses SQL Server 2005 as the back database. The establishment of the system offers an important means for site selection of supermarket, increases the efficiency of site selection of supermarket.

In deep space communication, due to the restricted transmitted power, sharply-attenuated of signals because of long distance and all the noise in space, the received signals from the deep space have low signal to noise ratio (SNR) and high carrier phase noise. The Ultra long point FFT algorithm and binary branch acquisition technique were studied and the modified binary branch FFT acquisition method was proposed. The more flexible method has faster acquisition ability and higher detection probability. Based on the software radio technology, the hardware platform of "FPGA + DSP" was built to implement the 216 FFT using modified two-arm acquisition technique, the carrier wave acquisition and tracking were implemented on the condition of extra-low SNR and the test result indicated the method in this paper can implement the quick detection under the 16dBHz SNR or below.

To automatic analysis of the image content,an architecture of content-based image analysis component is designed, which is compatible with existing remote sensing images catalogue and archive system. Thus, indexing can be generated on images content for the images archive. An learning algorithm relying on support vector machine (SVM) is also proposed to classify and label the region of interest in high resolution remote sensing images.This algorithm needs a small size and consumes little computing time online. At the same time, the algorithm can automatically generate semantic interpretations from images.

The multiplicative nature of the speckle noise in SAR images is a big problem in SAR image segmentation. A novel method of automatic segmentation of local SAR images based on the two-dimensional (2D) Pseudo Wigner-Ville distribution (PWVD) is proposed. Firstly, we put emphasis on the problem of expensive cost and the interference of cross terms to SAR image segmentation. Then, we propose local 2D-PWVD transform to SAR image. The resultant data can be arranged as N energy maps which have the same size as original image making use of 2D local energy maps of every pixel of original image. The different processing to the resultant data in frequency dimension is adopted according to different energy maps. Finally, the marker region image is formed by virtue of adding the filtered energy maps. The segmentation experiment for MSTAR chips are taken and the comparison between segmentation image of our method and segmentation image of min error, between segmentation image of our method and segmentation image of max energy algorithm have been made. The result shows that the segmentation image of our method obtained by the presented algorithm preserves the abundant detail information of source so as to demonstrate the validity of the proposed method.

This paper firstly analyzes the main factors that impact the layout of satellite antenna. The uniform geometrical theory of diffraction (UTD) is used to establish mathematical model for calculating the coupling of satellite antenna, and set up the objective function of the placement optimization. The genetic algorithm incorporating high-frequency simulation to minimize antenna coupling by optimally positioning satellite antenna is described in detail. The results of antenna placement on a realistic satellite show that this method is effective in the optimal design of satellite antenna layout for the purpose of electromagnetic compatibility.

A total of 94269 unfiltered CCD observations for 16 of the brightest galactic Cepheids, obtained by the SMEI instrument, were reduced with the Hertzsprung method to define individual times of light maxima. Then O-C residuals for all of 16 Cepheids were analyzed with the Eddington-Plakidis method and random fluctuations in periods for four of them, SU Cas (P=1^d.95), δ Cep (P=5^d.37), κ Pav (P=9^d.09), and α UMi (P=3^d.97) were detected. Such fluctuations for short period Cepheids are found for the first time. O-C diagrams as well as results of the Eddington-Plakidis test are presented.

Built in cooperation with the P.R of China, in October 29th of 2008, the Bolivarian Republic of Venezuela launched its first Telecommunication Satellite, the so called VENESAT-1 (Simón Bolívar Satellite), which operates in C (covering Center America, The Caribbean Region and most of South America), Ku (Bolivia, Cuba, Dominican Republic, Haiti, Paraguay, Uruguay, Venezuela) and Ka bands (Venezuela). The launch of VENESAT-1 represents the starting point for Venezuela as an active player in the field of space science and technology. In order to fulfill mission requirements and to guarantee the satellite's health, local professionals must provide continuous monitoring, orbit calculation, maneuvers preparation and execution, data preparation and processing, as well as data base management at the VENESAT-1 Ground Segment, which includes both a primary and backup site. In summary, data processing and real time data management are part of the daily activities performed by the personnel at the ground segment. Using published and unpublished information, this paper presents how human resource organization can enhance space information acquisition and processing, by analyzing the proposed organizational structure for the VENESAT-1 Ground Segment. We have found that the proposed units within the organizational structure reflect 3 key issues for mission management: Satellite Operations, Ground Operations, and Site Maintenance. The proposed organization is simple (3 hierarchical levels and 7 units), and communication channels seem efficient in terms of facilitating information acquisition, processing, storage, flow and exchange. Furthermore, the proposal includes a manual containing the full description of personnel responsibilities and profile, which efficiently allocates the management and operation of key software for satellite operation such as the Real-time Data Transaction Software (RDTS), Data Management Software (DMS), and Carrier Spectrum Monitoring Software (CSM) within the different organizational units. In all this process, the international cooperation has played a key role for the consolidation of its space capabilities, especially through the continuous and arduous exchange of information, documentation and expertise between Chinese and Venezuelan personnel at the ground stations. Based on the principles of technology transfer and human training, since 1999 the Bolivarian Republic of Venezuela has shown an increasing interest in developing local space capabilities for peaceful purposes. According to the analysis we have performed, the proposed organizational structure of the VENESAT-1 ground segment will allow the country to face the challenges imposed by the operation of complex technologies. By enhancing human resource organization, this proposal will help to fulfill mission requirements, and to facilitate the safe access, processing and storage of satellite data across the organization, during both nominal and potential contingency situations.

A novel knowledge discovery model, CEDPRS (CE-1 Satellite Data Preprocessing Rough Set), is presented for CE-1 satellite tracking data preprocessing. In order to develop CEDPRS, rough set is chosen as the theoretical tool for its good performance in knowledge discovery, and so are characteristics of the data as well as practical experiences. Then, good diagnosis rules are provided for the discovery and disposal of fault data as a result of CEDPRS applied to tracking data Preprocessing. Experimental results are obtained by introducing real task data, which demonstrate that the proposed CEDPRS model is sufficiently accurate and effective in satellite tracking data preprocessing.

In this paper, a new approach to maintain spatial information acquiring from remote-sensing images is presented, which is based on Object-Relational DBMS. According to this approach, the detected and recognized results of targets are stored and able to be further accessed in an ORDBMS-based spatial database system, and users can access the spatial information using the standard SQL interface. This approach is different from the traditional ArcSDE-based method, because the spatial information management module is totally integrated into the DBMS and becomes one of the core modules in the DBMS. We focus on three issues, namely the general framework for the ORDBMS-based spatial database system, the definitions of the add-in spatial data types and operators, and the process to develop a spatial Datablade on Informix. The results show that the ORDBMS-based spatial database support for image-based target detecting and recognition is easy and practical to be implemented.

To build and apply Temporal Geographic Information System (TGIS), to manage mining land spatio-temporal data is a key research aspect for present production administration and ecological environment protection. Spatio-temporal database, whose foundation is spatio-temporal data model, is the core of TGIS. Considering the feature of land use to change, this paper builds up a model of mining land spatio-temporal data based on ground-state amended model with some improvements. This data model stores space information and time information of mining land in spatial database. From judging the spatio-temporal information in historical and current database, the land use situation at different historical period can be recurred very conveniently. At the same time, the mutual transforming situation among lands at different periods can be educed from overlaying the lands by use of the related analyzed function of GIS. Accordingly, that will give an important reference to open out the rule of mining land evolution.

This paper presents the design procedure and implementation result of 800Mbps 16-QAM pulse shaping filter for payload data transmission system of remote sensing satellite. In order to achieve the high speed pulse shaping filter adapting to the current hardware components, the 16-QAM constellation mapping and the pulse shaping have been combined. Meanwhile, the poly-phase structure of FIR and the distributed algorithm based on look-up table have been used in favor of high speed shaping filter calculation in FPGA. In addition, the 800Mbps 16-QAM pulse shaping filter prototype is realized on the hardware by using the parallel circuit architecture and the high speed circuit technique. The test results have been shown to prove that the design method of the pulse shaping filter can be effectively applied to the high speed payload transmitter of remote sensing satellite.

The space-based information system (SBIS), as one part of the national space security systems, is also a core factor to dominate a War. This paper firstly presented the composition of the SBIS, and then discussed the development trend and application of the overseas SBIS. Finally, the paper proposed the countermeasures to develop the national SBIS according to the experience and inspiration.

In this paper, OLR (Outgoing Longwave Radiation) data monthly vorticity variations related to three earthquakes in Sichuan-Yunnan area have been analyzed so as to seek short-term (within three months) seismic anomalies. In order to obtain a reference field without any seismic information, OLR data of three years (2004, 2005, and 2006) without earthquakes are selected as the data source for normal field, then the monthly reference fields(from January to December) of this region are generated using it. The results indicate that OLR anomalies are possible to be detected in earthquakes of greater magnitude (Ms>6.0), the anomalies appeared 1-3 months prior to earthquakes and disappeared after the events, the affected area can reach million square kilometers, and the anomalous values are about 17-25W/m², that is to say, the OLR vorticity values near the epicenter area can be increased by about 10%. It should be noted that the epicenter of the impending earthquake is not just in the high value area of OLR anomalies, but located at a short distance away from it. And the relationship between anomalous amplitude and seismic magnitude is not a simple direct proportion.

With the air traffic congest problem becoming more and more severe, the study of air traffic flow management is more and more important. According to the character of air traffic flow management, the author analyzed the heuristic method and genetic algorithms, later put this two method together and give a new method of air traffic flow management-mixture genetic algorithms, It has global convergence, the simulation result demonstrates that the presented algorithm is effective.

A Ku band circularly polarized single-layer U-slot microstrip patch antenna with chamfering at the corners has been proposed in this paper. A parametric study has been carried out to investigate the effects caused by chamfering corners and location of the feeding probe. Simulation results show the bandwidth ( S11 <-10dB) is about 700MHz and the 3dB axial ratio bandwidth of the antenna is 3.7%. At the desired frequency, i.e,14-14.5GHz, the return loss is below -12dB and the axial ratio is below 3dB.

For magnetic detection satellite, it is hard to avoid electromagnetism interference on detection data. Whether Data transmitting system (DTS) could produce electromagnetism interference on detection data is uncertain. So we widely discussed and studied this problem. Firstly, in order to look for interference signal caused by DTS in routine data, the paper processed and analyzed the routine detection data from "Demeter" satellite and "Double Star" satellite, combining with some auxiliary data. And no abnormal signal caused by DTS has been observed. Secondly, for identifying unknown interference using the interference characteristics we have known, this paper summarized and analyzed the characteristics of the known interferences on detection data. The research achieved the conclusion that detection data didn't be affected by electromagnetism signal of DTS. Moreover, based on working principle of DTS, interference mechanism caused by DTS was simply analyzed, and some advices for avoiding interference were provided aiming at some potential problems. The analyzing process and research conclusions will offer an important reference for designing of preparing China Seismic Electromagnetic Satellite.

The congestion problem is one of the most important restrictions of wireless ad hoc networks. It is quite different from that of the traditional networks. In this paper, a routing algorithm based on potential, called RAP, is proposed to mitigate the congestion of wireless ad hoc networks. The RAP algorithm defines two potential fields for each node: vertical potential field and congestion level field. The mixture of these two fields shows the potential of a node for a certain destination. The data packets are routed along the steepest gradient direction to its destination. The RAP algorithm for wireless ad hoc networks can route packets bypass the congestion nodes and congestion zones to alleviate the congestion problem. To evaluate the performance of RAP algorithm, we conducted the simulation on NS2. The simulation results show that our RAP algorithm for wireless ad hoc networks can mitigate the congestion problem without much overhead.

The M-ary spread spectrum systems with zero correlation zone (ZCZ) sequences were fabricated and analyzed present in multipath. The analyzed results show the ZCZ sequence M-ary spread spectrum system has stronger anti-multipath interference ability than Walsh sequence M-ary spread spectrum system. The simulated channel is composed of a line _of _sight(LOS), 9 specular reflection and a diffuse multipath component whose power is 10dB less than that of the line-of-sight signal. In case of BER=1E-2 and 25% reflecting strength, the S/N of ZCZ sequence 4-ary spread spectrum systems has about 0.8dB improvement than that of Walsh sequence 4-ary spread spectrum system; In case of BER=3E-2 and 50% reflecting strength, the S/N has about 1.7 dB improvement. Those results imply that present system is useful to design high spectrum efficiency and strong anti-multipath interference spread spectrum systems.

In order to solve the problems existed in current decision support system, such as closed, model-oriented, forbidding uncertainty and risk, oriented to analysis of few determined scenario, a novel synthetic decision support system(SDSS) based on data farming is proposed and established in this paper. Taking data warehouse as platform, the SDSS searches unknown information and unexpected knowledge by use of data farming, while data mining is utilized to extract reliable, original and valuable knowledge from large quantities of data. The organic combination of data farming, data mining and data warehouse opens up a new way for research on decision support system, and simulated experiments verify the validity of this technology.

The development of airborne network is conducive to resource sharing, flight management and interoperability in civilian and military aviation fields. To enhance the integrated ability of airborne network, the paper focuses on dynamic network management and service integration architecture for airborne network (DNMSIAN). Adaptive routing based on the mapping mechanism between connection identification and routing identification can provide diversified network access, and ensure the credibility and mobility of the aviation information exchange. Dynamic network management based on trustworthy cluster can ensure dynamic airborne network controllable and safe. Service integration based on semantic web and ontology can meet the customized and diversified needs for aviation information services. The DNMSIAN simulation platform demonstrates that our proposed methods can effectively perform dynamic network management and service integration.

The paper is based on biology vision stared mechanism, applies the detective arithmetic operators of static image into the system of moving dim targets detection ,brings forward an adaptive detective model of moving dim targets based on energy difference between frames, and optimizes and selects the parameters in the mathematic model. Experiments completed by the paper proving, the adaptive detective model can detect moving dim targets real-timely and exactly. Detection and tracking of moving dim targets are the most important part of the system of watching and alarming. So it's essential to find and detect the targets in time. Because of claim of detecting targets at long bowls, the targets usually are regarded as the dot targets or pixels in the system of watching and alarming. So detection of infrared dim targets is one of key technology in the weapon system, and one important project in moving targets detection. We aim at slowing down signal-to-noise ratio in the detection of moving dim targets by the way of classical frame difference and rapid matching, bring out a new anisotropic moving detection model between frames in the study of theories of biology vision fixated mechanism, and analyze and research on selection of more parameters in the detection model. Experimental results show that the algorithm based on energy difference comparing between frames which is brought out by this paper is effective and practical to detect moving dim small targets.

Free Space Optical (FSO) communication is a communication pattern in which laser is used as the information carrier in atmosphere environment. FSO system has been widely applied in the fields of satellite communication and ground sight distance communication, with a promising application prospect and tremendous market potential. And space-time processing (using multiple antennas) is now recognized as a key to achieving reliable high data rate wireless communications and is being incorporated into the physical layer of many wireless standards. In this letter, error rate performance for space-time block coding (STBC) in FSO communication systems with direct detection operating over strong atmospheric turbulence channels is analyzed. The purpose of the paper is: (i) to determine the channel capacity of FSO system in the presence of atmospheric turbulence, (ii) to see how much this limit can be approached using the best known STBC techniques. In this paper, we use mathematics tool to establish the channel model of FSO system, and then apply the STBC to the FSO system, research the decoding method and simulate the performance using MATLAB tools. The mathematics analysis and simulation results show the great application expectation of STBC in the OOK channel of the FSO system.

In this paper, we describe a flat plate array for the satellite communication receiver, with small aperture, high efficiency and low cross polarization levels. The radiating element used is circular waveguide which is probe-fed using a stripline distribution networks providing uniform excitations to the 4×4 array. The networks are placed one behind the other for dual polarized purposes. The array is composed of 2×1 subarrays. The overall array thickness is about 1λ ( λ is the wavelength of the center frequency), and the array aperture is about 3.2λ. Simulated results on a Ku-band prototype are discussed. The bandwidth (VSWR below 2.0) is about 500MHz, cross-polarized radiation from both ports is below -35dB, the isolation between the ports is below -25dB, and the gain of the 4×4 array is about 20dBi. Simulated efficiency is about 75% (including the stripline feed networks).

The primary mirror is a key component of large-scale space telescope, and its thermal effects analysis is an important guideline to thermal design and control of optical system. Based on Finite Elements Analysis (FEA) method and thermodynamics coupling theory, the heat-induced distortion and the effects of temperature distribution such as edge, axial and radial temperature grads acted on the primary mirror are analyzed in this paper. According to the design requirement and the numerical simulation results, the effective means of thermal control for the primary mirror are suggested.

Because of the limit of the loop-band, traditional carrier tracking loop of GNSS receiver can't work in high dynamic conditions with large Doppler frequency, for which an open-loop carrier tracking method based on UKF is proposed. Upon this new tracking loop, the four-dimensionality UKF phase estimator and a compensator is designed to modify the estimative values. By simulating the high dynamic trace of the plat of GNSS receiver, this new method is compared to the closed loop mainly in the aspects of tracking errors, compensation effects and unlocking probability. Simulations show that (1) the proposed open-loop compensation method can give attention to the precision and the dynamics better, with high stability, (2) compared with the closed loop, the open-loop carrier tracking method can improve the tracking precision, with 50% decrease of the tracking errors; and (3) the convergence of this new method is much better, leading to lower unlocking probability.

Since the system capacity is severely limited, reducing the multiple access interfere (MAI) is necessary in the multiuser direct-sequence code division multiple access (DS-CDMA) system which is used in the telecommunication terminals data-transferred link system. In this paper, we adopt an adaptive multistage parallel interference cancellation structure in the demodulator based on the least mean square (LMS) algorithm to eliminate the MAI on the basis of overviewing various of multiuser dectection schemes. Neither a training sequence nor a pilot signal is needed in the proposed scheme, and its implementation complexity can be greatly reduced by a LMS approximate algorithm. The algorithm and its FPGA implementation is then derived. Simulation results of the proposed adaptive PIC can outperform some of the existing interference cancellation methods in AWGN channels. The hardware setup of mutiuser demodulator is described, and the experimental results based on it demonstrate that the simulation results shows large performance gains over the conventional single-user demodulator.

Low density parity check (LDPC) codes are a class of forward-error-correction codes. They are among the best-known codes capable of achieving low bit error rates (BER) approaching Shannon's capacity limit. Recently, LDPC codes have been adopted by the European Digital Video Broadcasting (DVB-S2) standard, and have also been proposed for the emerging IEEE 802.16 fixed and mobile broadband wireless-access standard. The consultative committee for space data system (CCSDS) has also recommended using LDPC codes in the deep space communications and near-earth communications. It is obvious that LDPC codes will be widely used in wired and wireless communication, magnetic recording, optical networking, DVB, and other fields in the near future. Efficient hardware implementation of LDPC codes is of great interest since LDPC codes are being considered for a wide range of applications. This paper presents an efficient partially parallel decoder architecture suited for quasi-cyclic (QC) LDPC codes using Belief propagation algorithm for decoding. Algorithmic transformation and architectural level optimization are incorporated to reduce the critical path. First, analyze the check matrix of LDPC code, to find out the relationship between the row weight and the column weight. And then, the sharing level of the check node updating units (CNU) and the variable node updating units (VNU) are determined according to the relationship. After that, rearrange the CNU and the VNU, and divide them into several smaller parts, with the help of some assistant logic circuit, these smaller parts can be grouped into CNU during the check node update processing and grouped into VNU during the variable node update processing. These smaller parts are called node update kernel units (NKU) and the assistant logic circuit are called node update auxiliary unit (NAU). With NAUs' help, the two steps of iteration operation are completed by NKUs, which brings in great hardware resource reduction. Meanwhile, efficient techniques have been developed to reduce the computation delay of the node processing units and to minimize hardware overhead for parallel processing. This method may be applied not only to regular LDPC codes, but also to the irregular ones. Based on the proposed architectures, a (7493, 6096) irregular QC-LDPC code decoder is described using verilog hardware design language and implemented on Altera field programmable gate array (FPGA) StratixII EP2S130. The implementation results show that over 20% of logic core size can be saved than conventional partially parallel decoder architectures without any performance degradation. If the decoding clock is 100MHz, the proposed decoder can achieve a maximum (source data) decoding throughput of 133 Mb/s at 18 iterations.

Although AOHR protocol has some excellent performance, no actual network utilizes AOHR as routing protocol. It is because that this protocol cannot interoperate with AODV protocol, which is the most famous routing protocol and used all over the world. The cost will be very huge to replace AODV protocol with AOHR protocol for existing networks, so the only feasible method is to modify AOHR protocol to interoperate with AODV as introduced in this paper. The simulation results prove that the modified AOHR protocol can help the existing AODV protocol provide routing service, and the interoperation of these two routing protocols is realized.

Max-min energy-aware AODV and OLSR hybrid routing (MEAOHR) protocol aims at prolonging the lifetime of network for AOHR protocol. With a little modification to the AODV protocol part of AOHR protocol, MEAOHR protocol can provide minimal energy information of every routing to destination nodes and source nodes by RREQ packets and RREP packets respectively. In this way, destination nodes and source nodes can choose a routing respectively with the max-min energy value among all routings as the path for packet delivery. Simulation results and analysis prove that MEAOHR protocol can effectively provide longer network's lifetime and steadier end-to-end delay without any performance loss compared to AOHR protocol.

Satellites channels are generally featured by high bit error rate (BER), long propagation delay, large bandwidth-delay product (BDP) and so on. This tends to make the traditional TCP suffer from serious performance degradation in satellite networks. Therefore, a TCP-compatible reliable transmission protocol (i.e., TCP-AX) for spatial information networks is proposed in this paper. And a bandwidth probing mechanism is designed to distinguish network congestion and link error. Simulation results show that TCP-AX has better performance than some popular enhanced TCP protocols.

The spatial information networks (SIN) plays a more and more important role in current communication networks, while its security problem is rigorous. To enhance the information survivability, based on the concept of defense-in-depth, this paper proposes an intrusion tolerant (IT) model which can be applied in SIN, analyzes it in detail on three-tier of intrusion defense, intrusion detection and intrusion tolerant. And some suggestions are made for each tier.

With the development of LEO satellite communication, it is the basic requirement that various kinds of services will be provided. Considering that weak channel collision detection ability, long propagation delay and heavy load in LEO satellite communication system, a valid adaptive access control protocol APRMA is proposed. Different access probability functions for different services are obtained and appropriate access probabilities for voice and data users are updated slot by slot based on the estimation of the voice traffic and the channel status. Finally simulation results demonstrate that the performance of system is improved by the APRMA compared with the conventional PRMA, with an acceptable trade-off between QoS of voice and delay of data. Also the APRMA protocol will be suitable for HAPS (high altitude platform station) with the characters of weak channel collision detection ability, long propagation delay and heavy load.

The site testing studies at the Maidanak Observatory in Uzbekistan for the period 1996-2007 are presented. Nightime seeing was measured with the ESO Differential Image Motion Monitor. The median zenith seeing (FWHM) value at 500 nm for the entire period of observations is 0.71 arcsec. A maximum clear sky season for Maidanak is July-September, with about 90% of possible clear time and a median seeing of 0.69 arcsec. The best monthly median seeing 0.62 arcsec observes in November. Negligible correlation between seeing and the wind velocity at ground level have been found. During an additional site testing campaign organized in July 1998, the median wavefront outer scale being 25.9 m and median isoplanatic angle being 2.48 arcsec were measured with the Generalized Seeing Monitor. This corresponds to a remarkably large atmospheric time constant. Simultaneous measurements of total seeing and microthermal measurements of surface layer optical turbulence were carried out in July-August 2002 which allowed us to estimate the surface layer contribution to the total seeing and which has been found to be about 8%.

Remote sensing is the science of gathering information about objects from measurements, made at a distance, without coming into physical contact with the objects under study. Remote sensing whether from ground, aerial and space platform has indeed brought a whole new persepective to archaeological research. They have made possible to "see" the evidences that are not observable otherwise. Usage and interpretations of imagery taken from aerial or space platform for archaeological purposes have been explored in many parts of the world. This paper explores applications of space based stereo imaging for archaeological prospection with three case studies: Badami and Mahabalipuram in India and Qin's Mausolium in china. 3D visualization and virtual reconstructions of landscape is a valuable tool for archaeological study. This papers also explores how 3D models can be further extended to study visibility in a landscape and also analyse topography and flooding dynamics.

In this paper, we analyze switching from the current flat-rate Internet pricing to adopt usage-based pricing schemes. Even if flat rate pricing is one of the main reasons for the success of the Internet, the only way to prevent network congestion, differentiate services and maximizes social welfare is to adopt usage-based pricing schemes. Our scheme is highly related to an optimal congestion and cost-sharing pricing scheme for multiclass services applied to communication networks developed by Yezekael Hayel, Bruno Tuffin and design a pricing scheme that maximizes the social welfare which is the total gross value minus the total expected delay cost.

In satellite communication systems, in order to overcome the loss on which the long distance space transmission brings and provide the reliable and high-quality means of communication to the earth station, the RF carrier power of receiving signals should be much greater than the noise power, that is to make the satellite link satisfy the carrier noise ratio request. As the primary means of making the carrier noise ratio to meet the requirement of system designed, communication link calculation will be able to identify the carrier noise ratio, earth station required and system capacity, or the earth station antenna size, receiver noise performance, transmitter power, etc. The paper introduces a general method of satellite communication link calculation, and then analyzes the impact of different working conditions such as single-carrier and multi-carrier on communication links calculation process especially on the result of carrier-to-noise ratio. The calculation methods are proposed in conclusion respective.

A novel feature link quality analysis method (FLQAM) applied in satellite adaptive frequency hopping communication is presented in this paper. The method uses a frequency domain feature to tell whether the tested frequency area is jammed or not, which is much simple and efficient compared with traditional methods. Simulations are performed in Matlab environment and show that the success detecting rates is above 95% when INR is over -1dB.

In this paper, a method to calculate the VLF transmitting antenna's bandwidth and frequency characteristic is proposed by comparison of normalized signal power spectrum at antenna feed point with that at far field point, since a VLF transmitting antenna behaves as a filter to the signal at its feed point. Power spectrum data from four VLF transmitting antennas (operation frequencies are 21.4k, 19.8k, 22.2k and 24.8k respectively) are available, and respective bandwidths are calculated by the new method. Results show the validity of the method. This method need no details of the antenna's parameters. It is a new and simple way to find out VLF antenna's bandwidth and its MSK efficiency.

This paper presents an efficient approach for relative navigation and parameter estimation of spacecraft flying in formation. The approach estimates the double differential carrier phase ambiguity in single epoch, avoiding the trouble of cycle-slip detection and fixing. Simulation results demonstrate that the proposed approach can achieve centimeter-level relative position accuracy and millimeter-level velocity accuracy.

In this paper the technical implementation details of the remote sensing satellite data service system called DISS (Data Integration and Service System) is presented in five parts: software structure, integration technology, semantic data query technology, base map browse technology, personalized order and individual distribution technology. The system is implemented in the end to give some advice for the similar internal remote sensing satellite systems.

To solve the buffer management problem in communication networks, based on the IPA (Infinitesimal Perturbation Analysis) method, a new algorithm was proposed. The algorithm regarded the buffer management problem as one minimization of the performance function with the decision variable (specially, the buffer threshold) describing the nod with SFM(Stochastic Fluid Model). IPA technique was used to derive sensitivity estimators for the performance function, thus provided SA(Stochastic Approximation) algorithms capable to optimally minimize the performance cost based on IPA gradient. The algorithm can be evaluated based on data observed from the sample path of the real system without any pre-knowledge of the inflow.

A novel circularly polarized, broad band, wide beam microstrip patch antenna is presented in this letter. The measured impedance bandwidth is 44.3% by using L-shaped probe-fed technique. This bandwidth can cover GPS, Galileo, and GLONASS satellite navigation frequency bands. Traditional printed circuit techniques are abandoned in this design, and the novel design of radiating metallic copper patch embedded in the dielectric holder is introduced in this work. Therefore the reliability of this antenna has been improved and it can be used for airborne navigation terminal with better environmental and mechanical performance.

Blind equalization is an effective way to suppress the inter-symbol interference (ISI), which is caused by multipath fading communication channels. An improved robust super-exponential method (ISEM) is proposed here and extended to single-input multioutput (SIMO) models which are commonly used in satellite communication systems. The method, combining super-exponential method (SEM) and minimum description length (MDL), makes the equalization achieve good results even when the signal to noise ratio (SNR) is low. ISEM estimates the noise power of the received signal and then equalizes it by reducing the noise affection. Compared with robust super-exponential method (RSEM) in [1], the presented method has better performance but less computation.

A new 3D model retrieval methodology is proposed by exploiting a novel Bayesian networks lightfield descriptor (BNLD). There are two key novelties in our approach: (1) a BN-based method for building lightfield descriptor; and (2) a 3D model retrieval scheme based on the proposed BNLD. To overcome the disadvantages of the existing 3D model retrieval methods, we explore BN for building a new lightfield descriptor. Firstly, 3D model is put into lightfield, about 300 binary-views can be obtained along a sphere, then Fourier descriptors and Zernike moments descriptors can be calculated out from binaryviews. Then shape feature sequence would be learned into a BN model based on BN learning algorithm; Secondly, we propose a new 3D model retrieval method by calculating Kullback-Leibler Divergence (KLD) between BNLDs. Beneficial from the statistical learning, our BNLD is noise robustness as compared to the existing methods. The comparison between our method and the lightfield descriptor-based approach is conducted to demonstrate the effectiveness of our proposed methodology.

This paper addresses the solution of reducing the error due to the model jump in an attitude determination system based on multiple GPS antennas. We mainly compare the adaptive extended Kalman filter and the interacting multiple model approach in terms of the ability of solving mismodeling error. A hybrid algorithm merging both approaches is also proposed to improve the robustness. A Monte Carlo simulation is carried out to demonstrate the filtering performance.

This paper presents a novel fault diagnosis software (called FDSAC-SPICE) based on SPICE simulator for analog circuits. Four important techniques in AFDS-SPICE, including visual user-interface(VUI), component modeling and fault modeling (CMFM), fault injection and fault simulation (FIFS), fault dictionary and fault diagnosis (FDFD), greatly increase design-for-test and diagnosis efficiency of analog circuit by building a fault modeling-injection-simulationdiagnosis environment to get prior fault knowledge of target circuit. AFDS-SPICE also generates accurate fault coverage statistics that are tied to the circuit specifications. With employing a dictionary diagnosis method based on node-signalcharacters and regular BPNN algorithm, more accurate and effective diagnosis results are available for analog circuit with tolerance.

A design scheme of a general portable communication simulator is proposed. The simulator is capable to provide VHF frequency-fixed signals, frequency-hopping signals, and spread spectrum signals. The detailed technical designs of key modules are presented, and so are their engineering implementation methods. Applying results demonstrate its capability of producing realistic communication signals as well as promising prospect of engineering applications.

This paper presents a bi-mode, high performance Discrete Wavelet Transform-based image compression core for future spacecrafts and micro-satellites. The hardware solution proposed here exploits an optimized CCSDS IDC algorithm and consists of a lossless mode and a lossly mode. The throughput of the core is improved 40 times using parallel architecture and pipeline technique, and a data rate of about 12.5M pixles/s can be sustained at 50MHz for the lossly mode. The experimental results indicate that this core has high performance at coding efficiency, data rate and error containment for both of the two modes.

A novel antenna is proposed in this article, which has simple structure, high gain, wide-band, omni direction and small physical size characteristics. Through optimized design, the maximum gain in omnidirectional plane is 5.0dB, the 3dB beam width in the normal plane ≥40°, the absolute VSWR band width of this antenna is 22.2GHz, and the relative VSWR band width is about 73% (VSWR<2), so the antenna can cover the K/Ka band. Because of the merits of the high gain and wide band, this antenna is not just used in the satellite communication, but also in the other domain such as the mobile communication.

This paper proposes a parallel computing method of multi-thread technology replacing the former serial-execution one according to the analysis of the radar imaging, the processing flow of NCS algorithm and the characteristic of multiprocessor and multi-core system, considering of the hard demand of high speed in imaging of raw spaceborne SAR data. A multi-thread program based on Linux and the pthread encapsulated is also provided. Through the experiments on HP Proliant DL580, it is proved that, compared with traditional serial NCS algorithm, the method of multi-thread presented in this paper makes use of system resource effectively and is good for parallel expansibility of imaging as well as achieving nice resolution.

Detecting dominant points is an important subject in pattern recognition and computer vision. The paper sums up the traditional corner detection methods based on Freeman codes and presents a new way to detect corner. Firstly, the points are classified using the differential code and the exact corners and uncertain corners are got. Then the curvature of the uncertain corners is calculated, and the points whose curvature is greater than the threshold are candidate corner. At last the right corners based on the Moving Line method is got. Experimental results show that the proposed method is superior to the conventional methods. Besides, the proposed method can be carried out more quickly.

With the continuous development of space technology, satellite technology is widely used in communications, earth observation, space remote sensing, meteorological observation, marine exploration, scientific research and other fields. Small satellites cause more and more people's attention because of its small size, light weight, good performance, reliability, short development cycle, and other characteristics. At the same time, attention has been paid to the development and application of this technology all over the world, particularly in the settlement of time and space coverage.

A robust control law using high-gain integral dynamic compensation is introduced for the slew maneuver control of a satellite with one mobile body. The movement of such a mobile body disturbs the satellite attitude and changes the inertia of the whole satellite significantly. The proposed method regards the model uncertainties and exogenous disturbances as unknown inputs to the plant and then a high-gain integrator together with a lead filter is used as an unknown input observer. The observed values are used to compensate the dynamic uncertainties. The unit quaternion is used to represent the orientation which allows overcoming problems arising from representation singularities. The kinematics of the quaternion and angular velocity have a standard form that the backstepping method is used and a Lyapunov candidate function is constructed. Under a certain frequency domain assumption, we can prove the boundedness of the states and the bounds can be designed to be arbitrarily small. Numerical simulation shows the effectiveness of the propsed controller.

This paper describes the design, construction and testing of a delay/Doppler-mapping receiver (DDMR) that was specially designed for gathering and processing Global Positioning System (GPS) reflected signals for earth remote sensing. The DDMR can process GPS L1-C/A signals received directly and after reflection, and compute complexvalued cross correlations of GPS L1-C/A reflected signals as well as navigation solutions acquired from direct signals in real time. The outputs of the DDMR can be used for altimetry applications, soil moisture measurement, ice characterization and ocean state retrieval, and other future applications. This paper presents the DDMR hardware architecture, signal processing issues and some preliminary experiment results.

GNSS reference station in well observation environment can provide stable, reliable and high-quality data for Continuously Operating Reference Station (CORS) Center. Reasonable CORS network can ensure the center software to operate efficiently and normally. It is introduced that how to design GNSS CORS Network and select reference station place. The Quality Checking of observation data with TEQ (Translation, Edit, Quality Checking) is introduced, which can provide an important criterion to judge station environment. The above methods are used to design the CORS Network and set station place in Changsha city of Hunan province.

GNSS carrier phase integer ambiguity resolution is the key for higher precision positioning and navigation. Due to more ambiguities with the multiple frequencies per system, the successful resolution of all ambiguities may not always be possible. However, a subset of the ambiguities can still be possible. In addition, resolving all ambiguities will increase the computational burden, and has slow convergence. In order to solve the problem, partial ambiguity fixing is applied to estimate the ambiguity in this paper. This paper first introduces the principle of ambiguity resolution and the concept of success rate. Then based on this background, the selection principle of an optimal subset is proposed and the algorithms are given. Simulation results show that, partial ambiguities by means of the presented method in this paper can be possible but full ambiguities can not. And resolving a subset of ambiguities can not only improve the ambiguity resolution performance and reliability but also reduce the convergent-time.

Based on the Sino-European cooperation in the Galileo satellite navigation system Search And Rescue(SAR) service, a multi-channel distress beacon signal simulator is presented here. The mathematic model and spectrum analysis of current 406 MHz distress beacons signals is presented which includes Emergency Position Indicating Radio Beacons (EPIRB) for Maritime, Personal Locator Beacons (PLB) for land (road and rail), and Emergency Locator Transmitter (ELT) for aeronautical applications. Based on Software Defined Radio (SDR) and digital IF techniques, the design of a SAR Signal Simulator (SAR-SS) is proposed, which can generate no less than 20 distress signals simultaneously. The Doppler shift and space propagation effect such as ionosphere delay, free space attenuation and etc, are simulated in SAR-SS, which provided a significant test and evaluation capability for SAR/Galileo project. The performance of SAR-SS is more accurate and stabile than the Cospas-Sarsat(C-S) requirement. SAR-SS will be a significant instrument for the Galileo system search and rescue project ground test.

New signal patterns and modulations are adopted in the modern GNSS and exhibit some innovative characteristics. Especially, the presence of two components - data and pilot in one composite signal is a significant feature and has provided breakthrough to improve the performance of the acquisition block. In this paper, two cooperative acquisition algorithms, namely non-coherent and coherent cooperation method, are improved and implemented in frequency domain, although the basic principle is from the literature. For each acquisition scheme, the detection probability and false alarm probability, which is known as the Receiver Operating Characteristic, are analyzed and compared based on the maximum search strategy from a statistical view. And then, theoretical results are demonstrated by Monte Carlo simulations with simplified Galileo E1 signals. The simulation results indicate the feasibility of algorithms and suggest that the coherent cooperation algorithm outperforms the non-coherent cooperation method in the effectiveness.

In order to acquire the weak signals of the GPS, the signal energy should be exploited as much as possible. A new civil signal L2C is available now. If we can use signals from one satellite but on different frequencies, the processing gain can be increased by combining the energy of the two signals. This paper researches on four different detection schemes utilizing combined legacy L1 C/A and new L2C signals in the acquisition process based on FFT method. Each of the four detection schemes based on the frequency and code delays relations of the two signals. Simulations are done to evaluate the performance of each detection scheme as well as the common non-coherent L1 C/A acquisition only. Advantages of the combined methods are obvious. Especially, we adopted a comparing NCH method, and a distinctive and attractive performance is achieved.

In this paper, taking GPS and Galileo signals for examples, we analyzed the compatibility of these two GNSS systems' signals. Spectral separation coefficient (SSC) is an important compatibility factor. Utilizing the simulation tools, we build a generation model of GPS/Galileo signals, and analyze the performance of the signal. Meanwhile, we calculate the SSC and quantization the effect of different transmitted power. Some simulation results are shown in the form of graphics and tables. What we are interested in are the signals from different systems at the same center frequency. Thus, we just take L1 (E1) into account. After that, we can easily use the model to complete other signals' simulations.

Chinese VLBI Network has been successfully applied for the tracking of the earth satellite Tance-1, the lunar satellites Smart-1 and Chang'E-1. However, in the case that the orbit of the satellite has the large predicted errors, the correlator model will not be precise enough that the tracking system can not produce good fringes and VLBI observables. Based on the blind fringe-searching results by taking advantages of satellite telemetry signals, we developed an algorithm to predict correlator model parameters. In the process of model parameters prediction, the model delay polynomials are calculated from the predicted orbit, followed by the comparisons with delays obtained from the blind fringe-searching results. The delayed differences which vary much slower and smaller than the model delay is then used to form the observation equation, and finally the correction of the model parameters are predicted with the least square method. The algorithm has been implemented in the software of correlation sub-system, which worked smoothly and successfully in the real time VLBI tracking of Chang'E-1 satellite.

Aiming the disposition of the Reference stations of SBAS(Satellite-Based Augmentattion System), on the basis of basic function of SBAS, two basic constraint requiremnts for the disposition of the Reference stations in China is proposed and analysed. These requirements are the geometry distribution for the calculation of the ephemeris error corrections and satellite clock error corrections; the geometric distribution of adequate available ionospheric grid points. On the Basis of these requirements and a existing ground network: Chinese Crust Deformation montoring network(CCDMN),the simulation analysis is conducted. The results illustrate that this dispositon of reference stations can meet the requirements with some complements. Thus, this scheme can be feasible for the construction of the SBAS in China.

The algorithm of multi-path signals restraining of BD Receiver based on cepstral are studied. The multi-path signals generating are firstly introduced, then the methods of multi-path signals processing based on cepstral are discussed, finally computer simulations are used to validate.

Autonomous orbit determination of navigation constellation based on cross-link range is studied in this paper. Considering the characteristics of near-circular orbits of navigation satellites and onboard computing ability, a set of nonsingular orbital elements are selected as state variables. Since the state variables are slow variables on the whole, maximum integration step used in the proposed algorithm, it can expand to 60 minutes, which is much longer than that of other methods. Meanwhile, instead of solving high-order variable coefficient linear differential equations using numerical method, the state transition matrix can directly refer to the result of analytical method. These two improved aspects can reduce the calculation burden of onboard computers obviously. And then the improved extended Kalman filter (EKF) is utilized to estimate the satellite position and velocity vectors of the constellation by fusing cross-link range data and satellite orbital dynamic information. Simulation results show that the proposed algorithm is feasible to improve the calculation efficiency while the orbit determination accuracy is satisfied, which is very important for realtime onboard data processing.

Long-term autonomous orbit determination is one of the key techniques of autonomous navigation for navigation constellation. Based only on cross-link range observation, which is not able to overcome the defect of entire constellation rotation and translation relative to inertial reference frame, the accuracy of autonomous orbit determination is reduced with time. In order to solve this problem, the approach of using inter-satellite orientation observation is put forward to estimate the constellation rotation and translation with the benefit of absolute position information provided by stars. In view of the fact that most navigation satellites moving in near circular orbits, and also in order to reduce the calculation burden of onboard computer, nonsingular orbital elements are chosen as state variables and analytical method is used to calculate the transition matrix in this paper. In addition, the extended Kalman filter is designed to fuse information of satellite dynamic model, cross-link range observation and inter-satellite orientation observation to determine the orbit. The simulation results based on the IGS Final Products of GPS constellation indicate that, at the certain error condition of range and orientation measurement, the URE of constellation is better than 2 meters within 120 days.

The exterior profile of a baffle is very important in an optical system. A design method of the baffle is presented, featuring the convenience, simplicity and quantification. Based on this design method, the equation of the sectional curve of baffle is given for conveniently fabricating the baffle; and the design dimensions of the baffle is minimized without any obstruction of light, which can considerably improve the control effect of the stray light directly entering into the imaging beam path.

BOC signal structure was introduced in this paper. BOC signal modulation and BOC(1,1) auto-correlation function were analyzed in detail. Based on the signal acquisition, tracking loop for BOC(1,1), a hardware design with FPGA chip was presented for the correlator, implemented using EP2S60 from Altera Co. The hardware correlator architecture and functions were described with two key modules, i.e. Pseudo-Random Noise (PRN) code generator and Numerical Control Oscillator(NCO). The practical test results show that the designed hardware correlator can work steadily and correctly, which is valid for the BOC(1,1) signal acquisition and tracking.

In recent years, with the development of satellite observation technologies, more and more active remote sensing technologies are adopted in spaceborne system. The spaceborne precipitation radar will depend heavily on high performance digital processing to collect meaningful rain echo data. It will increase the complexity of the spaceborne system and need high-performance and reliable digital receiver. This paper analyzes the frequency aliasing in the intermediate frequency signal sampling of digital down conversion in spaceborne radar, and gives an effective digital filter. By analysis and calculation, we choose reasonable parameters of the half-band filters to suppress the frequency aliasing on DDC. Compared with traditional filter, the FPGA resources cost in our system are reduced by over 50%. This can effectively reduce the complexity in the spaceborne digital receiver and improve the reliability of system.

Autonomous integrated navigation algorithm based on the GPS navigation system-assisted is studied aiming at the condition that the inertial navigation system error is gradually increased with the expansion of reckoning time. The inertial device mathematical model of random drift and inertial navigation system error equation are established through the analysis of the inertial properties of the system error sources. The filter of the inertial/GPS navigation is designed, which realizes the drift compensation of the inertial device. The valid arithmetic of the integrated navigation system and practicable technical case are proved through simulation. The research provides theoretical principles and practicable references to the realization of the satellite precision navigation.

The artificial satellite autonomous celestial navigation often uses starlight angular distance observed method. The perturbation terms beside the 2nd zonal harmonic of the non-spherical earth gravity(J2) are regarded as white noise. Aimed at the problem and in order to improve the model's precision, a new Autonomous Celestial Navigation Method Based on unscented Kalman filter (UKF) and Model Predictive Filter (MPF) is proposed. It takes advantages of both MPF and UKF. The advantages of the new algorithm include: the model error is assumed unknown and is estimated as part of the solution, the model error is not limited to Gaussian noise characteristics, and the algorithm can be implemented on-line to both filter noisy measurements and estimate state trajectories.

A new automatic fixed-point landing algorithm for UAV using the instantaneous speed obtained by image sensors and computer vision method is proposed. In the proposed scheme, once the specified land pad for landing is captured, the UAV will switch from auto-seeking mode to landing mode. In the landing mode, the feature point of the prospective zone is extracted and then being tracked. The noise in the motion parameter introduced by the feature point mismatching is reduced by fast iterative least square algorithm, and the accurate instantaneous speed of UAV is obtained. The simulation results show that the proposed algorithm efficiently improve the accuracy of the estimation of instantaneous velocity for the fixed-point landing system of UAV.

The paper presents two novel methods for compensation part of an Image Navigation and Registration System (INR). Relatively geometric projection method is applied to compensate the long-term deviations caused by the excursion of orbit. It transforms the view into the body frame of satellite and uses algebraic calculation instead of the trigonometric functions. The new method avoids the repetitious calculations of trigonometric function, and can clearly show the geometric relationships among satellites, optical vectors, and deviation of optical axis. Argument rotation algorithm is applied to compensate the short-term deviations cause by the change of attitude. It is realized by a multiplicative rotation model which describes rotation of rigid frame to a spin axis. The new algorithm discards the constrained equations and singular problems, directly shows the geometric images of spinning processes, and may useful to error estimation of compensation. Both methods are demonstrated by computer simulations to be effective and decrease the amount of calculation.

To solve the problem of traditional amplifiers that high unity-gain bandwidth is obtained in exchange of big-power, a low power wide band-width folded-cascode fully differential amplifier with cascode current-mirrors load is designed based on Smic0.18 um rf CMOS technology. Transitional capacitor and Miller capacitor are applied to enhance the stability of frequency-characteristic; Common-mode feedback circuit is added to stabilize the common-mode output voltage of differential structure; Test results show, with the power supply of 1.8V, the circuit has an open-loop gain of 76.07dB, a phase margin of 50.6°, a unity-gain bandwidth of 215.7MHz and a CMRR of 120dB, while consuming 1.75mW of power.

This paper investigates into the performance of sampling rate on time discrimination of PRN code in GNSS, proposes an innovative performance evaluation criterion for actual time discrimination of noncommensurate sampling technique, and then develops an algorithm to quickly obtain this criterion. Computer simulation verification guarantees the correctness of the proposed fast algorithm. The proposed algorithm can be adopted in all PRN code ranging based applications to choose the "better" sampling rate, which could achieve better time discrimination performance with lower sampling rate.

In this paper, a novel architecture of the correlator used for high dynamic satellite receivers is proposed. With this architecture, the correlator consists of several acquiring-tracking channels and a quick acquiring-assistant channel. Every acquiring-tracking channel can be used for acquiring and tracking an individual satellite. Moreover, with the quick acquiring-assistant channel, it can quickly acquire a satellite signal, and then track the satellite signal independently. The correlator is used to acquire and track GPS signals. The experiment results show that the correlator can incorporate with microprocessor to realize the function of acquiring and tracking GPS signal quickly and reliably. The results also demonstrate that the architecture of the correlator can be adopted in high dynamic satellite receivers.

GPS based spacecraft attitude autonomous determination technology is researched, and a Lyapunov stability theory based attitude control law with strong adaptivity and robustness is presented in the paper. A new strategy of spacecraft attitude autonomous determination technology is researched, which aligns two groups of baselines on the spacecraft. One group called short baselines resolves integer ambiguity since it's shorter than half of the carrier wave. The other group called long baselines is used to make up the shortages of shorter baseline based attitude determination precision. Adaptive and sliding mode variable structure controller with the stronger adaptability and robustness is designed considering uncertainty of inertia moment of spacecraft and outer disturbance torque. In the control process, an online uncertainty estimator corrects the parameters of sliding mode variable structure controller based on the adaptive law. Finally, numerical simulation about the integrated attitude closed loop composed of determination system and control system is executed on some section of spacecraft's orbit. The results of simulation sustain the effectiveness of the attitude determination and control algorithm presented in the paper.

Autonomous landing spacecraft precisely to selected zone is rather important for planetary exploration. This paper describes a vision aided inertial navigation scheme to meet the requirement of autonomous pinpoint planetary landing. Landmarks and opportunistic features are detected and tracked autonomously to revise the error of inertial navigation. The image coordinates of landmarks and features derived from navigation camera and the measurements of inertial measurement unit are integrated with extended Kalman flter to estimate the pose of spacecraft and opportunistic features' position in inertial reference frame. Numeric simulation demonstrates the validity of the proposed navigation scheme.

In order to meet the requirements of Location-based Service (LBS), there are many proposed positioning solutions that may be able to provide LBS support, such as GPS, Mobile Phone Location, RFID, and so on. With the most widely recognized system being the Global Positioning System (GPS) and Windows Mobile 5.0 system characteristics, this paper first provides three kinds method, i.e. invoking Win32 API, using Ports namespace and calling GPS Intermediate Driver, to receive GPS raw data on Windows Mobile devices. Since internet-based GPS VRS RTK workstation can provide real-time streaming of differential GPS corrections. The following text introduces a high precision Net-based RTK (NRTK) mobile positioning solution which is mainly equipped with a Windows Mobile 5.0 device and an Ashtech Z-Xtreme receiver. With it a rover-side (NtripClient) firstly connects to an NtripCaster which is a part of a VRS workstation, via GPRS /CDMA, using the IP and specified listening Port of the Tongji VRS workstation. Then the rover-side transmits NMEA GGA strings after the HTTP request to the NtripCaster. With that the Windows Mobile device continuously receives RTCM data back from the NtripCaster and instantly sends them out into the Ashtech Z-Xtreme receiver. Finally, the Ashtech Z-Xtreme receiver will work out vector solution information of the rover-side. Thus, this paper provides a multimode mobile LBS positioning solution based on NRTK and Windows Mobile 5.0.

Based on the analyses for the characteristics of high precise GPS deformation monitor, according to the spatial relationship among the satellites, base points and monitoring points, and using the carrier phases as the basic observations, and using the precise baseline vectors obtained in the first period observations between the base point and monitoring point as the initial condition, the new similar single-difference mathematical model and its corresponding algorithm are advanced to solve the monitor point deformation information at single epoch.This model or methodology is abbreviated to SSDM. The main error sources that effect the accuracy of deformation information solved by SSDM are discussed. In order to improve the correctness, reliability and stability of the deformation information series solved by the SSDM model, Kalman filtering algorithm is established. According to the SSDM theory, the GPS Deformation Monitor Information Quick Resolution Software, abbreviated to GQuickS, is developed successfully.The test results, solved by the SSDM theory and GQuickS, show that the resolution accuracy can reach ±2∼plusmn;3mm in horizontal component, and ±4∼±6mm in vertical component.

In broadband satellite system providing high-speed multimedia services, it is important to efficiently assign wireless resources according to the user's demands and dynamically take into account the variations of the propagation conditions especially for satellite system operating above 10 GHz. In this paper, a "smart" broadband satellite system was proposed. The system can automatically reconfigurate the transponders according to the channel and traffic states by SDR and adaptive coding and modulation (ACM) technology. By doing so, the system available capacity can be maximized and time-variant (here we call it elastic) while maintaining the QoS. This smart satellite system with elastic capacity can largely improve the spectrum utilization efficiency and better compete with other broadband system in the new century.

To acquire high quality image, the new generation Geostationary Meteorological Satellite in China (GMSC) adopts three-axis stabilized attitude control mode, besides an advanced control system is required to be designed to get higher pointing precision and degree of stability of the satellite. However, the ability of the control system is limited. Torque compensation technology is studied in this paper aiming at rejecting the disturbance factors, which cannot be absorbed by the control system. In the research of torque compensation technology, the main factors that influence the degree of stability of satellite are analyzed; the objects compensated are confirmed through analysis of simulation; the system technical concept of torque compensation is designed; the mathematical models of the compensated objects and compensation devices are founded; the torque compensation arithmetic is designed; the valid arithmetic of torque compensation is proved through simulation. The research provides theoretical principles to develop the new generation GMSC.

As the most advanced rateless fountain codes, Systematic Raptor codes has been adopted by the 3GPP standard as a forward error correction scheme in Multimedia Broadcast/Multicast Services (MBMS). It has been shown to be an efficient channel coding technique which guarantees high symbol diversity in overlay networks. The 3GPP standard outlined a time-efficient maximum-likelihood (ML) decoding scheme that can be implemented using Gaussian elimination. But when the number of encoding symbols grows large, Gaussian elimination need to deal with a large matrix with O (K³) binary arithmetic operations, so the larger K becomes, the worse ML decoding scheme performs. This paper presents a better time-efficient encoding and decoding scheme while maintaining the same symbol recoverable performance, this encoding and decoding scheme is named Rapid Raptor Code. It will be shown that the proposed Rapid Raptor code Scheme significantly improves traditional Raptor codes' efficiency while maintaining the same performance.

This paper briefly discusses the mathematical models, force models and methods of AOD (autonomous orbit determination) of navigation satellites, which are based on the least square collocation method using both cross-link ranging observations and prior information given. A variety of simulations are processed with the software developed by ourselves in this paper, and the results indicate that the method of AOD adopted in this paper can not only solve the rank deficiency problem successfully, but also achieve the equivalent precision to broadcast ephemeris.Meanwhile,the influence of the measurement noise in cross-link ranging and the quality of prior information to the precision of AOD is analyzed, and the necessity of considering tide perturbation in precise AOD is brought forward.

Virtual Method, proved to be great useful in manufacture, is now used in satellite thermal vacuum test. In this paper the configuration of the Spacecraft virtual thermal platform and the model building method are described and the results of a kind of paraboloid antenna virtual thermal tests is present. Spacecraft virtual thermal test platform (VTTP), which is validated to be feasible by the research in this paper, is built to shorten the research period of spacecraft and to reduce its cost. Now VTTP is used to calculate the temperature distribution of an antenna, and it is expected to be used in a whole satellite thermal test.

In the internetworking world, switches and routers have been deployed for workgroup and enterprise connectivity. In the past, switches mainly operated at Layer 2 (they were extensions of bridges), while routers were clearly Layer3 devices. Recently, the line has blurred and switches operating at Layer 3 are becoming more popular. This paper explains the Linux Bridge, Layer 2 Switches, Virtual LAN (VLAN) and Layer 3 Switches. The flow chart of Layer 3 switches and working routine related to Layer 3 switch technology were investigated in detail. This paper presents a new method to implement layer 3 switching that is entirely accomplished in software and is embedded implemented by code transplanting based on PowerPC 460GT platform.

Infrared lamp array is applied as absorbed heat flux of south and north surface OSR in the thermal balance test of communication satellite Sinosat-2. In thermal balance test, the accuracy of heat flux simulation is one of the key technologies. This paper will introduce the heat flux simulation technology.The uniformity degree is 7.8% for the 90% area of north lamp array above. Meanwhile, the uniformity degree is 7.9% for the 90% area of south lamp array below, which satisfy the requirement of test. Monitored Background Radiometer is used to actually measure the amount of energy absorbed by the N/S OSR surface. The method designed in this work satisfies the requirement of test, which simulates the external heat flux by infrared lamp array.

Considering autonomous and AD-HOC networking of AFF, such as topology, multiple access mode, integrated mode of inter-satellite communication and measurements, and data transfer protocol, are presented and studied in this paper. Inter-satellite non-coherence spread spectrum ranging via full-duplex asynchronous communication link of CCSDS Proximity-1 transfer frame is deeply researched, and Sufficient simulation and engineering experiments are implemented and plenty of results are obtained, which show that the integrated mode of intra-satellite communication and measurement achieves excellent precision, integrates multiple functions in one device with more effective utilization ratio of channel in radio link. The production of principles and technologies in this dissertation has many academic and engineering values, can be used in many fields in the future.

When space vehicles reentry atmosphere at hypersonic speed, a plasma sheath enveloping the spacecraft forms. The plasma sheath is a medium which is frequency dependent and lossy, so reflection and attenuation will happen when radio signals transport through the plasma sheath. In this paper, Finite Difference Time Domain using Z-transform method(ZT-FDTD) is used to analyze the problem. At first, Maxwell equations are transformed to make the expression independent of the medium properties, thus, the same equations can be used in different frequency dependent mediums, this technology achieves the feature of code portability. Then the ZT-FDTD method is extended to the three-dimensional space, by comparing the sectional drawing of the result in 3D with that in 1D to make sure of the correctness of the simulation in 3D, and then the method is used to study the scattering characteristics of objects in different situations in 3D. Finally we compare and give the analysis of different situations.

High speed communication buses are necessary for satellites and spacecrafts. In this paper, traditional buses such as FDDI, ISO 8802-4, and some new techniques, such as SFODB, RPR and AFDX.are briefly introduced. The comparisons between these buses are discussed. The topology, cable and characters of these protocols are analyzed. And from the comparison, it can be seen that SFODB, AFDX and RPR may be good candidates for the new generation of spacecraft buses in the future.

A station with limited motion antenna is usually used for the on-orbit control of a geostationary satellite. In order to enhance the capability of running a satellite, it is important to improve the orbit determination accuracy of the singlestation system. This paper presents a method for the orbit determination accuracy improvement with tracking and ranging data from a single station. This method includes two steps. The first step is improving antenna tracking accuracy by optimizing step tracking algorithm. Using big antennas or selecting mono-pulse tracking devices were paid more attention to improve tracking accuracy, which played an important role to reach good orbit determination accuracy in an orbit measurement campaign of a single station. While the influence of the antenna control unit software on orbit determination accuracy was neglected. This paper puts forward that the reformed tracking algorithm of the antenna control unit brings big improvement on tracking accuracy, which is derived from the comparison of orbit measurement results before and after software updating. The second step is to optimize the parameter settings of the orbit determination software. Reasonable weighted values are needed for orbit determination when using tracking and ranging data with different accuracies. Setting the weighted values according to their residual results of the orbit determination can utilize the measurement data with high precision sufficiently. The principal of 4σ should be adopted in eliminating limit setting of measurement data, which can make more than 99.98% data available. The orbit determination accuracy can be improved remarkably through the above method. For example, the orbit determination accuracy of a single station with a 13m limited motion antenna can achieve three-sigma position accuracy within 2km.

In this paper, the non-dominated sorting genetic algorithm II (NSGA-II) based on the concept of Pareto optimal is improved. A new algorithm with lower O(MNlogN) computational complexity to construct non-dominated set replaces the NSGA-II original fast non-dominated sorting algorithm with O(MN2) com-putational complexity. The new algorithm improves operating efficiency of NSGA-II significantly. Based on the combination of the improved NSGA-II algorithm and regional navigation satellite constellation design, a new idea to design regional navigation satellite constellation is proposed in this paper. The new idea is implemented by Satellite Tool Kits (STK) and Matlab: the improved NSGA-II algorithm is implemented by Matlab and the calculation of the objective function values is implemented by STK. STK/Connect interface is used to integrate STK and Matlab into one simulation. Simulation results show that new idea has some advantages over the traditional methods, being more efficient, more flexible and more comprehensive.

In Optical System such as Multi-Channel off-axis Three-Mirror Optical System with Large Field and Small F Number, beam-split is the most important factor of the optical system design. The traditional compensating method for splitter is using tilt plate and lenses. This compensating method requires long distance between the splitter and the focal plane. On the other hand, too many lenses using in this method will reduce the transmission efficiency of the optical system. The compensating lenses have optical-power, so we must modify the focal length of primary optical system, and then we have to rectify the other channels to make up the changing of the focal length in this channel. In Optical System such as Multi-Channel off-axis Three-Mirror Optical System, the distance between the splitter and the focal plane array is short, usually we don't have enough distance to place the tilted plate and lenses. So in those systems, the enough spatial distance for multi-channel beam-split is the bottleneck for the system design. For the cryogenic optical system, the compensating lenses have difficulty to work in so much different temperature. This paper advanced a new kind of compensating method for splitter, and it is an off-axis spherical lens which has falcate shape (the curvature of the two surface is approximately the same) and with no optical power. It not only can compensate the aberration of the system, and it is rather small in size, so it is propitious to the multichannel beam-split in the Multi-Channel off-axis Three-Mirror Optical System.

The Precipitation Radar (PR) on board the Meteorology Satellite is an active remote sensing radar to measure precipitation from space. The PR, operating at dual frequency, still under study, is designed to be an active phased array that allows a fast and sophisticated cross-track scanning. In order to confirm that PR functions properly and meets the performance requirements to quantitatively measure three-dimensional precipitation distribution from space, especially the feasibility and applicability of our waveform, the simulation of PR's receiving echoes is strongly required. In this paper, a space-based meteorological particle distribution model, which can mostly reflect the truly distribution of the particle's size distribution, is built. Then we calculate the phase variance of PR echo caused by particle's movement. At the end of this paper, we estimate the surface clutter interference through antenna side lobes, assuming a surface scattering model and a realistic antenna pattern for a phased array antenna.

The requirements of the space remote sensor for weather observation, ocean observation, disaster prediction, resource exploration and environment detection in China are researched and concluded. Based on the status of the earth observation system, considering the development layout of the Chinese space disaster observation system, the prediction of the Chinese space disaster observation system some suggestions are proposed.

OFDM is a new focused technology in satellite communication. This paper proposed a novel OFDM based on-board switching technology which has high spectrum efficiency and adaptability and supports the integration of terrestrial wireless communication systems and satellite communication systems. Then it introduced a realization scheme of this technology, and proposed the main problems to be solved and the relevant solutions of them.

Following the great success of satellite application and aerospace engineering,China has formally startedup moon exploration project,in the future China will execute exploration of more remote object.In this paper, combining the development step of Chinese deep space exploration, the author introduces the current situation of deep exploration techniques home and abroad, meanwhile the author briefly compares the advantage and disadvantage of spread-spectrum deep exploration system and USB deep exploration system, and the author also briefly describes the important status of intending spread-spectrum deep exploration system in the area of deep space exploration. According to the characteristic of deep space exploration, this paper analyzes the problem and key techniques such as spread-spectrum measurement system of remote space orbit, reception of the weak signal and high efficient coding and decoding, super large aperture antenna and antenna array combination technique, high power control amplifier technique, insulating of transmitting and receiving signals applied in deep space exploration,at the same time,the author proposes evolution suggestion of spread-spectrum exploration technique applied in deep space exploration. Meanwhile,through combining the current situation of spread-spectrum exploration system home and abroad,the author analyzes a few key techniques of spread-spectrum exploration system applied in deep space exploration.

In order to match the flexible requirements of GNSS receiver design, the solution of developing such a universal platform has grown in importance. In this light, this paper introduces a work for the realization of an experimental FPGA&DSP-based GNSS receiver platform, which is according to the Software Defined Radio (SDR) philosophy. Starting from the justification for the hardware devices selected, this paper firstly describes the whole structure. Then the design of base band channel based on FPGA is presented. This includes the design of an individual base band channel and the design of local code generation. The realization of signal acquisition and tracking in DSP is introduced. Finally a signal tracking experiment is introduced, which justified the platform's availability.

The Singular Value Decomposition (SVD) method is introduced to denoise the ECG signal during spaceflight. The theory base of SVD method is given briefly. The denoising process of the strategy is presented combining a segment of real ECG signal. We improve the algorithm of calculating Singular Value Ratio (SVR) spectrum, and propose a constructive approach of analysis characteristic patterns. We reproduce the ECG signal very well and compress the noise effectively. The SVD method is proved to be suitable for denoising the ECG signal.

Geomagnetic storms have a good correlation with solar activity and solar radiation variability. Many proton events and Geomagnetic storms have occurred during solar cycles21, 22, and 23. The solar activities during the last three cycles, gave us a good indication of the climatic change and its behavior during the 21st century. High energetic eruptive flares were recorded during the decline phase of the last three solar cycles. The appearances of the second peak on the decline phase of solar cycles have been detected. Halloween storms during Nov. 2003 and its effects on the geomagnetic storms have been studied analytically. The data of amplitude and phase of most common indicators of geomagnetic activities during solar cycle 23 have been analyzed.

One of the most popular N-body models that has been under investigation in the last ten years, is the so-called ring problem of (N+1) bodies, otherwise known as the regular polygon problem of (N+1) bodies. Here we present an overview of the scientific work that has been done throughout these years as well as the major results obtained so far. An extended bibliography is displayed at the end of this article, aiming to become a source of information for further analytical study.

The remote synchronization system for the onboard crystal oscillator (RESSOX) of the quasi-zenith satellite system (QZSS) has been studied at AIST since 2003. RESSOX reduces the overall cost and satellite power consumption, the onboard weight and volume, and has a longer lifetime than a system with an onboard atomic time standard. The targets of our research are synchronization to within 10 ns between the ground station time standard and the onboard QZSS crystal oscillators and stability better than 1×1013 at 100,000 s. RESSOX has been developed in four stages: (1) arrangement of hardware simulators and feasibility study, (2) QZSS experiment preparation, (3) RESSOX algorithm development, and (4) space experiments using geostationary satellites. After launch in 2010, one more stage will be added: (5) demonstration of RESSOX using QZSS. The achievements in the first four stages and a plan of the final stage will be summarized.

The paper addresses the means for gathering energy from sunlight in space and transmitting it to Earth via Solar Power Satellites. The motivating factor is that the output of our sun is the largest potential energy source available, with the capability of providing inexhaustible quantities of clean electrical energy to every location on Earth. The challenge is that considerable financial, intellectual and diplomatic resources must be focused on designing and implementing new types of energy infrastructures in space and on the ground. These include: 1) next-generation space platforms, arrays, and power transmission systems; 2) more flexible and powerful launch vehicles for delivering materials to space; 3) specialized receivers, converters and storage systems on earth, and the in-orbit position allocations, spectrum and software that make these systems work together efficiently and safely.

Space-based solar power (SSP) generation is being touted as a solution to our ever-increasing energy consumption and dependence on fossil fuels. Satellites in Earth's orbit can capture solar energy through photovoltaic cells and transmit that power to ground based stations. Solar cells in orbit are not hindered by weather, clouds, or night. The energy generated by this process is clean and pollution-free. Although the concept of space-based solar power was initially proposed nearly 40 years ago, the level of technology in photovoltaics, power transmission, materials, and efficient satellite design has finally reached a level of maturity that makes solar power from space a feasible prospect. Furthermore, new strategies in methods for solar energy acquisition and transmission can lead to simplifications in design, reductions in cost and reduced risk. This paper proposes using a distributed array of small satellites to collect power from the Sun, as compared to the more traditional SSP design that consists of one monolithic satellite. This concept mitigates some of SSP's most troublesome historic constraints, such as the requirement for heavy lift launch vehicles and the need for significant assembly in space. Instead, a larger number of smaller satellites designed to collect solar energy are launched independently. A high frequency beam will be used to aggregate collected power into a series of transmission antennas, which beam the energy to Earth's surface at a lower frequency. Due to the smaller power expectations of each satellite and the relatively short distance of travel from low earth orbit, such satellites can be designed with smaller arrays. The inter-satellite rectenna devices can also be smaller and lighter in weight. Our paper suggests how SSP satellites can be designed small enough to fit within ESPA standards and therefore use rideshare to achieve orbit. Alternatively, larger versions could be launched on Falcon 9s or on Falcon 1s with booster stages. The only satellites that are constrained to a significant mass are the beam-down satellites, which still require significant transmission arrays to sufficiently focus the beams targeting corresponding ground stations. With robust design and inherent redundancy built-in, power generation and transmission will not be interrupted in the event of mishaps like space debris collision. Furthermore, the "plug and play" nature of this system significantly reduces the cost, complexity, and risk of upgrading the system. The distributed nature of smallsat clusters maximizes the use of economies of scale. This approach retains some problems of older designs and introduces additional ones. Mitigations will be explored further. For example, the distributed nature of the system requires very precise coordination between and among satellites and a mature attitude control and determination system. Such a design incorporates multiple beaming stages, which has the potential to reduce overall system efficiency. Although this design eliminates the need for space assembly, it retains the challenge of significant on-orbit deployment of solar and transmission arrays. Space power "beaming" is a three step process that involves: 1) conversion of dc power generated by solar cells on the satellite into an electromagnetic wave of suitable frequency, 2) transmission of that wave to power stations on ground, and 3) conversion of the radio waves back into dc power. A great deal of research has been done on the use of microwaves for this purpose. Various factors that affect efficient power generation and transmission will be analyzed in this paper. Based on relevant theory and performance and optimization models, the paper proposes solutions that will help make space-based solar power generation a practical and viable option for addressing the world's growing energy needs.

System engineering aspects, like concurrent engineering (CE) in the aerospace sector, has been studied by many authors. The change and evolution in this regard is continually influenced by the information technology advances. But global cooperation is only discussed by developed countries and high technology corporations. A review of CE and its ramifications in the aerospace industry is presented. Based on the current literature, the general lifecycle of a spacecraft and its phases are explained as well as the tools that are implemented in today's industry. In this paper we propose a new approach for the product development process in the spacecraft production industry the Aerospace Concurrent Engineering (ACE), which is mainly focused in the technology itself, its optimal design and environment impact rather than costs and marketing impact. And the potential of globally oriented research and implementation of space programs is discussed for its consideration.

With the development of modern science and technology, outer space is stepping into our life, work and other areas, which attracts more and more people's attention on spatial resources. However, it is difficult for an unspecialized person to know much professional knowledge, such as astronautics about the space. In this paper, we have developed a spatial situation simulation system based on STK, which has integrated the complex field environment associated with the land, sea, air, space and electronic scenarios by an easier understanding way. The design and implementation of the spatial situation simulation system will benefit people to research and develop the outer space by providing a dynamic simulation platform and abundant data resources.

A novel fault diagnosis method based on the combination of offline identification and online observing is proposed in this paper, which can meet the requirement of both model complexity and real-time need for the satellite attitude control system. Accurate neural network models, both normal mode and faulty mode, can be obtained by off-line identification based on the data of fault simulation in different fault modes. With a parallel estimator derived from all models With all, fault determination based on threshold logic is designed for online fault detecting and isolating. Real-time simulation results, on the embedded fault simulation platform of satellite attitude control system, illustrate the effectiveness and superiority.

This paper introduces the technical feature of a former developed MDO (Multidisciplinary Design Optimization) architecture for spacecraft design, which is called Spacecraft Distributed Design Environment (SDIDE). SDIDE is an interactive spacecraft design system based on distributed network computing environment. It applies MDO in the whole lifecycle of spacecraft design, and makes nearly all kinds of system-level and discipline-level analysis tools work collaboratively. SDIDE uses a flexible bus scheme based on Common Object Request Broker Architecture (CORBA) to improve the integration and efficiency. The paper takes the structural optimization of the Tsinghua University "NS-1" small satellite as an example to illustrate the usage of the software system of SDIDE in assisting the overall design of satellite. The result of calculation shows that the software system can effectively decrease the cost of developing a satellite system and improve the overall performance of the satellite, accordingly proving the practicality and feasibility of the SDIDE architecture into the design process of a spacecraft.

In order to simulate the process of control and instruction transmitting to switch the work mode of the precipitation radar (PR), as well as receive and store the measured data of the PR, an integrated software is required to implement the 1553B bus communication and to unpack, retransmit, and display of the Consultative Committee for Space Data Systems (CCSDS) telemetry data packet. In this paper, the communication between the simulation equipment and the PR is integrated. Data receiving, procession and storing are measured in the program environment of VB. On the view of practical application, such as measured data's re-loading, analyzing and displaying in the form of graphics after experiment, program's automatic run and control under the circumstance of log-time work or harsh working environment, the integrated program develops two special sub-softwares to meet the above needs.

Due to the flexible ability, research on software GPS receiver is now attracting more and more attention. In order to evaluate a software GPS receiver's performance, there are two way to provide GPS signal. One is to use a set of real GPS signal measurements collected by a commercial front-end. The other way is to use software GPS signal simulator to generate digitized IF GPS signal. This paper develops a software-based IF GPS signal simulator for the L1 C/A code signal. The design principles, implementation factors, and verification are described in this paper. Firstly, a mathematical signal model is developed, which includes various error source, such as satellite clock error, ionosphere error, and troposphere error. Then one channel structure of IF GPS signal simulator represented one satellite is given. How to simulate the main modules in this structure is introduced. As the key point of IF GPS signal simulator, two iterative algorithms are introduced. Finally the simulator is verified by using a software GPS receiver.