Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931201
A. Tai, L. Alkalai, S. Chau
The goal of the guarded software upgrading (GSU) framework is to minimize mission performance loss due to onboard software upgrading activities and that due to system failure caused by residual faults in an upgraded version. We exploit inherent system resource redundancies as the means of fault tolerance to meet the development cost and onboard resource constraints. Furthermore, we devise a message-driven confidence-driven protocol to facilitate effective and efficient error containment and recovery.
{"title":"Onboard guarded software upgrading: motivation and framework","authors":"A. Tai, L. Alkalai, S. Chau","doi":"10.1109/AERO.2001.931201","DOIUrl":"https://doi.org/10.1109/AERO.2001.931201","url":null,"abstract":"The goal of the guarded software upgrading (GSU) framework is to minimize mission performance loss due to onboard software upgrading activities and that due to system failure caused by residual faults in an upgraded version. We exploit inherent system resource redundancies as the means of fault tolerance to meet the development cost and onboard resource constraints. Furthermore, we devise a message-driven confidence-driven protocol to facilitate effective and efficient error containment and recovery.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129027389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931178
R. Hammett
Spacecraft utilize complex digital electronic controls to perform their missions. Although these systems have benefited from the availability of ever-faster computers and miniaturized electronics, overall control system architectures have changed little, utilizing a shared, centralized computer programmed to service many subsystems. These centralized systems perform well, but are a challenge to design and integrate, requiring complex custom software, custom I/O electronics and extensive vehicle wiring. The availability of microprocessors, memories and serial data terminals small and rugged enough to be embedded directly into subsystem mechanical components has opened the door to revolutionary new distributed architectures. These so-called "smart" or intelligent components can be interconnected into a network to form a distributed architecture. This paper discusses work done to define these distributed architectures and to construct prototype components. Important issues addressed include the physical network required to distribute data and power to components, highly reliable, fault-tolerant operation, the importance of industry standards and a discussion of packaging and installation considerations.
{"title":"Networking intelligent components to create intelligent spacecraft","authors":"R. Hammett","doi":"10.1109/AERO.2001.931178","DOIUrl":"https://doi.org/10.1109/AERO.2001.931178","url":null,"abstract":"Spacecraft utilize complex digital electronic controls to perform their missions. Although these systems have benefited from the availability of ever-faster computers and miniaturized electronics, overall control system architectures have changed little, utilizing a shared, centralized computer programmed to service many subsystems. These centralized systems perform well, but are a challenge to design and integrate, requiring complex custom software, custom I/O electronics and extensive vehicle wiring. The availability of microprocessors, memories and serial data terminals small and rugged enough to be embedded directly into subsystem mechanical components has opened the door to revolutionary new distributed architectures. These so-called \"smart\" or intelligent components can be interconnected into a network to form a distributed architecture. This paper discusses work done to define these distributed architectures and to construct prototype components. Important issues addressed include the physical network required to distribute data and power to components, highly reliable, fault-tolerant operation, the importance of industry standards and a discussion of packaging and installation considerations.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126198849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931739
T. Hoffman, C. Guiar
This paper describes some of the processes employed by the X2000/IFDP system engineering team to manage risk. This paper will describe the difficult system engineering task undertaken by the X2000/IFDP team of trying to develop a technology rich avionics system for a divergent interplanetary mission set. The ability to balance the risks inherent in technology development against the tight requirements of interplanetary missions was the job of the system engineering team. This job posed a unique set of challenges for the team requiring that new processes be developed. Many of the successful processes employed by the X2000/IFDP System Engineering team will be discussed in detail. The bottom line of each of the processes involved early and deep involvement by each of the affected subsystems. This allowed the system design issues to be worked in sufficient detail that the requirements and associated risks could be clearly identified.
{"title":"X2000/IFDP system engineering process for risk management","authors":"T. Hoffman, C. Guiar","doi":"10.1109/AERO.2001.931739","DOIUrl":"https://doi.org/10.1109/AERO.2001.931739","url":null,"abstract":"This paper describes some of the processes employed by the X2000/IFDP system engineering team to manage risk. This paper will describe the difficult system engineering task undertaken by the X2000/IFDP team of trying to develop a technology rich avionics system for a divergent interplanetary mission set. The ability to balance the risks inherent in technology development against the tight requirements of interplanetary missions was the job of the system engineering team. This job posed a unique set of challenges for the team requiring that new processes be developed. Many of the successful processes employed by the X2000/IFDP System Engineering team will be discussed in detail. The bottom line of each of the processes involved early and deep involvement by each of the affected subsystems. This allowed the system design issues to be worked in sufficient detail that the requirements and associated risks could be clearly identified.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127574002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931219
J. Powell, G. Maise, J. Paniagua, J. Rather
StarTram is a revolutionary concept for low-cost, high volume Earth-to-Orbit transport of passengers and/or cargo. StarTram is an evacuated launch tube that is magnetically levitated above the Earth's surface, up to a maximum altitude of /spl sim/18 km above the local terrain. Although the concept is advanced, it is within the limits of existing technology. The launch tube is levitated by the magnetic repulsive force between a set of superconducting (SC) cables attached to the tube and a set of SC cables on the ground beneath. A total current of 14 mega-amps in the levitated cables and an oppositely directed current of 280 mega-amps in the ground cables, produces a repulsive force of 4 tonnes/m at an altitude of 22 km above sea level (18 km above local ground level). These forces levitate a robust 7 meter diameter launch tube with an adequate margin of safety. The launch tube is stabilized, both vertically and horizontally, against the net upwards magnetic force and wind forces, by an array of high tensile strength (e.g., Kevlar) tethers that are anchored to the ground. Traveling inside the launch tube is a reusable StarTram Space Vehicle (SSV) that is magnetically levitated and accelerated to near orbital velocity in an evacuated tunnel at ground level. The SSV carries a set of lightweight SC magnets that inductively interact with a guideway of simple normal aluminum loops that operate at ambient temperature to stably levitate the moving vehicle. A separate AC current winding in the guideway pushes on the SSV's SC magnets, accelerating it. After the SSV reaches 8 km/sec at the end of its 1280 km long acceleration tunnel, it transitions into the ascending, magnetically levitated 220 km long launch tube, in which it coasts upwards to the launch point at an altitude of /spl sim/22 km The SSV then enters the upper atmosphere at a launch angle of 5 degrees. A subsequent 0.34 km/sec /spl Delta/V burn by a conventional LOX-kerosine rocket engine on the SSV inserts it into orbit. For a high-traffic system, StarTram can deliver payloads into orbit at a projected cost of $30 per kilogram This includes amortization of the launch complex, vehicle, and energy costs.
{"title":"StarTram: a new approach for low-cost Earth-to-orbit transport","authors":"J. Powell, G. Maise, J. Paniagua, J. Rather","doi":"10.1109/AERO.2001.931219","DOIUrl":"https://doi.org/10.1109/AERO.2001.931219","url":null,"abstract":"StarTram is a revolutionary concept for low-cost, high volume Earth-to-Orbit transport of passengers and/or cargo. StarTram is an evacuated launch tube that is magnetically levitated above the Earth's surface, up to a maximum altitude of /spl sim/18 km above the local terrain. Although the concept is advanced, it is within the limits of existing technology. The launch tube is levitated by the magnetic repulsive force between a set of superconducting (SC) cables attached to the tube and a set of SC cables on the ground beneath. A total current of 14 mega-amps in the levitated cables and an oppositely directed current of 280 mega-amps in the ground cables, produces a repulsive force of 4 tonnes/m at an altitude of 22 km above sea level (18 km above local ground level). These forces levitate a robust 7 meter diameter launch tube with an adequate margin of safety. The launch tube is stabilized, both vertically and horizontally, against the net upwards magnetic force and wind forces, by an array of high tensile strength (e.g., Kevlar) tethers that are anchored to the ground. Traveling inside the launch tube is a reusable StarTram Space Vehicle (SSV) that is magnetically levitated and accelerated to near orbital velocity in an evacuated tunnel at ground level. The SSV carries a set of lightweight SC magnets that inductively interact with a guideway of simple normal aluminum loops that operate at ambient temperature to stably levitate the moving vehicle. A separate AC current winding in the guideway pushes on the SSV's SC magnets, accelerating it. After the SSV reaches 8 km/sec at the end of its 1280 km long acceleration tunnel, it transitions into the ascending, magnetically levitated 220 km long launch tube, in which it coasts upwards to the launch point at an altitude of /spl sim/22 km The SSV then enters the upper atmosphere at a launch angle of 5 degrees. A subsequent 0.34 km/sec /spl Delta/V burn by a conventional LOX-kerosine rocket engine on the SSV inserts it into orbit. For a high-traffic system, StarTram can deliver payloads into orbit at a projected cost of $30 per kilogram This includes amortization of the launch complex, vehicle, and energy costs.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122115506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931223
B. Kish, W. Gibboney, M. Veth, M. Morán
This paper presents development and testing results of the Computer Replacement Program (CRP) for the Joint Surveillance Target Attack Radar System (Joint STARS). Joint STARS, which consists of a modified Boeing 707-300 (E-8C) developed by Northrop Grumman and Common Ground Stations developed by Motorola, provides theater commanders near real-time surveillance and attack support information on moving and stationary targets. Diminishing manufacturing sources and an emphasis on life-cycle cost reduction required a modernization program that took maximum advantage of commercial equipment. The primary program objectives were maximizing marketplace support, reducing life-cycle costs and facilitating cyclic upgrades. CRP implemented this via a commercial off-the-shelf-based open architecture. The Computer Replacement Program met all its development objectives and will be fielded on the entire 15-aircraft Joint STARS fleet. Lessons learned included applying innovative acquisition processes in an open architecture, adapting to processes while under schedule pressure, ensuring early operational tester involvement, and estimating laboratory and ground testing in addition to flight-testing. The views expressed in this paper are those of the authors and do not represent views of the U.S. government or their contractors.
{"title":"The computer replacement program for the joint surveillance target attack radar system","authors":"B. Kish, W. Gibboney, M. Veth, M. Morán","doi":"10.1109/AERO.2001.931223","DOIUrl":"https://doi.org/10.1109/AERO.2001.931223","url":null,"abstract":"This paper presents development and testing results of the Computer Replacement Program (CRP) for the Joint Surveillance Target Attack Radar System (Joint STARS). Joint STARS, which consists of a modified Boeing 707-300 (E-8C) developed by Northrop Grumman and Common Ground Stations developed by Motorola, provides theater commanders near real-time surveillance and attack support information on moving and stationary targets. Diminishing manufacturing sources and an emphasis on life-cycle cost reduction required a modernization program that took maximum advantage of commercial equipment. The primary program objectives were maximizing marketplace support, reducing life-cycle costs and facilitating cyclic upgrades. CRP implemented this via a commercial off-the-shelf-based open architecture. The Computer Replacement Program met all its development objectives and will be fielded on the entire 15-aircraft Joint STARS fleet. Lessons learned included applying innovative acquisition processes in an open architecture, adapting to processes while under schedule pressure, ensuring early operational tester involvement, and estimating laboratory and ground testing in addition to flight-testing. The views expressed in this paper are those of the authors and do not represent views of the U.S. government or their contractors.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126365566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931207
Eunjeong Lee, Jang-Horng Yu, T. L. Wilson
We have constructed a superconductor-magnet momentum wheel, which is based on passive magnetic levitation and the flux pinning effect of high-temperature superconductivity. The high-temperature superconductor (HTS) flywheel has high angular momentum storage capacity because its drag torque is essentially velocity-independent and extremely small, enabling high-speed rotation. It has mass of 1.1 kg with an angular momentum capacity of 3.5 J sec. It occupies a volume of 12.7 cm in diameter and 5 cm in height. It operates within the restricted power budget of a micro satellite with a total power supply of 10 W only. It consumes less than 1 W for sustenance. While there exist momentum wheels comparable to ours in one respect, there is none better than ours in all respects of angular momentum storage, volume and low power consumption.
{"title":"High-temperature superconductor-magnet momentum wheel for micro satellite","authors":"Eunjeong Lee, Jang-Horng Yu, T. L. Wilson","doi":"10.1109/AERO.2001.931207","DOIUrl":"https://doi.org/10.1109/AERO.2001.931207","url":null,"abstract":"We have constructed a superconductor-magnet momentum wheel, which is based on passive magnetic levitation and the flux pinning effect of high-temperature superconductivity. The high-temperature superconductor (HTS) flywheel has high angular momentum storage capacity because its drag torque is essentially velocity-independent and extremely small, enabling high-speed rotation. It has mass of 1.1 kg with an angular momentum capacity of 3.5 J sec. It occupies a volume of 12.7 cm in diameter and 5 cm in height. It operates within the restricted power budget of a micro satellite with a total power supply of 10 W only. It consumes less than 1 W for sustenance. While there exist momentum wheels comparable to ours in one respect, there is none better than ours in all respects of angular momentum storage, volume and low power consumption.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"477 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123054364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931400
K. Cavanaugh
Qualtech Systems, Inc. (QSI) has developed an architecture that utilizes the existing TEAMS (Testability Engineering and Maintenance Systems) integrated tool set as the foundation to a computing environment for modeling and rigorous design analysis. This architecture is called a Virtual Test Bench (VTB) for Integrated Diagnostics. The VTB approach addresses design for testability, safety, and risk reduction because it provides an engineering environment to develop/provide: 1. Accurate, comprehensive, and graphical model based failure mode, effects and diagnostic analysis to understand failure modes, their propagation, effects, and ability of diagnostics to address these failure modes. 2. Optimization of diagnostic methods and test sequencing supporting the development of an effective mix of diagnostic methods. 3. Seamless integration from analysis, to run-time implementation, to maintenance process and life cycle support. undetected fault lists, ambiguity group lists, and optimized diagnostic trees. 4. A collaborative, widely distributed engineering environment to "ring-out" the design before it is built and flown. The VTB architecture offers an innovative solution in a COTS package for system/component modeling, design for safety, failure mode/effect analysis, testability engineering, and rigorous integration/testing of the IVHM (Integrated Vehicle Health Management) function with the rest of the vehicle. The VTB approach described in this paper will use the TEAMS software tool to generate detailed, accurate "failure" models of the design, assess the propagation of the failure mode effects, and determine the impact on safety, mission and support costs. It will generate FMECA, mission reliability assessments, incorporate the diagnostic and prognostic test designs, and perform testability analysis. Diagnostic functions of the VTB include fault detection and isolation metrics undetected fault lists, ambiguity group lists, and optimized diagnostic trees.
Qualtech Systems, Inc. (QSI)开发了一种架构，该架构利用现有的TEAMS(可测试性工程和维护系统)集成工具集作为建模和严格设计分析的计算环境的基础。这种架构被称为集成诊断的虚拟测试台(VTB)。VTB方法解决了可测试性、安全性和降低风险的设计，因为它提供了一个工程环境来开发/提供:准确，全面，基于图形模型的故障模式，影响和诊断分析，以了解故障模式，它们的传播，影响和诊断能力，以解决这些故障模式。2. 优化诊断方法和测试测序，支持开发有效的诊断方法组合。3.从分析到运行时实现，再到维护过程和生命周期支持的无缝集成。未检测到的故障列表、模糊组列表和优化的诊断树。4. 一个协作的，广泛分布的工程环境，在它被建造和飞行之前“完成”设计。VTB架构为系统/组件建模、安全设计、故障模式/影响分析、可测试性工程以及IVHM(集成车辆健康管理)功能与车辆其余部分的严格集成/测试提供了一个创新的COTS解决方案。本文描述的VTB方法将使用TEAMS软件工具生成详细、准确的设计“故障”模型，评估故障模式影响的传播，并确定对安全、任务和支持成本的影响。它将生成FMECA，任务可靠性评估，结合诊断和预测测试设计，并执行可测试性分析。VTB的诊断功能包括故障检测与隔离指标、未检出故障列表、模糊组列表、优化诊断树等。
{"title":"An integrated diagnostics virtual test bench for life cycle support","authors":"K. Cavanaugh","doi":"10.1109/AERO.2001.931400","DOIUrl":"https://doi.org/10.1109/AERO.2001.931400","url":null,"abstract":"Qualtech Systems, Inc. (QSI) has developed an architecture that utilizes the existing TEAMS (Testability Engineering and Maintenance Systems) integrated tool set as the foundation to a computing environment for modeling and rigorous design analysis. This architecture is called a Virtual Test Bench (VTB) for Integrated Diagnostics. The VTB approach addresses design for testability, safety, and risk reduction because it provides an engineering environment to develop/provide: 1. Accurate, comprehensive, and graphical model based failure mode, effects and diagnostic analysis to understand failure modes, their propagation, effects, and ability of diagnostics to address these failure modes. 2. Optimization of diagnostic methods and test sequencing supporting the development of an effective mix of diagnostic methods. 3. Seamless integration from analysis, to run-time implementation, to maintenance process and life cycle support. undetected fault lists, ambiguity group lists, and optimized diagnostic trees. 4. A collaborative, widely distributed engineering environment to \"ring-out\" the design before it is built and flown. The VTB architecture offers an innovative solution in a COTS package for system/component modeling, design for safety, failure mode/effect analysis, testability engineering, and rigorous integration/testing of the IVHM (Integrated Vehicle Health Management) function with the rest of the vehicle. The VTB approach described in this paper will use the TEAMS software tool to generate detailed, accurate \"failure\" models of the design, assess the propagation of the failure mode effects, and determine the impact on safety, mission and support costs. It will generate FMECA, mission reliability assessments, incorporate the diagnostic and prognostic test designs, and perform testability analysis. Diagnostic functions of the VTB include fault detection and isolation metrics undetected fault lists, ambiguity group lists, and optimized diagnostic trees.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129285096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931351
J.P. Choi, V. Chan
Efficiency improvements using prediction and adaptation methods over satellite channels with weather-induced impairments are presented. Considering scintillation and rain attenuation as two dominant factors for signal fading over satellite-Earth paths over 10 GHz, we develop statistical and spectral analyses of these processes, and obtain simple linear estimators for received signal attenuation using autoregressive (AR) models. Using these estimators, we present results where we can predict the received signal attenuation within /spl plusmn/0.5 dB 1 second ahead and within /spl plusmn/1.0 dB 4 seconds ahead. For adaptation, we change signal transmission power, modulation symbol size, and/or code rate adaptively. In particular, we introduce a continuous power control and discrete rate control strategy, through which we build a set of modulation/code states, and discretely change the modulation symbol size and the code rate from state to state. Within each state, continuous power contral is implemented. The quantitative analysis of power consumption indicates that there is a substantial gain in performance with the adaptive schemes, e.g., as much as 13 dB on a lightly rainy day.
{"title":"Prediction and adaptation of satellite channels with weather-induced impairments","authors":"J.P. Choi, V. Chan","doi":"10.1109/AERO.2001.931351","DOIUrl":"https://doi.org/10.1109/AERO.2001.931351","url":null,"abstract":"Efficiency improvements using prediction and adaptation methods over satellite channels with weather-induced impairments are presented. Considering scintillation and rain attenuation as two dominant factors for signal fading over satellite-Earth paths over 10 GHz, we develop statistical and spectral analyses of these processes, and obtain simple linear estimators for received signal attenuation using autoregressive (AR) models. Using these estimators, we present results where we can predict the received signal attenuation within /spl plusmn/0.5 dB 1 second ahead and within /spl plusmn/1.0 dB 4 seconds ahead. For adaptation, we change signal transmission power, modulation symbol size, and/or code rate adaptively. In particular, we introduce a continuous power control and discrete rate control strategy, through which we build a set of modulation/code states, and discretely change the modulation symbol size and the code rate from state to state. Within each state, continuous power contral is implemented. The quantitative analysis of power consumption indicates that there is a substantial gain in performance with the adaptive schemes, e.g., as much as 13 dB on a lightly rainy day.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127440495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931279
S. Horan, Ruhai Wang
The throughput results for file transfers using file sizes ranging from 1 Kbytes through 1 Mbytes using both the standard TCP/IP and SCPS protocol stacks over a PPP link are reported. Channel properties were simulated using a space channel simulator with a range of balanced and unbalanced link speeds and channel error rates. The throughput results show the effects of link configuration and channel error rate on file transfer time. The host computer configuration options for the protocols are factored into the comparison. The throughput reporting shows the effects of header compression and selection of congestion algorithm upon the results. The TCP/IP ftp and SCPS-FP using the VJ congestion control algorithm results give similar results and better results than SCPS-FP with the Vegas congestion control algorithm in these experiments. No noticeable delay effects were noted with links delays corresponding to GEO orbits with file transfers of 1 Mbytes.
{"title":"Internet-type protocol testing in a simulated small satellite environment","authors":"S. Horan, Ruhai Wang","doi":"10.1109/AERO.2001.931279","DOIUrl":"https://doi.org/10.1109/AERO.2001.931279","url":null,"abstract":"The throughput results for file transfers using file sizes ranging from 1 Kbytes through 1 Mbytes using both the standard TCP/IP and SCPS protocol stacks over a PPP link are reported. Channel properties were simulated using a space channel simulator with a range of balanced and unbalanced link speeds and channel error rates. The throughput results show the effects of link configuration and channel error rate on file transfer time. The host computer configuration options for the protocols are factored into the comparison. The throughput reporting shows the effects of header compression and selection of congestion algorithm upon the results. The TCP/IP ftp and SCPS-FP using the VJ congestion control algorithm results give similar results and better results than SCPS-FP with the Vegas congestion control algorithm in these experiments. No noticeable delay effects were noted with links delays corresponding to GEO orbits with file transfers of 1 Mbytes.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133153690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931388
C. Liebe, S. Mobasser
Sun sensors have been widely used as a part of spacecraft attitude determination subsystems to provide a measurement of the Sun vector in spacecraft coordinates. An experimental MEMS based Sun sensor is presented. This prototype sun sensor is comprised of a silicon wafer mask with several hundred small apertures placed on top of a CCD focal plane array at a distance of 750 /spl mu/m. An image of the apertures is formed on the focal plane when the sun illuminates this setup. Sun angles can be derived by analyzing the image. The experimental data presented indicates that this sun sensor can achieve accuracies on the order of a few arcminutes or better. It is projected that this type of sun sensor, utilizing an active pixel sensor focal plane array, will be the size of three dimes stacked on top of each other. It will have a mass of less than 30 g and consume less than 20 mW. This will make this type of sun sensor ideal for micro/nano spacecraft and small rovers.
{"title":"MEMS based Sun sensor","authors":"C. Liebe, S. Mobasser","doi":"10.1109/AERO.2001.931388","DOIUrl":"https://doi.org/10.1109/AERO.2001.931388","url":null,"abstract":"Sun sensors have been widely used as a part of spacecraft attitude determination subsystems to provide a measurement of the Sun vector in spacecraft coordinates. An experimental MEMS based Sun sensor is presented. This prototype sun sensor is comprised of a silicon wafer mask with several hundred small apertures placed on top of a CCD focal plane array at a distance of 750 /spl mu/m. An image of the apertures is formed on the focal plane when the sun illuminates this setup. Sun angles can be derived by analyzing the image. The experimental data presented indicates that this sun sensor can achieve accuracies on the order of a few arcminutes or better. It is projected that this type of sun sensor, utilizing an active pixel sensor focal plane array, will be the size of three dimes stacked on top of each other. It will have a mass of less than 30 g and consume less than 20 mW. This will make this type of sun sensor ideal for micro/nano spacecraft and small rovers.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131344848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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