Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931513
Jennifer C. Davis, Jerry X. Tu, Sean P. Byme James, Lisowski, SciTec
We describe a method for estimating sea surface temperature (SST) using MWIR band data from the AVHRR polar orbiter. Currently, SST is routinely calculated with a split-window, nonlinear multichannel algorithm incorporating data from AVHRR Channels 4 and 5 (10.3-11.3 and 11.5-12.5 /spl mu/m, respectively). The accuracy of these results is dependent to a certain degree upon regional variations and is inherently limited by the spatial resolution of the measurements. Nevertheless, these SST maps are generally considered reliable, and are widely used for studying ocean currents and their effect on weather patterns. We are interested, however, in testing the feasibility of using MWIR data in the absence of LWIR measurements for estimating SST both at night, when reflected solar radiance is not an issue, as well as during the day, when it is. A MWIR SST algorithm of the type we discuss would be using data, for example, from a satellite without LWIR capabilities in order to calculate a parameter that is ancillary to the satellite mission (but which is nevertheless of high interest). The SST algorithms we describe are based upon the comparison of MODTRAN ocean radiance values, at a variety of surface temperatures and calculated over the aforementioned AVHRR bands, to the values of the collected pixels in these bands. These MODTRAN calculations are scene-specific, as viewing angle and atmospheric conditions are important input parameters. MODTRAN is therefore launched from within the main SST program architecture for a range of different temperatures. The results of such calculations could conceivably be implemented, however, as a look-up table for a grid of LZAs, standard atmospheres and temperatures. Before the temperature of the pixels can be assessed, the scene must be screened for clouds, which tend to lower the temperature estimation for contaminated pixels. We accomplish this screening using our CloudDI algorithm, a modified least squares template-matching approach. Finally, we test the validity of our results against the AVHRR SST algorithms as well as against available ground truth. Since the MODTRAN calculations require sensor geometry and atmospheric conditions as input parameters, it is possible, in theory, to correct for the effect of high levels of water vapor on the SST results in certain situations.
{"title":"Estimation of sea surface temperature using the AVHRR mid-wave IR band","authors":"Jennifer C. Davis, Jerry X. Tu, Sean P. Byme James, Lisowski, SciTec","doi":"10.1109/AERO.2001.931513","DOIUrl":"https://doi.org/10.1109/AERO.2001.931513","url":null,"abstract":"We describe a method for estimating sea surface temperature (SST) using MWIR band data from the AVHRR polar orbiter. Currently, SST is routinely calculated with a split-window, nonlinear multichannel algorithm incorporating data from AVHRR Channels 4 and 5 (10.3-11.3 and 11.5-12.5 /spl mu/m, respectively). The accuracy of these results is dependent to a certain degree upon regional variations and is inherently limited by the spatial resolution of the measurements. Nevertheless, these SST maps are generally considered reliable, and are widely used for studying ocean currents and their effect on weather patterns. We are interested, however, in testing the feasibility of using MWIR data in the absence of LWIR measurements for estimating SST both at night, when reflected solar radiance is not an issue, as well as during the day, when it is. A MWIR SST algorithm of the type we discuss would be using data, for example, from a satellite without LWIR capabilities in order to calculate a parameter that is ancillary to the satellite mission (but which is nevertheless of high interest). The SST algorithms we describe are based upon the comparison of MODTRAN ocean radiance values, at a variety of surface temperatures and calculated over the aforementioned AVHRR bands, to the values of the collected pixels in these bands. These MODTRAN calculations are scene-specific, as viewing angle and atmospheric conditions are important input parameters. MODTRAN is therefore launched from within the main SST program architecture for a range of different temperatures. The results of such calculations could conceivably be implemented, however, as a look-up table for a grid of LZAs, standard atmospheres and temperatures. Before the temperature of the pixels can be assessed, the scene must be screened for clouds, which tend to lower the temperature estimation for contaminated pixels. We accomplish this screening using our CloudDI algorithm, a modified least squares template-matching approach. Finally, we test the validity of our results against the AVHRR SST algorithms as well as against available ground truth. Since the MODTRAN calculations require sensor geometry and atmospheric conditions as input parameters, it is possible, in theory, to correct for the effect of high levels of water vapor on the SST results in certain situations.","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":"124962077","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.2001.931198
S. Barr, A. Mehta
With smaller and smaller Printed Wiring Board (PWB) form factors, such as CompactPCI/sup (R)/, the need for smaller packages with high I/Os has grown significantly. A Jet Propulsion Laboratory/NASA technology and system development program that services various spacecraft missions uses a 3U CompactPC/sup (R)/ form factor. The System Input/Output board requires a large amount of I/Os and has limited area, so conventional packages, such as quad flat packs (QFP) will not fit. Thus, the use of Ball Grid Arrays (BGAs) with much smaller package dimensions than leaded packages were needed to meet area requirements and were evaluated for space flight applications. Since this type of package has not been used in past space flight environments, it was necessary to determine the robustness and reliability of the solder joints. The D-BGAs were qualified by developing assembly, inspection and rework techniques as well as environmental tests. The test article was a printed wiring assembly (PWA) consisting of four daisy chained D-BGA packages. Visual inspection of the outer solder joints and real time X-ray were used to verify solder quality prior to testing. The test article was electrically monitored for shorts and opens at or above 1 /spl mu/s during all environmental tests. Three environmental tests were conducted: random vibration at 0.2 g/sup 2//Hz, pyre shock at 2000 g for 50 ms, and thermal cycling from -55/spl deg/C to 100/spl deg/C for 200 cycles. After testing, Scanning Electron Microscope (SEM) analysis was performed on various DBGA cross sections to determine the quality of the package-to-board interface. The 472 D-BGA solder attachments passed the above environmental tests meeting the minimum requirements for use on space flight electronics.
{"title":"Dimpled ball grid array qualification testing for space flight applications","authors":"S. Barr, A. Mehta","doi":"10.1109/AERO.2001.931198","DOIUrl":"https://doi.org/10.1109/AERO.2001.931198","url":null,"abstract":"With smaller and smaller Printed Wiring Board (PWB) form factors, such as CompactPCI/sup (R)/, the need for smaller packages with high I/Os has grown significantly. A Jet Propulsion Laboratory/NASA technology and system development program that services various spacecraft missions uses a 3U CompactPC/sup (R)/ form factor. The System Input/Output board requires a large amount of I/Os and has limited area, so conventional packages, such as quad flat packs (QFP) will not fit. Thus, the use of Ball Grid Arrays (BGAs) with much smaller package dimensions than leaded packages were needed to meet area requirements and were evaluated for space flight applications. Since this type of package has not been used in past space flight environments, it was necessary to determine the robustness and reliability of the solder joints. The D-BGAs were qualified by developing assembly, inspection and rework techniques as well as environmental tests. The test article was a printed wiring assembly (PWA) consisting of four daisy chained D-BGA packages. Visual inspection of the outer solder joints and real time X-ray were used to verify solder quality prior to testing. The test article was electrically monitored for shorts and opens at or above 1 /spl mu/s during all environmental tests. Three environmental tests were conducted: random vibration at 0.2 g/sup 2//Hz, pyre shock at 2000 g for 50 ms, and thermal cycling from -55/spl deg/C to 100/spl deg/C for 200 cycles. After testing, Scanning Electron Microscope (SEM) analysis was performed on various DBGA cross sections to determine the quality of the package-to-board interface. The 472 D-BGA solder attachments passed the above environmental tests meeting the minimum requirements for use on space flight electronics.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"107 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":"128030886","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.2001.931225
J. Miyano
The engine air-start test program was carried out as one of the flight tests for the XF-2, Japanese next generation support fighter. The objective of the program was to demonstrate the aircraft's capability to recover from in-flight engine shutdown. The XF-2 being a single engine aircraft, this is one of major requirements to the aircraft. The planning and results of the tests are described. Tests were planned with emphasis on the safe execution because the engine is shut down during the flight tests. In all air-start conditions tested the air-start succeeded without exceeding the criteria; the time to ignition, the time to thrust recovery and the maximum exhaust gas temperature, and it was confirmed that the aircraft is capable to recover from in-flight engine shutdown.
{"title":"The engine air-start test of XF-2","authors":"J. Miyano","doi":"10.1109/AERO.2001.931225","DOIUrl":"https://doi.org/10.1109/AERO.2001.931225","url":null,"abstract":"The engine air-start test program was carried out as one of the flight tests for the XF-2, Japanese next generation support fighter. The objective of the program was to demonstrate the aircraft's capability to recover from in-flight engine shutdown. The XF-2 being a single engine aircraft, this is one of major requirements to the aircraft. The planning and results of the tests are described. Tests were planned with emphasis on the safe execution because the engine is shut down during the flight tests. In all air-start conditions tested the air-start succeeded without exceeding the criteria; the time to ignition, the time to thrust recovery and the maximum exhaust gas temperature, and it was confirmed that the aircraft is capable to recover from in-flight engine shutdown.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"6 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":"131141007","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.2001.931245
R. Mackey
This paper outlines the mathematical foundation for a general method of anomaly detection from time-correlated sensor data. This method is a component of BEAM, but as an individual algorithm is capable of fault detection and partial classification. The method is applicable to a broad class of problems and is designed to respond to any departure from normal operation, including faults or events that lie outside the training envelope. We will also consider training of the detector and interface to a larger diagnostic system. Lastly we examine a brief illustration taken from aircraft testing that demonstrates the power and versatility of this method.
{"title":"Generalized cross-signal anomaly detection on aircraft hydraulic system","authors":"R. Mackey","doi":"10.1109/AERO.2001.931245","DOIUrl":"https://doi.org/10.1109/AERO.2001.931245","url":null,"abstract":"This paper outlines the mathematical foundation for a general method of anomaly detection from time-correlated sensor data. This method is a component of BEAM, but as an individual algorithm is capable of fault detection and partial classification. The method is applicable to a broad class of problems and is designed to respond to any departure from normal operation, including faults or events that lie outside the training envelope. We will also consider training of the detector and interface to a larger diagnostic system. Lastly we examine a brief illustration taken from aircraft testing that demonstrates the power and versatility of this method.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"40 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":"131263285","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.2001.931172
Marcel L. Hernandez
This paper is concerned with the development of a general framework for the management of multiple sensors in tracking a single target. To achieve this aim we draw on concepts from data fusion, particle filtering and heuristic optimization. Previous work gave the multi-sensor fusion management algorithm which provided a rigid scheme under which sensors were placed to maximize the probability of detecting the target. We present an adaptation to this scheme in which sensor placements are chosen to minimize a measure of uncertainty in the target position. We demonstrate the algorithm in an anti-submarine warfare scenario in which we use passive sonobuoys to generate bearings and frequency (Doppler) data, We show that the quality of the track increases dramatically with the combined use of the two data sources and that the new sensor management algorithm further improves the track, and uses significantly fewer sensors in the process.
{"title":"Efficient data fusion for multi-sensor management","authors":"Marcel L. Hernandez","doi":"10.1109/AERO.2001.931172","DOIUrl":"https://doi.org/10.1109/AERO.2001.931172","url":null,"abstract":"This paper is concerned with the development of a general framework for the management of multiple sensors in tracking a single target. To achieve this aim we draw on concepts from data fusion, particle filtering and heuristic optimization. Previous work gave the multi-sensor fusion management algorithm which provided a rigid scheme under which sensors were placed to maximize the probability of detecting the target. We present an adaptation to this scheme in which sensor placements are chosen to minimize a measure of uncertainty in the target position. We demonstrate the algorithm in an anti-submarine warfare scenario in which we use passive sonobuoys to generate bearings and frequency (Doppler) data, We show that the quality of the track increases dramatically with the combined use of the two data sources and that the new sensor management algorithm further improves the track, and uses significantly fewer sensors in the process.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"36 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":"127795245","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.2001.931361
M. Braasch
As the Global Positioning System (GPS) has matured over the last decade, expectations regarding system performance have grown steadily. This has placed pressure on receiver manufacturers and system providers to be ever more creative in their efforts to mitigate error sources. Historically, multipath has been the dominant error source in differential GPS (DGPS). However, with the recent decision to deactivate Selective Availability, multipath has become a significant error source for all GPS users. In 1991, the narrow correlator was introduced to the market and was shown to reduce multipath errors by as much as 90% over conventional receivers. Over the past several years, a number of multipath-mitigation techniques have been developed and promoted. This paper explores the theory behind each technique and provides a performance comparison. The inherent assumptions and limitations of each technique are discussed as well.
{"title":"Performance comparison of multipath mitigating receiver architectures","authors":"M. Braasch","doi":"10.1109/AERO.2001.931361","DOIUrl":"https://doi.org/10.1109/AERO.2001.931361","url":null,"abstract":"As the Global Positioning System (GPS) has matured over the last decade, expectations regarding system performance have grown steadily. This has placed pressure on receiver manufacturers and system providers to be ever more creative in their efforts to mitigate error sources. Historically, multipath has been the dominant error source in differential GPS (DGPS). However, with the recent decision to deactivate Selective Availability, multipath has become a significant error source for all GPS users. In 1991, the narrow correlator was introduced to the market and was shown to reduce multipath errors by as much as 90% over conventional receivers. Over the past several years, a number of multipath-mitigation techniques have been developed and promoted. This paper explores the theory behind each technique and provides a performance comparison. The inherent assumptions and limitations of each technique are discussed as well.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"25 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":"133051161","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.2001.931502
E. Njoku, Yunjin Kim, M. Spencer, W. Tsai, Y. Rahmat-Samii, M. Thomson
An L-band radiometer-radar concept has been studied for spaceborne remote sensing of land surface soil moisture, freeze-thaw state, and ocean surface salinity. The integrated design provides simultaneous passive and active measurements with potential for enhanced geophysical retrieval accuracy and spatial resolution. The design takes advantage of cost savings achievable using shared subsystems and hardware. The baseline system concept has been evaluated to determine the feasibility of the technical approach and as a point of departure for system trade-offs. The unique features of this concept are the integration of the radiometer and radar sensors, the use of a deployable-mesh conically scanned reflector antenna, and the use of unfocused synthetic aperture radar (SAR) processing. Taken together, these features represent a significant departure from conventional radiometer, scatterometer, and SAR approaches. The conical wide-swath scan is a desirable feature that provides constant incidence angle and antenna pattern characteristics across the swath, simplified data processing (passive and active), and frequent global sampling. The concept is targeted for a low-cost, short-development-cycle mission, suitable for NASA's Earth System Science Pathfinder (ESSP) series.
{"title":"A spaceborne L-band radiometer-radar concept for land and ocean surface monitoring","authors":"E. Njoku, Yunjin Kim, M. Spencer, W. Tsai, Y. Rahmat-Samii, M. Thomson","doi":"10.1109/AERO.2001.931502","DOIUrl":"https://doi.org/10.1109/AERO.2001.931502","url":null,"abstract":"An L-band radiometer-radar concept has been studied for spaceborne remote sensing of land surface soil moisture, freeze-thaw state, and ocean surface salinity. The integrated design provides simultaneous passive and active measurements with potential for enhanced geophysical retrieval accuracy and spatial resolution. The design takes advantage of cost savings achievable using shared subsystems and hardware. The baseline system concept has been evaluated to determine the feasibility of the technical approach and as a point of departure for system trade-offs. The unique features of this concept are the integration of the radiometer and radar sensors, the use of a deployable-mesh conically scanned reflector antenna, and the use of unfocused synthetic aperture radar (SAR) processing. Taken together, these features represent a significant departure from conventional radiometer, scatterometer, and SAR approaches. The conical wide-swath scan is a desirable feature that provides constant incidence angle and antenna pattern characteristics across the swath, simplified data processing (passive and active), and frequent global sampling. The concept is targeted for a low-cost, short-development-cycle mission, suitable for NASA's Earth System Science Pathfinder (ESSP) series.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"34 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":"124425808","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.2001.931186
H. Kaakani
Deep submicron Silicon on Insulator (SOI) technology advancements at Honeywell have enabled new generations of radiation hard memory products. This paper covers plans and results of our SOI technology development programs for SRAM products and giant magneto resistive (GMR) non-volatile memory.
{"title":"Radiation hardened memory development at Honeywell","authors":"H. Kaakani","doi":"10.1109/AERO.2001.931186","DOIUrl":"https://doi.org/10.1109/AERO.2001.931186","url":null,"abstract":"Deep submicron Silicon on Insulator (SOI) technology advancements at Honeywell have enabled new generations of radiation hard memory products. This paper covers plans and results of our SOI technology development programs for SRAM products and giant magneto resistive (GMR) non-volatile memory.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"7 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":"134509735","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.2001.931511
R. Popp, H. Maney, J. Jones
The focus of this paper is to describe several recent applications of multi-platform ground moving target indicator (GMTI) tracking technology for surveillance and reconnaissance coalition environments. As part of the U.S. Air Force's 1999 Joint Expeditionary Force experiment (JEFX), we demonstrated (in stand-alone mode) GMTI tracking technology for a simulated ground target scenario consisting of 20,000+ military and civilian ground vehicles and GMTI sensor data based on multiple U.S. and coalition radar simulators (i.e., U.S. Joint STARS and Global Hawk, U.K. ASTOR, French HORIZON, Italy CRESO). As part of NATO's Joint Project Optic Windmill (JPOW) V/Clean Hunter 2000 (CN00), we demonstrated the real-time operation of GMTI tracking technology in a live military coalition exercise environment. Two such systems were supported at JPOW V/CN00: (i) an on-board system consisting of the GMTI tracker ported to a DEC ALPHA on the Navy's P3 APY-6 platform, and used by operators to track ground targets based on GMTI data produced by the APY-6 radar system alone, and (ii) an off-board system consisting of the GMTI tracker ported to a Sun Quad Ultra 80 at NATO HQ AIRNORTH at Ramstein AFB Germany, and used to track ground targets based on real GMTI data produced by both the P3 APY-6 and the French HORIZON. In addition, simulated GMTI data from the JSTARS, Global Hawk, and ASTOR radar simulators was also produced and tracked based on a simulated ground target scenario consisting of 30,000+ military and civilian ground vehicles.
{"title":"Multi-platform GMTI tracking for surveillance and reconnaissance coalition environments","authors":"R. Popp, H. Maney, J. Jones","doi":"10.1109/AERO.2001.931511","DOIUrl":"https://doi.org/10.1109/AERO.2001.931511","url":null,"abstract":"The focus of this paper is to describe several recent applications of multi-platform ground moving target indicator (GMTI) tracking technology for surveillance and reconnaissance coalition environments. As part of the U.S. Air Force's 1999 Joint Expeditionary Force experiment (JEFX), we demonstrated (in stand-alone mode) GMTI tracking technology for a simulated ground target scenario consisting of 20,000+ military and civilian ground vehicles and GMTI sensor data based on multiple U.S. and coalition radar simulators (i.e., U.S. Joint STARS and Global Hawk, U.K. ASTOR, French HORIZON, Italy CRESO). As part of NATO's Joint Project Optic Windmill (JPOW) V/Clean Hunter 2000 (CN00), we demonstrated the real-time operation of GMTI tracking technology in a live military coalition exercise environment. Two such systems were supported at JPOW V/CN00: (i) an on-board system consisting of the GMTI tracker ported to a DEC ALPHA on the Navy's P3 APY-6 platform, and used by operators to track ground targets based on GMTI data produced by the APY-6 radar system alone, and (ii) an off-board system consisting of the GMTI tracker ported to a Sun Quad Ultra 80 at NATO HQ AIRNORTH at Ramstein AFB Germany, and used to track ground targets based on real GMTI data produced by both the P3 APY-6 and the French HORIZON. In addition, simulated GMTI data from the JSTARS, Global Hawk, and ASTOR radar simulators was also produced and tracked based on a simulated ground target scenario consisting of 30,000+ military and civilian ground vehicles.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"475 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":"133472223","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.2001.931262
C. Jenkins, J. Ash, D. Marker
One of the great enabling technologies for 21st Century space science missions will be gossamer spacecraft. Since resolution is proportional to diameter at the diffraction limit, larger antennas and optic apertures mean greater opportunities for increasing scientific knowledge. Due to finite launch vehicle capacity (launch mass and volume), these large (>12 m) apertures must also be ultra-low mass. This implies some sort of membrane/ inflatable structure. The current paper discusses the effects of local defects on reflector performance. Unlike classical glass optics for example, membrane apertures cannot be ground and polished to precision tolerances. The manufacturing process must account for minimum thresholds of surface smoothness and mechanical property irregularities. For example, sufficient numbers of small regions of thickness or Young's modulus irregularities can lead to unacceptable surface error. This paper reports on analysis of such local defects on the surface precision of gossamer apertures. A nonlinear finite element code is used to model the effect of single and multiple defects in curved membranes. Two measures of performance are used. First, we compute the deviation of the local slope for a given defect geometry and property irregularity. Secondly, we compute the spatial influence function of the defect both on the neighboring uniform membrane, as well as on nearby like defects. Indications of manufacturing tolerances required to achieve minimum acceptable performance are discussed.
{"title":"Local defect study of membrane antennas and reflectors","authors":"C. Jenkins, J. Ash, D. Marker","doi":"10.1109/AERO.2001.931262","DOIUrl":"https://doi.org/10.1109/AERO.2001.931262","url":null,"abstract":"One of the great enabling technologies for 21st Century space science missions will be gossamer spacecraft. Since resolution is proportional to diameter at the diffraction limit, larger antennas and optic apertures mean greater opportunities for increasing scientific knowledge. Due to finite launch vehicle capacity (launch mass and volume), these large (>12 m) apertures must also be ultra-low mass. This implies some sort of membrane/ inflatable structure. The current paper discusses the effects of local defects on reflector performance. Unlike classical glass optics for example, membrane apertures cannot be ground and polished to precision tolerances. The manufacturing process must account for minimum thresholds of surface smoothness and mechanical property irregularities. For example, sufficient numbers of small regions of thickness or Young's modulus irregularities can lead to unacceptable surface error. This paper reports on analysis of such local defects on the surface precision of gossamer apertures. A nonlinear finite element code is used to model the effect of single and multiple defects in curved membranes. Two measures of performance are used. First, we compute the deviation of the local slope for a given defect geometry and property irregularity. Secondly, we compute the spatial influence function of the defect both on the neighboring uniform membrane, as well as on nearby like defects. Indications of manufacturing tolerances required to achieve minimum acceptable performance are discussed.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"444 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":"133659871","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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