Pub Date : 2001-03-10DOI: 10.1109/AERO.2001.931375
X. Zhang, L. Feinberg, D. Leisawitz, D. Leviton, A. Martino, J. Mather
We are developing a Wide-Field Imaging Interferometry Testbed (WIIT) in support of design studies for NASA's future space interferometry missions, in particular the SPIRIT and SPECS far-infrared/submillimeter interferometers. WIIT operates at optical wavelengths and uses Michelson beam combination to achieve both wide-field imaging and high-resolution spectroscopy. It will be used chiefly to test the feasibility of using a large-format detector array at the image plane of the sky to obtain wide-field interferometry images through mosaicing techniques. In this setup each detector pixel records interferograms corresponding to averaging a particular pointing range on the sky as the optical path length is scanned and as the baseline separation and orientation is varied. The final image is constructed through spatial and spectral Fourier transforms of the recorded interferograms for each pixel, followed by a mosaic/joint-deconvolution procedure of all the pixels. In this manner the image within the pointing range of each detector pixel is further resolved to an angular resolution corresponding to the maximum baseline separation for fringe measurements. We present the motivation for building the testbed, show the optical, mechanical, control and data system design, and describe the image processing requirements and algorithms. WITT is presently under construction at NASA's Goddard Space Flight Center.
{"title":"The wide-field imaging interferometry testbed","authors":"X. Zhang, L. Feinberg, D. Leisawitz, D. Leviton, A. Martino, J. Mather","doi":"10.1109/AERO.2001.931375","DOIUrl":"https://doi.org/10.1109/AERO.2001.931375","url":null,"abstract":"We are developing a Wide-Field Imaging Interferometry Testbed (WIIT) in support of design studies for NASA's future space interferometry missions, in particular the SPIRIT and SPECS far-infrared/submillimeter interferometers. WIIT operates at optical wavelengths and uses Michelson beam combination to achieve both wide-field imaging and high-resolution spectroscopy. It will be used chiefly to test the feasibility of using a large-format detector array at the image plane of the sky to obtain wide-field interferometry images through mosaicing techniques. In this setup each detector pixel records interferograms corresponding to averaging a particular pointing range on the sky as the optical path length is scanned and as the baseline separation and orientation is varied. The final image is constructed through spatial and spectral Fourier transforms of the recorded interferograms for each pixel, followed by a mosaic/joint-deconvolution procedure of all the pixels. In this manner the image within the pointing range of each detector pixel is further resolved to an angular resolution corresponding to the maximum baseline separation for fringe measurements. We present the motivation for building the testbed, show the optical, mechanical, control and data system design, and describe the image processing requirements and algorithms. WITT is presently under construction at NASA's Goddard Space Flight Center.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"49 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":"114815356","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.2001.931326
J. E. Land
This paper presents a comprehensive model of how military and commercial operators achieve benefits in Health and Usage Monitoring Systems (HUMS) equipped helicopters. The model uncovers the substantial set of the potential benefits and presents a framework that each operator can use as a tool to analyze particular benefits that are tuned to the operating environment for which HUMS is being used or being considered. The model presents real-life cases to show the benefits that can be achieved from operational HUMS systems and actual operational data and analysis. The paper examines HUMS as it affects potential roles and missions of helicopters, including commercial and military. Consideration is given to such issues as fleet readiness, management of spares assets, cost of M&O staff, and effects of aircraft downtime. The model includes all sources of costs for the HUMS, including the costs of equipment, installation costs, downtimes for installation, cost of support of the HUMS, etc. The model also looks into the perceived future operational environment, where the operator and the aircraft manufacturer are integrated into a real-time team to get the best performance from the deployed fleet. A major emphasis of the paper is the use of practical, real-life experience as a feedback into the HUMS system. The system includes equipment, operating procedures and personnel, integrated into a cohesive force.
{"title":"HUMS-the benefits-past, present and future","authors":"J. E. Land","doi":"10.1109/AERO.2001.931326","DOIUrl":"https://doi.org/10.1109/AERO.2001.931326","url":null,"abstract":"This paper presents a comprehensive model of how military and commercial operators achieve benefits in Health and Usage Monitoring Systems (HUMS) equipped helicopters. The model uncovers the substantial set of the potential benefits and presents a framework that each operator can use as a tool to analyze particular benefits that are tuned to the operating environment for which HUMS is being used or being considered. The model presents real-life cases to show the benefits that can be achieved from operational HUMS systems and actual operational data and analysis. The paper examines HUMS as it affects potential roles and missions of helicopters, including commercial and military. Consideration is given to such issues as fleet readiness, management of spares assets, cost of M&O staff, and effects of aircraft downtime. The model includes all sources of costs for the HUMS, including the costs of equipment, installation costs, downtimes for installation, cost of support of the HUMS, etc. The model also looks into the perceived future operational environment, where the operator and the aircraft manufacturer are integrated into a real-time team to get the best performance from the deployed fleet. A major emphasis of the paper is the use of practical, real-life experience as a feedback into the HUMS system. The system includes equipment, operating procedures and personnel, integrated into a cohesive force.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"1 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":"114828793","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.2001.931353
S. Kayalar, N. Mysoor, C. Andricos
A new Spacecraft Transponding Modem (STM) is being developed for deep space communication applications. The STM receives an X-band (7.17 GHz) uplink signal and generates an X-band (8.4 GHz) and a Ka-band (32.0 GHz) coherent or noncoherent downlink signals. The STM architecture incorporates two miniature linear phase modulators. These modulators are used to modulate the X-band and Ka-band downlink frequencies with the downlink telemetry, turnaround ranging, or regenerative PN-ranging signals. The linear phase modulators are designed with custom developed MMIC chips. The phase modulator MMICs, the amplifiers, and driver circuits are laid out on drop-in alumina substrates. These modulator designs meet the following requirements: phase deviation range of /spl plusmn/140 degrees at X-band and Ka-band downlink carrier frequencies, phase linearity of less than 8%, phase modulation input bandwidth of greater than 100 MHz, and differential input with sinewave or squarewave modulating format.
{"title":"Development of linear phase modulator for spacecraft transponding modem","authors":"S. Kayalar, N. Mysoor, C. Andricos","doi":"10.1109/AERO.2001.931353","DOIUrl":"https://doi.org/10.1109/AERO.2001.931353","url":null,"abstract":"A new Spacecraft Transponding Modem (STM) is being developed for deep space communication applications. The STM receives an X-band (7.17 GHz) uplink signal and generates an X-band (8.4 GHz) and a Ka-band (32.0 GHz) coherent or noncoherent downlink signals. The STM architecture incorporates two miniature linear phase modulators. These modulators are used to modulate the X-band and Ka-band downlink frequencies with the downlink telemetry, turnaround ranging, or regenerative PN-ranging signals. The linear phase modulators are designed with custom developed MMIC chips. The phase modulator MMICs, the amplifiers, and driver circuits are laid out on drop-in alumina substrates. These modulator designs meet the following requirements: phase deviation range of /spl plusmn/140 degrees at X-band and Ka-band downlink carrier frequencies, phase linearity of less than 8%, phase modulation input bandwidth of greater than 100 MHz, and differential input with sinewave or squarewave modulating format.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"116 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":"116018152","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.2001.931282
M.C. Spinolo
NASA is a critical information source in this Age of Information. With the advent and maturity of the Internet, the demand for NASA information has grown beyond science data archives to near real time and even real time data, particularly on the Earth and near Earth ecosystems. NASA also has prospered a policy of sharing mission responsibility with non-NASA entities, which still require tracking support from the NASA network. This paper discusses the issues in conflict when trying to solve the paradox of securing a critical national resource and participating as a good citizen of the Information Age. By illustrating several ground network architecture examples, these issues are highlighted. Recommendations for using the NASA tracking networks are given.
{"title":"Commercial and Internet trends and the NASA spaceflight ground network","authors":"M.C. Spinolo","doi":"10.1109/AERO.2001.931282","DOIUrl":"https://doi.org/10.1109/AERO.2001.931282","url":null,"abstract":"NASA is a critical information source in this Age of Information. With the advent and maturity of the Internet, the demand for NASA information has grown beyond science data archives to near real time and even real time data, particularly on the Earth and near Earth ecosystems. NASA also has prospered a policy of sharing mission responsibility with non-NASA entities, which still require tracking support from the NASA network. This paper discusses the issues in conflict when trying to solve the paradox of securing a critical national resource and participating as a good citizen of the Information Age. By illustrating several ground network architecture examples, these issues are highlighted. Recommendations for using the NASA tracking networks are given.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"191 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":"123650711","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.2001.931482
D. Abraham
Non-Rayleigh reverberation in active sonar systems causes an increase in the number of false alarms when detection algorithms are designed under the assumption that the reverberation is actually Rayleigh distributed. Many models have been used to represent non-Rayleigh reverberation and then build appropriate detectors including the Rayleigh mixture model, K-distribution, and McDaniel's model. The detectors for these models de-emphasize the tails of the distribution. Thus, a natural non-parametric alternative would be to use a power-law non-linearity with a power less than one. In this paper the efficacy is used to evaluate the power-law detector for the above reverberation models with a non-fluctuating target. For the K-distribution and McDaniel's model, it was seen that the power-law can achieve the same efficacy as the locally optimal non-linearity with a simpler implementation. However, choosing the optimal power-law requires modeling the reverberation with McDaniel's model and a numerical optimization, the former of which can result in mismatch errors if there is not a good fit with the observed reverberation. Thus, a different technique is considered in which the power is chosen so that the transformed data have the same higher order moment measure (skewness, kurtosis, or scintillation index) as the Rayleigh distribution. It wag seen that matching kurtosis resulted in the best average performance, but also the highest variability when the higher order moments must be estimated from auxiliary data. Matching the scintillation index provided the worst average performance, but the least variability, and matching the skewness was in between these extremes in terms of both average performance and variability.
{"title":"Efficacy analysis of the power-law detector for non-Rayleigh distributed reverberation in active sonar systems","authors":"D. Abraham","doi":"10.1109/AERO.2001.931482","DOIUrl":"https://doi.org/10.1109/AERO.2001.931482","url":null,"abstract":"Non-Rayleigh reverberation in active sonar systems causes an increase in the number of false alarms when detection algorithms are designed under the assumption that the reverberation is actually Rayleigh distributed. Many models have been used to represent non-Rayleigh reverberation and then build appropriate detectors including the Rayleigh mixture model, K-distribution, and McDaniel's model. The detectors for these models de-emphasize the tails of the distribution. Thus, a natural non-parametric alternative would be to use a power-law non-linearity with a power less than one. In this paper the efficacy is used to evaluate the power-law detector for the above reverberation models with a non-fluctuating target. For the K-distribution and McDaniel's model, it was seen that the power-law can achieve the same efficacy as the locally optimal non-linearity with a simpler implementation. However, choosing the optimal power-law requires modeling the reverberation with McDaniel's model and a numerical optimization, the former of which can result in mismatch errors if there is not a good fit with the observed reverberation. Thus, a different technique is considered in which the power is chosen so that the transformed data have the same higher order moment measure (skewness, kurtosis, or scintillation index) as the Rayleigh distribution. It wag seen that matching kurtosis resulted in the best average performance, but also the highest variability when the higher order moments must be estimated from auxiliary data. Matching the scintillation index provided the worst average performance, but the least variability, and matching the skewness was in between these extremes in terms of both average performance and variability.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"114 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":"124121272","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.2001.931401
K. Blemel, C. Furse
This paper presents how the industry, universities, and government agencies are working to develop in-situ wiring sensor systems to detect, diagnose, predict and prevent wiring related problems in aerospace vehicles. The authors begin with a brief introduction to wiring related problems and the safety and economic impacts caused by deterioration and abuse. Next, the authors present how the Navy is funding development of "smart" wiring systems such as arc fault detecting circuit breakers, wiring harnesses and connectors. The paper presents how smart wiring incorporates real time signal processing, rule based reasoning and microsystems and sensor technologies to form an early warning system using web-based information technologies. Next the paper present plans to install and test smart wiring in new and legacy aircraft. The paper concludes with a discussion of how smart wiring has a far reaching impact in aerospace systems through application in prognostic health management of engines, avionics, and control systems attached to smart wiring.
{"title":"Applications of microsystems and signal processing for wiring integrity monitoring","authors":"K. Blemel, C. Furse","doi":"10.1109/AERO.2001.931401","DOIUrl":"https://doi.org/10.1109/AERO.2001.931401","url":null,"abstract":"This paper presents how the industry, universities, and government agencies are working to develop in-situ wiring sensor systems to detect, diagnose, predict and prevent wiring related problems in aerospace vehicles. The authors begin with a brief introduction to wiring related problems and the safety and economic impacts caused by deterioration and abuse. Next, the authors present how the Navy is funding development of \"smart\" wiring systems such as arc fault detecting circuit breakers, wiring harnesses and connectors. The paper presents how smart wiring incorporates real time signal processing, rule based reasoning and microsystems and sensor technologies to form an early warning system using web-based information technologies. Next the paper present plans to install and test smart wiring in new and legacy aircraft. The paper concludes with a discussion of how smart wiring has a far reaching impact in aerospace systems through application in prognostic health management of engines, avionics, and control systems attached to smart wiring.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"129 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":"124487702","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.2001.931493
D. W. Ricker, A.J. Cutezo
Echolocation in shallow water is often characterized by high spurious detection rates generated by heavy tailed (impulse like) boundary reverberation. While persistent echoes that are delay/Doppler consistent over several interrogations are best detected and left to a subsequent classifier stage, impulsive transient events in the time series can be suppressed by preprocessing the data stream with a nonlinear filter. A simple preprocessor consisting of a linear predictor with a thresholded non-linearity has been used to attenuate sporadic impulse like events and successfully reduce the heavy pdf tails of synthesized Rayleigh mixture reverberation matched to actual data. It is shown that the preprocessor was able to restore nearly all of the ROC performance of a matched filter and reduce the false alarm yet maintain the detection rate when applied to real data from a shallow water rocky bottom area.
{"title":"Non-linear preprocessing of heavy tailed reverberation","authors":"D. W. Ricker, A.J. Cutezo","doi":"10.1109/AERO.2001.931493","DOIUrl":"https://doi.org/10.1109/AERO.2001.931493","url":null,"abstract":"Echolocation in shallow water is often characterized by high spurious detection rates generated by heavy tailed (impulse like) boundary reverberation. While persistent echoes that are delay/Doppler consistent over several interrogations are best detected and left to a subsequent classifier stage, impulsive transient events in the time series can be suppressed by preprocessing the data stream with a nonlinear filter. A simple preprocessor consisting of a linear predictor with a thresholded non-linearity has been used to attenuate sporadic impulse like events and successfully reduce the heavy pdf tails of synthesized Rayleigh mixture reverberation matched to actual data. It is shown that the preprocessor was able to restore nearly all of the ROC performance of a matched filter and reduce the false alarm yet maintain the detection rate when applied to real data from a shallow water rocky bottom area.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"41 2 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":"125749685","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.2001.931736
S. Cornford, M. Feather, K. Hicks
At JPL we have developed, and implemented, a process for achieving life-cycle risk management. This process has been embodied in a software tool and is called Defect Detection and Prevention (DDP). The DDP process can be succinctly stated as: determine where we want to be, what could get in the way and how we will get there. The 'determine where we want to be' is captured as trees of requirements and the 'what could get in the way' is captured as trees of potential failure modes. Scoring the impacts of these failure modes on the requirements results in a prioritized set of failure modes. The user then selects from a set of PACTs (Preventative measures, Analyses, process Controls and Tests) each of which has an effectiveness versus the various failure modes. It is the goal of the DDP process to optimally select the subset of the PACTs/spl Dagger/ which minimizes the residual risk subject to the project resource constraints.
{"title":"DDP-a tool for life-cycle risk management","authors":"S. Cornford, M. Feather, K. Hicks","doi":"10.1109/AERO.2001.931736","DOIUrl":"https://doi.org/10.1109/AERO.2001.931736","url":null,"abstract":"At JPL we have developed, and implemented, a process for achieving life-cycle risk management. This process has been embodied in a software tool and is called Defect Detection and Prevention (DDP). The DDP process can be succinctly stated as: determine where we want to be, what could get in the way and how we will get there. The 'determine where we want to be' is captured as trees of requirements and the 'what could get in the way' is captured as trees of potential failure modes. Scoring the impacts of these failure modes on the requirements results in a prioritized set of failure modes. The user then selects from a set of PACTs (Preventative measures, Analyses, process Controls and Tests) each of which has an effectiveness versus the various failure modes. It is the goal of the DDP process to optimally select the subset of the PACTs/spl Dagger/ which minimizes the residual risk subject to the project resource constraints.","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":"128424059","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.2001.931378
A. Yacoubian, W. Lin, D. Olson, Y. Shi, J. Bechtel
Polymer based electro-optic (EO) modulators have the potential to provide low cost and lightweight alternative for antenna remoting and RF links because of their wide bandwidth (>100 GHz) and low drive voltage (V/sub /spl pi//<1 V) capabilities. Low noise figure and low power consumption systems require low insertion loss modulators. There are two major causes of loss in EO modulators: waveguide propagation loss (typically 1 dB/cm), and fiber-to-waveguide coupling loss. In this paper we investigate methods to minimize fiber-to-waveguide coupling loss which is mainly due to mode size mismatch. Pigtails using standard single mode fiber produce coupling loss on the order of 3 to 5 dB/connection. In order to improve mode size matching yet maintain low drive voltage, we incorporate waveguide and fibers tapers. Experimental results indicate improvement of up to 3 dB/connection (6 dB/device) using waveguide tapers, and up to 2 dB/connection (4 dB/device) using fiber tapers.
{"title":"Electro-optic modulator coupling loss improvement by tapering waveguides and fibers","authors":"A. Yacoubian, W. Lin, D. Olson, Y. Shi, J. Bechtel","doi":"10.1109/AERO.2001.931378","DOIUrl":"https://doi.org/10.1109/AERO.2001.931378","url":null,"abstract":"Polymer based electro-optic (EO) modulators have the potential to provide low cost and lightweight alternative for antenna remoting and RF links because of their wide bandwidth (>100 GHz) and low drive voltage (V/sub /spl pi//<1 V) capabilities. Low noise figure and low power consumption systems require low insertion loss modulators. There are two major causes of loss in EO modulators: waveguide propagation loss (typically 1 dB/cm), and fiber-to-waveguide coupling loss. In this paper we investigate methods to minimize fiber-to-waveguide coupling loss which is mainly due to mode size mismatch. Pigtails using standard single mode fiber produce coupling loss on the order of 3 to 5 dB/connection. In order to improve mode size matching yet maintain low drive voltage, we incorporate waveguide and fibers tapers. Experimental results indicate improvement of up to 3 dB/connection (6 dB/device) using waveguide tapers, and up to 2 dB/connection (4 dB/device) using fiber tapers.","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":"130105036","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.2001.931264
J. Bautista, J. Bowen, N.E. Fernandez, Z. Fujiwara, J. Loreman, S. Petty, J. L. Prater, R. Grunbacher, R. Lai, M. Nishimoto, M. R. Murti, J. Laskar
Exploration of the Solar System with automated spacecraft that are more than ten astronomical units from Earth requires very large antennae employing extremely sensitive receivers. A key figure of merit in the specification of the spacecraft-to-earth telecommunications link is the ratio of the antenna gain to operational noise temperature (G/Top) of the system. The Deep Space Network (DSN) receivers are cryogenic, low-noise amplifiers (LNAs). InP HEMT LNA modules are demonstrating noise temperatures less than ten times the quantum noise limit (10 hf/k) from 1 to 100 GHz. To date, the lowest noise LNA modules developed for the DSN have demonstrated noise temperatures of under 4 K at 8.4 GHz and 11 K at 32 GHz. The development and demonstration of cryogenic, InP HEMT based front-end amplifiers for the DSN requires accurate component and module characterization, and modeling from 1 to 100 GHz at physical temperatures down to and below 12 K, because of the broad band frequency response of InP HEMTs. The characterization and modeling begins with the HEMT chip, proceeds to the multi-stage HEMT LNA module, and culminates with the complete front-end cryogenic receiver package for the antenna. This paper presents an overview of this development process with emphasis on comparison between modeled and measured results at 8.4 GHz. Results are shown for devices, LNA modules, front-end receiver packages employing these modules, and antennae employing these packages.
{"title":"Cryogenic, X-band and Ka-band InP HEMT based LNAs for the Deep Space Network","authors":"J. Bautista, J. Bowen, N.E. Fernandez, Z. Fujiwara, J. Loreman, S. Petty, J. L. Prater, R. Grunbacher, R. Lai, M. Nishimoto, M. R. Murti, J. Laskar","doi":"10.1109/AERO.2001.931264","DOIUrl":"https://doi.org/10.1109/AERO.2001.931264","url":null,"abstract":"Exploration of the Solar System with automated spacecraft that are more than ten astronomical units from Earth requires very large antennae employing extremely sensitive receivers. A key figure of merit in the specification of the spacecraft-to-earth telecommunications link is the ratio of the antenna gain to operational noise temperature (G/Top) of the system. The Deep Space Network (DSN) receivers are cryogenic, low-noise amplifiers (LNAs). InP HEMT LNA modules are demonstrating noise temperatures less than ten times the quantum noise limit (10 hf/k) from 1 to 100 GHz. To date, the lowest noise LNA modules developed for the DSN have demonstrated noise temperatures of under 4 K at 8.4 GHz and 11 K at 32 GHz. The development and demonstration of cryogenic, InP HEMT based front-end amplifiers for the DSN requires accurate component and module characterization, and modeling from 1 to 100 GHz at physical temperatures down to and below 12 K, because of the broad band frequency response of InP HEMTs. The characterization and modeling begins with the HEMT chip, proceeds to the multi-stage HEMT LNA module, and culminates with the complete front-end cryogenic receiver package for the antenna. This paper presents an overview of this development process with emphasis on comparison between modeled and measured results at 8.4 GHz. Results are shown for devices, LNA modules, front-end receiver packages employing these modules, and antennae employing these packages.","PeriodicalId":329225,"journal":{"name":"2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542)","volume":"2 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":"130166940","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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