Range sidelobes sources, waveform modulation, and compensation techniques are summarized, with emphasis on implementation issues associated with large time-bandwidth product waveforms. Previous efforts have addressed specific wideband phased-array-radar design issues for linear frequency modulation and biphase coded waveforms. The authors extend these efforts to include system error characterization requirements and predistortion/postprocessing compensation technique tradeoffs. Hardware errors are modeled in terms of the corresponding error modulation superimposed on the desired radar waveforms. Deterministic and nondeterministic hardware error imposed by frequency-dependent interchannel gain/phase-delay variation and additive noise effects is examined. Performance measures are examined for specific waveform classes. The interaction between antenna pattern and error modulation is described along with the associated system-level impacts. It is shown that deterministic error components can be suppressed via compensation techniques.<>
{"title":"Wideband waveform distortion and compensation techniques","authors":"M. Belcher, R. Howard, M. Mitchell","doi":"10.1109/NTC.1991.147998","DOIUrl":"https://doi.org/10.1109/NTC.1991.147998","url":null,"abstract":"Range sidelobes sources, waveform modulation, and compensation techniques are summarized, with emphasis on implementation issues associated with large time-bandwidth product waveforms. Previous efforts have addressed specific wideband phased-array-radar design issues for linear frequency modulation and biphase coded waveforms. The authors extend these efforts to include system error characterization requirements and predistortion/postprocessing compensation technique tradeoffs. Hardware errors are modeled in terms of the corresponding error modulation superimposed on the desired radar waveforms. Deterministic and nondeterministic hardware error imposed by frequency-dependent interchannel gain/phase-delay variation and additive noise effects is examined. Performance measures are examined for specific waveform classes. The interaction between antenna pattern and error modulation is described along with the associated system-level impacts. It is shown that deterministic error components can be suppressed via compensation techniques.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122338058","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}
A lightweight broadband phased array element was designed and manufactured using microstrip patch technology for an airborne telemetry antenna application. The electrical requirements of the element included nearly a 10 percent bandwidth, dual orthogonal linear polarization, +or-60 degrees azimuth coverage, and low mismatch loss. In addition to the electrical requirements, the lightweight element had to be easy to manufacture and exhibit good mechanical integrity. The final element design demonstrated a 16 dB return loss at 2.2. and 2.4 GHz and a 20 dB return loss at 2.3 GHz. Information about design tradeoffs, fabrication, and measurements is presented.<>
{"title":"Design of a lightweight broadband element for an airborne phased array","authors":"W. Cooke, V. Tripp, J. Montgomery","doi":"10.1109/NTC.1991.148013","DOIUrl":"https://doi.org/10.1109/NTC.1991.148013","url":null,"abstract":"A lightweight broadband phased array element was designed and manufactured using microstrip patch technology for an airborne telemetry antenna application. The electrical requirements of the element included nearly a 10 percent bandwidth, dual orthogonal linear polarization, +or-60 degrees azimuth coverage, and low mismatch loss. In addition to the electrical requirements, the lightweight element had to be easy to manufacture and exhibit good mechanical integrity. The final element design demonstrated a 16 dB return loss at 2.2. and 2.4 GHz and a 20 dB return loss at 2.3 GHz. Information about design tradeoffs, fabrication, and measurements is presented.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"198 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121751643","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}
Millimeter-wave radar seeker functions for detecting, classifying, identifying, and tracking ground targets are described. The adverse effects of both naturally occurring and man-made obscurant material are discussed. Obscurants considered include clear air components, fog, rain, frozen hydrometeors, and specially designed smokes. The phenomenological characteristics that affect radar performance are discussed in terms of signal absorption, signal backscatter, signal depolarization, and signal scintillation. It is noted that signal attenuation, via absorption, remains the major justification for creating man-made obscurant materials for protecting targets from millimeter-wave radars. While a minimal obscurant backscatter has the advantage of not giving away target area positions, a higher obscurant backscatter can itself degrade radar target detection by creating false targets and by decreasing the target-to-interference power ratio. The effects of conducting obscurant materials which remain spatially aligned in a wind field and the actual inhomogeneities in an obscurant cloud are discussed.<>
{"title":"Effects of obscurant materials on millimeter wave seekers","authors":"R.N. Trebits, B. Perry, J. Bach","doi":"10.1109/NTC.1991.148048","DOIUrl":"https://doi.org/10.1109/NTC.1991.148048","url":null,"abstract":"Millimeter-wave radar seeker functions for detecting, classifying, identifying, and tracking ground targets are described. The adverse effects of both naturally occurring and man-made obscurant material are discussed. Obscurants considered include clear air components, fog, rain, frozen hydrometeors, and specially designed smokes. The phenomenological characteristics that affect radar performance are discussed in terms of signal absorption, signal backscatter, signal depolarization, and signal scintillation. It is noted that signal attenuation, via absorption, remains the major justification for creating man-made obscurant materials for protecting targets from millimeter-wave radars. While a minimal obscurant backscatter has the advantage of not giving away target area positions, a higher obscurant backscatter can itself degrade radar target detection by creating false targets and by decreasing the target-to-interference power ratio. The effects of conducting obscurant materials which remain spatially aligned in a wind field and the actual inhomogeneities in an obscurant cloud are discussed.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133621074","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}
The concept of reconfigurable, multiple beam antenna arrays is discussed as a likely step in the development of future airborne radar systems. The system advantages of reconfigurable multiple beams are explored in terms of airborne tactical radars and their application. Implementation and design issues associated with a reconfigurable, multiple beam antenna array are discussed. A reconfigurable subarray approach is postulated as the most advantageous architecture.<>
{"title":"Reconfigurable arrays for airborne radars","authors":"B. Derryberry, J. Mynk","doi":"10.1109/NTC.1991.148023","DOIUrl":"https://doi.org/10.1109/NTC.1991.148023","url":null,"abstract":"The concept of reconfigurable, multiple beam antenna arrays is discussed as a likely step in the development of future airborne radar systems. The system advantages of reconfigurable multiple beams are explored in terms of airborne tactical radars and their application. Implementation and design issues associated with a reconfigurable, multiple beam antenna array are discussed. A reconfigurable subarray approach is postulated as the most advantageous architecture.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134175842","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}
The University of Massachusetts has developed two high-power portable polarimetric radars operating at 95 and 225 GHz. The 95 GHz polarimeter employs an extended-interaction klystron amplifier capable of 1500 W peak power output. The system is configured to measure the complex scattering matrix of a target by transmitting a pair of orthogonally polarized pulses in rapid succession. A noncoherent 225 GHz polarimetric radar which directly characterizes the target Mueller matrix by transmitting a sequence of six polarization states has also been developed. The 225 GHz system utilizes an extended-interaction klystron oscillator that generates a 60 W peak power pulse. The authors review the design of the 95 and 225 GHz radars, and highlight significant measurements and applications.<>
{"title":"Pulsed polarimetric millimeter-wave radars that utilize extended interaction amplifier and oscillator tubes","authors":"J. Mead, R. McIntosh","doi":"10.1109/NTC.1991.148043","DOIUrl":"https://doi.org/10.1109/NTC.1991.148043","url":null,"abstract":"The University of Massachusetts has developed two high-power portable polarimetric radars operating at 95 and 225 GHz. The 95 GHz polarimeter employs an extended-interaction klystron amplifier capable of 1500 W peak power output. The system is configured to measure the complex scattering matrix of a target by transmitting a pair of orthogonally polarized pulses in rapid succession. A noncoherent 225 GHz polarimetric radar which directly characterizes the target Mueller matrix by transmitting a sequence of six polarization states has also been developed. The 225 GHz system utilizes an extended-interaction klystron oscillator that generates a 60 W peak power pulse. The authors review the design of the 95 and 225 GHz radars, and highlight significant measurements and applications.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"558 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115033031","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}
The author describes the efforts of Time Domain Systems Incorporated (TDS), a small company specializing in the development of RF monocycle waveform applications. the areas of application are primarily short-range communications and radar. Monocyclic RF is a subset of ultrawideband (UWB) electromagnetics. UWB signals are defined as having greater than 25% relative bandwidth as defined by BW/f/sub c/. Single RF cycles easily qualify with bandwidths of approximately 100% TDS's focus is on RF monocycles with periods from a few nanoseconds down to tens of picoseconds, corresponding to centre frequencies of 200 MHz to 20 GHz.<>
{"title":"UWB waveforms and coding for communications and radar","authors":"L. Fullerton","doi":"10.1109/NTC.1991.148002","DOIUrl":"https://doi.org/10.1109/NTC.1991.148002","url":null,"abstract":"The author describes the efforts of Time Domain Systems Incorporated (TDS), a small company specializing in the development of RF monocycle waveform applications. the areas of application are primarily short-range communications and radar. Monocyclic RF is a subset of ultrawideband (UWB) electromagnetics. UWB signals are defined as having greater than 25% relative bandwidth as defined by BW/f/sub c/. Single RF cycles easily qualify with bandwidths of approximately 100% TDS's focus is on RF monocycles with periods from a few nanoseconds down to tens of picoseconds, corresponding to centre frequencies of 200 MHz to 20 GHz.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115686806","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}
A technique is developed for the generation of filters for pulse compression sidelobe reduction in radar systems. This technique has two advantages over the standard Wiener filtering technique: it minimizes sidelobe energy over multiple input sequences, and it can shape the sidelobe energy through the application of a weighting function that indicates which sidelobes are most important to reduce. Two example applications are provided, showing the effectiveness of this technique in generating filters for orthogonal code pairs and in generating filters for compressions with low sidelobes near the main peak.<>
{"title":"Optimal sidelobe suppression for biphase codes","authors":"J. M. Baden, M. Cohen","doi":"10.1109/NTC.1991.148000","DOIUrl":"https://doi.org/10.1109/NTC.1991.148000","url":null,"abstract":"A technique is developed for the generation of filters for pulse compression sidelobe reduction in radar systems. This technique has two advantages over the standard Wiener filtering technique: it minimizes sidelobe energy over multiple input sequences, and it can shape the sidelobe energy through the application of a weighting function that indicates which sidelobes are most important to reduce. Two example applications are provided, showing the effectiveness of this technique in generating filters for orthogonal code pairs and in generating filters for compressions with low sidelobes near the main peak.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121536393","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}
The author demonstrates the application of neural network technology to optimal scheduling of control gains in real-time flight control systems commonly used in the real-time control of an advanced fighter aircraft and high-performance aerospace vehicles where a priori target outputs are not known, and must be generated in real-time. A learning algorithm and an appropriate performance model have been used to synthesize a nonlinear functional relationship between varying plant parameters and control gains. A performance model is used to exemplify the desired responses and force the plant/controller dynamics via a neural network to imitate the model. The performance model contains the proper dynamics to supply desired responses to given test inputs. An arbitrary cost function is used to indicate the quality of plant/controller performance according to which the adjustments to the weights within the neural network are made by the learning algorithm. The process is repeated until the neural network produces an optimal set of gains for each point in the plant parameter space.<>
{"title":"Neural network based control system design of an advanced fighter aircraft","authors":"A. Bhatti","doi":"10.1109/NTC.1991.147978","DOIUrl":"https://doi.org/10.1109/NTC.1991.147978","url":null,"abstract":"The author demonstrates the application of neural network technology to optimal scheduling of control gains in real-time flight control systems commonly used in the real-time control of an advanced fighter aircraft and high-performance aerospace vehicles where a priori target outputs are not known, and must be generated in real-time. A learning algorithm and an appropriate performance model have been used to synthesize a nonlinear functional relationship between varying plant parameters and control gains. A performance model is used to exemplify the desired responses and force the plant/controller dynamics via a neural network to imitate the model. The performance model contains the proper dynamics to supply desired responses to given test inputs. An arbitrary cost function is used to indicate the quality of plant/controller performance according to which the adjustments to the weights within the neural network are made by the learning algorithm. The process is repeated until the neural network produces an optimal set of gains for each point in the plant parameter space.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125846047","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}
B. Mitchell, W. Esaias, G. Feldman, R. Kirk, C. McClain, M. Lewis
The ocean color mission, a spaceflight mission designed to provide daily, high precision, moderate resolution, multispectral visible observations of global ocean radiance for research in biogeochemical processes, climate change, and oceanography, is described. Data delivery will commence in autumn 1993. Data will be taken from an ocean color instrument in a near noon sun-synchronous orbit. Local, high-resolution data will be available by direct broadcast. Recorded, reduced resolution global data coverage and limited high resolution data will be transmitted to the Goddard Space Flight Center for analysis and distribution. The mission establishes a new paradigm for acquisition of satellite data: NASA will purchase data of a specified quality from a contractor to be selected by a competitive selection. The ocean color mission will provide the first observation of the bio-optical state of the global oceans with sufficient resolution and coverage in space and time to fully characterize the mean and variance of this aspect of the planet's biosphere.<>
{"title":"Satellite ocean color data for studying oceanic biogeochemical cycles","authors":"B. Mitchell, W. Esaias, G. Feldman, R. Kirk, C. McClain, M. Lewis","doi":"10.1109/NTC.1991.148031","DOIUrl":"https://doi.org/10.1109/NTC.1991.148031","url":null,"abstract":"The ocean color mission, a spaceflight mission designed to provide daily, high precision, moderate resolution, multispectral visible observations of global ocean radiance for research in biogeochemical processes, climate change, and oceanography, is described. Data delivery will commence in autumn 1993. Data will be taken from an ocean color instrument in a near noon sun-synchronous orbit. Local, high-resolution data will be available by direct broadcast. Recorded, reduced resolution global data coverage and limited high resolution data will be transmitted to the Goddard Space Flight Center for analysis and distribution. The mission establishes a new paradigm for acquisition of satellite data: NASA will purchase data of a specified quality from a contractor to be selected by a competitive selection. The ocean color mission will provide the first observation of the bio-optical state of the global oceans with sufficient resolution and coverage in space and time to fully characterize the mean and variance of this aspect of the planet's biosphere.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127598564","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}
T. Matsueda, K. Kuraoka, K. Goma, T. Sumi, R. Okamura
The authors present an overview of the baseline configuration of the JEMRMS (Japanese Experiment Module Remote Manipulator System) and summarize the status of the system and element development tests. JEMRMS has mother-daughter type manipulators: a 10 m long mother arm (main arm) and a 2 m-long daughter arm (small fine arm). The main arm (MA) provides that capability of transferring, retrieving, and berthing user (mission) payload or a JEM element in the vicinity of the servicing bay, called the exposed facility. The small fine arm (SFA), which is attached to the MA, performs dexterous tasks such as assembly of antenna and change-out test samples. The MA is routinely controlled by an automatic control mode, but can also be controlled by a manual mode using a six degree-of-freedom hand controller. The SFA is controlled by a manual control mode mainly in a bilateral (force feedback) and master-slave fashion. The MA is commonly used for the SFA as will as the MA and provides a human operator with the feedback force detected by a force moment sensor at the SFA wrist.<>
{"title":"JEMRMS system design and development status","authors":"T. Matsueda, K. Kuraoka, K. Goma, T. Sumi, R. Okamura","doi":"10.1109/NTC.1991.148052","DOIUrl":"https://doi.org/10.1109/NTC.1991.148052","url":null,"abstract":"The authors present an overview of the baseline configuration of the JEMRMS (Japanese Experiment Module Remote Manipulator System) and summarize the status of the system and element development tests. JEMRMS has mother-daughter type manipulators: a 10 m long mother arm (main arm) and a 2 m-long daughter arm (small fine arm). The main arm (MA) provides that capability of transferring, retrieving, and berthing user (mission) payload or a JEM element in the vicinity of the servicing bay, called the exposed facility. The small fine arm (SFA), which is attached to the MA, performs dexterous tasks such as assembly of antenna and change-out test samples. The MA is routinely controlled by an automatic control mode, but can also be controlled by a manual mode using a six degree-of-freedom hand controller. The SFA is controlled by a manual control mode mainly in a bilateral (force feedback) and master-slave fashion. The MA is commonly used for the SFA as will as the MA and provides a human operator with the feedback force detected by a force moment sensor at the SFA wrist.<<ETX>>","PeriodicalId":320008,"journal":{"name":"NTC '91 - National Telesystems Conference Proceedings","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134150178","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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