Based upon this author proposed multidimensional, multichannel detection theory, this paper unifies various proposed novel concepts of super high resolution, channel equalization, solution to arbitrary multidimensional pattern synthesis, random media models, additive noise models, and the unification of error-correcting, convolution, concatenated codes etc. in terms of optimal multidimension codes via cascaded input-output transfer function models.
{"title":"Notice of RetractionMultichannel super high resolution. Novel channel equalization and multidimensional arbitrary pattern synthesis","authors":"A.K. Gupta","doi":"10.1109/NRC.1998.677994","DOIUrl":"https://doi.org/10.1109/NRC.1998.677994","url":null,"abstract":"Based upon this author proposed multidimensional, multichannel detection theory, this paper unifies various proposed novel concepts of super high resolution, channel equalization, solution to arbitrary multidimensional pattern synthesis, random media models, additive noise models, and the unification of error-correcting, convolution, concatenated codes etc. in terms of optimal multidimension codes via cascaded input-output transfer function models.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114565828","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}
If modern airborne radar systems are to function properly, the radar antenna radiation patterns must meet certain specifications. Previously, most radar antennas were designed and tested in a clean antenna environment, i.e., there are no near field scattering from host structures, or radome effects. However, these higher order effects are a matter of increasing concern with added performance demands in the ever increasing jammer and clutter interference environments. We investigated the capabilities and limitations of currently available analysis techniques and computer codes for installed performance of airborne radar antenna systems. Then we developed a novel cascaded technique which could predict total installed performance of airborne radar antenna systems, i.e., the near field scattering from aircraft structures and radome effects. The cascaded technique utilized a ray-tracing method in both airframe and radome simulation. Thus, the cascaded technique can efficiently predict the total installed performance of large radar antenna systems on an aircraft structure.
{"title":"Installed performance analysis of radar antenna systems","authors":"J.J. Kim, O. Kesler","doi":"10.1109/NRC.1998.678021","DOIUrl":"https://doi.org/10.1109/NRC.1998.678021","url":null,"abstract":"If modern airborne radar systems are to function properly, the radar antenna radiation patterns must meet certain specifications. Previously, most radar antennas were designed and tested in a clean antenna environment, i.e., there are no near field scattering from host structures, or radome effects. However, these higher order effects are a matter of increasing concern with added performance demands in the ever increasing jammer and clutter interference environments. We investigated the capabilities and limitations of currently available analysis techniques and computer codes for installed performance of airborne radar antenna systems. Then we developed a novel cascaded technique which could predict total installed performance of airborne radar antenna systems, i.e., the near field scattering from aircraft structures and radome effects. The cascaded technique utilized a ray-tracing method in both airframe and radome simulation. Thus, the cascaded technique can efficiently predict the total installed performance of large radar antenna systems on an aircraft structure.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127350728","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}
Composite Optics Incorporated (COI) is a member of a consortium to flight test a passive millimeter wave (PMMW) camera, funded through ARPA TRP. The PMMW camera is being developed by TRW and will be able to deliver clear images of an airport runway through fog, rain, darkness, and other low visibility conditions. COI was tasked with the design and manufacture of the flight demonstration radome. The key electrical requirement was to maintain low loss (/spl les/1.0 dB insertion loss) while maintaining plane wave properties (constant phase within /spl plusmn/14/spl deg/ at 89 GHz) across the aperture of the camera. The radome was to utilize standard off-the-shelf materials and be compatible with a Boeing 707 as it would be flight tested on the Air Force's "Speckled Trout".
{"title":"Design of an 89 GHz radome","authors":"C. Gibson, M. Bonebright, S. Weisbrod","doi":"10.1109/NRC.1998.678030","DOIUrl":"https://doi.org/10.1109/NRC.1998.678030","url":null,"abstract":"Composite Optics Incorporated (COI) is a member of a consortium to flight test a passive millimeter wave (PMMW) camera, funded through ARPA TRP. The PMMW camera is being developed by TRW and will be able to deliver clear images of an airport runway through fog, rain, darkness, and other low visibility conditions. COI was tasked with the design and manufacture of the flight demonstration radome. The key electrical requirement was to maintain low loss (/spl les/1.0 dB insertion loss) while maintaining plane wave properties (constant phase within /spl plusmn/14/spl deg/ at 89 GHz) across the aperture of the camera. The radome was to utilize standard off-the-shelf materials and be compatible with a Boeing 707 as it would be flight tested on the Air Force's \"Speckled Trout\".","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127439720","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}
Over the last few years there has been considerable interest in developing highly effective target tracking algorithms. This interest in robust tracking techniques is spawned by the need to process data that often includes a large number of false detections and missed detections. These conditions are amplified by the need to detect and track increasingly smaller targets as well as targets in harsh clutter conditions. Such ambiguities serve to further exacerbate the tracking problem which must already produce plot to track assignments for closely spaced and crossing targets. With the availability of increased processing power, techniques such as multiple hypotheses tracking (MHT) that were traditionally viewed as impractical, due to the large computational requirements, are now receiving considerable attention due to their ability to handle the ambiguities. This paper discusses the implementation of a fast (MHT) algorithm for robust tracking of radar targets in the presence of the false detections, missed detections, and crossing targets.
{"title":"Evaluation of fast MHT algorithms","authors":"T. Bhattacharya, A. Premji, T. Nohara, P. Weber","doi":"10.1109/NRC.1998.678003","DOIUrl":"https://doi.org/10.1109/NRC.1998.678003","url":null,"abstract":"Over the last few years there has been considerable interest in developing highly effective target tracking algorithms. This interest in robust tracking techniques is spawned by the need to process data that often includes a large number of false detections and missed detections. These conditions are amplified by the need to detect and track increasingly smaller targets as well as targets in harsh clutter conditions. Such ambiguities serve to further exacerbate the tracking problem which must already produce plot to track assignments for closely spaced and crossing targets. With the availability of increased processing power, techniques such as multiple hypotheses tracking (MHT) that were traditionally viewed as impractical, due to the large computational requirements, are now receiving considerable attention due to their ability to handle the ambiguities. This paper discusses the implementation of a fast (MHT) algorithm for robust tracking of radar targets in the presence of the false detections, missed detections, and crossing targets.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115092738","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}
This paper describes a 75-110 GHz millimeter-wave system with versatile functionality, for studying fundamental scattering, emission and absorption behaviors in the laboratory or in restricted field conditions. The primary studies of interest currently concern absorption spectra or behavior of pollutant gases and particulates; scattering and emission from clouds and fog; scattering, absorption and emission from snow and other natural dense media; and the reflection-transmission behavior of periodic structures such as waveguide gratings. A block diagram level design of the instrument is presented. The 75-110 GHz spectrum is monitored by using 2 receiver IF sections and dividing the region into 9 GHz wide segments. Frequency stability is maintained by locking all oscillators to a high quality ovenized crystal oscillator. Preselection is done at the input using quasioptical techniques in order to reduce insertion loss which would be encountered in waveguide filters. The system operates as a spectrometer, pulse radar, step frequency radar and radiometer.
{"title":"A multi-mode W-band radar/radiometer for experimental studies","authors":"S. Nadimi, J. Bredow","doi":"10.1109/NRC.1998.677980","DOIUrl":"https://doi.org/10.1109/NRC.1998.677980","url":null,"abstract":"This paper describes a 75-110 GHz millimeter-wave system with versatile functionality, for studying fundamental scattering, emission and absorption behaviors in the laboratory or in restricted field conditions. The primary studies of interest currently concern absorption spectra or behavior of pollutant gases and particulates; scattering and emission from clouds and fog; scattering, absorption and emission from snow and other natural dense media; and the reflection-transmission behavior of periodic structures such as waveguide gratings. A block diagram level design of the instrument is presented. The 75-110 GHz spectrum is monitored by using 2 receiver IF sections and dividing the region into 9 GHz wide segments. Frequency stability is maintained by locking all oscillators to a high quality ovenized crystal oscillator. Preselection is done at the input using quasioptical techniques in order to reduce insertion loss which would be encountered in waveguide filters. The system operates as a spectrometer, pulse radar, step frequency radar and radiometer.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128392510","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}
An efficient method for computing azimuth estimates from amplitude monopulse ratios is required for an advanced radar system. Computational load requirements are inherently high because typically several thousand clutter target reports per scan survive the thresholds of the target detection logic. Monopulse editing is relied upon to merge likely target reports or discard clutter targets with azimuth estimates outside of the beamwidth. This paper describes an efficient and accurate method for computing azimuth estimates. Theoretical plots of azimuth estimation accuracy are presented for a specific example of an 18-element linear array UHF radar which provides an azimuth beamwidth of about 6/spl deg/. Tradeoffs among accuracy, computational load, and computer memory are discussed.
{"title":"Efficient methods for computing azimuth estimates from amplitude monopulse ratios","authors":"R.N. Spong","doi":"10.1109/NRC.1998.678019","DOIUrl":"https://doi.org/10.1109/NRC.1998.678019","url":null,"abstract":"An efficient method for computing azimuth estimates from amplitude monopulse ratios is required for an advanced radar system. Computational load requirements are inherently high because typically several thousand clutter target reports per scan survive the thresholds of the target detection logic. Monopulse editing is relied upon to merge likely target reports or discard clutter targets with azimuth estimates outside of the beamwidth. This paper describes an efficient and accurate method for computing azimuth estimates. Theoretical plots of azimuth estimation accuracy are presented for a specific example of an 18-element linear array UHF radar which provides an azimuth beamwidth of about 6/spl deg/. Tradeoffs among accuracy, computational load, and computer memory are discussed.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121005244","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}
Automotive adaptive cruise control (ACC) requires a forward looking sensor to provide data on the location of other vehicles and objects relative to the direction of travel of the host vehicle. This involves discrimination of closely spaced vehicles and accurate measurement of the position of individual vehicles and objects. These angle discrimination and angle measurement requirements, together with the sensor field-of-view (FOV) needed, drive the antenna requirements and antenna architecture for an automotive forward looking radar (FLR). This paper develops the key antenna parameters of beamwidth, beam overlap and number of beams. Alternate antenna architectures and their suitability for ACC are then discussed.
{"title":"Antenna requirements and architecture tradeoffs for an automotive forward looking radar","authors":"S.W. Alland","doi":"10.1109/NRC.1998.678029","DOIUrl":"https://doi.org/10.1109/NRC.1998.678029","url":null,"abstract":"Automotive adaptive cruise control (ACC) requires a forward looking sensor to provide data on the location of other vehicles and objects relative to the direction of travel of the host vehicle. This involves discrimination of closely spaced vehicles and accurate measurement of the position of individual vehicles and objects. These angle discrimination and angle measurement requirements, together with the sensor field-of-view (FOV) needed, drive the antenna requirements and antenna architecture for an automotive forward looking radar (FLR). This paper develops the key antenna parameters of beamwidth, beam overlap and number of beams. Alternate antenna architectures and their suitability for ACC are then discussed.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"348 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125626356","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}
X-band (9.5-10.0 GHz) backscatter at near grazing incidence (0.2 deg) from the sea off the coast of Kauai, Hawaii was measured with a radar characterized by a high spatial resolution in range (0.3 m) and a high temporal resolution (2000 Hz PRF). Extensive amounts (over 1200 s per measurement) of vertically and horizontally polarized sea clutter data were taken for upwind and crosswind transmit geometries. Each type of data was analyzed over time scales varying from long (200 s), to intermediate (5 s), to short (50 ms), and over range swaths varying from full (160 m), to intermediate (30 m), to short (an individual range cell, 0.3 m). The different types of data each exhibited the spiky behavior which has come to be expected from sea backscatter observed at low grazing angles and high range resolutions, while showing, between themselves, marked transmit geometry and polarization dependent contrasts, with the horizontally polarized, upwind sea clutter being especially notable for its frequently occurring, significant high frequency spectral content.
{"title":"Spiky sea clutter at low grazing angles and high range resolutions","authors":"F. Posner","doi":"10.1109/NRC.1998.678036","DOIUrl":"https://doi.org/10.1109/NRC.1998.678036","url":null,"abstract":"X-band (9.5-10.0 GHz) backscatter at near grazing incidence (0.2 deg) from the sea off the coast of Kauai, Hawaii was measured with a radar characterized by a high spatial resolution in range (0.3 m) and a high temporal resolution (2000 Hz PRF). Extensive amounts (over 1200 s per measurement) of vertically and horizontally polarized sea clutter data were taken for upwind and crosswind transmit geometries. Each type of data was analyzed over time scales varying from long (200 s), to intermediate (5 s), to short (50 ms), and over range swaths varying from full (160 m), to intermediate (30 m), to short (an individual range cell, 0.3 m). The different types of data each exhibited the spiky behavior which has come to be expected from sea backscatter observed at low grazing angles and high range resolutions, while showing, between themselves, marked transmit geometry and polarization dependent contrasts, with the horizontally polarized, upwind sea clutter being especially notable for its frequently occurring, significant high frequency spectral content.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"1967 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130107057","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}
High-frequency over-the-horizon (HF-OTH) radar uses ionospheric refraction to detect targets at thousands of kilometers. A timely surveillance of large areas requires relatively short dwells (coherent integration times) of less than 10 seconds. The resulting resolution in the Doppler Fourier transform is sufficient for detecting fast targets such as aircraft, but slow targets such as ships require integration times 12-30 seconds long to distinguish the ship peaks from the much more powerful ocean clutter. By modeling the first-order clutter as sinusoidal and subtracting it, we are able to expose ships in dwells as short as 3 seconds that would otherwise be masked by the mainlobe spread of the clutter. This technique is applied to data from the US Navy's relocatable OTHR (ROTHR). This approach is an alternative to superresolution techniques and may sometimes be more robust.
{"title":"HF radar ship detection through clutter cancellation","authors":"B. Root","doi":"10.1109/NRC.1998.678015","DOIUrl":"https://doi.org/10.1109/NRC.1998.678015","url":null,"abstract":"High-frequency over-the-horizon (HF-OTH) radar uses ionospheric refraction to detect targets at thousands of kilometers. A timely surveillance of large areas requires relatively short dwells (coherent integration times) of less than 10 seconds. The resulting resolution in the Doppler Fourier transform is sufficient for detecting fast targets such as aircraft, but slow targets such as ships require integration times 12-30 seconds long to distinguish the ship peaks from the much more powerful ocean clutter. By modeling the first-order clutter as sinusoidal and subtracting it, we are able to expose ships in dwells as short as 3 seconds that would otherwise be masked by the mainlobe spread of the clutter. This technique is applied to data from the US Navy's relocatable OTHR (ROTHR). This approach is an alternative to superresolution techniques and may sometimes be more robust.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131855253","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}
E. Adler, J. Clark, M. Conn, Phuong Phu, B. Scheiner
A flexible test bed radar architecture is described which includes an integrated RF electronics package that can support multiple radar applications, including surveillance, fire control, target acquisition, and tracking. This type of architecture can significantly reduce the cost, power, size, and weight of electronics on future weapon delivery platforms. The Army Research Laboratory (ARL) is developing technology to support multimode radar requirements. These requirements include the detection and location of moving or stationary low radar cross section targets in heavy ground clutter and the classification and/or recognition of these targets. We address these requirements with commercial-off-the-shelf (COTS) products and the integration of several enabling technologies. The test bed radar includes a direct digital synthesizer (DDS) for frequency-diverse waveform generation, a flexible wideband transceiver for bandwidth extension and frequency translation, and an open architecture signal processor with embedded wideband analog-to-digital converters for real-time acquisition and processing. Efficient signal processing algorithms have been developed to demonstrate multimode radar capability. This paper discusses the various subassemblies, algorithm efficiency, and field experiment results.
{"title":"Low-cost enabling technology for multimode radar requirements","authors":"E. Adler, J. Clark, M. Conn, Phuong Phu, B. Scheiner","doi":"10.1109/NRC.1998.677976","DOIUrl":"https://doi.org/10.1109/NRC.1998.677976","url":null,"abstract":"A flexible test bed radar architecture is described which includes an integrated RF electronics package that can support multiple radar applications, including surveillance, fire control, target acquisition, and tracking. This type of architecture can significantly reduce the cost, power, size, and weight of electronics on future weapon delivery platforms. The Army Research Laboratory (ARL) is developing technology to support multimode radar requirements. These requirements include the detection and location of moving or stationary low radar cross section targets in heavy ground clutter and the classification and/or recognition of these targets. We address these requirements with commercial-off-the-shelf (COTS) products and the integration of several enabling technologies. The test bed radar includes a direct digital synthesizer (DDS) for frequency-diverse waveform generation, a flexible wideband transceiver for bandwidth extension and frequency translation, and an open architecture signal processor with embedded wideband analog-to-digital converters for real-time acquisition and processing. Efficient signal processing algorithms have been developed to demonstrate multimode radar capability. This paper discusses the various subassemblies, algorithm efficiency, and field experiment results.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129369973","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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