Pub Date : 2010-05-10DOI: 10.1109/RADAR.2010.5494439
An Daoxiang, Huang Xiaotao, Jin Tian, Zhou Zhimin
Due to the reference signal based on the fixed reference range is used in the range migration (RM) algorithm, the RM algorithm is not available to process an airborne squint-mode spotlight synthetic aperture radar (SAR) data. Thus, a modified RM algorithm is developed, which can be applied on processing large scene squinted-mode spotlight SAR data without division. Based on the squint-mode spotlight SAR imaging geometry, the modified reference signal is used to dechirp the received signal. Then, using the principle of stationary phase, the presented formulation of the modified RM algorithm is analyzed. Finally, the effectiveness of the proposed method is demonstrated by some numerical simulations via a squint-mode spotlight SAR simulator.
{"title":"A modified range migration algorithm for airborne squint-mode spotlight SAR imaging","authors":"An Daoxiang, Huang Xiaotao, Jin Tian, Zhou Zhimin","doi":"10.1109/RADAR.2010.5494439","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494439","url":null,"abstract":"Due to the reference signal based on the fixed reference range is used in the range migration (RM) algorithm, the RM algorithm is not available to process an airborne squint-mode spotlight synthetic aperture radar (SAR) data. Thus, a modified RM algorithm is developed, which can be applied on processing large scene squinted-mode spotlight SAR data without division. Based on the squint-mode spotlight SAR imaging geometry, the modified reference signal is used to dechirp the received signal. Then, using the principle of stationary phase, the presented formulation of the modified RM algorithm is analyzed. Finally, the effectiveness of the proposed method is demonstrated by some numerical simulations via a squint-mode spotlight SAR simulator.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133474676","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494639
R. Takahashi, K. Hirata, Hisakazu Maniwa
In this paper, an altitude estimation technique for the radar target over the sea at low elevation angle is proposed for surface based phased array radar. The proposed method can be applied to conventional monopulse radar as well as multichannel digital array radar. The target altitude is obtained by maximum likelihood estimation technique. Reducing number of unknown parameters is achieved by introducing the precise specular multipath model tailored to the low elevation angle tracking operation. As a result, two frequency-independent parameters, the target altitude and the wave height are treated as unknown. Results of computer simulation indicate that the proposed method outperform conventional monopulse method under the specular multipath condition with and without frequency hopping operation.
{"title":"Altitude estimation of low elevation target over the sea for surface based phased array radar","authors":"R. Takahashi, K. Hirata, Hisakazu Maniwa","doi":"10.1109/RADAR.2010.5494639","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494639","url":null,"abstract":"In this paper, an altitude estimation technique for the radar target over the sea at low elevation angle is proposed for surface based phased array radar. The proposed method can be applied to conventional monopulse radar as well as multichannel digital array radar. The target altitude is obtained by maximum likelihood estimation technique. Reducing number of unknown parameters is achieved by introducing the precise specular multipath model tailored to the low elevation angle tracking operation. As a result, two frequency-independent parameters, the target altitude and the wave height are treated as unknown. Results of computer simulation indicate that the proposed method outperform conventional monopulse method under the specular multipath condition with and without frequency hopping operation.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131670970","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494652
M. Lamanna
The S-APAS (Scalable Multifunction Radio Frequency — Active Phased Array System) architecture has already been presented in previous papers [1] [2] [3]. The potential use of this architecture, in different versions and different operating bands, have been also analyzed on the basis of parallel technological developments [4] [5] [6] [7] [8]. However, the most challenging issue for the S-APAS architecture is a suitable design which allows this architecture to work at different operating frequencies and with wide instantaneous bandwidth, by using the same T/R modules and the same framework structure, while offering the best radio frequency performance at different frequencies. The main problems in defining such a wideband version of the S-APAS architecture are both in the technological aspects, i.e. producing T/R modules, with enough performance at frequencies of interest, and in system design, i.e. defining an array structure that is capable to provide high performance radio frequency figures while changing frequency, by means of a suitably reconfigurable beamforming and beamshaping. This paper tackles these problems, in order to assess feasibility of the wide band approach both in terms of technological capability and architectural feasibility. Regarding the first problem, the technological capabilities of the T/R components, in particular the GaN amplifier, are examined, starting from the wideband characteristics of the present generation of GaN components and analyzing the medium term improvements which have been planned in this area. With regard to the wideband architecture, a frequency tapered array design approach [9] is taken into consideration and its properties are analyzed, in order to evaluate the best configuration that is applicable to the S-APAS architecture.
{"title":"Design of a high performance wideband S-APAS architecture","authors":"M. Lamanna","doi":"10.1109/RADAR.2010.5494652","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494652","url":null,"abstract":"The S-APAS (Scalable Multifunction Radio Frequency — Active Phased Array System) architecture has already been presented in previous papers [1] [2] [3]. The potential use of this architecture, in different versions and different operating bands, have been also analyzed on the basis of parallel technological developments [4] [5] [6] [7] [8]. However, the most challenging issue for the S-APAS architecture is a suitable design which allows this architecture to work at different operating frequencies and with wide instantaneous bandwidth, by using the same T/R modules and the same framework structure, while offering the best radio frequency performance at different frequencies. The main problems in defining such a wideband version of the S-APAS architecture are both in the technological aspects, i.e. producing T/R modules, with enough performance at frequencies of interest, and in system design, i.e. defining an array structure that is capable to provide high performance radio frequency figures while changing frequency, by means of a suitably reconfigurable beamforming and beamshaping. This paper tackles these problems, in order to assess feasibility of the wide band approach both in terms of technological capability and architectural feasibility. Regarding the first problem, the technological capabilities of the T/R components, in particular the GaN amplifier, are examined, starting from the wideband characteristics of the present generation of GaN components and analyzing the medium term improvements which have been planned in this area. With regard to the wideband architecture, a frequency tapered array design approach [9] is taken into consideration and its properties are analyzed, in order to evaluate the best configuration that is applicable to the S-APAS architecture.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131908558","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494497
Junhyeong Bae, N. Goodman
In prior work, we have applied matched illumination strategies to target identification by a closed-loop radar system. In the closed-loop system, multiple waveforms are transmitted in succession, but each is customized based on the returns from prior transmissions. In this prior work, however, the matched waveforms were not constrained to be constant modulus. This current paper evaluates the performance of closed-loop radar with constant-modulus matched illumination. We also compare the performance of non-constant-modulus illumination under a peak power constraint. Finally, we use simple target models and assume unknown orientation, rather than the deterministic or Gaussian target models used in earlier work.
{"title":"Evaluation of modulus-constrained matched illumination waveforms for target identification","authors":"Junhyeong Bae, N. Goodman","doi":"10.1109/RADAR.2010.5494497","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494497","url":null,"abstract":"In prior work, we have applied matched illumination strategies to target identification by a closed-loop radar system. In the closed-loop system, multiple waveforms are transmitted in succession, but each is customized based on the returns from prior transmissions. In this prior work, however, the matched waveforms were not constrained to be constant modulus. This current paper evaluates the performance of closed-loop radar with constant-modulus matched illumination. We also compare the performance of non-constant-modulus illumination under a peak power constraint. Finally, we use simple target models and assume unknown orientation, rather than the deterministic or Gaussian target models used in earlier work.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115516903","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494561
Y. F. Lok, Jian Wang, A. Palevsky
This paper describes the radar signal features of a typical wind turbine and the simulation of the wind turbine signal based on a high resolution Doppler radar. The simulated signal is under-sampled with lower PRF to match an air traffic control (ATC) radar. The simulated signal is compared to the ATC radar data collected at two different sites. Remarkable similarities of the signal features are identified. These features may help to improve the primary radar detection and tracking performance in the future.
{"title":"Simulation of radar signal on wind turbine","authors":"Y. F. Lok, Jian Wang, A. Palevsky","doi":"10.1109/RADAR.2010.5494561","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494561","url":null,"abstract":"This paper describes the radar signal features of a typical wind turbine and the simulation of the wind turbine signal based on a high resolution Doppler radar. The simulated signal is under-sampled with lower PRF to match an air traffic control (ATC) radar. The simulated signal is compared to the ATC radar data collected at two different sites. Remarkable similarities of the signal features are identified. These features may help to improve the primary radar detection and tracking performance in the future.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"191 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114857723","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494634
Michael J. Kastle, J. A. Malas
Discrepancies can result when creating common data sets consisting of comparable synthetic and measured range complex scattered field samples when the phase references of each do not coincide. This can be especially true when using signal processing techniques to produce one dimensional (range profiles) or two dimensional (Synthetic Aperture Radar or SAR images) representations of the target scattered field where range bins and cross-range bins are formed. Range profiles and SAR images can be misaligned or have different bin amplitudes due to target scatterers in synthetic and measured scenarios shifted with respect to one another. Obtaining equivalent data samples requires attention to the measured data calibration process and phase reference location. This paper will address the common phase reference problem by an analysis of experimental data for specific targets and rotation system. Suggestions are provided for possible solutions to current challenges. The data analysis will include synthetic and measured range data comparisons, range calibration, and target position and range alignment processes using Theodolite laser measurements.
{"title":"Establishing a common phase reference for comparing synthetic data to RF range measurements","authors":"Michael J. Kastle, J. A. Malas","doi":"10.1109/RADAR.2010.5494634","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494634","url":null,"abstract":"Discrepancies can result when creating common data sets consisting of comparable synthetic and measured range complex scattered field samples when the phase references of each do not coincide. This can be especially true when using signal processing techniques to produce one dimensional (range profiles) or two dimensional (Synthetic Aperture Radar or SAR images) representations of the target scattered field where range bins and cross-range bins are formed. Range profiles and SAR images can be misaligned or have different bin amplitudes due to target scatterers in synthetic and measured scenarios shifted with respect to one another. Obtaining equivalent data samples requires attention to the measured data calibration process and phase reference location. This paper will address the common phase reference problem by an analysis of experimental data for specific targets and rotation system. Suggestions are provided for possible solutions to current challenges. The data analysis will include synthetic and measured range data comparisons, range calibration, and target position and range alignment processes using Theodolite laser measurements.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116279489","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494532
M. Inggs, Gunther Lange, Y. Paichard
The prediction of radar coverage as a function of the position of the radar has always been a key step in radar network planning. In the past, simple geometric models backed up by the deployment of siting radars were the only options for potential site evaluation, but the development of sophisticated propagation models (e.g. AREPS [1]) has moved the technology forward to another level of prediction accuracy. Modelling takes into account atmospheric refraction, as well as terrain effects and clutter. In previous papers [2], [3] we have shown that the modelling can also cater for multistatic radar systems. In this paper we have extended our modelling to give a statistical measure of the effectiveness of a site that measures the signal to noise ratio (SNR) or (for multistatic radar) the signal to interference ratio (SIR) over regions of interest. The area is pixellated into values of SNR and SIR, and pixels meeting the required SNR and / SIR are counted. We show some results for a multistatic radar. We conclude by indicating how we plan to include ground clutter. We mention how this method of obtaining quantitative coverage performance can be used with all forms of radar, and will be able to improve future networks of cognitive radars.
{"title":"A quantitative method for mono- and multistatic radar coverage area prediction","authors":"M. Inggs, Gunther Lange, Y. Paichard","doi":"10.1109/RADAR.2010.5494532","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494532","url":null,"abstract":"The prediction of radar coverage as a function of the position of the radar has always been a key step in radar network planning. In the past, simple geometric models backed up by the deployment of siting radars were the only options for potential site evaluation, but the development of sophisticated propagation models (e.g. AREPS [1]) has moved the technology forward to another level of prediction accuracy. Modelling takes into account atmospheric refraction, as well as terrain effects and clutter. In previous papers [2], [3] we have shown that the modelling can also cater for multistatic radar systems. In this paper we have extended our modelling to give a statistical measure of the effectiveness of a site that measures the signal to noise ratio (SNR) or (for multistatic radar) the signal to interference ratio (SIR) over regions of interest. The area is pixellated into values of SNR and SIR, and pixels meeting the required SNR and / SIR are counted. We show some results for a multistatic radar. We conclude by indicating how we plan to include ground clutter. We mention how this method of obtaining quantitative coverage performance can be used with all forms of radar, and will be able to improve future networks of cognitive radars.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123701518","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494565
P. Falcone, F. Colone, C. Bongioanni, P. Lombardo
In this paper the practical feasibility of a WiFi transmissions based passive bistatic radar (PBR) is analyzed. The required data processing steps are described there including the adopted techniques for: (i) the control of the signal Ambiguity Function usually yielding a high sidelobe level and (ii) the removal of the undesired signal contributions which strongly limit the useful dynamic range. The performance of the conceived system is evaluated with reference to typical signals broadcasted by a IEEE 802.11 access point exploiting an OFDM modulation. The achievable results are presented against a real data set collected by an experimental setup. This allowed us to preliminarily demonstrate the potentialities of a WiFi-based PBR for local area surveillance applications.
{"title":"Experimental results for OFDM WiFi-based passive bistatic radar","authors":"P. Falcone, F. Colone, C. Bongioanni, P. Lombardo","doi":"10.1109/RADAR.2010.5494565","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494565","url":null,"abstract":"In this paper the practical feasibility of a WiFi transmissions based passive bistatic radar (PBR) is analyzed. The required data processing steps are described there including the adopted techniques for: (i) the control of the signal Ambiguity Function usually yielding a high sidelobe level and (ii) the removal of the undesired signal contributions which strongly limit the useful dynamic range. The performance of the conceived system is evaluated with reference to typical signals broadcasted by a IEEE 802.11 access point exploiting an OFDM modulation. The achievable results are presented against a real data set collected by an experimental setup. This allowed us to preliminarily demonstrate the potentialities of a WiFi-based PBR for local area surveillance applications.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"194 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122128925","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494481
Zhaoping Wu, T. Su
A radar target track-before-detect (TBD) algorithm using particle filter (PF) is presented in this paper. System dynamic model and measurement model are established based on a sequence of radar range-Doppler measurements using the new algorithm. Furthermore, a linear extended target model is proposed, which is more capable of describing a maneuvering target than the conventional point target model. The likelihood ratio function of the new model is also derived in this paper. Due to the accumulation of the PF-TBD over time and the effectiveness of the proposed target model, an improved probability of detection for dim target is obtained. The experimental simulations demonstrate that the proposed method is capable of detecting and tracking a target with SNR of 1 dB robustly.
{"title":"Radar target detect using particle filter","authors":"Zhaoping Wu, T. Su","doi":"10.1109/RADAR.2010.5494481","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494481","url":null,"abstract":"A radar target track-before-detect (TBD) algorithm using particle filter (PF) is presented in this paper. System dynamic model and measurement model are established based on a sequence of radar range-Doppler measurements using the new algorithm. Furthermore, a linear extended target model is proposed, which is more capable of describing a maneuvering target than the conventional point target model. The likelihood ratio function of the new model is also derived in this paper. Due to the accumulation of the PF-TBD over time and the effectiveness of the proposed target model, an improved probability of detection for dim target is obtained. The experimental simulations demonstrate that the proposed method is capable of detecting and tracking a target with SNR of 1 dB robustly.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117096939","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 : 2010-05-10DOI: 10.1109/RADAR.2010.5494581
Jia Xu, Ji Yu, Yingning Peng, X. Xia
Based on the internal coupling relationship among radial velocity, range-walk and Doppler frequency of moving target's echoes, this paper proposes a novel method, i.e., Radon-Fourier transform (RFT), to realize the long-time coherent integration for radar target detection. The RFT realizes the echoes spatial-temporal decoupling via joint searching along range and velocity directions, as well as the successive coherent integration via the Doppler filter bank. Besides, it is shown that RFT is a kind of generalized Doppler filter bank processing for targets with across range unit (ARU) range walk. Finally, numerical experiments are provided to demonstrate the effectiveness of the proposed methods.
{"title":"Long-time coherent integration for radar target detection base on Radon-Fourier transform","authors":"Jia Xu, Ji Yu, Yingning Peng, X. Xia","doi":"10.1109/RADAR.2010.5494581","DOIUrl":"https://doi.org/10.1109/RADAR.2010.5494581","url":null,"abstract":"Based on the internal coupling relationship among radial velocity, range-walk and Doppler frequency of moving target's echoes, this paper proposes a novel method, i.e., Radon-Fourier transform (RFT), to realize the long-time coherent integration for radar target detection. The RFT realizes the echoes spatial-temporal decoupling via joint searching along range and velocity directions, as well as the successive coherent integration via the Doppler filter bank. Besides, it is shown that RFT is a kind of generalized Doppler filter bank processing for targets with across range unit (ARU) range walk. Finally, numerical experiments are provided to demonstrate the effectiveness of the proposed methods.","PeriodicalId":125591,"journal":{"name":"2010 IEEE Radar Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129529694","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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