{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T16:32:08Z","timestamp":1779381128795,"version":"3.53.1"},"reference-count":47,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2016,7,8]],"date-time":"2016-07-08T00:00:00Z","timestamp":1467936000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["No.61401078"],"award-info":[{"award-number":["No.61401078"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["No.61301273"],"award-info":[{"award-number":["No.61301273"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Research Fund forHightechnology Project","award":["No.9140A07020614DZ02099"],"award-info":[{"award-number":["No.9140A07020614DZ02099"]}]},{"name":"Research Startup Fund of the University of Electronic Science and Technology of China","award":["Y02002010201089"],"award-info":[{"award-number":["Y02002010201089"]}]},{"name":"Fundamental Research Funds for Central Universities","award":["ZYGX2014J015"],"award-info":[{"award-number":["ZYGX2014J015"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Being equipped with a millimeter-wave radar allows a low-flying helicopter to sense the surroundings in real time, which significantly increases its safety. However, nonhomogeneous clutter environments, such as a multiple target situation and a clutter edge environment, can dramatically affect the radar signal detection performance. In order to improve the radar signal detection performance in nonhomogeneous clutter environments, this paper proposes a new automatic censored cell averaging CFAR detector. The proposed CFAR detector does not require any prior information about the background environment and uses the hypothesis test of the first-order difference (FOD) result of ordered data to reject the unwanted samples in the reference window. After censoring the unwanted ranked cells, the remaining samples are combined to form an estimate of the background power level, thus getting better radar signal detection performance. The simulation results show that the FOD-CFAR detector provides low loss CFAR performance in a homogeneous environment and also performs robustly in nonhomogeneous environments. Furthermore, the measured results of a low-flying helicopter validate the basic performance of the proposed method.<\/jats:p>","DOI":"10.3390\/s16071055","type":"journal-article","created":{"date-parts":[[2016,7,8]],"date-time":"2016-07-08T09:46:07Z","timestamp":1467971167000},"page":"1055","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Automatic Censoring CFAR Detector Based on Ordered Data Difference for Low-Flying Helicopter Safety"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0316-9322","authenticated-orcid":false,"given":"Wen","family":"Jiang","sequence":"first","affiliation":[{"name":"School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yulin","family":"Huang","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianyu","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2016,7,8]]},"reference":[{"key":"ref_1","unstructured":"Mangogno, A.J. (2001, January 14\u201318). Development of a helicopter obstacle detection and air data. Proceedings of the IEEE 20th Digital Avionics Conference, Daytona Beach, CA, USA."},{"key":"ref_2","unstructured":"Almsted, L.D., Becker, R.C., and Zelenka, R.E. (1997, January 26). Affordable MMW aircraft collision avoidance system. Proceedings of the AeroSense\u201997, International Society for Optics and Photonics, lOrlando, FL, USA."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Seidel, C., Schwartz, I., and Kielhorn, P. (2008, January 2). Helicopter collision avoidance and brown-out recovery with HELLAS. Proceedings of the SPIE Europe Security and Defence, International Society for Optics and Photonics, Cardiff, UK.","DOI":"10.1117\/12.800180"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"875","DOI":"10.1109\/7.532250","article-title":"A system for obstacle detection during rotorcraft low altitude flight","volume":"32","author":"Bhanu","year":"1996","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Lynch, D. (2004). Introduction to RF Stealth, Scitech Publishing.","DOI":"10.1049\/SBRA120E"},{"key":"ref_6","unstructured":"Skolnick, M. (2008). Radar Handbook, McGraw-Hill Companies."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1109\/TAES.2007.357150","article-title":"Novel minimum time trajectory planning in terrain following flights","volume":"43","author":"Malaek","year":"2007","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1109\/TAES.2012.6129620","article-title":"Dynamic based cost functions for TF\/TA flights","volume":"48","author":"Malaek","year":"2012","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_9","unstructured":"Ariyur, K.B., Lommel, P., and Enns, D.F. (2005, January 8\u201310). Reactive inflight obstacle avoidance via radar feedback. Proceedings of the 2005 IEEE American Control Conference, Portland, OR, USA."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Goshi, D.S., Case, T.J., McKitterick, J.B., and Bui, L.Q. (2012, January 23\u201327). Multifunctional millimeter-wave radar system for helicopter safety. Proceedings of the International Society for Optics and Photonics, SPIE Defense, Security, and Sensing, Baltimore, MD, USA.","DOI":"10.1117\/12.920828"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1109\/7.913669","article-title":"Radar-assisted collision avoidance\/guidance strategy for planar flight","volume":"37","author":"Kumar","year":"2001","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Migliaccio, C., Nguyen, B., Pichot, C., Yonemoto, N., Yamamoto, K., Yamada, K., Nasui, H., Mayer, W., Gronau, A., and Menzel, W. (2006, January 5\u20138). Millimeter-wave radar for rescue helicopters. Proceedings of the 9th International Conference on Control, Automation, Robotics and Vision, Singapore, Singapore.","DOI":"10.1109\/ICARCV.2006.345237"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Yonemoto, N., Yamamoto, K., Yamada, K., Yasui, H., Tanaka, N., Migliaccio, C., Dauvignac, J.Y., and Pichot, C. (2006, January 17\u201321). Performance of obstacle detection and collision warning system for civil helicopters. Proceedings of the Defense and Security Symposium on International Society for Optics and Photonics, Orlando, FL, USA.","DOI":"10.1117\/12.666693"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Kwag, Y.K., and Chung, C.H. (2007, January 23\u201327). UAV based collision avoidance radar sensor. Proceedings of the IEEE International Geoscience and Remote Sensing Symposium, Barcelona, Spain.","DOI":"10.1109\/IGARSS.2007.4422877"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"3534","DOI":"10.1109\/TIP.2011.2155079","article-title":"An algorithm for power line detection and warning based on a millimeter-wave radar video","volume":"20","author":"Ma","year":"2011","journal-title":"IEEE Trans. Image Process."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Goshi, D., Mai, K., Liu, Y., and Bui, L. (2012, January 22\u201325). A millimeter-wave sensor development system for small airborne platforms. Proceedings of the 2012 IEEE Radar Conference (RADAR), Glasgow, UK.","DOI":"10.1109\/RADAR.2012.6212194"},{"key":"ref_17","first-page":"414","article-title":"Adaptive detection mode with threshold control as a function of spatially sampled clutter-level estimates","volume":"29","author":"Finn","year":"1968","journal-title":"RCA Rev."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1109\/TAES.1982.309210","article-title":"Analysis of some modified cell-averaging CFAR processors in multiple-target situations","volume":"18","author":"Weiss","year":"1982","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"16046","DOI":"10.3390\/s140916046","article-title":"Modified Anderson-Darling Test-Based Target Detector in Non-Homogenous Environments","volume":"14","author":"Li","year":"2014","journal-title":"Sensors"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Gini, F., and Rangaswamy, M. (2008). Knowledge Based Radar Detection, Tracking and Classification, John Wiley & Sons.","DOI":"10.1002\/9780470283158"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"837","DOI":"10.1109\/7.869503","article-title":"Intelligent CFAR processor based on data variability","volume":"36","author":"Smith","year":"2000","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1109\/7.869508","article-title":"Adaptive CFAR processor for nonhomogeneous environments","volume":"36","author":"Khalighi","year":"2000","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1109\/97.948451","article-title":"Robust adaptive threshold for control of false alarms","volume":"8","author":"Sarma","year":"2001","journal-title":"IEEE Signal Process. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1007\/s11760-008-0075-2","article-title":"A generalized switching CFAR processor based on test cell statistics","volume":"3","author":"Tabet","year":"2009","journal-title":"Signal Image Video Process."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1519","DOI":"10.1109\/TAES.2013.6558002","article-title":"A Computationally Efficient CFAR Algorithm Based on a Goodness-of-Fit Test for Piecewise Homogeneous Environments","volume":"49","author":"Kim","year":"2013","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1049\/iet-rsn:20060113","article-title":"Design and experimental validation of knowledge-based constant false alarm rate detectors","volume":"1","author":"Farina","year":"2007","journal-title":"IET Radar Sonar Navig."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"25072","DOI":"10.3390\/s151025072","article-title":"A Novel Fusion-Based Ship Detection Method from Pol-SAR Images","volume":"15","author":"Wang","year":"2015","journal-title":"Sensors"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1049\/ip-rsn:20040560","article-title":"Distributed CA-CFAR and OS-CFAR detection using fuzzy spaces and fuzzy fusion rules","volume":"151","author":"Hammoudi","year":"2004","journal-title":"IEE Radar Sonar Navig."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1231","DOI":"10.1016\/j.sigpro.2004.04.005","article-title":"Distributed IVI-CFAR detection in non-homogeneous environments","volume":"84","author":"Hammoudi","year":"2004","journal-title":"Signal Process."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1049\/iet-rsn:20070133","article-title":"Constant false-alarm rate algorithm based on test cell information","volume":"2","author":"Cao","year":"2008","journal-title":"IEE Radar Sonar Navig."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"750","DOI":"10.1109\/TAES.1978.308625","article-title":"Range resolution of targets using automatic detectors","volume":"14","author":"Trunk","year":"1978","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1109\/TAES.1980.308885","article-title":"Detectability Loss Due to Greatest of Selection in a Cell-Averaging CFAR","volume":"1","author":"Hansen","year":"1980","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"23071","DOI":"10.3390\/s150923071","article-title":"Aircraft Detection in High-Resolution SAR Images Based on a Gradient Textural Saliency Map","volume":"15","author":"Tan","year":"2015","journal-title":"Sensors"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1109\/TAES.1983.309350","article-title":"Radar CFAR thresholding in clutter and multiple target situations","volume":"19","author":"Rohling","year":"1983","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"427","DOI":"10.1109\/7.7185","article-title":"Analysis of CFAR processors in nonhomogeneous background","volume":"24","author":"Gandhi","year":"1988","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"338","DOI":"10.1109\/TAES.1977.308466","article-title":"Adaptive detection algorithms for multiple-target situations","volume":"13","author":"Rickard","year":"1977","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"286","DOI":"10.1109\/7.135454","article-title":"Automatic censored CFAR detection for nonhomogeneous environments","volume":"28","author":"Himonas","year":"1992","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1049\/ip-rsn:20045006","article-title":"Automatic censoring CFAR detector based on ordered data variability for nonhomogeneous environments","volume":"152","author":"Farrouki","year":"2005","journal-title":"IEE Radar Sonar Navig."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"2611","DOI":"10.1016\/j.sigpro.2008.04.016","article-title":"Automatic dual censoring cell-averaging CFAR detector in non-homogenous environments","volume":"88","author":"Zaimbashi","year":"2008","journal-title":"Signal Process."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1253","DOI":"10.1016\/j.aeue.2014.07.006","article-title":"Automatic censoring CFAR detector for heterogeneous environments","volume":"68","author":"Boudemagh","year":"2014","journal-title":"AEU-Int. J. Electron. Commun."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Cao, T.T.V., Palmer, J., and Berry, P.E. (2010, January 10\u201314). False alarm control of CFAR algorithms with experimental bistatic radar data. Proceedings of the 2010 IEEE Radar Conference, Arlington, USA.","DOI":"10.1109\/RADAR.2010.5494633"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"4948","DOI":"10.3390\/s8084948","article-title":"Ship detection in SAR image based on the alpha-stable distribution","volume":"8","author":"Wang","year":"2008","journal-title":"Sensors"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1049\/iet-rsn.2008.0119","article-title":"Performance analysis of ordered-statistic greatest of-constant false alarm rate with binary integration for M-sweeps","volume":"4","author":"Meng","year":"2010","journal-title":"IEE Radar Sonar Navig."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1747","DOI":"10.1109\/TAES.2012.6178094","article-title":"A CFAR detector in a nonhomogenous Weibull clutter","volume":"48","author":"Pourmottaghi","year":"2012","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"558","DOI":"10.1016\/j.sigpro.2007.08.017","article-title":"Weighted order statistic and fuzzy rules CFAR detector for Weibull clutter","volume":"88","author":"Zaimbashi","year":"2008","journal-title":"Signal Process."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"2176","DOI":"10.1109\/TAES.2014.130040","article-title":"Performance prediction of the incoherent detector for a weibull fluctuating target","volume":"50","author":"Cui","year":"2014","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"356","DOI":"10.1109\/TAES.2013.6404108","article-title":"Performance prediction of the incoherent radar detector for correlated generalized Swerling-chi fluctuating targets","volume":"49","author":"Cui","year":"2013","journal-title":"IEEE Trans. Aerosp. Electron. Syst."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/7\/1055\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:25:39Z","timestamp":1760210739000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/7\/1055"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,7,8]]},"references-count":47,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2016,7]]}},"alternative-id":["s16071055"],"URL":"https:\/\/doi.org\/10.3390\/s16071055","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,7,8]]}}}