{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T19:42:56Z","timestamp":1777405376382,"version":"3.51.4"},"reference-count":35,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2022,5,18]],"date-time":"2022-05-18T00:00:00Z","timestamp":1652832000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Key Research and Development Program of China","award":["2016YFC0301206"],"award-info":[{"award-number":["2016YFC0301206"]}]},{"name":"National Key Research and Development Program of China","award":["61531017"],"award-info":[{"award-number":["61531017"]}]},{"name":"National Key Research and Development Program of China","award":["2018R52046"],"award-info":[{"award-number":["2018R52046"]}]},{"name":"National Natural Science Foundation of China","award":["2016YFC0301206"],"award-info":[{"award-number":["2016YFC0301206"]}]},{"name":"National Natural Science Foundation of China","award":["61531017"],"award-info":[{"award-number":["61531017"]}]},{"name":"National Natural Science Foundation of China","award":["2018R52046"],"award-info":[{"award-number":["2018R52046"]}]},{"name":"Science and Technology Department of Zhejiang Province","award":["2016YFC0301206"],"award-info":[{"award-number":["2016YFC0301206"]}]},{"name":"Science and Technology Department of Zhejiang Province","award":["61531017"],"award-info":[{"award-number":["61531017"]}]},{"name":"Science and Technology Department of Zhejiang Province","award":["2018R52046"],"award-info":[{"award-number":["2018R52046"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>In order to meet the requirements of communication security and concealment, as well as to protect marine life, bionic covert communication has become a hot research topic for underwater acoustic communication (UAC). In this paper, we propose a bionic covert UAC (BC-UAC) method based on the time\u2013frequency contour (TFC) of the bottlenose dolphin whistle, which can overcome the safety problem of traditional low signal\u2013noise ratio (SNR) covert communication and make the detected communication signal be excluded as marine biological noise. In the proposed BC-UAC method, the TFC of the bottlenose dolphin whistle is segmented to improve the transmission rate. Two BC-UAC schemes based on the segmented TFC of the whistle, the BC-UAC scheme using the whistle signal with time-delay (BC-UAC-TD) and the BC-UAC scheme using the whistle signal with frequency-shift (BC-UAC-FS), are addressed. The original whistle signal is used as a synchronization signal. Moreover, the virtual time reversal mirror (VTRM) technique is adopted to equalize the channel for mitigating the multipath effect. The performance of the proposed BC-UAC method, in terms of the Pearson correlation coefficient (PCC) and bit error rate (BER), is evaluated under simulated and measured underwater channels. Numerical results show that the proposed BC-UAC method performs well on covertness and reliability. Furthermore, the covertness of the bionic modulated signal in BC-UAC-TD is better than that of BC-UAC-FS, although the reliability of BC-UAC-FS is better than that of BC-UAC-TD.<\/jats:p>","DOI":"10.3390\/e24050720","type":"journal-article","created":{"date-parts":[[2022,5,18]],"date-time":"2022-05-18T11:59:37Z","timestamp":1652875177000},"page":"720","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Bionic Covert Underwater Acoustic Communication Based on Time\u2013Frequency Contour of Bottlenose Dolphin Whistle"],"prefix":"10.3390","volume":"24","author":[{"given":"Lei","family":"Xie","sequence":"first","affiliation":[{"name":"College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"},{"name":"Zhejiang Provincial Key Laboratory of Information Processing, Communication and Networking, Hangzhou 310027, China"}]},{"given":"Jiahui","family":"Zhu","sequence":"additional","affiliation":[{"name":"College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"}]},{"given":"Yuqing","family":"Jia","sequence":"additional","affiliation":[{"name":"College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1366-1030","authenticated-orcid":false,"given":"Huifang","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"},{"name":"Zhoushan Ocean Research Center, Zhoushan 316021, China"},{"name":"State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, China"},{"name":"The Engineering Research Center of Oceanic Sensing Technology and Equipment, Ministry of Education, Zhoushan 316021, China"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,18]]},"reference":[{"key":"ref_1","first-page":"109","article-title":"Effects of anthropogenic noise on animals","volume":"Volume 66","author":"Slabbekoorn","year":"2018","journal-title":"Springer Handbook of Auditory Research"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"SKKF03","DOI":"10.35848\/1347-4065\/ab87f0","article-title":"Time-frequency modulation based mimicking dolphin whistle for covert underwater acoustic communication","volume":"59","author":"Lee","year":"2020","journal-title":"Jpn. J. Appl. Phys."},{"key":"ref_3","first-page":"143","article-title":"Bounds for low probability of detection for underwater acoustic communication","volume":"42","author":"Diamant","year":"2017","journal-title":"IEEE J. Ocean. Eng."},{"key":"ref_4","unstructured":"Schoolcraft, R. (1991, January 4\u20137). Low probability of detection communications-LPD waveform design and detection techniques. Proceedings of the 1991 IEEE Military Communications Conference (MILCOM1991), McLean, VA, USA."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2898","DOI":"10.1121\/1.3493454","article-title":"Covert underwater acoustic communications","volume":"128","author":"Ling","year":"2010","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"786","DOI":"10.1109\/TAES.2003.1238736","article-title":"Cyclic code shift keying: A low probability of intercept communication technique","volume":"39","author":"Dillard","year":"2003","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1662","DOI":"10.1109\/JSAC.2008.081206","article-title":"Multiband OFDM for covert acoustic communications","volume":"26","author":"Leus","year":"2008","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3632","DOI":"10.1121\/1.2996329","article-title":"Low probability of detection underwater acoustic communications using direct-sequence spread spectrum","volume":"124","author":"Yang","year":"2008","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1016\/j.phycom.2018.07.007","article-title":"Biologically inspired covert underwater acoustic communication\u2014A review","volume":"30","author":"Qiao","year":"2018","journal-title":"Commun. Phys."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"565","DOI":"10.1098\/rsbl.2009.0099","article-title":"Sonar-induced temporary hearing loss in dolphins","volume":"5","author":"Mooney","year":"2009","journal-title":"Biol. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"606","DOI":"10.3389\/fmars.2019.00606","article-title":"The effects of ship noise on marine mammals\u2014A review","volume":"6","author":"Erbe","year":"2019","journal-title":"Front. Mar. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"647","DOI":"10.3389\/fmars.2019.00647","article-title":"Managing the effects of noise from ship traffic, seismic surveying and construction on marine mammals in Antarctica","volume":"6","author":"Erbe","year":"2019","journal-title":"Front. Mar. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1016\/j.apacoust.2011.09.009","article-title":"A framework for the automated real-time detection of short tonal sounds from ocean observatories","volume":"73","author":"Zaugg","year":"2012","journal-title":"Appl. Acoust."},{"key":"ref_14","first-page":"93","article-title":"Detection and classification of marine mammals using an LFAS system","volume":"32","author":"Ijsselmuide","year":"2004","journal-title":"Can. Acoust."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2833","DOI":"10.1121\/1.2982368","article-title":"Automatic detection of marine mammals using information entropy","volume":"124","author":"Erbe","year":"2008","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Shinego, M., Edelson, G., Menas, F., Richman, M., and Nation, R. (2001). Underwater acoustic data communications for autonomous platform command, control and communications. Technical Report, BAE Systems and Technology Inc.","DOI":"10.21236\/ADA389546"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"EL300","DOI":"10.1121\/1.4795219","article-title":"Covert underwater acoustic communication using dolphin sounds","volume":"133","author":"Liu","year":"2013","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_18","unstructured":"Jia, Y., Liu, G., and Zhang, L. (2015, January 29\u201331). Bionic camouflage underwater acoustic communication based on sea lion sounds. Proceedings of the 2015 International Conference on Control (ICCAIS), Changshu, China."},{"key":"ref_19","first-page":"156","article-title":"Bio-inspired steganography for secure underwater acoustic communications","volume":"56","author":"Jiang","year":"2018","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"24927","DOI":"10.1109\/ACCESS.2020.2970746","article-title":"A basic bio-inspired camouflage communication frame design and applications for secure underwater communication among military underwater platforms","volume":"8","author":"Jiang","year":"2020","journal-title":"IEEE Access"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Bilal, M., Liu, S., Qiao, G., Wan, L., and Tao, Y. (2020). Bionic Morse coding mimicking humpback whale song for covert underwater communication. Appl. Sci., 10.","DOI":"10.3390\/app10010186"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Li, C., Jiang, J., Duan, F., Wang, X., and Sun, Z. (2020, January 29\u201331). Bio-inspired covert underwater acoustic communication based on sperm whale clicks with frequency-hopping modulation. Proceedings of the 2020 Information Communication Technologies Conference (ICTC), Nanjing, China.","DOI":"10.1109\/ICTC49638.2020.9123262"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Severson, J. (2009). Modeling and Frequency Tracking of Marine Mammal Whistle Calls, Massachusetts Institude of Technology.","DOI":"10.1575\/1912\/2708"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Liu, S., Ma, T., Qiao, G., and Kuang, B. (2016, January 5\u20138). Bionic communication by dolphin whistle with continuous-phase based on MSK modulation. Proceedings of the 2016 IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC), Hong Kong, China.","DOI":"10.1109\/ICSPCC.2016.7753725"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1016\/j.apacoust.2018.09.026","article-title":"A sonar-embedded disguised communication strategy by combining sonar waveforms and whale call pulses for underwater sensor platforms","volume":"145","author":"Jiang","year":"2019","journal-title":"Appl. Acoust."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"101288","DOI":"10.1016\/j.phycom.2021.101288","article-title":"A frequency hopping pattern inspired bionic underwater acoustic communication","volume":"46","author":"Qiao","year":"2021","journal-title":"Commun. Phys."},{"key":"ref_27","unstructured":"Dol, H.S., Quesson, B.A.J., and Benders, F.P.A. (2008, January 10\u201312). Covert underwater communication with marine mammal sounds. Proceedings of the Undersea Defense Technology\u2014UDT Europe 2008, Glasgow, UK."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2194","DOI":"10.1002\/wcm.2676","article-title":"An underwater acoustic communication scheme exploiting biological sounds","volume":"16","author":"ElMoslimany","year":"2016","journal-title":"Wirel. Commun. Mob. Comput."},{"key":"ref_29","unstructured":"Liu, S., Qiao, G., Yu, Y., Zhang, L., and Chen, T. (2013, January 23\u201327). Biologically inspired covert underwater acoustic communication using high frequency dolphin clicks. Proceedings of the OCEANS 2013, San Diego, CA, USA."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/j.apacoust.2018.06.001","article-title":"Covert underwater communication by camouflaging sea piling sounds","volume":"142","author":"Liu","year":"2018","journal-title":"Appl. Acoust."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"180341","DOI":"10.1109\/ACCESS.2020.3027022","article-title":"Mimicking ship-radiated noise with chaos signal for covert underwater acoustic communication","volume":"8","author":"Huang","year":"2020","journal-title":"IEEE Access"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2043","DOI":"10.1109\/TWC.2016.2623604","article-title":"Dolphins first: Dolphin-aware communications in multi-hop underwater cognitive acoustic networks","volume":"16","author":"Li","year":"2016","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1121\/1.429474","article-title":"Synthesis and modification of the whistles of the bottlenose dolphin, tursiops truncatus","volume":"108","author":"Buck","year":"2000","journal-title":"J. Acoust. Soc. Am."},{"key":"ref_34","first-page":"1450","article-title":"Acoustic pulse compression using passive phase-conjugate processing","volume":"95","author":"Dowling","year":"1994","journal-title":"Acoust. Phys."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"119980","DOI":"10.1109\/ACCESS.2020.3004282","article-title":"Synthesis and modification of cetacean tonal sounds for underwater bionic covert detection and communication","volume":"8","author":"Jiang","year":"2020","journal-title":"IEEE Access"}],"container-title":["Entropy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1099-4300\/24\/5\/720\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:13:59Z","timestamp":1760138039000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1099-4300\/24\/5\/720"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,18]]},"references-count":35,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2022,5]]}},"alternative-id":["e24050720"],"URL":"https:\/\/doi.org\/10.3390\/e24050720","relation":{},"ISSN":["1099-4300"],"issn-type":[{"value":"1099-4300","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,5,18]]}}}