{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,1]],"date-time":"2026-03-01T03:21:39Z","timestamp":1772335299925,"version":"3.50.1"},"reference-count":34,"publisher":"Acoustical Society of America (ASA)","issue":"2","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2008,8,1]]},"abstract":"<jats:p>Passive time reversal has aroused considerable interest in underwater communications as a computationally inexpensive means of mitigating the intersymbol interference introduced by the channel using a receiver array. In this paper the basic technique is extended by adaptively weighting sensor contributions to partially compensate for degraded focusing due to mismatch between the assumed and actual medium impulse responses. Two algorithms are proposed, one of which restores constructive interference between sensors, and the other one minimizes the output residual as in widely used equalization schemes. These are compared with plain time reversal and variants that employ postequalization and channel tracking. They are shown to improve the residual error and temporal stability of basic time reversal with very little added complexity. Results are presented for data collected in a passive time-reversal experiment that was conducted during the MREA\u201904 sea trial. In that experiment a single acoustic projector generated a 2\u22154-PSK (phase-shift keyed) stream at 200\u2215400 baud, modulated at 3.6kHz, and received at a range of about 2km on a sparse vertical array with eight hydrophones. The data were found to exhibit significant Doppler scaling, and a resampling-based preprocessing method is also proposed here to compensate for that scaling.<\/jats:p>","DOI":"10.1121\/1.2946711","type":"journal-article","created":{"date-parts":[[2008,8,5]],"date-time":"2008-08-05T22:35:14Z","timestamp":1217975714000},"page":"1038-1053","update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":43,"title":["Adaptive spatial combining for passive time-reversed communications"],"prefix":"10.1121","volume":"124","author":[{"given":"Jo\u00e3o","family":"Gomes","sequence":"first","affiliation":[{"name":"Institute for Systems and Robotics , Instituto Superior T\u00e9cnico, 1049-001 Lisboa, Portugal"}]},{"given":"Ant\u00f3nio","family":"Silva","sequence":"additional","affiliation":[{"name":"Universidade do Algarve Institute for Systems and Robotics, , Campus de Gambelas, 8005-139 Faro, Portugal"}]},{"given":"S\u00e9rgio","family":"Jesus","sequence":"additional","affiliation":[{"name":"Universidade do Algarve Institute for Systems and Robotics, , Campus de Gambelas, 8005-139 Faro, Portugal"}]}],"member":"231","reference":[{"key":"2023072803545573200_c1","doi-asserted-by":"publisher","first-page":"171","DOI":"10.1121\/1.400496","article-title":"Phase conjugation in underwater acoustics","volume":"89","year":"1991","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c2","doi-asserted-by":"publisher","first-page":"25","DOI":"10.1121\/1.423233","article-title":"Phase conjugation in the ocean: Experimental demonstration of an acoustic time-reversal mirror","volume":"103","year":"1998","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c3","doi-asserted-by":"publisher","first-page":"1450","DOI":"10.1121\/1.408482","article-title":"Acoustic pulse compression using passive phase-conjugate processing","volume":"95","year":"1994","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c4","doi-asserted-by":"publisher","first-page":"961","DOI":"10.1121\/1.413521","article-title":"Reduced-complexity spatial and temporal processing of underwater acoustic communication signals","volume":"98","year":"1995","journal-title":"J. Acoust. Soc. Am."},{"issue":"5","key":"2023072803545573200_c5","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1038\/scientificamerican1199-91","article-title":"Time-reversed acoustics","volume":"281","year":"1999","journal-title":"Sci. Am."},{"key":"2023072803545573200_c6","doi-asserted-by":"publisher","first-page":"1173","DOI":"10.1121\/1.1856411","article-title":"Retrofocusing techniques for high rate acoustic communications","volume":"117","year":"2005","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c7","doi-asserted-by":"publisher","first-page":"602","DOI":"10.1109\/JOE.2002.1040942","article-title":"An initial demonstration of underwater acoustic communication using time reversal","volume":"27","year":"2002","journal-title":"IEEE J. Ocean. Eng."},{"key":"2023072803545573200_c8","doi-asserted-by":"publisher","first-page":"852","DOI":"10.1109\/JOE.2005.862137","article-title":"Underwater acoustic communications using time reversal","volume":"30","year":"2005","journal-title":"IEEE J. Ocean. Eng."},{"key":"2023072803545573200_c9","doi-asserted-by":"publisher","first-page":"821","DOI":"10.1109\/48.972122","article-title":"Underwater acoustic communication by passive-phase conjugation: Theory and experimental results","volume":"26","year":"2001","journal-title":"IEEE J. Ocean. Eng."},{"key":"2023072803545573200_c10","article-title":"Underwater acoustic communication using a \u2018virtual\u2019 electronic time-reversal mirror approach","author":"Chevret","year":"2000"},{"key":"2023072803545573200_c11","doi-asserted-by":"publisher","first-page":"2067","DOI":"10.1121\/1.2338286","article-title":"Spatial diversity in passive time reversal communications","volume":"120","year":"2006","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c12","doi-asserted-by":"publisher","first-page":"487","DOI":"10.1109\/JOE.2006.876139","article-title":"Improvement of time-reversal communications using adaptive channel equalizers","volume":"31","year":"2006","journal-title":"IEEE J. Ocean. Eng."},{"key":"2023072803545573200_c13","doi-asserted-by":"publisher","first-page":"780","DOI":"10.1121\/1.1841692","article-title":"Intersymbol interference in underwater acoustic communications using time-reversal signal processing","volume":"117","year":"2005","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c14","doi-asserted-by":"publisher","first-page":"247","DOI":"10.1121\/1.2203602","article-title":"Point-to-point underwater acoustic communications using spread-spectrum passive phase conjugation","volume":"120","year":"2006","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c15","doi-asserted-by":"publisher","first-page":"170","DOI":"10.1109\/JOE.2005.850911","article-title":"Multiple-input-multiple-output coherent time reversal communications in a shallow-water acoustic channel","volume":"31","year":"2006","journal-title":"IEEE J. Ocean. Eng."},{"key":"2023072803545573200_c16","first-page":"1847","article-title":"Asymmetric underwater acoustic communication using a time-reversal mirror","year":"2000"},{"key":"2023072803545573200_c17","doi-asserted-by":"publisher","first-page":"824","DOI":"10.1109\/JOE.2004.831618","article-title":"Multichannel equalization by decision-directed passive phase conjugation: Experimental results","volume":"29","year":"2004","journal-title":"IEEE J. Ocean. Eng."},{"key":"2023072803545573200_c18","volume-title":"Digital Communications","year":"2000","edition":"4th ed."},{"key":"2023072803545573200_c19","doi-asserted-by":"publisher","first-page":"229","DOI":"10.1109\/JOE.2003.811895","article-title":"Temporal resolution of time-reversal and passive phase-conjugation processing","volume":"28","year":"2003","journal-title":"IEEE J. Ocean. Eng."},{"key":"2023072803545573200_c20","volume-title":"Fundamentals of Acoustic Field Theory and Space-Time Signal Processing","year":"1995"},{"key":"2023072803545573200_c21","doi-asserted-by":"publisher","first-page":"3234","DOI":"10.1121\/1.423040","article-title":"A time-reversal mirror with variable range focusing","volume":"103","year":"1998","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c22","doi-asserted-by":"publisher","first-page":"145","DOI":"10.1121\/1.1582450","article-title":"Robust time reversal focusing in the ocean","volume":"114","year":"2003","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c23","first-page":"449","article-title":"Navy applications of high frequency acoustics","year":"2004"},{"key":"2023072803545573200_c24","doi-asserted-by":"publisher","first-page":"885","DOI":"10.1109\/26.141454","article-title":"Optimum diversity combining and equalization in digital data transmission with applications to cellular mobile radio\u2014Part I: Theoretical considerations","volume":"40","year":"1992","journal-title":"IEEE Trans. Commun."},{"key":"2023072803545573200_c25","doi-asserted-by":"publisher","first-page":"1621","DOI":"10.1121\/1.408135","article-title":"Adaptive multichannel combining and equalization for underwater acoustic communications","volume":"94","year":"1993","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c26","doi-asserted-by":"publisher","first-page":"943","DOI":"10.1121\/1.413520","article-title":"Matched-signal (\u201cMESS\u201d) processing by the ocean","volume":"98","year":"1995","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c27","doi-asserted-by":"publisher","first-page":"1349","DOI":"10.1121\/1.395269","article-title":"Gaussian beam tracing for computing ocean acoustic fields","volume":"82","year":"1987","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c28","doi-asserted-by":"publisher","first-page":"312","DOI":"10.1109\/18.52478","article-title":"New criteria for blind deconvolution of nonminimum phase systems (channels)","volume":"36","year":"1990","journal-title":"IEEE Trans. Inf. Theory"},{"key":"2023072803545573200_c29","first-page":"1161","article-title":"Joint passive time reversal and multichannel equalization for underwater communications","year":"2006"},{"key":"2023072803545573200_c30","volume-title":"Fundamentals of Adaptive Filtering","year":"2003"},{"key":"2023072803545573200_c31","unstructured":"S.\u2008Jesus, C.\u2008Soares, P.\u2008Felisberto, A.\u2008Silva, L.\u2008Farinha, and C.\u2008Martins, \u201cAcoustic maritime rapid environmental assessment during the MREA\u201904 sea trial,\u201d Technical Report No. 02\u221505, Centro de Investigacao Tecnologica do Algarve, Universidade do Algarve, 2005, URL: ftp:\/\/ftp.ualg.pt\/users\/sjesus\/pubs\/B21.pdf, accessed on 6\u221528\u22152008."},{"key":"2023072803545573200_c32","doi-asserted-by":"publisher","first-page":"5","DOI":"10.1109\/49.553674","article-title":"Reduced-complexity equalization techniques for broadband wireless channels","volume":"15","year":"1997","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"2023072803545573200_c33","doi-asserted-by":"publisher","first-page":"263","DOI":"10.1121\/1.1907106","article-title":"Performance analysis of adaptive equalization for coherent acoustic communications in the time-varying ocean environment","volume":"118","year":"2002","journal-title":"J. Acoust. Soc. Am."},{"key":"2023072803545573200_c34","doi-asserted-by":"publisher","first-page":"52","DOI":"10.1109\/48.820736","article-title":"A computationally efficient doppler compensation system for underwater acoustic communications","volume":"25","year":"2000","journal-title":"IEEE J. Ocean. Eng."}],"container-title":["The Journal of the Acoustical Society of America"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.aip.org\/asa\/jasa\/article-pdf\/124\/2\/1038\/14783171\/1038_1_online.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.aip.org\/asa\/jasa\/article-pdf\/124\/2\/1038\/14783171\/1038_1_online.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,7,28]],"date-time":"2023-07-28T03:55:08Z","timestamp":1690516508000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.aip.org\/jasa\/article\/124\/2\/1038\/841335\/Adaptive-spatial-combining-for-passive-time"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2008,8,1]]},"references-count":34,"journal-issue":{"issue":"2","published-print":{"date-parts":[[2008,8,1]]}},"URL":"https:\/\/doi.org\/10.1121\/1.2946711","relation":{},"ISSN":["0001-4966","1520-8524"],"issn-type":[{"value":"0001-4966","type":"print"},{"value":"1520-8524","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[2008,8]]},"published":{"date-parts":[[2008,8,1]]}}}