{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,2,21]],"date-time":"2025-02-21T16:17:45Z","timestamp":1740154665164,"version":"3.37.3"},"reference-count":20,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2024,5,9]],"date-time":"2024-05-09T00:00:00Z","timestamp":1715212800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010453","name":"National Development and Reform Commission","doi-asserted-by":"publisher","award":["Y8C01FAC00"],"id":[{"id":"10.13039\/501100010453","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"In this paper, a matching method for altimeter and transponder signals in Sub-optimal Maximum Likelihood Estimate (SMLE) tracking mode is proposed. In the in-orbit calibration of the altimeter in SMLE tracking mode using the reconstructive transponder, it is necessary to separate the forwarding signal from the ground echo signal. At the same time, the fluctuations in the received signal of the altimeter, which are caused by the forwarding signal of the transponder, can be eliminated. The transponder generates a bias when measuring the arrival time of the transmitting signal from the altimeter and embeds this bias in both the transponder-recorded data and the altimeter-recorded data. Therefore, the two sets of data have one-to-one correspondence, and they are superimposed using the sliding sum method. Moreover, the distance between the altimeter and the transponder is a parabolic geometric relationship, and the outliers are eliminated by the fitting error minimization decision, and the transponder signal is separated from the ground echo. The final altimeter transmitting\u2013receiving signal path is obtained. Furthermore, the principles underlying this method can be used for any transponder that can adjust the response signal delay during calibration.<\/jats:p>","DOI":"10.3390\/rs16101682","type":"journal-article","created":{"date-parts":[[2024,5,9]],"date-time":"2024-05-09T14:31:16Z","timestamp":1715265076000},"page":"1682","source":"Crossref","is-referenced-by-count":0,"title":["A Signal Matching Method of In-Orbit Calibration of Altimeter in Tracking Mode Based on Transponder"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-3561-3634","authenticated-orcid":false,"given":"Qingyu","family":"Fang","sequence":"first","affiliation":[{"name":"The CAS Key Laboratory of Microwave and Remote Sensing Technology, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"University of the Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Wei","family":"Guo","sequence":"additional","affiliation":[{"name":"The CAS Key Laboratory of Microwave and Remote Sensing Technology, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China"}]},{"given":"Caiyun","family":"Wang","sequence":"additional","affiliation":[{"name":"The CAS Key Laboratory of Microwave and Remote Sensing Technology, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China"}]},{"given":"Peng","family":"Liu","sequence":"additional","affiliation":[{"name":"The CAS Key Laboratory of Microwave and Remote Sensing Technology, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China"}]},{"given":"Te","family":"Wang","sequence":"additional","affiliation":[{"name":"The CAS Key Laboratory of Microwave and Remote Sensing Technology, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China"}]},{"given":"Sijia","family":"Han","sequence":"additional","affiliation":[{"name":"The CAS Key Laboratory of Microwave and Remote Sensing Technology, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"University of the Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Shijie","family":"Yang","sequence":"additional","affiliation":[{"name":"The CAS Key Laboratory of Microwave and Remote Sensing Technology, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"University of the Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Yufei","family":"Zhang","sequence":"additional","affiliation":[{"name":"National Satellite Ocean Application Service, Beijing 100081, China"}]},{"given":"Hailong","family":"Peng","sequence":"additional","affiliation":[{"name":"National Satellite Ocean Application Service, Beijing 100081, China"}]},{"given":"Chaofei","family":"Ma","sequence":"additional","affiliation":[{"name":"National Satellite Ocean Application Service, Beijing 100081, China"}]},{"given":"Bo","family":"Mu","sequence":"additional","affiliation":[{"name":"National Satellite Ocean Application Service, Beijing 100081, China"}]}],"member":"1968","published-online":{"date-parts":[[2024,5,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"394","DOI":"10.1007\/978-3-642-79721-7_40","article-title":"The Use of Transponders in Altimetry","volume":"Volume 113","author":"Marson","year":"1995","journal-title":"Gravity and Geoid: Joint Symposium of the International Gravity Commission and the International Geoid Commission"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2458","DOI":"10.1016\/j.asr.2022.07.001","article-title":"Performance evaluation of the CDN1 altimetry Cal\/Val transponder to internal and external constituents of uncertainty","volume":"70","author":"Mertikas","year":"2022","journal-title":"Adv. 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