{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T01:12:09Z","timestamp":1782436329909,"version":"3.54.5"},"reference-count":25,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2024,1,16]],"date-time":"2024-01-16T00:00:00Z","timestamp":1705363200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2023YFC2907104"],"award-info":[{"award-number":["2023YFC2907104"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["42130810"],"award-info":[{"award-number":["42130810"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["202301AS070008"],"award-info":[{"award-number":["202301AS070008"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2023YFC2907104"],"award-info":[{"award-number":["2023YFC2907104"]}],"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":["42130810"],"award-info":[{"award-number":["42130810"]}],"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":["202301AS070008"],"award-info":[{"award-number":["202301AS070008"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Yunnan Fundamental Research Projects","award":["2023YFC2907104"],"award-info":[{"award-number":["2023YFC2907104"]}]},{"name":"Yunnan Fundamental Research Projects","award":["42130810"],"award-info":[{"award-number":["42130810"]}]},{"name":"Yunnan Fundamental Research Projects","award":["202301AS070008"],"award-info":[{"award-number":["202301AS070008"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Low-resistivity objects produce eddy currents when excited with electromagnetic waves of a certain frequency and then generate an eddy electromagnetic field. A portable frequency-domain electromagnetic exploration system can be used to identify this eddy electromagnetic field, and then the low-resistivity objects can be positioned. At present, portable frequency-domain electromagnetic method (FEM) exploration systems use analog signal compensation, and the sounding depth is generally calculated using empirical formulas. In order to improve the rationality of signal compensation, this paper puts forward a digital signal compensation technology, including a device design, an information extraction method, and a primary field calibration method, and makes an exploration prototype based on the digital signal compensation technology. Using 10 nV as the minimum potential detection capability, the sounding depth of the portable FEM was analyzed, and it was found that when investigating a target with the same depth, a lower frequency required a larger emission current. If this could not be met, the sounding depth became smaller, and a phenomenon appeared in which the lower the operating frequency, the smaller the sounding depth. Through the detection of known underground garages, the apparent conductivity and normalized secondary field anomalies with higher sensitivity were obtained, which indicates that the detection system based on the digital signal compensation technology is effective in practical exploration. Via long-distance detection experiments on cars, it was confirmed that the sounding depth of the portable multi-frequency FEM in practical work indeed decreases with a decrease in the operating frequency.<\/jats:p>","DOI":"10.3390\/s24020566","type":"journal-article","created":{"date-parts":[[2024,1,16]],"date-time":"2024-01-16T08:12:37Z","timestamp":1705392757000},"page":"566","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Digital Signal Compensation and Sounding Depth Analysis of Portable Frequency-Domain Electromagnetic Exploration System"],"prefix":"10.3390","volume":"24","author":[{"given":"Huipeng","family":"Liu","sequence":"first","affiliation":[{"name":"School of Geosciences and Info-Physics, Central South University, Changsha 410083, China"},{"name":"Yunnan Key Laboratory of Geotechnical Engineering and Geohazards, Kunming 650051, China"},{"name":"Kunming Prospecting Design Institute of China Nonferrous Metal Industry Co., Ltd., Kunming 650051, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9395-4150","authenticated-orcid":false,"given":"Jianxin","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Geosciences and Info-Physics, Central South University, Changsha 410083, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fang","family":"Wang","sequence":"additional","affiliation":[{"name":"Yunnan Key Laboratory of Geotechnical Engineering and Geohazards, Kunming 650051, China"},{"name":"Kunming Prospecting Design Institute of China Nonferrous Metal Industry Co., Ltd., Kunming 650051, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leiyun","family":"Qian","sequence":"additional","affiliation":[{"name":"Yunnan Key Laboratory of Geotechnical Engineering and Geohazards, Kunming 650051, China"},{"name":"Kunming Prospecting Design Institute of China Nonferrous Metal Industry Co., Ltd., Kunming 650051, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2937-4658","authenticated-orcid":false,"given":"Rong","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Geosciences and Info-Physics, Central South University, Changsha 410083, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,1,16]]},"reference":[{"key":"ref_1","first-page":"4352","article-title":"Research status and development trend of portable near-surface FDEM instrument","volume":"60","author":"Liu","year":"2017","journal-title":"Chin. 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