{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:51:37Z","timestamp":1760147497292,"version":"build-2065373602"},"reference-count":24,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,2,9]],"date-time":"2023-02-09T00:00:00Z","timestamp":1675900800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"Multi-Parameter Integrated Inversion of Terrestrial GNSS reflection signals in the hydrology river (NSFC)","doi-asserted-by":"publisher","award":["42104031"],"award-info":[{"award-number":["42104031"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The global navigation satellite system\u2013interferometric reflectometry (GNSS-IR) was developed more than a decade ago to monitor soil moisture content (SMC); a system that is essentially finished has emerged. The standard GNSS-IR model typically considers soil to be a single layer of medium and measures the average SMC between 1 and 10 cm below the soil surface. The majority of the SMC is not distributed uniformly along the longitudinal axis. This study is based on a simulation platform and suggests a SMC-stratified measurement model that can be used to recover the SMC at different depths in the sink and reverse osmosis to address the issue that conventional techniques cannot accurately measure soil moisture at different depths. The soil moisture of each layer was assessed by utilizing the GNSS signals reflected by various soil layers, and this study employed total transmission when the vertical linearly polarized component of the electromagnetic wave was conveyed by the GNSS signal reflected by the soil. This work employed the Hilbert transform to obtain the interference signal envelope, which increases the visibility of the interference signal\u2019s \u201cnotch\u201d and reduces the burr impact of the interference signal brought on by ambient noise. The accuracy of the SMC measurement at the bottom declines due to the soil\u2019s attenuation of the GNSS signal power, but the correlation between the predetermined value and SMC retrieved by the GNSS-IR multilayer SMC measurement model similarly approached 0.92.<\/jats:p>","DOI":"10.3390\/s23041949","type":"journal-article","created":{"date-parts":[[2023,2,10]],"date-time":"2023-02-10T02:09:59Z","timestamp":1675994999000},"page":"1949","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Multilayer Model in Soil Moisture Content Retrieval Using GNSS Interferometric Reflectometry"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3013-3918","authenticated-orcid":false,"given":"Jie","family":"Li","sequence":"first","affiliation":[{"name":"Electronic Information Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xuebao","family":"Hong","sequence":"additional","affiliation":[{"name":"Electronic Information Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Feng","family":"Wang","sequence":"additional","affiliation":[{"name":"Electronic Information Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5702-5474","authenticated-orcid":false,"given":"Lei","family":"Yang","sequence":"additional","affiliation":[{"name":"Electronic Information Engineering, Beihang University, Beijing 100191, China"},{"name":"School of Information Science and Technology, University of Jinan, Jinan 250022, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dongkai","family":"Yang","sequence":"additional","affiliation":[{"name":"Electronic Information Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,2,9]]},"reference":[{"unstructured":"Egido, A., Ruffini, G., Caparrini, M., Martin-Puig, C., Farr\u00e9s, E., and Banque, X. (2008). Soil Moisture Monitorization Using GNSS Reflected Signals. arXiv.","key":"ref_1"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"525","DOI":"10.1007\/s10291-015-0462-4","article-title":"An algorithm for soil moisture estimation using GPS-interferometric reflectometry for bare and vegetated soil","volume":"20","author":"Chew","year":"2015","journal-title":"GPS Solut."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1033","DOI":"10.1109\/JSTARS.2022.3230090","article-title":"A New Algorithm for Measuring Vegetation Growth Using GNSS Interferometric Reflectometry","volume":"16","author":"Li","year":"2022","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Dahl-Jensen, T., Andersen, O., Williams, S., Helm, V., and Khan, S. (2021). GNSS-IR Measurements of Inter Annual Sea Level Variations in Thule, Greenland from 2008\u20132019. Remote Sens., 13.","key":"ref_4","DOI":"10.3390\/rs13245077"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"6555","DOI":"10.1109\/TGRS.2013.2297681","article-title":"Inverse Modeling of GPS Multipath for Snow Depth Estimation\u2014Part I: Formulation and Simulations","volume":"52","author":"Larson","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"6564","DOI":"10.1109\/TGRS.2013.2297688","article-title":"Inverse Modeling of GPS Multipath for Snow Depth Estimation\u2014Part II: Application and Validation","volume":"52","author":"Larson","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1109\/JSTARS.2009.2033608","article-title":"A Physical Model for GPS Multipath Caused by Land Reflections: Toward Bare Soil Moisture Retrievals","volume":"3","author":"Zavorotny","year":"2010","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1007\/s10291-007-0076-6","article-title":"Using GPS multipath to measure soil moisture fluctuations: Initial results","volume":"12","author":"Larson","year":"2008","journal-title":"GPS Solut."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2090","DOI":"10.1109\/LGRS.2014.2320052","article-title":"Improving the Accuracy of Soil Moisture Retrievals Using the Phase Difference of the Dual-Polarization GNSS-R Interference Patterns","volume":"11","author":"Camps","year":"2014","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"doi-asserted-by":"crossref","unstructured":"Jia, Y., and Savi, P. (2016, January 10\u201315). Polarimetric GNSS-R measurements for soil moisture and vegetation sensing. Proceedings of the 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) 2016, Beijing, China.","key":"ref_10","DOI":"10.1109\/IGARSS.2016.7730370"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"4767","DOI":"10.5194\/hess-21-4767-2017","article-title":"Use of reflected GNSS SNR data to retrieve either soil moisture or vegetation height from a wheat crop","volume":"21","author":"Zhang","year":"2017","journal-title":"Hydrol. Earth Syst. Sci."},{"doi-asserted-by":"crossref","unstructured":"Zribi, M., Motte, E., Baghdadi, N., Baup, F., Dayau, S., Fanise, P., Guyon, D., Huc, M., and Wigneron, J.P. (2018). Potential Applications of GNSS-R Observations over Agricultural Areas: Results from the GLORI Airborne Campaign. Remote Sens., 10.","key":"ref_12","DOI":"10.3390\/rs10081245"},{"doi-asserted-by":"crossref","unstructured":"Camps, A., Park, H., Castellvi Esturi, J., Corbera, J., and Ascaso, E. (2020). Single-Pass Soil Moisture Retrievals Using GNSS-R: Lessons Learned. Remote Sens., 12.","key":"ref_13","DOI":"10.3390\/rs12122064"},{"doi-asserted-by":"crossref","unstructured":"Shekhar, S., Prakash, R., Pandey, D., Vidyarthi, A., Tyagi, S., Putrevu, D., and Misra, A. (2021, January 11\u201316). Sensitivity of Multipath Peak Frequency of Navigation with Indian Constellation (NavIC) towards Surface Soil Moisture over Bare Land. Proceedings of the 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, Brussels, Belgium.","key":"ref_14","DOI":"10.1109\/IGARSS47720.2021.9554474"},{"doi-asserted-by":"crossref","unstructured":"Koch, F., Schlenz, F., Prasch, M., Appel, F., Ruf, T., and Mauser, W. (2016). Soil Moisture Retrieval Based on GPS Signal Strength Attenuation. Water, 8.","key":"ref_15","DOI":"10.3390\/w8070276"},{"key":"ref_16","first-page":"1","article-title":"GNSS Pseudo Interference Reflectometry for Ground-Based Soil Moisture Remote Sensing: Theory and Simulations","volume":"19","author":"Hong","year":"2021","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"111881","DOI":"10.1016\/j.measurement.2022.111881","article-title":"GNSS-IR Multisatellite Combination for Soil Moisture Retrieval Based on Wavelet Analysis Considering Detection and Repair of Abnormal Phases","volume":"203","author":"Yueji","year":"2022","journal-title":"Measurement"},{"unstructured":"Anyaegbu, E. (2006, January 26\u201329). A frequency domain quasi-open tracking loop for GNSS receivers. Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation, Fort Worth, TX, USA.","key":"ref_18"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"103011","DOI":"10.1016\/j.dsp.2021.103011","article-title":"Feasibility of retrieving effective reflector height using GNSS-IR from a single-frequency android smartphone SNR data","volume":"112","author":"Altuntas","year":"2021","journal-title":"Digit. Signal Process."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1048","DOI":"10.1109\/JSTARS.2020.3041162","article-title":"Integration of Smartphones Into Small Unmanned Aircraft Systems to Sense Water in Soil by Using Reflected GPS Signals","volume":"14","author":"Kurum","year":"2020","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_21","first-page":"1","article-title":"Review of crop growth and soil moisture monitoring from a ground-based instrument implementing the Interference Pattern GNSS-R Technique","volume":"46","author":"Bosch","year":"2011","journal-title":"Radio Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1501","DOI":"10.1109\/JSTARS.2014.2300116","article-title":"Normalized Microwave Reflection Index: A Vegetation Measurement Derived From GPS Networks","volume":"7","author":"Larson","year":"2014","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2797","DOI":"10.1029\/1998JB900033","article-title":"Noise in GPS coordinate time series","volume":"104","author":"Mao","year":"1999","journal-title":"J. Geophys. Res."},{"key":"ref_24","first-page":"151","article-title":"GPS Signal to Noise Ratio Analysis and Using for Real-Time Tide Monitoring","volume":"Volume I","author":"Sun","year":"2017","journal-title":"Proceedings of the China Satellite Navigation Conference (CSNC) 2017"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/4\/1949\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T18:28:55Z","timestamp":1760120935000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/4\/1949"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,2,9]]},"references-count":24,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2023,2]]}},"alternative-id":["s23041949"],"URL":"https:\/\/doi.org\/10.3390\/s23041949","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2023,2,9]]}}}