{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:47:46Z","timestamp":1760240866273,"version":"build-2065373602"},"reference-count":18,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2019,10,15]],"date-time":"2019-10-15T00:00:00Z","timestamp":1571097600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The wideband electromagnetic imaging system using a parabolic reflector is a device for detecting and locating electromagnetic interference sources (EMIS). When multiple coherent interference sources are detected, the confusion will occur due to the coherent noise that is caused by interference phenomenons. Previous works have removed the coherent noise by using iterative techniques, but they face a limitation in removing noise in that the coherent noise pattern changes with frequency in a wideband. In this paper, an adaptive homomorphic filtering is proposed to overcome the limitations of conventional methods from 1 GHz\u20136 GHz. The coherent noise existing in the several electromagnetic images is studied, and it is confirmed that the variation of the coherent noise pattern is related to the position, the number, and the frequency of EMIS. Then, by analyzing the probability density of coherent noise intensity, an adaptive Gaussian filter is carefully designed to remove coherent noise. The filter parameters are selected by the minimum description length criterion (MDL) to apply to compute directly the local amount of Gaussian smoothing at each pixel of each image. The results of the experiments and simulations demonstrate that the proposed method can significantly improve the quality of electromagnetic images in terms of maximum sidelobe level (MSL) by 15 dB and dynamic range (DR) of the system over 20 dB, compared with conventional narrowband denoising methods.<\/jats:p>","DOI":"10.3390\/s19204469","type":"journal-article","created":{"date-parts":[[2019,10,16]],"date-time":"2019-10-16T03:32:54Z","timestamp":1571196774000},"page":"4469","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Coherent Noise Suppression Using Adaptive Homomorphic Filtering for Wideband Electromagnetic Imaging System"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9715-2515","authenticated-orcid":false,"given":"Yanju","family":"Zhu","sequence":"first","affiliation":[{"name":"School of Electronic and Information Engineering, Beihang University, Beijing 110191, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9387-9074","authenticated-orcid":false,"given":"Shuguo","family":"Xie","sequence":"additional","affiliation":[{"name":"School of Electronic and Information Engineering, Beihang University, Beijing 110191, China"}]}],"member":"1968","published-online":{"date-parts":[[2019,10,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Xie, S., Wang, T., Hao, X., Yang, M., Zhu, Y., and Li, Y. (2019). Localization and Frequency Identification of Large-Range Wide-band Electromagnetic Interference Sources in Electromagnetic Imaging System. Electronics, 8.","DOI":"10.3390\/electronics8050499"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1720","DOI":"10.1109\/TIP.2010.2045029","article-title":"Multiplicative Noise Removal Using Variable Splitting and Constrained Optimization","volume":"7","author":"Bioucas","year":"2010","journal-title":"IEEE Trans. Image Process."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"518","DOI":"10.1016\/j.acha.2015.10.003","article-title":"Multiplicative noise removal in imaging: An exp-model and its fixed-point proximity algorithm","volume":"41","author":"Jian","year":"2016","journal-title":"Appl. Comput. Harmonic Anal."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"160","DOI":"10.1016\/j.sigpro.2017.01.032","article-title":"Sparse Analysis Model Based Multiplicative Noise Removal with Enhanced Regularization","volume":"137","author":"Dong","year":"2017","journal-title":"Signal Process."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"6257","DOI":"10.1109\/TGRS.2013.2295824","article-title":"Subspace-Based Technique for Speckle Noise Reduction in SAR Images","volume":"52","author":"Norashikin","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_6","unstructured":"Devanand, B. (2015). Additive And Multiplicative Noise Removal From Medical Images Using Bivariate Thresholding by Dual Tree Complex Wavelet Transform, Department of EEE Faculty of Engineering and Technology of Shri Shankaracharya Technical Campus."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4389","DOI":"10.1109\/TIP.2017.2713946","article-title":"MuLoG, or How to Apply Gaussian Denoisers to Multi-Channel SAR Speckle Reduction?","volume":"26","author":"Charles","year":"2017","journal-title":"IEEE Trans. Image Process."},{"key":"ref_8","first-page":"3552","article-title":"Ratio-based Multi-temporal SAR Images Denoising: RABASAR","volume":"6","author":"Weiying","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1007\/s00340-018-7101-z","article-title":"Apodization for improving the two-point resolution of coherent optical systems with defect of focus","volume":"124","author":"Andra","year":"2018","journal-title":"Appl. Phys. B"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1688","DOI":"10.1109\/PROC.1965.4341","article-title":"Some effects of target-induced scintillation on optical radar performance","volume":"53","author":"Goodman","year":"1965","journal-title":"Proc. IEEE"},{"key":"ref_11","first-page":"9","article-title":"Statistical properties of laser speckle patterns","volume":"Volume 9","author":"Goodman","year":"1975","journal-title":"Laser Speckle and Related Phenomena"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1160","DOI":"10.1364\/JOSA.66.001160","article-title":"Properties of speckle integrated with a finite aperture and logarithmically transformed","volume":"66","author":"Arsenault","year":"1976","journal-title":"J. Opt. Soc. Am."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"746","DOI":"10.1198\/016214501753168398","article-title":"Model Selection and the Principle of Minimum Description Length","volume":"96","author":"Hansen","year":"2001","journal-title":"J. Am. Stat. Assoc."},{"key":"ref_14","unstructured":"Giovani, G. (2000, January 11\u201314). Local Smoothness in Terms of Variance: The Adaptive Gaussian Filter. Proceedings of the British Machine Vision Conference 2000, BMVC 2000, Bristol, UK."},{"key":"ref_15","first-page":"1","article-title":"Spherical Reverse Beamforming for Sound Source Localization Based on the Inverse Method","volume":"19","author":"Chao","year":"2019","journal-title":"Sensors"},{"key":"ref_16","first-page":"1","article-title":"Printed Antenna Arrays with High Side Lobe Suppression","volume":"6","author":"Aleksandar","year":"2008","journal-title":"Act. Passiv. Electron. Compon."},{"key":"ref_17","first-page":"1","article-title":"An Antenna Array Sidelobe Level Reduction Approach through Invasive Weed Optimization","volume":"4","author":"Geng","year":"2018","journal-title":"Int. J. Antennas Propag."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1109\/TAP.2007.913176","article-title":"Optimized Element Spacing for Low Sidelobe Concentric Ring Arrays","volume":"56","author":"Randy","year":"2008","journal-title":"IEEE Trans. Antennas Propag."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/20\/4469\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:26:29Z","timestamp":1760189189000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/20\/4469"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,10,15]]},"references-count":18,"journal-issue":{"issue":"20","published-online":{"date-parts":[[2019,10]]}},"alternative-id":["s19204469"],"URL":"https:\/\/doi.org\/10.3390\/s19204469","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2019,10,15]]}}}