{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,4]],"date-time":"2025-11-04T23:31:30Z","timestamp":1762299090093,"version":"build-2065373602"},"reference-count":44,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2019,8,28]],"date-time":"2019-08-28T00:00:00Z","timestamp":1566950400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Radio Frequency Interference (RFI) is currently a major problem in Communications and Earth Observation, but it is even more dramatic in Microwave Radiometry because of the low power levels of the received signals. Its impact has been attested in several Earth Observation missions. On-board mitigation systems are becoming a requirement to detect and remove affected measurements, increasing thus radiometric accuracy and spatial coverage. However, RFI mitigation methods have not been tested yet in the context of some particular radiometer topologies, which rely on the use of coarsely quantized streams of data. In this study, the impact of quantization and sampling in the performance of several known RFI mitigation algorithms is studied under different conditions. It will be demonstrated that in the presence of clipping, quantization changes fundamentally the time-frequency properties of the contaminated signal, strongly impairing the performance of most mitigation methods. Important design considerations are derived from this analysis that must be taken into account when defining the architecture of future instruments. In particular, the use of Automatic Gain Control (AGC) systems is proposed, and its limitations are discussed.<\/jats:p>","DOI":"10.3390\/rs11172023","type":"journal-article","created":{"date-parts":[[2019,8,28]],"date-time":"2019-08-28T11:23:18Z","timestamp":1566991398000},"page":"2023","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Impact of Signal Quantization on the Performance of RFI Mitigation Algorithms"],"prefix":"10.3390","volume":"11","author":[{"given":"Ra\u00fal","family":"D\u00edez-Garc\u00eda","sequence":"first","affiliation":[{"name":"CommSensLab\u2013\u2018Mar\u00eda de Maeztu\u2019 unit, Campus Nord, Edifici D4, Universitat Polit\u00e8cnica de Catalunya\u2014BarcelonaTech and CTE\/UPC, 08034 Barcelona, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9514-4992","authenticated-orcid":false,"given":"Adriano","family":"Camps","sequence":"additional","affiliation":[{"name":"CommSensLab\u2013\u2018Mar\u00eda de Maeztu\u2019 unit, Campus Nord, Edifici D4, Universitat Polit\u00e8cnica de Catalunya\u2014BarcelonaTech and CTE\/UPC, 08034 Barcelona, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2019,8,28]]},"reference":[{"key":"ref_1","unstructured":"National Research Council (2010). Spectrum Management for Science in the 21st Century, The National Academies Press."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Draper, D., and Newell, D. (2015, January 26\u201331). An assessment of radio frequency interference using the GPM Microwave Imager. Proceedings of the 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Milan, Italy.","DOI":"10.1109\/IGARSS.2015.7326998"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1109\/MGRS.2014.2320879","article-title":"Passive Remote Sensing and Radio Frequency Interference (RFI): An Overview of Spectrum Allocations and RFI Management Algorithms","volume":"2","author":"Misra","year":"2014","journal-title":"IEEE Geosci. Remote Sens. Mag."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3742","DOI":"10.1109\/TGRS.2009.2031104","article-title":"Microwave radiometer radio-frequency interference detection algorithms: A comparative study","volume":"47","author":"Misra","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"765","DOI":"10.1080\/01621459.1954.10501232","article-title":"A test of goodness of fit","volume":"49","author":"Anderson","year":"1954","journal-title":"J. Am. Stat. Assoc."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"163","DOI":"10.2307\/1403192","article-title":"A test for normality of observations and regression residuals","volume":"55","author":"Jarque","year":"1987","journal-title":"Int. Stat. Rev. Revue Int. Stat."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"316","DOI":"10.1080\/00031305.1990.10475751","article-title":"A suggestion for using powerful and informative tests of normality","volume":"44","author":"Belanger","year":"1990","journal-title":"Am. Stat."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1080\/01621459.1967.10482916","article-title":"On the Kolmogorov-Smirnov test for normality with mean and variance unknown","volume":"62","author":"Lilliefors","year":"1967","journal-title":"J. Am. Stat. Assoc."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"591","DOI":"10.1093\/biomet\/52.3-4.591","article-title":"An analysis of variance test for normality (complete samples)","volume":"52","author":"Shapiro","year":"1965","journal-title":"Biometrika"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1093\/biomet\/67.2.455","article-title":"A simple test for normality against asymmetric alternatives","volume":"67","author":"Lin","year":"1980","journal-title":"Biometrika"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Kristensen, S.S., Balling, J., Skou, N., and S\u00f8bj\u0153rg, S.S. (2012, January 22\u201327). RFI in SMOS data detected by polarimetry. Proceedings of the 2012 IEEE International Geoscience and Remote Sensing Symposium, Munich, Germany.","DOI":"10.1109\/IGARSS.2012.6350593"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"155","DOI":"10.3390\/a4030155","article-title":"Radio-frequency interference detection and mitigation algorithms for synthetic aperture radiometers","volume":"4","author":"Camps","year":"2011","journal-title":"Algorithms"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1311","DOI":"10.1109\/TGRS.2015.2477435","article-title":"Improved MUSIC-based SMOS RFI source detection and geolocation algorithm","volume":"54","author":"Park","year":"2015","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Oliva, R. (2018, January 22\u201327). Mitigation of SMOS RFI Contamination Based on BT Frequency Extrapolation. Proceedings of the IGARSS 2018\u20142018 IEEE International Geoscience and Remote Sensing Symposium, Valencia, Spain.","DOI":"10.1109\/IGARSS.2018.8518532"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1086\/321780","article-title":"Removal of the GLONASS C\/A signal from OH spectral line observations using a parametric modeling technique","volume":"135","author":"Ellingson","year":"2001","journal-title":"Astrophys. J. Suppl. Ser."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2004RS003155","article-title":"Examination of a simple pulse-blanking technique for radio frequency interference mitigation","volume":"40","author":"Niamsuwan","year":"2005","journal-title":"Radio Sci."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Bradley, D., Brambora, C., Wong, M.E., Miles, L., Durachka, D., Farmer, B., Mohammed, P., Piepmier, J., Medeiros, J., and Martin, N. (2010, January 25\u201330). Radio-frequency interference (RFI) mitigation for the soil moisture active\/passive (SMAP) radiometer. Proceedings of the 2010 IEEE International Geoscience and Remote Sensing Symposium, Honolulu, HI, USA.","DOI":"10.1109\/IGARSS.2010.5652482"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"239","DOI":"10.3390\/a4040239","article-title":"Radio frequency interference detection and mitigation algorithms based on spectrogram analysis","volume":"4","author":"Tarongi","year":"2011","journal-title":"Algorithms"},{"key":"ref_19","unstructured":"Querol, J. (2018). Radio Frequency Interference Detection and Mitigation Techniques for Navigation and Earth Observation. [Ph.D. Thesis, Universitat Polit\u00e8cnica de Catalunya]."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3191","DOI":"10.1109\/TGRS.2018.2882306","article-title":"Development of an On-Board Wide-Band Processor for Radio Frequency Interference Detection and Filtering","volume":"57","author":"Misra","year":"2018","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Lahtinen, J., Kovanen, A., Lehtinen, K., Kristensen, S.S., S\u00f8bj\u00e6rg, S.S., Skou, N., and D\u2019Addio, S. (2018, January 27\u201330). Real-Time RFI Processor for the Next Generation Satellite Radiometers. Proceedings of the 2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad), Cambridge, MA, USA.","DOI":"10.1109\/MICRORAD.2018.8430725"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1658","DOI":"10.1109\/JSTARS.2019.2910640","article-title":"Real-Time RFI Processor for Future Spaceborne Microwave Radiometers","volume":"12","author":"Lahtinen","year":"2019","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"594","DOI":"10.1109\/TGRS.2007.914809","article-title":"SMOS: The Payload","volume":"46","author":"McMullan","year":"2008","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Bosch-Lluis, X., Ramos-P\u00e9rez, I., Camps, A., Rodriguez-Alvarez, N., Marchan-Hernandez, J.F., Valencia, E., Nieto, J.M., and Guerrero, M.A. (2009, January 12\u201317). Digital beamforming analysis and performance for a digital L-band Pseudo-correlation radiometer. Proceedings of the 2009 IEEE International Geoscience and Remote Sensing Symposium, Cape Town, South Africa.","DOI":"10.1109\/IGARSS.2009.5417702"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1566","DOI":"10.1109\/36.934088","article-title":"A two-dimensional Doppler-radiometer for earth observation","volume":"39","author":"Camps","year":"2001","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Ruf, C., and Gross, S. (2010, January 23\u201328). Digital radiometers for earth science. Proceedings of the 2010 IEEE MTT-S International Microwave Symposium, Anaheim, CA, USA.","DOI":"10.1109\/MWSYM.2010.5517441"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Bosch-Lluis, X., Camps, A., Marchan-Hernandez, J., Ramos-P\u00e9rez, I., Prehn, R., Izquierdo, B., Banque, X., and Yeste, J. (August, January 31). FPGA-based implementation of a polarimetric radiometer with digital beamforming. Proceedings of the 2006 IEEE International Symposium on Geoscience and Remote Sensing, Denver, CO, USA.","DOI":"10.1109\/IGARSS.2006.304"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"775","DOI":"10.1029\/RS008i008p00775","article-title":"Digital-correlation techniques in radio science","volume":"8","author":"Hagen","year":"1973","journal-title":"Radio Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"6066","DOI":"10.3390\/s110606066","article-title":"A general analysis of the impact of digitization in microwave correlation radiometers","volume":"11","author":"Camps","year":"2011","journal-title":"Sensors"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Ruf, C., Misra, S., Gross, S., and De Roo, R. (August, January 31). Detection of RFI by its amplitude probability distribution. Proceedings of the 2006 IEEE International Symposium on Geoscience and Remote Sensing, Denver, CO, USA.","DOI":"10.1109\/IGARSS.2006.592"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"694","DOI":"10.1109\/TGRS.2005.861411","article-title":"RFI detection and mitigation for microwave radiometry with an agile digital detector","volume":"44","author":"Ruf","year":"2006","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"3129","DOI":"10.1109\/TGRS.2008.916483","article-title":"A demonstration of the effects of digitization on the calculation of kurtosis for the detection of RFI in microwave radiometry","volume":"46","author":"Misra","year":"2008","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Weber, R., and Faye, C. (1998). Coarsely Quantized Spectral Estimation of radio Astronomic Sources in Highly Corruptive Environments. Signal Analysis and Prediction, Springer.","DOI":"10.1007\/978-1-4612-1768-8_7"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Nita, G.M., Gary, D.E., and Hellbourg, G. (2016, January 17\u201320). Spectral kurtosis statistics of quantized signals. Proceedings of the 2016 Radio Frequency Interference (RFI), Socorro, NM, USA.","DOI":"10.1109\/RFINT.2016.7833535"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1109\/PROC.1966.4567","article-title":"The spectrum of clipped noise","volume":"54","author":"Middleton","year":"1966","journal-title":"Proc. IEEE"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"3096","DOI":"10.1109\/JSTARS.2017.2654541","article-title":"Performance Assessment of Time-Frequency RFI Mitigation Techniques in Microwave Radiometry","volume":"10","author":"Querol","year":"2017","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"3672","DOI":"10.1109\/TGRS.2007.903680","article-title":"Time and frequency blanking for radio-frequency interference mitigation in microwave radiometry","volume":"45","author":"Guner","year":"2007","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Forte, G., Querol, J., Park, H., and Camps, A. (2013, January 21\u201326). Digital back-end for RFI detection and mitigation in earth observation. Proceedings of the 2013 IEEE International Geoscience and Remote Sensing Symposium-IGARSS, Melbourne, Australia.","DOI":"10.1109\/IGARSS.2013.6723177"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1248","DOI":"10.3390\/a2031248","article-title":"RFI mitigation in microwave radiometry using wavelets","volume":"2","author":"Camps","year":"2009","journal-title":"Algorithms"},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Querol, J., Alonso-Arroyo, A., Onrubia, R., Pascual, D., and Camps, A. (2015, January 26\u201331). Assessment of back-end RFI mitigation techniques in passive remote sensing. Proceedings of the 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Milan, Italy.","DOI":"10.1109\/IGARSS.2015.7326890"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"353","DOI":"10.1109\/19.492748","article-title":"Statistical theory of quantization","volume":"45","author":"Widrow","year":"1996","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Widrow, B., and Koll\u00e1r, I. (2008). Quantization Noise, Cambridge University Press.","DOI":"10.1017\/CBO9780511754661"},{"key":"ref_43","first-page":"173","article-title":"Statistical theory of quantization: Results and limits","volume":"28","author":"Kollar","year":"1984","journal-title":"Period. Polytech. Electr. Eng."},{"key":"ref_44","unstructured":"Leon-Garcia, A. (1994). Probability and Random Processes for Electrical Engineering: Student Solutions Manual, Pearson Education India."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/17\/2023\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:14:40Z","timestamp":1760188480000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/17\/2023"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,8,28]]},"references-count":44,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2019,9]]}},"alternative-id":["rs11172023"],"URL":"https:\/\/doi.org\/10.3390\/rs11172023","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2019,8,28]]}}}