{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,23]],"date-time":"2026-02-23T22:17:18Z","timestamp":1771885038509,"version":"3.50.1"},"reference-count":40,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2023,9,20]],"date-time":"2023-09-20T00:00:00Z","timestamp":1695168000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Research Foundation\u2014Flanders (FWO)","award":["G0D3819N"],"award-info":[{"award-number":["G0D3819N"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Accurately positioning energy-constrained devices in indoor environments is of great interest to many professional, care, and personal applications. Hybrid RF\u2013acoustic ranging systems have shown to be a viable technology in this regard, enabling accurate distance measurements at ultra-low energy costs. However, they often suffer from self-interference due to multipaths in indoor environments. We replace the typical single loudspeaker beacons used in these systems with a phased loudspeaker array to promote the signal-to-interference-plus-noise ratio towards the tracked device. Specifically, we optimize the design of a low-cost uniform planar array (UPA) through simulation to achieve the best ranging performance using ultrasonic chirps. Furthermore, we compare the ranging performance of this optimized UPA configuration to a traditional, single-loudspeaker system. Simulations show that vertical phased-array configurations guarantee the lowest ranging errors in typical shoe-box environments, having a limited height with respect to their length and width. In these cases, a P50 ranging error of around 3 cm and P95 ranging error below 30 cm were achieved. Compared to a single-speaker system, a 10 \u00d7 2 vertical phased array was able to lower the P80 and P95 up to an order of magnitude.<\/jats:p>","DOI":"10.3390\/s23187997","type":"journal-article","created":{"date-parts":[[2023,9,20]],"date-time":"2023-09-20T22:38:45Z","timestamp":1695249525000},"page":"7997","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Accurate and Low-Power Ultrasound\u2013Radiofrequency (RF) Indoor Ranging Using MEMS Loudspeaker Arrays"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9651-3964","authenticated-orcid":false,"given":"Chesney","family":"Buyle","sequence":"first","affiliation":[{"name":"KU Leuven, WaveCore, Department of Electrical Engineering (ESAT), Ghent Technology Campus, 9000 Ghent, Belgium"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8172-9650","authenticated-orcid":false,"given":"Lieven","family":"De Strycker","sequence":"additional","affiliation":[{"name":"KU Leuven, WaveCore, Department of Electrical Engineering (ESAT), Ghent Technology Campus, 9000 Ghent, Belgium"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9158-9628","authenticated-orcid":false,"given":"Liesbet","family":"Van der Perre","sequence":"additional","affiliation":[{"name":"KU Leuven, WaveCore, Department of Electrical Engineering (ESAT), Ghent Technology Campus, 9000 Ghent, Belgium"}]}],"member":"1968","published-online":{"date-parts":[[2023,9,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Harter, A., Hopper, A., Steggles, P., Ward, A., and Webster, P. 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