Hybrid Ultrasound/Radio Real Time Location Systems
I have been a member of the Scientific Committee of the Indoor Positioning and Indoor Navigation (IPIN) Conference for the last years (2012-2015). In 2012 and 2013 I also moderated the industry panel debates at the IPIN conferences.
Our work in indoor positioning is mainly on ultrasound-based systems and some of the earliest papers below as well as some of the patents form the basis for the ultrasound indoor positioning system described in Scientific American, January 2008: A Positioning System That Goes Where GPS Can't. The ultrasound-alone system was commercialized by Sonitor Technologies and has later also been integrated with Aeroscout's Wi-Fi solutions as well as Sonitor's own Wi-Fi solution.
The ultrasound-alone system is superb in pinpointing the precise room where an object is localized. On the other hand it requires infrastructure in every room. On the other hand Wi-Fi positioning systems are not so good at achieving 100% accuracy in pin-pointing rooms in a building, and may erroneously locate 5-10 % of the positions outside the room. The best system is obtained by combining them in order to benefit from the best properties of both Wi-Fi (radio) and ultrasound.
The photo shows an experimental array used for forming steered ultrasound beams for zones inside a room.
- T. Dahl, J. Ealo, H. J. Bang, S. Holm, P. Khuri-Yakub, Applications of airborne ultrasound in human-computer interaction, Ultrasonics, Sept 2014.
- S. Holm, "Ultrasound positioning based on time-of-flight and signal strength," in Proc. 2012 Int. Conf. Indoor Positioning and Indoor Navigation, Sydney, Nov. 2012
- C. Medina, S: Holm, J. C: Segura, "Feasibility of ultrasound positioning based on signal strength," in Proc. 2012 Int. Conf. Indoor Positioning and Indoor Navigation, Sydney, Nov. 2012
- E. García, S. Holm, J. J. García, J. Ureña, "Link Budget for Low Bandwidth and Coded Ultrasonic Indoor Location Systems ", in Proc. Int Conf. Indoor Positioning and Indoor Navigation, Portugal, Sept. 2011.
- E. García, S. Holm, J. J. García, J. Ureña, Enlace ultrasónico para LPS Codificado versus LPS de Bajo Ancho de Banda, Seminario Anual de Automática, Electrónica Industrial e Instrumentación, Badajoz, Spain, July 2011.
- S. Holm, C.-I. Nilsen, "Robust ultrasonic indoor positioning using transmitter arrays," in Proc. Int. Conf. on Indoor Positioning and Indoor Navigation, Zurich, Sept.. 2010.
- S. Holm, "Hybrid ultrasound-RFID indoor positioning: Combining the best of both worlds," IEEE Int. Conf. RFID, Orlando, FL April 27-28, 2009.
- S. Holm, "Airborne Ultrasound Data Communications: The Core of an Indoor Positioning System," in Proc IEEE Ultrasonics Symposium, Rotterdam, Netherlands, Sep. 2005.
- S. Holm, O.B. Hovind, S. Rostad, R. Holm, "Indoor data communications using airborne ultrasound," in Proc. IEEE Int. Conf. Acoust., Speech, Sign. Proc., Philadelphia, PA, March 2005.
- A. L. L. Ramos, S. Holm, S. Gudvangen, R. Otterlei, "A Spectral Subtraction Based Algorithm for Real-time Noise Cancellation with Application to Gunshot Acoustics," Int. J. Electron. and Telecomm., vol 59 (no 1), 2013.
- A. L. L. Ramos, S. Holm, S. Gudvangen, R. Otterlei, A Modified Spectral Subtraction Algorithm for Real-time Noise Reduction Applied to Gunshot Acoustics, Int. Conf. Signals and Electronic Systems, Wroclaw, Poland, Sept 2012.
- A. L. L. Ramos, S. Holm, S. Gudvangen, R. Otterlei, Real-time Vehicle Noise Cancellation Techniques for Gunshot Acoustics, SPIE Defense, Security + Sensing, Baltimore, MD, Apr. 2012.
- A. L. L. Ramos, S. Holm, S. Gudvangen, R. Otterlei, Delay-and-sum Beamforming for Direction of Arrival Estimation Applied to Gunshot Acoustics, SPIE Defense, Security + Sensing, Orlando, Florida, Apr. 2011.