In this article, a time-of-flight detection technique in the frequency domain is described for an ultrasonic Local Positioning System (LPS) based on encoded beacons. Beacon transmissions have been synchronized and become simultaneous by means of the DS-CDMA (Direct-Sequence Code Division Multiple Access) technique. Every beacon has been associated to a 255-bit Kasami code. The detection of signal arrival instant at the receiver, from which the distance to each beacon can be obtained, is based on the application of the Generalized Cross-Correlation (GCC), by using the cross-spectral density between the received signal and the sequence to be detected. Prior filtering to enhance the frequency components around the carrier frequency (40 kHz) has improved estimations when obtaining the correlation function maximum, which implies an improvement in distance measurement precision. Positioning has been achieved by using hyperbolic trilateration, based on the Time Differences of Arrival (TDOA) between a reference beacon and the others.
References
[1]
Kolodziej, K.W.; Hjelm, J. Local Position Systems—LBS Applications and Services; CRC: Boca Raton, FL, USA, 2006.
[2]
Sukaviriya, N.; Podlaseck, M.; Kjeldsen, R.; Levas, A.; Pingali, G.; Pinhanez, C. Embedding interactions in a retail store environment: The design and lessons learned. Proceedings of the 9th IFIP International Conference on Human-Computer Interaction, Zurich, Switzerland, 1–5 September 2003.
[3]
K？lin, T.; Müller, L.; Rüegg, M. Evaluating the behaviour of museum visitors using RFID. Proceedings of the International Conference on Indoor Positioning and Indoor Navigation (IPIN), Zurich, Switzerland, 15–17 September 2010.
[4]
Rob, D.W.; Griesser, M.; Gereke, A. Realizing an emergency call system on a real-time location application platform for healthcare. Proceedings of the International Conference on Indoor Positioning and Indoor Navigation (IPIN), Zurich, Switzerland, 15–17 September 2010.
[5]
Choi, B.S.; Lee, J.W.; Lee, J.J.; Park, K.T. A hierarchical algorithm for indoor mobile robots localization using RFID sensor fusion. IEEE Trans. Ind. Electron 2011, 58, 2226–2235, doi:10.1109/TIE.2011.2109330.
[6]
Manley, E.D.; Nahas, H.A.; Deogun, J.S. Localization and tracking in sensor systems. Proceedings of the IEEE International Conference on Sensor Networks, Ubiquitous and Trustworthy Computing, SUTC ’06, Taiwan, 5–7 June 2006; pp. 1–6.
[7]
Gigl, T.; Janssen, G.J.M.; Dizdarevic, V.; Witrisal, K.; Irahhauten, Z. Analysis of a UWB indoor positioning system based on received signal strength. Proceedings of the 4th Positioning, Navigation and Communication WPNC ’07, Hannover, Germany, 22 March 2007; pp. 97–101.
[8]
Jimenez, A.R.; Seco, F. Precise localisation of archaeological findings with a new ultrasonic 3D positioning sensor. Sens. Actuat. A Phys 2005, 123–124, 224–233.
[9]
Hazas, M.; Ward, A. A novel broadband ultrasonic location system. Proceedings of the 4th International Conference on Ubiquitous Computing, UbiComp ’02, G？teborg, Sweden, September 2002; pp. 264–280.
[10]
Ouzid, O.M.; Tian, G.Y.; Neasham, J.; Sharif, B. Investigation of sampling frequency requirements for acoustic source localisation using wireless sensor networks. Appl. Acoust 2011, doi:10.1016/j.apacoust.2010.12.013.
[11]
Villadangos, J.M.; Ure？a, J.; Mazo, M.; Hernández, A.; de Marziani, C.; Pérez, M.C.; álvarez, F.; Jesús García, J.; Jiménez, A.; Gude, I. Ultrasonic local positioning system with large covered area. Proceedings of the IEEE International Symposium on Intelligent Signal Processing, WISP ’07, Alcala de Henares, Spain, 3–5 October 2007; pp. 1–6.
[12]
Perez, M.C.; Ure？a, J.; Hernandez, A.; Jimenez, A.; Ruiz, D.; Alvarez, F.J.; de Marziani, C. Performance comparison of different codes in an ultrasonic positioning system using DS-CDMA. Proceedings of the IEEE International Symposium on Intelligent Signal Processing, WISP ’09, Budapest, Hungary, 26–28 August 2009; pp. 125–130.
[13]
Jiménez, A.; Hernández, A.; Ure？a, J.; Alonso, M.; de Marziani, C.; Pérez, M.C.; Mazo, M.; Villadangos, J.M.; García, J.J.; álvarez, F. FPGA-based implementation of an ultrasonic beacon for a local positioning system. Proceedings of the 32nd IEEE International Annual Conference on Industrial Electronics, Control and Instrumentation, IECON ’06, Paris, France, 6–10 November 2006; 1, pp. 43–46.
[14]
Villadangos, J.M.; Ure？a, J.; Mazo, M.; Hernández, A.; de Marziani, C.; Jiménez, A.; álvarez, F. Improvement of cover area in ultrasonic local positioning system using cylindrical PVDF transducer. Proceedings of the International Symposium in Industrial Electronics, ISIE ’07, Vigo, Spain, 4–7 June 2007; pp. 1473–1477.
[15]
Knapp, C.H.; Carter, G.C. The generalized correlation method for estimation of time delay. IEEE Trans. Acoust. Speech Signal Process 1976, 24, 320–327, doi:10.1109/TASSP.1976.1162830.
[16]
Abutaleb, H.R.; Momenzadeh, H. An improved method for TDOA-based speech source localization. Proceedings of the 15th International Congress on Sound and Vibration, ICSV ’15, Daejeon, Korea, 6–10 July 2008; pp. 2939–2946.
[17]
Hu, J.-S.; Yang, C.-H. Estimation of sound source number and directions under a multisource reverberant environment. EURASIP J. Adv. Signal Process 2010, 2010, 870756:1–870756:14.
[18]
Chen, J.; Benesty, J.; Huang, Y. Time delay estimation in room acoustic environments: An overview. EURASIP J. Adv. Signal Process 2006, 2006, 26503:1–26503:19.
[19]
Pro-Wave Electronics Corporation, Product Specification. Available online: http://www.prowave.com.tw/english/products/ut/open-type/328s180.htm (accessed on 14 August 2011).
