Measuring Time-of-Flight in an Ultrasonic LPS System Using Generalized Cross-Correlation

Sensors

José Manuel Villladangos¹  Jesús Ure༚¹  Juan Jesús Garc໚¹  Manuel Mazo¹  Álvaro Hernández¹  Ana Jiménez¹  Daniel Ruíz¹ 

[1] Department of Electronics, Polytechnic School, University of Alcalá, Ctra. Madrid-Barcelona Km. 33,600, Alcalá de Henares, Madrid 28805, Spain; E-Mails:

关键词: generalized cross-correlation;    ultrasonic LPS;    phase transform;    Kasami codes;   

DOI  :  10.3390/s111110326

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2011 by the authors; licensee MDPI, Basel, Switzerland.