TY - JOUR
T1 - Measuring Time-of-Flight in an Ultrasonic LPS System Using Generalized Cross-Correlation
JF - Sensors
Y1 - 2011
A1 - Villladangos, José Manuel
A1 - Jesús Ureña
A1 - J.J. Garcia
A1 - Manuel Mazo
A1 - Álvaro Hernández
A1 - Ana Jiménez
A1 - Ruíz, Daniel
A1 - C. De Marziani
KW - generalized cross-correlation; ultrasonic LPS; phase transform; Kasami codes
AB - 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.
CY - Basilea
VL - 11
IS - 11
JO - Sensors
ER -