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The current development of railway transport gives a significant importance to the design of suitable and reliable safety systems. Among them, the common track circuit can be improved to enhance its performance, by providing redundancy, immunity to noise and more information from the track circuit. This work proposes a novel track circuit based on the encoding of the electrical transmissions with...
Ultrasonic local positioning systems (US-LPS) utilize hyperbolic trilateration to avoid the necessity of synchronizing the beacons and the tag. In actual systems the beacons emit coded signals which are processed in the tag to obtain the time-differences of arrival, with one of the beacons as reference. The absolute position is computed using an iterative method to solve the non-linear equation system...
Loosely Synchronous (LS) codes improves the performance of Local Positioning Systems (LPS) in terms of noise immunity, capability of simultaneous measurements and precision in the location, provided that the multipath spread and the relative time offset between the codes are within the zero correlation zone (ZCZ) that they achieve in their correlation functions. Furthermore, these codes can be very...
This paper presents a system modelling for aqueous-liquids characterization by ultrasounds. The main goal of the proposed model is the use of different kind of signals, based on encoding along a large bandwidth in order to obtain information about the liquid mixtures to be characterized. The validation of the model has been carried out by comparing it with experimental results. Besides, the experimental...
In this work, several code division multiple access encoding schemes are evaluated for their application in ultrasonic sensory systems based on the determination of times-of-flight. Proper encoding improves the performance of such systems in terms of noise immunity, capability of simultaneous measurements and precision in the distance measurements. Important applications that include encoded ultrasonic...
This paper is the Special Section of the IEEE Transactions on Instrumentation and Measurement (TIM) on the 2007 IEEE International Symposium on Intelligent Signal Processing (WISP'2007), which is the fifth symposium on this matter organized by the IEEE Instrumentation and Measurement Society. It was held in Alcala de Henares, Madrid, Spain, on October 3-5, 2007, with the main aim of highlighting how...
In this work the specific software tools designed to manage a high performance data acquisition board to be used in active multi-sensory systems is presented. Specifically, the developments which has been carried out allow to monitor the coded emission/reception of two sensory barriers for obstacle detection on railways, based on infrared (IR) and ultrasonic (US) sensors. Additionally, it has been...
In this work a classification system for basic ultrasonic reflectors (plane, corner and edge) in three-dimensional (3D) environments is presented. The classification system is based on the principal component analysis (PCA) technique and the times-of-flight (TOF) are used as classification parameter. The system provides a sensorial structure to simultaneously obtain up to 16 TOF in every emission/scanning...
This work describes the design of a ultrasonic local positioning system (ULPS) with large covered area. The beacons have been designed with a cylindrical PVDF transducer (piezofilm transducer) to which a conical reflector has been connected to enlarge the covered area and to guarantee 3D indoor positioning. The proposed ULPS for mobile robots (MR) uses simultaneous emissions from ultrasonic beacons...
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