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Modern microprocessors have many micro architectural features. Quantifying the performance impact of one feature such as dynamic branch prediction can be difficult. On one hand, a timing simulator can predict the difference in performance given two different implementations of the technique, but simulators can be quite inaccurate. On the other hand, real systems are very accurate representations of...
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...
Ultra-wideband (UWB) technology is currently considered the most attractive solution to develop a Local Positioning System. In fact, the IEEE 802.15.4a standard includes a link (MAC) and physical (PHY) layer with indoor positioning capabilities. This paper presents a study of the typical modulations schemes used with UWB and its adaptation to ultrasonic frequencies. Moreover, several tests of the...
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...
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...
One of the main drawbacks of ultrasonic transducers is the difficulty to determine the bearing angle of echoes coming from an obstacle placed in front. Echoes often provide only the distance to the reflector inside the emission cone of the transducer, so some applications associate several transducers with the same scanning area to obtain more information about the common reflectors. This work proposes...
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...
This paper presents a novel method to correlate loosely synchronized (LS) codes generated from mutually orthogonal complementary sets of sequences (CSS). The proposed correlator significantly reduces the total number of multiplications and additions to be performed, in comparison with straightforward correlators. This fast correlator, together with the interference free window that LS codes exhibit,...
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