Showing papers by "J.M. Villadangos published in 2006"

Inter-Symbol Interference Reduction on Macro-Sequences Generated from Complementary Set of Sequences

Abstract: The encoding of emissions by complementary sets of sequences is usually used in communications and multi-sensor systems where asynchronous detection is required These sets of sequences have ideal properties in the addition of their auto-correlation and cross-correlation functions Furthermore, it is possible to obtain efficient correlation algorithms that reduce the hardware complexity, allowing real-time signal processing Nevertheless, because more than one sequence is assigned to a user, it is necessary to design efficient emission schemes to emit in the smallest time the assigned code A simple method consists in setting an emission order of the sequence bits -for example interleaving their bits or linking the sequences- Thus, a new code or sequence called "macro-sequence" is generated which can be emitted by a simple two-phase modulation Nevertheless, with this method, the correlation properties of the obtained macro-sequence are not ideal In this work a post-process algorithm for the macro-sequence correlation is developed in order to reduce the degradation effect that the emission procedure introduces, improving its detection

FPGA-based Implementation of an Ultrasonic Beacon for a Local Positioning System

Abstract: Ultrasonic transducers have been often used to develop Local Positioning Systems (LPS) in the field of intelligent spaces In these systems, it is necessary to design an ultrasonic beacon, which is distributed in the environment to cover a determined area where mobile robots or people can be located This work describes the design and the implementation of an ultrasonic beacon in an FPGA-based platform The design is flexible enough to allow the real-time configuration of the ultrasonic emission, according to parameters as efficient encoding or suitable modulation schemes Furthermore, the beacons have available a I2C link, so they are in permanent communication for exchanging configuration parameters and synchronization, not only among them, but also with a central configuration module

Work in Progress: Project Oriented Embedded Digital Systems Design Hardware Laboratory

Abstract: This paper shows the teaching experience on embedded digital systems based on microcontrollers in the degrees on Electrical and Electronic engineering in the University of Alcala, rendering special attention to the laboratory practices. The oriented laboratory practices are elaborated in order to achieve two main objectives: first, the students must build from the beginning a complete system based on a microcontroller and, second, they must apply a top down methodology including finite state machine or Petri nets.

Relative Positioning System Using Simultaneous Round Trip Time of Flight Measurements

Abstract: The determination of the relative position among mobile objects or members of a robot team is a useful information when the systems are not restricted to a particular environment and they cannot depend on an external infrastructure to obtain their location information. The solution for this kind of problems cannot be divided and treated separately for each object. Therefore it is necessary to implement mechanisms that allow to simultaneously determine the spatial relations among objects not knowing their absolute location in the environment. After that, a positioning algorithm can be computed whose complexity depends on the number of observations made and the precision required in the system. In this work, the implementation of a relative positioning system is described where only acoustic emissions are made in order to obtain information about the other objects. These data are obtained by using simultaneous round-trip-time-of-flight measurements. Finally, using this information, the object positions are computed with a multidimensional scaling technique, and a closer solution is achieved with least-square algorithms.