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This work presents the FPGA design of a DC/AC pulse width modulated converter for teaching purposes. The design allows to change in real time the PWM modulation scheme, the amplitude and frequency of the desired first harmonic, as well as the harmonic spectrum depending on the requirements of the application. Therefore, a teaching platform to be used in practices related to power electronic subjects...
In recent years, communications systems through mains, known as PLC (Powerline Communication), have received a lot of interest as part of intelligent networks or smart grids, as well as for multimedia applications at homes. In broadband PLC, systems using multicarrier modulations allow the mitigation of selective frequency fading in the channel. Nevertheless, these modulations require accurate time...
Non-Intrusive Load Monitoring System (NILM) is a collection of techniques and technologies aiming to disaggregate the energy consumption from smart meters to device level consumption. This disaggregation allows us to supervise the activity related to particular devices (e.g. machines in factories or appliances in houses) without intrusiveness along the time. Furthermore, NILM systems enable large...
Ocean noise is a complex phenomenon in underwater environments. Different processes such as shipping traffic, wind, rain or animals contribute with a different signature to the background noise, which can worsen underwater systems performance. However, in the simulation of underwater systems the common approach is to consider an additive white Gaussian noise with a certain given value. Usually, the...
Ultra-Wideband (UWB) has a high interest in research and industry for accurate indoor positioning. This technology comprises signals with a bandwidth of at least 500 MHz at a power decay of −10dB. This large bandwidth con-feres the capability of resolving multipath, penetrating through obstacles and accurate ranging. However, NLOS (Non-Line-Of-Sight) conditions produced by obstacles in indoor environments...
This paper presents the different levels of signal processing applied to an extensive Ultrasonic Local Positioning System (ULPS) intended for mobile robot (MR) indoor navigation. The working area is covered using several single LPSs, each of them composed of a set of closely arranged ultrasonic beacons. Low-level signal processing deals with the simultaneous encoded emission of the beacons that compose...
Within the emerging new technologies in Smart Grids, the concern about Non-Intrusive Load Monitoring (NILM) techniques has increased over the last five years. These techniques aim to disaggregate the energy consumption on a household or commercial building into individual appliances from the use of a single-point sensor. Most efforts attempt to disaggregate by using a low sampling frequency and by...
This paper presents the design and implementation of a System-on-Chip (SoC) based on a FPGA (Field-Programmable Gate Array) device to control and configure an ultrasonic beacon array for an extensive ultrasonic Local Positioning System (LPS). The SoC is based on a MicroBlaze microprocessor and some advanced peripherals. Among them, it is possible to remark a LPS controller, in charge of managing the...
Smartphone capabilities can significantly enhance mobile and context-aware applications that depend on location information. Whereas outdoor Location Based Services (LBS) are highly developed thanks to GPS, indoor LBS still demand a positioning technology that provides accurate location data. In this paper, an ultrasonic signal acquisition module for fine-grained indoor positioning of portable devices,...
The use of Ultra -WideBand (UWB) techniques is considered an attractive solution for indoor Local Positioning Systems (LPS). In this case, the positioning is usually performed by hyperbolic trilateration techniques measuring the time difference of arrival (TDOA) between the received signals coming from the beacons placed in the environment. The detection of the true arrival instant for the used encoded...
This paper presents an improved navigation system for Mobile Robots (MR) in extensive areas using different Ultrasonic Local Positioning Systems (ULPS) and the complement of Isolated Beacons (IB) in regions without LPS coverage. Each single LPS has a high accuracy in positioning but a limited coverage area. The proposal of this paper is the use of a set of additional Isolated Beacons to cover areas...
Accurate distance estimation is a key part for certain active sensing systems as ultrasonic Indoor Positioning Systems (IPSs). In these systems, receive filters play a key role for the achievement of robust and accurate position estimations. For that reason, this paper carries out the performance comparison of different receive filters, namely matched-filter, generalized cross-correlation function,...
Underwater Wireless Sensor Network applications require the design of efficient communications links due to the rough environment. Acoustic signals make feasible the data transmission based on Direct Sequence Code Division Multiple Access (DS-CDMA) techniques, because compensates the multipath effect and allow receivers to simultaneously distinguish among multiple independent emitters. For that purpose,...
In this paper we present a privacy-oriented Ultrasonic Local Positioning System (U-LPS) allowing users with portable devices, such as smartphones or tablets, to accurately determine their position in indoor environments. Indoor U-LPSs have been widely used to provide location information with centimeter or even sub-centimeter level accuracy at high rates. However, most of these systems demand specific...
The obtention of distances to different Access Points from RSSI readings in indoor environments is a difficult task due to intrinsic RF propagation effects like refraction, diffraction, reflection or absorption. This paper proposes a new model of distances estimation from RSSI data based on Genetic Programming; this new model estimates the distances from the receiver position to each WiFi AP depending...
The development of Local Positioning Systems (LPSs), that allow user positioning in areas where solutions based on GNSS (Global Navigation Satellite System) fail (as indoor environments), has been an active research field in the last years. In LPSs based on Ultra-Wideband (UWB), near-far effect is a significant issue that severely constrains the system performance. In this work, we present a novel...
The underwater channel is a highly variable medium due to the influence of several effects on the acoustic signal, and the physical variability of the environment. This behavior makes the underwater channel a very difficult one to model, and also a complex environment to work with. In acoustic-based positioning or sonar systems, where it is important to know accurately the time-of-flights of the signals,...
The detection of local maxima is particularly important in sensory transmission systems that use correlation techniques. In these systems, reception blocks try to recover the information by correlating the received signal with the emitted pattern. In this paper a system capable of discriminating the auto-correlation maximum, even in high noise environments, is proposed. The local maximum detector...
In this paper multilevel complementary pairs of sequences without limitation in length and the generation of multilevel Loosely Synchronized (LS) sequences with flexible Zero Correlation Zones (ZCZ) length are proposed. The existence of efficient correlators and the fewer restrictions on the length of the multilevel LS sequences compared to binary LS ones, makes them worthwhile for their application...
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