1,721,003 research outputs found
SYSTEM FOR DETECTING THE POSITION OF AIRCRAFTS AND/OR MOTOR VEHICLES ON AIRPORT RUNWAYS AND TRAFFIC WAYS
No full textSystem for detecting the position of aircrafts and/or motor vehicles in the airport runways and traffic ways, along which there are installed lighting signallers (2), comprising: radar devices (4) installed in at least a portion of said lighting signallers (2). Each radar device (4) is intended to localize the position of an aircraft (3) and/or motor vehicle situated in a section of runway (1) or traffic way, which is near the corresponding lighting signaller (2), where the radar device (4) itself is installed; and means for transmitting the data processed by each radar device (4) to a remote unit, in order to detect the position of the aircrafts (3) and/or motor vehicles. According to a variant of the invention, in place of the radar devices (4), other position detecting devices are employed, each comprising an accelerometer (41) or a thermal sensor
poligono di tiro
No full textL’invenzione descrive un poligono di tiro comprendenteuno schermo (5), su cui vengono proiettate immagini dibersagli (9) e su cui tiratori sparano con armi diqualsiasi natura, mezzi emettitori (17) di fasci diradiazioni diretti verso lo schermo (5).Un’unità di controllo (30) si occupa di rilevare un tiroe di calcolare se è stato realizzato un centro. [FIG. 1
Frequency-domain equalization for space-time block-coded systems
No full textIn this paper, conventional and turbo-channel-equalization algorithms processing two samples of the received signal per channel symbol and operating in the frequency domain are proposed for space-time block-coded systems. In the class of conventional equalization techniques, minimum-mean-square-error (MAISE) linear and decision-feedback equalizers (DFE) are derived and a synthesis technique based on the well-known Levinson-Durbin algorithm is proposed for the latter. Similarly, iterative linear and decision-feedback-equalization algorithms for turbo receivers are devised. Performance results show the efficacy of the proposed equalization techniques and their superiority over other frequency-domain-equalization strategies
Block channel equalization in the frequency domain
No full textIn this paper, channel equalization algorithms processing two samples of the received signal per channel symbol and operating in the frequency domain are described in a unifying framework. First, minimum mean-square error linear and decision-feedback equalizers are derived, and a synthesis technique based on the well-known Levinson-Durbin algorithm is proposed for the latter. Then, iterative linear and decision-feedback equalization algorithms for turbo processing are devised. Performance results for both uncoded and coded phase-shift keying transmissions show the efficacy of the proposed equalization techniques and their superiority over other existing frequency-domain equalization strategies
On the Use of Zadeh's Series Expansion for Modeling and Estimation of Indoor Powerline Channels
No full textIndoor powerline channels usually exhibit a cyclic input–output behavior due to the time-varying impedance of power loads. This makes typical time-invariant system models unsuitable to provide a faithful representation of such channels. In this paper, starting from the so-called Zadeh's series expansion, a discrete-time parametric representation of a linear periodically time-varying system is developed, and it is shown how a reduced-complexity version of it can be adopted to model indoor powerline channels. Then, various methods for estimating the parameters of the proposed representation are developed and compared in terms of performance and complexity. Numerical results evidence that our reduced complexity model is able to provide an accurate representation of indoor powerline channels and is of practical interest for both smart-grid applications and home area networks
Reduced-Complexity Algorithms for Indoor Map-Aware Localization Systems
Full text linkThe knowledge of environmental maps (i.e., map-awareness) can appreciably improve the accuracy of optimal methods for position estimation in indoor scenarios. This improvement, however, is achieved at the price of a significant complexity increase with respect to the case of map-unawareness, specially for large maps. This is mainly due to the fact that optimal map-aware estimation
algorithms require integrating highly nonlinear functions or solving nonlinear and nonconvex constrained optimization problems. In this paper, various techniques for reducing the complexity of such estimators are developed. In particular, two novel strategies for restricting the search domain of map-aware position estimators are developed and the exploitation of state-of-the-art numerical
integration and optimization methods is investigated; this leads to the development of a new family of suboptimal map-aware localization algorithms. Our numerical and experimental results evidence that the accuracy of these algorithms is very close to that offered by their optimal counterparts, despite their significantly lower computational complexity
Design and Implementation of a Wideband Channel Sounder for Low-Voltage Powerlines
No full textEstimating the input-output behavior of low voltage powerline channels for indoor high speed data communications requires the availability of proper wideband channel sounding tools. In fact, the properties of real world powerline channels are substantially different from those commonly exhibited by their wireless counterparts, so that standard methods for wireless channel sounding cannot be adapted to a powerline scenario. In this paper, after providing some general design guidelines for powerline channel sounding, a detailed description of a FPGA-based implementation of a wideband powerline channel sounder is provided. Such a tool is based on low cost hardware and is flexible, since it can be easily customized to user needs using a set of simple graphical user interfaces. Some of its specific applications, namely the estimation of the time-varying transfer function of an indoor powerline channel and the evaluation of the power spectral density of the noise affecting it, are illustrated to show the potentialities of the developed equipment
The Impact of Load Characterization on the Average Properties of Statistical Models for Powerline Channels
No full textIn this paper the impact of load characterization on
the statistical modeling of indoor powerline channels is investigated in the bandwidth 100 kHz–50 MHz. Our analysis refers to the mean properties of such channels (so that their time-varying features are ignored) and is based on: a) the use of the statistical channel simulator, which has beenvalidated through experimental
measurements, described in [23]; b) the availability of a set of experimental results about the impedance of various appliances. Our
numerical and experimental results evidence that, on the one hand,for frequencies beyond 20 MHz the influence of load characterization on the accuracy of statistical channel modelling is marginal; however, on the other hand, for frequencies in the order of 0–20 MHz the properties of the loads connected to a power network can appreciably affect the properties of the channel model
GQR-based models for directional wireless channels
No full textIn this paper novel reduced complexity statistical models for the representation of directional wireless channels affected by Rayleigh fading are developed. Their derivation is based on the evaluation of Fourier integrals by means of Gaussian quadrature rules (GQRs). The proposed models represent a communication channel as a tapped-angle and -delay line with non uniform spacing between successive taps. The application of the GQR approach to three different scenarios is also illustrated. Numerical results evidence that these models can provide a simple and accurate stochastic representation of directional fading channels
Equalization of Narrowband Indoor Powerline Channels for High Data Rate OFDM Communications
No full textIn this paper the well known Zadeh’s series representation of a linear periodically time varying system is exploited to develop linear equalization techniques for narrowband powerline communications based on orthogonal frequency division multiplexing. Numerical and experimental results referring to the band 200-500 kHz evidence that a coherent receiver exploiting the proposed equalizers can significantly outperform both its counterpart based on conventional channel estimation/ equalization techniques and differential detection with a limited complexity. This leads to the conclusion that a coherent receiver incorporating the proposed equalization techniques represents a technically appealing solution for narrowband high data rate powerline communications in indoor scenarios
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