Performance of an Echo Canceller and Channel Estimator for On-Channel Repeaters in DVB-T/H Networks

This paper investigates the design and performance of an FIR echo canceller for on-channel repeaters in DVB-T/H network within the framework of the PLUTO project. The possible approaches for echo cancellation are briefly reviewed and the main guidelines for the design of such systems are presented. The main system parameters are discussed. The performance of an FIR echo canceller based on an open loop feedforward approach for channel estimation is tested for different radio channel conditions and for different number of taps of the FIR filter. It is shown that a minimum number of taps is recommended to achieve a certain mean rejection ratio or isolation depending on the type of channel. The expected degradation in performance due to the use of fixed point rather than floating point arithmetic in hardware implementation is presented for different number of bits. Channel estimation based on training sequences is investigated. The performance of Maximum Length Sequences and Constant Amplitude Zero Autocorrelation (CAZAC) Sequences is compared for different channels. Recommendations are given for training sequence type, length and level for DVB-T/H on-channel repeater deployment

Non-linear response to electric field in extended Hubbard models

The electric-field response of a one-dimensional ring of interacting fermions, where the interactions are described by the extended Hubbard model, is investigated. By using an accurate real-time propagation scheme based on the Chebyshev expansion of the evolution operator, we uncover various non-linear regimes for a range of interaction parameters that allows modeling of metallic and insulating (either charge density wave or spin density wave insulators) rings. The metallic regime appears at the phase boundary between the two insulating phases and provides the opportunity to describe either weakly or strongly correlated metals. We find that the {\it fidelity susceptibility} of the ground state as a function of magnetic flux piercing the ring provides a very good measure of the short-time response. Even completely different interacting regimes behave in a similar manner at short time-scales as long as the fidelity susceptibility is the same. Depending on the strength of the electric field we find various types of responses: persistent currents in the insulating regime, dissipative regime or damped Bloch-like oscillations with varying frequencies or even irregular in nature. Furthermore, we also consider the dimerization of the ring and describe the response of a correlated band insulator. In this case the distribution of the energy levels is more clustered and the Bloch-like oscillations become even more irregular

POTENTIAL OF STATIC, KINEMATIC, AND RTK IN OPEN SKY USING GPS ONLY AND GPS + GLONASS SIGNALS

ABSTRACT: It is now simple to use Global Navigation Satellite System (GNSS) anyplace due to the rapid developments and variety of GNSS satellite techniques. Several satellite systems, including GPS, GLONASS, BIUDO, and GALILEO, are widely available and used. The Differential Global Navigation Satellite System (DGNSS) is being utilized for many different applications, particularly those involving surveying and mapping. For establishing control points (Cps) in the open sky with moderate accuracy, it may be helpful to compare the usage of post-processing methods including static and kinematic also real-time kinematic (RTK) for position accuracy to differentiate their accuracies. The comparison depends on using the constellation of GPS only and GPS + GLONASS. For this purpose, fieldwork employing the three approaches with the two constellations (GPS and GLONASS) was done on five test points. The selected points were in the open sky, and the raw data was collected on tripods in the three methods. Leica 8.4 Geo Office software was used for the raw data processing after the five Cps were observed using a Leica Viva GS15 dual frequency receiver which supports GPS and GLONASS signals. The 3D position accuracy of the Cps was obtained by the three approaches using signals from GPS + GLONASS and GPS only. The advantages and disadvantages of using each approach were discusse

Managing nitrate pollution in a Tunisian irrigated area: A multi-criteria analysis approach

In Tunisia, the extension of irrigated area is justified by its important role in the development and diversification of agricultural production. Nevertheless, the strong intensification of the agricultural activities may lead to the pollution of underground water resources due to an excess use of fertilisers and other chemical products. In fact, the high nitrate concentrations observed in some Tunisian irrigated areas, are related to the excessive use of nitrate fertilizers in intensive agriculture. The objective of the present study is to implement decision-making methods allowing a better combination of factors production by optimization of an economic objective and an environmental objective. This research is based on multi-criteria modelling through the optimization of two conflict objectives: an economic objective as settled by farmer in the short or medium-run (Gross margin), and an environmental objective (nitrate pollution reduction) as a long-run objective of the decision maker in order to ensure the continuity of agriculture activities and ecosystems sustainability. Data were collected through a survey conducted in the irrigated area of Kalaât El Andalous in Tunisia with a sample containing 57 farms. Efficient solutions were obtained and compared through the "constraints", "NISE" and "compromises" methods. Main results obtained indicate a significant degree of conflict between these two objectives. Indeed the maximization of the total gross margin involves an increase in the degrees of nitrate pollution and conversely. Finally, some policy implications are presented.Nitrate pollution, environmental impact, multicriteria analysis, Environmental Economics and Policy,

POTENTIAL OF STATIC, KINEMATIC, AND RTK IN OPEN SKY USING GPS ONLY AND GPS + GLONASS SIGNALS

ABSTRACT: It is now simple to use Global Navigation Satellite System (GNSS) anyplace due to the rapid developments and variety of GNSS satellite techniques. Several satellite systems, including GPS, GLONASS, BIUDO, and GALILEO, are widely available and used. The Differential Global Navigation Satellite System (DGNSS) is being utilized for many different applications, particularly those involving surveying and mapping. For establishing control points (Cps) in the open sky with moderate accuracy, it may be helpful to compare the usage of post-processing methods including static and kinematic also real-time kinematic (RTK) for position accuracy to differentiate their accuracies. The comparison depends on using the constellation of GPS only and GPS + GLONASS. For this purpose, fieldwork employing the three approaches with the two constellations (GPS and GLONASS) was done on five test points. The selected points were in the open sky, and the raw data was collected on tripods in the three methods. Leica 8.4 Geo Office software was used for the raw data processing after the five Cps were observed using a Leica Viva GS15 dual frequency receiver which supports GPS and GLONASS signals. The 3D position accuracy of the Cps was obtained by the three approaches using signals from GPS + GLONASS and GPS only. The advantages and disadvantages of using each approach were discusse

Field effect on surface states in a doped Mott-Insulator thin film

Surface effects of a doped thin film made of a strongly correlated material are investigated both in the absence and presence of a perpendicular electric field. We use an inhomogeneous Gutzwiller approximation for a single band Hubbard model in order to describe correlation effects. For low doping, the bulk value of the quasiparticle weight is recovered exponentially deep into the slab, but with increasing doping, additional Friedel oscillations appear near the surface. We show that the inverse correlation length has a power-law dependence on the doping level. In the presence of an electrical field, considerable changes in the quasiparticle weight can be realized throughout the system. We observe a large difference (as large as five orders of magnitude) in the quasiparticle weight near the opposite sides of the slab. This effect can be significant in switching devices that use the surface states for transport

Long-range sediment transport in the world’s oceans by stably stratified turbidity currents

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