A fully digital model for Kalman filters

The Kalman filter is a mathematical method, whose purpose is to process noisy measurements in order to obtain an estimate of some relevant parameters of a system. It represents a valuable tool in the GNSS area, with some of its main applications related to the computation of the user PVT solution and to the integration of GNSS receivers with INS or other sensors. The Kalman filter is based on a state space representation, that describes the analyzed system as a set of differential equations that establishes the connections between the inputs, the outputs and the state variables of the analyzed system. In the continuous time domain there exists a large class of physical processes with a time evolution well described by means of stochastic differential equations. A typical problem is the need for an equivalent system in the discrete time, due to the discrete nature of the data to be processed. In the literature, it is quite common to solve this problem in the continuous time domain and to approximate the solution using a Taylor series approximation, to obtain an approximate discrete time version of the continuous time problem. By the way, other methods exist, based on the possibility to transform a continuous-time system to a discrete-time system by means of transformations from the Laplace complex plane to the z plane. These methods are widely used in the digital signal processing community, for example, to design digital filters from their analog counterparts. The main advantage of this approach is that it is very easily implemented by applying some mechanical rules. Moreover the nature of the approximation introduced by the Laplace-z transformation is a-priori known and clearly readable in the frequency domain. In the following the classical methods based on the Taylor approximation and on the Laplace-z transformations will be analyzed and compare

Quantum control and long-range quantum correlations in dynamical Casimir arrays

The recent observation of the dynamical Casimir effect in a modulated superconducting waveguide, coronating thirty years of world-wide research, empowered the quantum technology community with a powerful tool to create entangled photons on-chip. In this work we show how, going beyond the single waveguide paradigm using a scalable array, it is possible to create multipartite nonclassical states, with the possibility to control the long-range quantum correlations of the emitted photons. In particular, our finite-temperature theory shows how maximally entangled $NOON$ states can be engineered in a realistic setup. The results here presented open the way to new kinds of quantum fluids of light, arising from modulated vacuum fluctuations in linear systems

Comparative Interference Vulnerability Assessment of GPS TMBOC and Galileo CBOC Signals

Aim of this paper is to present an interference impact assessment in the context of Global Navigation Satellite Systems (GNSS), focusing on the new modulations based on the Multiplexed Binary Offset Carrier(MBOC) scheme that will be used for modernized GPS L1C and Galileo E1 civil signals. Simulation results are presented and discussed in order to perform a comparative analysis of GPS L1C and Galileo E1 civil signals in presence of Continuous Wave(CW) interference. Performance is discussed versus the main signal and receiver parameters that could affect the interference robustness of the signals and the receiver. In detail, both double and single channel (data and/or pilot) tracking schemes have been assessed, varying the receiver bandwidth, integration time, correlator type and spacing. The obtained results show that tracking both data and pilot channels (correlating the incoming signal with coherent local replica, including both the channels), similar performance can be obtained by a receiver for GPS L1C and Galileo E1 Open Service (OS) signals. On the other hand, some differences can be noticed when the receivers take advantage of only one channel (e.g. tracking only the pilot channels), due to their different power levels and modulation formats. Some final remarks are also drawn in order to provide also some guidelines to the reader on how to reduce the interference impact on MBOC signals by means of a proper receiver setup

GIRASOLE (Galileo Safety of Life Receivers Development) WP 3.2.1: Rail Core Technologies Investigation – Interference Mitigation

The main goal of this document is to assemble the large quantity of information related to RFI available in literature for a railway environment study with special focus on different types of interference sources and on the detection and mitigation techniques

Performance Assessment of a Commercial GPS Receiver for Networking Applications

none3noRecent years have seen an exponential increase of DVD equipped and navigation assisted cars. Nowadays a car trip can be both entertaining for passengers and computer assisted for drivers. In a further integration of automotive and information technologies, cars will be able to communicate to each other and to the Internet supporting safety, infotainment and pollution prevention applications. The research area which investigates topics, Vehicular Ad hoc NETworks (VANETs), is being widely investigated by both industry and academia. Position information plays a central role in many communication routing schemes designed for VANETs. This trend is justified by the feasibility of algorithms that route packets based on geographical proximity to the destination and by the widespread availability of navigation systems in cars. Geographical information is usually assumed accurate and precise. None of the algorithms available in literature, to the best of our knowledge, take into account possible position estimation errors. This paper is a first step in assessing the precision of a commercial GPS receiver for the support of vehicular communications. As we shall see, the performance of the receiver under investigation heavily depends on the type of urban area within this is employed. We believe that a strong understanding of the accuracy of such estimates is important to improve the performance and reliability of a vehicular network infrastructure. © IEEE.mixedSavasta S.; Pini M.; Marfia G.Savasta S.; Pini M.; Marfia G

Codes Cross-Correlation Impact on the Interference Vulnerability of Galileo E1 OS and GPS L1C Signals

This paper presents an assessment study of the impact of the spreading code properties in the reception of Galileo E1 Open Service (OS) and GPS L1C Multiplexed Binary Offset Carrier (MBOC) signals. The distortion of the discrimination function due to codes cross-correlations properties is analyzed, considering the features of the modulation schemes and investigating also different code families. Simulation results demonstrate that the S-curve of the code synchronization loop can be affected by an asymmetry and a bias in the lock point. Such a distortion can be noticed only in case of receiving a single channel (e.g. the pilot channel), whereas it is not present if the received signal is correlated with a coherent local replica including both data and pilot channels. This effect depends on the code cross-correlation properties and on the receiver setup (reception of data/pilot channels, variable correlators spacing). As a demonstration of its impact on a real single channel receiver, it is also shown that in presence of an interfering signal such a distortion can be magnified and lead to relevant performance degradatio

Method for assessing the interference impact on GNSS receivers

The definition of new families of curves named interference error envelope (IEE) and interference running average (IRA) is presented. Such tools are able to assess the impact of RF interference on different GNSS receivers, taking into account the features of the in-band interference source. In fact the actual impact on the final performance is strictly related to the specific receiver architectures. Continuous wave (CW) and wide band (WB) interference signals are considered in order to assess by means of IEE and IRA the robustness of new modulations based on the multiplexed binary offset carrier (MBOC) scheme for several receiver configurations, by varying the discriminator spacing, type, and the front-end filter bandwidth. Interference robustness is evaluated and compared with those of the well-known binary phase shift keying (BPSK) and binary offset carrier BOC(1,1) modulations. Simulation and theoretical results are validated by means of laboratory tests, proving the reliability of IEE curves for interference impact assessmen