This paper deals with a Software Defined Radio (SDR) receiver capable to process GPS and Galileo ... more This paper deals with a Software Defined Radio (SDR) receiver capable to process GPS and Galileo signals jointly. A large set of possible solution can be implemented, with the main aim of assessing the performance of the receiver for the considered architectures. For this reason, software receivers, either real-time or non-real-time, are fundamental tools to enable research and new developments in the field of GNSSs. In this paper our intent is to discuss some of the choices one can face when implementing an SDR GNSS receiver, switching from the theory to the practice. We focus our attention on the pseudorange construction and the Position, Velocity and Time (PVT) estimation stage, discussing different algorithms to implement these blocks. Our aim is to offer an insight on the options to implement those stages of the receiving chain, in a practical vision which is difficult to find in the available literature.
This paper shows the design and development of a truly low cost attitude determination and naviga... more This paper shows the design and development of a truly low cost attitude determination and navigation system based primarily on non-dedicated mass market GNSS receivers and antennas, aided by MEMS inertial sensors. GNSS/INS integration combines the advantages of absolute satellite-based positioning with the high dynamic performance and data rates of inertial sensors, having become the standard approach in navigation systems for Unmanned Aerial Vehicles (UAV) among other applications. We have used a Tightly-Coupled (TC) algorithm aimed at the integration of GPS and INS devices, designed to exploit the measurements provided by four GNSS receivers and a MEMS IMU. This task is accomplished by forming double differences (DD) of carrier-phase measurements and properly solving the ambiguities on-the-fly. The robustness of the algorithm is enhanced by exploiting unambiguous DD of code-phase observables or un-differenced pseudoranges when carrier phase ambiguity fix is not reliable. In order...
U nmanned aerial vehicles (UAV) are finding increased application in both domestic and government... more U nmanned aerial vehicles (UAV) are finding increased application in both domestic and governmental applications. Small UAVs (maximum take off weight less than 20 kilograms) comprise the category of the smallest and lightest platforms that also fly at lower altitudes (under less than 150 meters). Designs for this class of device have focused on creating UAVs that can operate in urban canyons or even inside buildings, fly along hallways, and carry listening and recording devices, transmitters , or miniature TV cameras. Operational requirements for these kinds of UAVs typically encompass flying close to the ground and in relatively narrow spaces with a lot of obstacles. This introduces problems for a simplistic application of technologies used in larger UAVs. In particular, the rotary wing UAV platforms used in those scenarios provide vertical takeoff and landing and hovering capability, but they are intrinsically unstable systems requiring high-rate and accurate attitude and position...
The advent of the first two satellites of the final Galileo constellation launched by Soyuz from ... more The advent of the first two satellites of the final Galileo constellation launched by Soyuz from Europe’s spaceport in French Guiana on October 21st is a major milestone for the European as well as global satellite navigation field. In fact, these two satellites pave the way for a much awaited set of experiments testing the benefits brought about by an additional constellation in orbit, Galileo. The European constellation formed by last generation satellites carrying very precise hydrogen maser clocks, and transmitting sophisticated navigation payloads, is expected to increase positioning availability and improve satellite geometry so far as to decrease positioning errors with respect to the use of GPS satellites exclusively. In this paper, signal acquisition, tracking and demodulation of the signal broadcast by the first Galileo satellite (the so-called IOV-PFM Galileo satellite) in the E1 bandwidth is performed. Starting to monitor this satellite from December 2011, we were able t...
2010 4th International Conference on Signal Processing and Communication Systems, 2010
Many navigation problems involve constraints. For example, motor vehicle travel tends to be const... more Many navigation problems involve constraints. For example, motor vehicle travel tends to be constrained by road and building boundaries. We consider filtering problems where censuring functions can be used to constrain the measurements. It is established that the ensuing filtered estimates are unbiased, provided that the underlying probability density functions are even and the censuring functions are odd. A loosely-coupled GPS and inertial navigation system (INS) application is discussed in which an integrated solution exhibits improved performance during GPS outages when a priori information is used to constrain the altitude measurements I.
System set up 6 The radio frequency (RF) signal was received by means of a fixed, non-direction... more System set up 6 The radio frequency (RF) signal was received by means of a fixed, non-directional rooftop antenna, co-located at ISMB premises in Torino at the following coordinates: latitude = 45°03'54.99" N, longitude = 7°39'32.29" E, height = 311.97 meters.
2012 International Conference on Localization and GNSS, 2012
On the 20 th of October 2011, the first two satellites of the Galileo constellation have been lau... more On the 20 th of October 2011, the first two satellites of the Galileo constellation have been launched successfully. The possibility to have these two satellites in orbit represented a great opportunity for researchers to receive and monitor the first Galileo signals. After the satellite switch-on, we continuously monitored the signal broadcast by both the satellites, using a software radio receiver. This paper shows the analysis on the navigation message that was broadcast by the IOV-PFM Galileo satellite on the E1 bandwidth, starting from December 2011. In particular, we were able to observe a valid ephemeris data on December 21 st and December 22 nd . The successful interpretation of the navigation message enabled the first GPS+Galileo experimentations using real signals that were performed in static condition, through code-phase measurements.
2013 International Conference on Localization and GNSS (ICL-GNSS), 2013
In this paper, the structure of a tracking loop with Extended Kalman Filter (EKF) is analyzed. Pa... more In this paper, the structure of a tracking loop with Extended Kalman Filter (EKF) is analyzed. Particular emphasis is given to the NCO update rule, which is seldom mentioned or studied in previous literature. Furthermore, the structure of an EKF-based software receiver is proposed including the special modules dedicated to the initialization and maintenance of the tracking loop. The EKF-based tracking architecture has been compared with a traditional one based on an FLL/PLL+DLL architecture, and the benefit of the EKF within the tracking stage has been evaluated in terms of final positioning accuracy. Further tests have been carried out to compare the Position-Velocity-Time (PVT) solution of this receiver with the one provided by two commercial receivers: a mass-market GPS module (Ublox LEA-5T) and a professional one (Septentrio PolaRx2e@). The results show that the accuracy in PVT of the software receiver can be remarkably improved if the tracking is designed with a proper EKF architecture and the performance we can achieve is even better than the one obtained by the mass market receiver, even when a simple one-shot least-squares approach is adopted for the computation of the navigation solution.
2012 IEEE International Geoscience and Remote Sensing Symposium, 2012
ABSTRACT As more and more attention is received by the underlying passive potential of Global Nav... more ABSTRACT As more and more attention is received by the underlying passive potential of Global Navigation Satellite Systems (GNSS) signals, reflectometry and scatterometry are visited in this paper in order to assess water surface identification and aircraft altimetry performance. This is possible thanks to the high reflectivity of Global Positioning System (GPS) signals in the L-Band frequency range on water as well as ice and snow covered surfaces which compensates for the otherwise low signal intensity. Indeed, GNSS reflectometry belongs to the class of bistatic radar systems where transmitter and receiver reside at different locations and signals pass through a reflecting surface. Code phase and carrier phase based time delay measurements between the direct path and reflected signals, are used to determine the small aircraft's height with respect to the reflecting surface. On the other hand, specular reflection points are computed, and a comparison of the reflected power to the direct received power is shown to yield a good water surface identification performance. Code and carrier phase measurements are implemented in this paper to obtain cm level height estimates.
2012 International Conference on Localization and GNSS, 2012
Thanks to advances in the development of Micro-Electromechanical Systems (MEMS), it has been poss... more Thanks to advances in the development of Micro-Electromechanical Systems (MEMS), it has been possible to fabricate small dimension and cheap accelerometers and gyros, which are being used in many applications where the GPS/INS integration is carried out, as for example to identify track defects, navigation, geo-referencing, agriculture, etc. Although these MEMS devices have a low-cost, they present different errors which degrade the accuracy of the navigation systems in a short period of time. Therefore, a suitable modelling of these errors is necessary in order to improve the system performance. In this work, Allan Variance and Power Spectral Density techniques are used to identify the random processes that affect the inertial sensor data. Once the random components are identified, they are modelled using first-order Gauss-Markov and random walk processes. Two models are assessed augmenting the states of the Extended Kalman Filter (EKF) to 6 and 9. Subsequently, another analysis and modelling of the inertial sensors which combines Autoregressive Filters and Wavelet De-noising is implemented and in this case the EKF of the loosely coupled GPS/INS integration strategy is augmented with 6, 12 and 18 states. Finally, the results show a comparison between these sensor error models with real data under GPS outage conditions.
In recent years, Kalman filter (KF)-based tracking loop architectures have gained much attention ... more In recent years, Kalman filter (KF)-based tracking loop architectures have gained much attention in the Global Navigation Satellite System field and have been widely investigated due to its robust and better performance compared with traditional architectures. However, less attention has been paid to the in-depth theoretical analysis of the tracking structure and to the effects of Kalman tuning. A new approach is proposed to analyze the KF-based tracking loop. A control system model is derived according to the mathematical expression of the Kalman system. Based on this model, the influence of the choice of the setting parameters on the temporal evolution of the system response is discussed from the perspective of a control system. As a result, a reasoned and complete suite of criteria to tune the initial error covariance as well as the process and measurements noise covariances is demonstrated. Furthermore, a strategy is presented to make the system more robust in higher order dynamics without degrading the accuracy of carrier phase and Doppler frequency estimates.
The paper investigates approaches for loosely coupled GPS/INS integration. Error performance is c... more The paper investigates approaches for loosely coupled GPS/INS integration. Error performance is calculated using a reference trajectory. A performance improvement can be obtained by exploiting additional map information (for example, a road boundary). A constrained solution has been developed and its performance compared with an unconstrained one. The case of GPS outages is also investigated showing how a Kalman filter that operates on the last received GPS position and velocity measurements provides a performance benefit. Results are obtained by means of simulation studies and real data.
This paper considers estimation problems where inequality constraints are imposed on the outputs ... more This paper considers estimation problems where inequality constraints are imposed on the outputs of linear systems and can be modeled by nonlinear functions. In this case, censoring functions can be designed to constrain measurements for use by filters and smoothers. It is established that the filter and smoother output estimates are unbiased, provided that the underlying probability density functions are even and the censoring functions are odd. The Bounded Real Lemma is employed to ensure that the output estimates satisfy a performance criterion. A global positioning system (GPS) and inertial navigation system (INS) integration application is discussed in which a developed solution exhibits improved performance during GPS outages when a priori information is used to constrain the altitude and velocity measurements.
The minimum-variance smoother solution for input estimation is described and it is shown that the... more The minimum-variance smoother solution for input estimation is described and it is shown that the resulting estimates are unbiased. The smoothed input and state estimates are used to iteratively identify unknown process noise variances. The use of smoothed estimates, as opposed to filtered estimates, leads to improved approximate Cramér-Rao lower bounds for the unknown parameters. It is also shown that the sequence of iterates are monotonic and asymptotically approach the actual values under prescribed conditions. A nonlinear mining navigation application is described in which unknown parameters are estimated.
The convergence of an expectation-maximization (EM) algorithm for state matrix estimation is inve... more The convergence of an expectation-maximization (EM) algorithm for state matrix estimation is investigated. It is shown for the expectation step that the design and observed error covariances are monotonically dependent on the residual error variances. For the maximization step, it is established that the residual error variances are monotonically dependent on the design and observed error covariances. The state matrix estimates are observed to be unbiased when the measurement noise is negligible. A navigation application is discussed in which the use of estimated parameters improves filtering performance.
The accuracy of INS degrades with time and therefore GPS/INS integration provides an ideal combin... more The accuracy of INS degrades with time and therefore GPS/INS integration provides an ideal combination to overcome the limits of INS only and have a reduced error in position, velocity and attitude computation. We explore the feasibility of an integrated positioning system using a Differential GPS (DGPS) and an Inertial Navigation System (INS). The work is aimed at a development of a low-cost multi sensor device that will equip every machine and vehicle in a coal mining in order to monitor their movements in real time and avoid possible ...
The accuracy of INS degrades with time and therefore GPS/INS integration provides an ideal combin... more The accuracy of INS degrades with time and therefore GPS/INS integration provides an ideal combination to overcome the limits of INS only and have a reduced error in position, velocity and attitude computation. Accurate analysis of inertial sensor error is essential to ensuring the effectiveness of the optimal GPS/INS integration and set the states variables of a Kalman filter properly. In this paper Allan Variance has been selected as the technique to investigate all the types of noise in a low-cost IMU system. The work at first presents the details of this ...
Europe's GNSS program-Galileo-entered a new phase of development with the recent launch of t... more Europe's GNSS program-Galileo-entered a new phase of development with the recent launch of two in-orbit validation satellites, which comprise the first elements of the system's full operational constellation. In this article, a team of italian researchers present the initial results of their analysis of the Galileo signals
This paper discusses the convergence of a Kalman filter-based Expectation-Maximisation algorithm ... more This paper discusses the convergence of a Kalman filter-based Expectation-Maximisation algorithm for estimating unknown model parameters. Under prescribed conditions, the parameter estimates converge to the actual values. Mining navigation applications are discussed in which good parameter estimates are required. An inertial alignment example is presented, which demonstrates that the sequence of process noise covariance estimates is monotonically decreasing. A position tracking application is also discussed in which it is demonstrated that the sequence of state matrix estimates is similarly monotonic decreasing.
This paper deals with a Software Defined Radio (SDR) receiver capable to process GPS and Galileo ... more This paper deals with a Software Defined Radio (SDR) receiver capable to process GPS and Galileo signals jointly. A large set of possible solution can be implemented, with the main aim of assessing the performance of the receiver for the considered architectures. For this reason, software receivers, either real-time or non-real-time, are fundamental tools to enable research and new developments in the field of GNSSs. In this paper our intent is to discuss some of the choices one can face when implementing an SDR GNSS receiver, switching from the theory to the practice. We focus our attention on the pseudorange construction and the Position, Velocity and Time (PVT) estimation stage, discussing different algorithms to implement these blocks. Our aim is to offer an insight on the options to implement those stages of the receiving chain, in a practical vision which is difficult to find in the available literature.
This paper shows the design and development of a truly low cost attitude determination and naviga... more This paper shows the design and development of a truly low cost attitude determination and navigation system based primarily on non-dedicated mass market GNSS receivers and antennas, aided by MEMS inertial sensors. GNSS/INS integration combines the advantages of absolute satellite-based positioning with the high dynamic performance and data rates of inertial sensors, having become the standard approach in navigation systems for Unmanned Aerial Vehicles (UAV) among other applications. We have used a Tightly-Coupled (TC) algorithm aimed at the integration of GPS and INS devices, designed to exploit the measurements provided by four GNSS receivers and a MEMS IMU. This task is accomplished by forming double differences (DD) of carrier-phase measurements and properly solving the ambiguities on-the-fly. The robustness of the algorithm is enhanced by exploiting unambiguous DD of code-phase observables or un-differenced pseudoranges when carrier phase ambiguity fix is not reliable. In order...
U nmanned aerial vehicles (UAV) are finding increased application in both domestic and government... more U nmanned aerial vehicles (UAV) are finding increased application in both domestic and governmental applications. Small UAVs (maximum take off weight less than 20 kilograms) comprise the category of the smallest and lightest platforms that also fly at lower altitudes (under less than 150 meters). Designs for this class of device have focused on creating UAVs that can operate in urban canyons or even inside buildings, fly along hallways, and carry listening and recording devices, transmitters , or miniature TV cameras. Operational requirements for these kinds of UAVs typically encompass flying close to the ground and in relatively narrow spaces with a lot of obstacles. This introduces problems for a simplistic application of technologies used in larger UAVs. In particular, the rotary wing UAV platforms used in those scenarios provide vertical takeoff and landing and hovering capability, but they are intrinsically unstable systems requiring high-rate and accurate attitude and position...
The advent of the first two satellites of the final Galileo constellation launched by Soyuz from ... more The advent of the first two satellites of the final Galileo constellation launched by Soyuz from Europe’s spaceport in French Guiana on October 21st is a major milestone for the European as well as global satellite navigation field. In fact, these two satellites pave the way for a much awaited set of experiments testing the benefits brought about by an additional constellation in orbit, Galileo. The European constellation formed by last generation satellites carrying very precise hydrogen maser clocks, and transmitting sophisticated navigation payloads, is expected to increase positioning availability and improve satellite geometry so far as to decrease positioning errors with respect to the use of GPS satellites exclusively. In this paper, signal acquisition, tracking and demodulation of the signal broadcast by the first Galileo satellite (the so-called IOV-PFM Galileo satellite) in the E1 bandwidth is performed. Starting to monitor this satellite from December 2011, we were able t...
2010 4th International Conference on Signal Processing and Communication Systems, 2010
Many navigation problems involve constraints. For example, motor vehicle travel tends to be const... more Many navigation problems involve constraints. For example, motor vehicle travel tends to be constrained by road and building boundaries. We consider filtering problems where censuring functions can be used to constrain the measurements. It is established that the ensuing filtered estimates are unbiased, provided that the underlying probability density functions are even and the censuring functions are odd. A loosely-coupled GPS and inertial navigation system (INS) application is discussed in which an integrated solution exhibits improved performance during GPS outages when a priori information is used to constrain the altitude measurements I.
System set up 6 The radio frequency (RF) signal was received by means of a fixed, non-direction... more System set up 6 The radio frequency (RF) signal was received by means of a fixed, non-directional rooftop antenna, co-located at ISMB premises in Torino at the following coordinates: latitude = 45°03'54.99" N, longitude = 7°39'32.29" E, height = 311.97 meters.
2012 International Conference on Localization and GNSS, 2012
On the 20 th of October 2011, the first two satellites of the Galileo constellation have been lau... more On the 20 th of October 2011, the first two satellites of the Galileo constellation have been launched successfully. The possibility to have these two satellites in orbit represented a great opportunity for researchers to receive and monitor the first Galileo signals. After the satellite switch-on, we continuously monitored the signal broadcast by both the satellites, using a software radio receiver. This paper shows the analysis on the navigation message that was broadcast by the IOV-PFM Galileo satellite on the E1 bandwidth, starting from December 2011. In particular, we were able to observe a valid ephemeris data on December 21 st and December 22 nd . The successful interpretation of the navigation message enabled the first GPS+Galileo experimentations using real signals that were performed in static condition, through code-phase measurements.
2013 International Conference on Localization and GNSS (ICL-GNSS), 2013
In this paper, the structure of a tracking loop with Extended Kalman Filter (EKF) is analyzed. Pa... more In this paper, the structure of a tracking loop with Extended Kalman Filter (EKF) is analyzed. Particular emphasis is given to the NCO update rule, which is seldom mentioned or studied in previous literature. Furthermore, the structure of an EKF-based software receiver is proposed including the special modules dedicated to the initialization and maintenance of the tracking loop. The EKF-based tracking architecture has been compared with a traditional one based on an FLL/PLL+DLL architecture, and the benefit of the EKF within the tracking stage has been evaluated in terms of final positioning accuracy. Further tests have been carried out to compare the Position-Velocity-Time (PVT) solution of this receiver with the one provided by two commercial receivers: a mass-market GPS module (Ublox LEA-5T) and a professional one (Septentrio PolaRx2e@). The results show that the accuracy in PVT of the software receiver can be remarkably improved if the tracking is designed with a proper EKF architecture and the performance we can achieve is even better than the one obtained by the mass market receiver, even when a simple one-shot least-squares approach is adopted for the computation of the navigation solution.
2012 IEEE International Geoscience and Remote Sensing Symposium, 2012
ABSTRACT As more and more attention is received by the underlying passive potential of Global Nav... more ABSTRACT As more and more attention is received by the underlying passive potential of Global Navigation Satellite Systems (GNSS) signals, reflectometry and scatterometry are visited in this paper in order to assess water surface identification and aircraft altimetry performance. This is possible thanks to the high reflectivity of Global Positioning System (GPS) signals in the L-Band frequency range on water as well as ice and snow covered surfaces which compensates for the otherwise low signal intensity. Indeed, GNSS reflectometry belongs to the class of bistatic radar systems where transmitter and receiver reside at different locations and signals pass through a reflecting surface. Code phase and carrier phase based time delay measurements between the direct path and reflected signals, are used to determine the small aircraft's height with respect to the reflecting surface. On the other hand, specular reflection points are computed, and a comparison of the reflected power to the direct received power is shown to yield a good water surface identification performance. Code and carrier phase measurements are implemented in this paper to obtain cm level height estimates.
2012 International Conference on Localization and GNSS, 2012
Thanks to advances in the development of Micro-Electromechanical Systems (MEMS), it has been poss... more Thanks to advances in the development of Micro-Electromechanical Systems (MEMS), it has been possible to fabricate small dimension and cheap accelerometers and gyros, which are being used in many applications where the GPS/INS integration is carried out, as for example to identify track defects, navigation, geo-referencing, agriculture, etc. Although these MEMS devices have a low-cost, they present different errors which degrade the accuracy of the navigation systems in a short period of time. Therefore, a suitable modelling of these errors is necessary in order to improve the system performance. In this work, Allan Variance and Power Spectral Density techniques are used to identify the random processes that affect the inertial sensor data. Once the random components are identified, they are modelled using first-order Gauss-Markov and random walk processes. Two models are assessed augmenting the states of the Extended Kalman Filter (EKF) to 6 and 9. Subsequently, another analysis and modelling of the inertial sensors which combines Autoregressive Filters and Wavelet De-noising is implemented and in this case the EKF of the loosely coupled GPS/INS integration strategy is augmented with 6, 12 and 18 states. Finally, the results show a comparison between these sensor error models with real data under GPS outage conditions.
In recent years, Kalman filter (KF)-based tracking loop architectures have gained much attention ... more In recent years, Kalman filter (KF)-based tracking loop architectures have gained much attention in the Global Navigation Satellite System field and have been widely investigated due to its robust and better performance compared with traditional architectures. However, less attention has been paid to the in-depth theoretical analysis of the tracking structure and to the effects of Kalman tuning. A new approach is proposed to analyze the KF-based tracking loop. A control system model is derived according to the mathematical expression of the Kalman system. Based on this model, the influence of the choice of the setting parameters on the temporal evolution of the system response is discussed from the perspective of a control system. As a result, a reasoned and complete suite of criteria to tune the initial error covariance as well as the process and measurements noise covariances is demonstrated. Furthermore, a strategy is presented to make the system more robust in higher order dynamics without degrading the accuracy of carrier phase and Doppler frequency estimates.
The paper investigates approaches for loosely coupled GPS/INS integration. Error performance is c... more The paper investigates approaches for loosely coupled GPS/INS integration. Error performance is calculated using a reference trajectory. A performance improvement can be obtained by exploiting additional map information (for example, a road boundary). A constrained solution has been developed and its performance compared with an unconstrained one. The case of GPS outages is also investigated showing how a Kalman filter that operates on the last received GPS position and velocity measurements provides a performance benefit. Results are obtained by means of simulation studies and real data.
This paper considers estimation problems where inequality constraints are imposed on the outputs ... more This paper considers estimation problems where inequality constraints are imposed on the outputs of linear systems and can be modeled by nonlinear functions. In this case, censoring functions can be designed to constrain measurements for use by filters and smoothers. It is established that the filter and smoother output estimates are unbiased, provided that the underlying probability density functions are even and the censoring functions are odd. The Bounded Real Lemma is employed to ensure that the output estimates satisfy a performance criterion. A global positioning system (GPS) and inertial navigation system (INS) integration application is discussed in which a developed solution exhibits improved performance during GPS outages when a priori information is used to constrain the altitude and velocity measurements.
The minimum-variance smoother solution for input estimation is described and it is shown that the... more The minimum-variance smoother solution for input estimation is described and it is shown that the resulting estimates are unbiased. The smoothed input and state estimates are used to iteratively identify unknown process noise variances. The use of smoothed estimates, as opposed to filtered estimates, leads to improved approximate Cramér-Rao lower bounds for the unknown parameters. It is also shown that the sequence of iterates are monotonic and asymptotically approach the actual values under prescribed conditions. A nonlinear mining navigation application is described in which unknown parameters are estimated.
The convergence of an expectation-maximization (EM) algorithm for state matrix estimation is inve... more The convergence of an expectation-maximization (EM) algorithm for state matrix estimation is investigated. It is shown for the expectation step that the design and observed error covariances are monotonically dependent on the residual error variances. For the maximization step, it is established that the residual error variances are monotonically dependent on the design and observed error covariances. The state matrix estimates are observed to be unbiased when the measurement noise is negligible. A navigation application is discussed in which the use of estimated parameters improves filtering performance.
The accuracy of INS degrades with time and therefore GPS/INS integration provides an ideal combin... more The accuracy of INS degrades with time and therefore GPS/INS integration provides an ideal combination to overcome the limits of INS only and have a reduced error in position, velocity and attitude computation. We explore the feasibility of an integrated positioning system using a Differential GPS (DGPS) and an Inertial Navigation System (INS). The work is aimed at a development of a low-cost multi sensor device that will equip every machine and vehicle in a coal mining in order to monitor their movements in real time and avoid possible ...
The accuracy of INS degrades with time and therefore GPS/INS integration provides an ideal combin... more The accuracy of INS degrades with time and therefore GPS/INS integration provides an ideal combination to overcome the limits of INS only and have a reduced error in position, velocity and attitude computation. Accurate analysis of inertial sensor error is essential to ensuring the effectiveness of the optimal GPS/INS integration and set the states variables of a Kalman filter properly. In this paper Allan Variance has been selected as the technique to investigate all the types of noise in a low-cost IMU system. The work at first presents the details of this ...
Europe's GNSS program-Galileo-entered a new phase of development with the recent launch of t... more Europe's GNSS program-Galileo-entered a new phase of development with the recent launch of two in-orbit validation satellites, which comprise the first elements of the system's full operational constellation. In this article, a team of italian researchers present the initial results of their analysis of the Galileo signals
This paper discusses the convergence of a Kalman filter-based Expectation-Maximisation algorithm ... more This paper discusses the convergence of a Kalman filter-based Expectation-Maximisation algorithm for estimating unknown model parameters. Under prescribed conditions, the parameter estimates converge to the actual values. Mining navigation applications are discussed in which good parameter estimates are required. An inertial alignment example is presented, which demonstrates that the sequence of process noise covariance estimates is monotonically decreasing. A position tracking application is also discussed in which it is demonstrated that the sequence of state matrix estimates is similarly monotonic decreasing.
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Papers by Gianluca Falco