Jorge Cogo

An statistical filtering models comparison for GNSS LEO satellite navigation

In this work the performance of different statistical filtering models used for estimating states of aerospace vehicles, particularly LEO satellites, based on measurements of GNSS systems are compared. This problem is non-linear in nature, since both the state variables model and the output function are non-linear. Thus we resort to the use of the extension of the Kalman filter called EKF. Different models based on several kinematic and dynamic approaches are considered. For the performance assessment we use representative simulation scenarios. Finally, as a real application example, the case of GPS measurements taken on board the Argentine SAC-D satellite is analyzed.

Comparación de Métodos de Filtrado Estadístico para Navegación de Satélites LEO con Señales GNSS

In this paper two methods of statistical filtering for satellite navigation in low earth orbit (LEO) with GNSS signals are compared. This problem is of a nonlinear nature, because both the state variables model and the output function are nonlinear. Hence, this is usually handled via extensions to the Kalman Filter. Two such variants of extended Kalman filter are compared, one that uses GNSS measurements directly and other that solves the nonlinearity states/measurements prior to the filtering. The latter can be thought of as a variant of the socalled Positioning Kalman Filtering (PKF), while maintaining the nonlinear state model.

High speed acquisition and storage platform for SDR applications development

In this work we present the design of an FPGA based platform for acquiring and storing signals for SDR applications. The system comprises an embedded RISC processor, an A/D converter, RAM memory chips and a DMA controller core. This last component was designed from scratch to meet the high data rate and bulk requirements.

Osculating orbital elements estimation for GNSS-based satellite navigation

The pseudorange and delta-range GNSS measurements are widely used for on-board satellite orbit determination. A point estimate of the satellite state can be obtained from these measurements. Alternatively, through the knowledge of the forces acting on it, a dynamic model of the system can be utilized to obtain better states estimates through the processing of these measurements. This satellite state can be represented by its coordinates of position and velocity, or by the orbital elements that describe its orbit. Unlike previous approaches, in which the mean orbital elements averaged along one orbit are used, in this work a filtering scheme based on the osculating orbital elements is proposed. A comparison is made with the point navigation solution obtained in a simulation scenario with a satellite in a non-circular non-equatorial orbit.

Attitude Estimation Using GPS Carrier Phase Single Differences

This paper presents a system that implements single phase differentiation to estimate the attitude of a vehicle. To do so, it takes advantage of the special characteristics of an experimental multi-antenna GPS receiver with a common oscillator. As a result, the precision achieved in the final estimation of attitude is greater than the one obtained using double phase differentiation. To make this possible, an initial calibration process is needed. The algorithms developed process information offline but, after some necessary adjustments, could be implemented in real time. In addition to the analysis of the system, several tests were performed the results of which are also presented in this paper.