Design And Analysis Of High Sensitivity Algorithms For Heo Orbit Gnss Receivers

The utilization of GNSS receivers in space present a great advantage in terms of determination of position and velocity as makes these operations simpler. However, its application is conditioned by the type of dynamics and the orbital configuration of the GNSS satellites constellations. In HEO orbits the receiver has to deal with stringent dynamics conditions at perigee and with very low level of received signal power at apogee.One of the tasks of project HEOP, led by Deimos, in cooperation with RUAG Space and funded by the European Space Agency ( ESA), is the analysis of the design and simulation of a GNSS receiver capable of working under such conditions, focusing on the acquisition algorithms. In this case, the PROBA3 mission [ 2] has been taken as a reference for a HEO orbital mission.This project has focused in the development of two tools. The first one is the Space Service Volume Analysis Tool ( SSVAT). The SSVAT is a System Service simulator [ 1] adapted to HEO mission and Galileo signals that will allow performing system analysis to determine the expected performance of the receiver at different altitudes above the Earth. The other is the Digital Signal Processing Test Bed ( DSPTB). The latter is an implementation of a simulated receiver capable of processing realistic Base Band GNSS signals. The DSPTB implementation has followed two approaches. The first one assumes a realistic approach based on an AGGA4 [ 3] chip receiver. The second approach assumes the implementation of an enhanced processor that allows the integration of advanced acquisition techniques as the Double-Block Zero-Padding Transition Insensitive ( DBZPTI) algorithm [ 4].In this paper, the architecture and implementation of both tools is presented, and some representative results are shown.