Simulation of Multi-element Antenna Systems for Navigation Applications

The application of user terminals with multiple antenna inputs for use with the global satellite navigation systems like GPS and Galileo becomes more and more attraction in last years. Multiple antennas may be spread over the user platform and provide signals required for the platform attitude estimation or may be arranged in an antenna array to be used together with array processing algorithms for improving signal reception, e.g. for multipath and interference mitigation. In order to generate signals for testing of receivers with multiple antenna inputs and corresponding receiver algorithms in a laboratory environment a unique HW signal simulation tool for wavefront simulation has been developed. The signals for a number of antenna elements in a flexible user defined geometry are first generated as digital signals in baseband and then mixed up to individual RF-outputs. The paper describes the principle function of the system and addresses some calibration issues. Measurement set-ups and results of data processing with simulated signals for different applications are shown and discussed

A Multi Antenna Receiver for Galileo SoL Applications

One of the main features of the Galileo Satellite Navigation System is integrity. To ensure a reliable and robust navigation for Safety of Life applications, like CAT III aircraft landings, new receiver technologies are indispensable. Therefore, the German Aerospace Centre originated the development of a complete safety-of-life Galileo receiver to demonstrate the capabilities of new digital beam-forming and signal-processing algorithms for the detection and mitigation of interference. To take full advantage of those algorithms a carefully designed analogue signal processing is needed. The development addresses several challenging questions in the field of antenna design, frontend development and digital signal processing. The paper will give an insight in the activity and will present latest results

Galileo -The European Satellite Navigation System

General Overview of Galile

Absolute Calibration of Time Receivers with DLR's GPS/Galileo HW Simulator

A usual way for time transfer between atomic clocks operated at different locations is the use of the well known GNSS Common View technique. This technique is based on time receivers measuring the time differences between the connected atomic clock and the GNSS satellite clocks. The obtained results can be used for time scale generation such as UTC or TAI. In order to produce a very accurate time scale from all provided time differences measured with different GNSS time receivers the accurate calibration of them is essential. In the last years two main methods for time receiver calibration were proposed. One is to compare the obtained time differences relative to a calibrated receiver. Following the second method one performs an absolute calibration of time receivers using a GPS HW simulator. In this paper the absolute calibration of time receivers with DLR’s GPS/Galileo HW simulator is analyzed and described in detail. The primary step is to calibrate the simulator itself. In this context the most important facts and values which have to be measured are explained. After the calibration of the simulator the receiver is fed with satellite signals generated by the simulator belonging to a standard GPS satellite constellation to determine the absolute offset of the receiver (internal delay) compared to the simulator output. Additionally the precision of a combined GPS/Galileo receiver for frequency transfer is investigated and determined

First Results of Baseband Wavefront Generation with a Digital Channel Matrix for Testing of CRPA

Digital baseband wavefront generation offers high flexibility and allows the simulation and testing of relative large multi-element antenna systems compared to analogue solutions at RF. A digital matrix processor for baseband wavefront generation was developed by DLR, which is combined with a multi-channel GNSS signal simulator. This paper presents performance test results of the digital matrix, in particular for the key feature of wavefront generation, its capability to produce defined carrier phase shifts by complex weighting of the I/Q baseband signals originating from the GNSS simulator before the signals are up-converted to RF

Airborne measurements of DME interferers at the European hotspot.

In March 2009 the German aerospace centre (DLR) has measured DME interference over the European DME hot spot in various altitudes. The aim of these measurements was to determine the interference situation in the GALILEO E5 and GPS L5 bands caused by distance measuring equipment (DME) stations on the ground. First results at the hot spot show a strong reception in low altitudes of a small number of stations. By increasing the altitude the number of visible stations is increased dramatically. The general power level hence is reduced. The general goal of this activity is to derive a DME interference model