GALANT

Galileo Antenna Demonstrator

Figure 1. Test of DLR’s SoL receiver demonstrator.

Figure 2. GALANT receiver with reduced size

Figure 3. Antenna pattern resulting from adaptive beamforming.

Future navigation services provided by upcoming satellite systems like Galileo will require corresponding improvements of the receiving systems. Particularly, interference and multipath signals may cause a significant degradation of the performance and thus make it impossible, to obtain exact and reliable positioning data. These restrictions and uncertainties cannot be tolerated for Safety-of-Life (SoL) applications e.g. in aeronautics and shipping. In order to overcome this problem, adaptively steered antenna arrays are employed, which enable the use of new beamforming and signal processing algorithms. They provide a more exact and reliable navigation solution, by suppressing interferences and multipath signals and improving the reception of the information signal from the direction of the satellite.

For the development and the test of these algorithms as well as for the demonstration of new ranges of application the Institute of Communications and Navigation develops a complete GNSS receiver demonstrator. New techniques of antenna array processing are employed to suppress interference and multipath signals. The goal is the development of a complete, robust SoL receiving system including antenna array, RF front end, digital signal processing, navigation solution, integrity assessment and the inclusion of inertial sensor information.

In order to deploy digital beamforming and array processing the signal of each antenna element passes through a complete RF front end, IF circuit and AD converter before the antenna pattern is generated by processing the data from all elements in real-time mode.

The SoL receiver demonstrator comprises a 2x2 active antenna array and allows for the reception of GPS and Galileo signals. Thus, the antenna elements and the front end are designed to operate in the L1/E1 and E5a frequency bands. A very broad beam characteristic is essential to obtain good scanning capabilities down to the horizon. The directions-of-arrival of satellite signals and interferers are estimated by suitable algorithms and digital signal processing. Adaptive beamforming is then used to suppress interfering and multipath signals.

The GALANT receiver was successfully tested in the Galileo Test Environment (GATE) in Berchtesgaden in mobile operation and in real time under realistic conditions.

The technical data of the receiver demonstrator are