Key Strategies for Safety-of-Life Receiver Development

Kurzfassung

It is well known from the open literature that interference is a serious threat for the new Galileo services especially in the E5 and E6 bands. In particular for the Safety-of–Life (SoL) applications like aviation high power pulsed radars and DMEs are a major concern. To cope with such interference it is essential for the development of a SoL receiver to consider the impact of interference on each part of the receiving chain. For this reason a new project was launched by the Institute of Communications and Navigation of the German Aerospace Center (DLR). The aim of this project is to perform the necessary predevelopment research as well as to develop, build and demonstrate an integrated SoL receiver system, which is robust against interference and multipath effects. Since array antennas with digital beamforming offer a very high potential for suppression of interference and multipath signals, the integration of an array antenna has been included in the receiver design from the early beginning of the project. Some of the most challenging tasks to achieve the project goal include: - Development of antenna elements and arrays optimized for the reception of GPS and Galileo signals - Design of robust front-ends suitable for multi-constellation multi-frequency reception with multiple antennas - Robust and reliable calibration of the full analog receiving chain including antenna and front end - Development and analysis of powerful interference detection and mitigation techniques enhanced for Galileo - Development and analysis of algorithms for providing integrity for SoL applications by receiver autonomous or assisted strategies. The proposed antenna array allows a polarization selective reception as well as adaptive nulling and sidelobe suppression. Through this, the impact of jamming and interference, as well as of multipath can be dramatically reduced. The receiver demonstrator at the recent implementation stage consists of a planar 2x2 adaptive antenna array and a multichannel L1 GPS/Galileo navigation receiver. L1 was chosen here for demonstration purposes, in order to make use of GPS L1 signals, although interference is mainly expected at E5 and E6. In the further development the design will be extended to L1/E5 reception. The demonstrator is easily expandable to a 3x3 uniformly spaced rectangular array configuration, which is chosen as goal for the final implementation. This paper gives an overview of the complete receiver architecture and the innovative key technologies utilized to ensure the high demands on robustness and reliability of SoL receivers. Especially sensitive but also highly robust multifrequency reception requires novel innovative concepts which are presented in the paper. The main parts of the demonstrator are shown in Fig. 1, where the user interface, the board containing the front-ends (left), and the 2x2 microstrip antenna array (right) are presented.