PAASAR – ESA CSC: Connectivity & Secure Communications

Objectives

The PAASAR (Phased Array Antenna for Search and Rescue) Consortium has developed a novel technology for the monitoring of Search and Rescue (SAR) signals: a Phased Array Antenna (PAA) capable of receiving the signals of at least 4 and up to as many as 20+ GNSS/SAR (Galileo, GPS and/or GLONASS) satellites in view with a single antenna array, allowing for the simultaneous reception of the SAR signals relayed by all the satellites in view. The goal is to create a Phased Array Antenna Monitoring Facility to replace the need for traditional MEOLUT facilities requiring multiple tracking dish antennas for reception of SAR signals from multiple spacecraft.

The prime objectives of the PAASAR project is to:

Implement a prototype PAA consisting of 50 antenna elements
Achieve beam forming to at least 4 satellites, and more if available
Acquire SAR/Galileo signal from those satellites
Verification and Validation of the prototype system
MEOLUT design and Business Case development

The development of a SAR receiver and localisation determination is not included in this project.

All the prime objectives of the project were achieved.

The accuracy of the system is dependent on the number of satellites that can be tracked simultaneously. Conventional systems are restricted in the number of satellites that can be tracked by the number of dishes. The PAASAR Proof of Concept (POC) system is a single, compact phased array composed of 50 small antennas that are combined in the digital domain to multiple independent beams. This will allow for simultaneous tracking of all satellites in view with a single, stationary antenna array, and thus has no limitation in the number of satellites that can be tracked simultaneously. Therefore the PAASAR system provides a better performance than conventional systems by maximizing the # of tracked satellites and processing them on one location. Further advantages of using a solid-state antenna instead of multiple steerable dish antennas includes a smaller footprint, no re-pointing time (satellite hand-over) and less maintenance costs therefore providing in a more reliable system. Additionally the PAASAR system is able to calibrate itself continuously.

The developed PAASAR POC (Figures 1 and 2) shows all advantages of a phased array for SAR able to track multiple satellites and calibrate itself in order to provide increased performance over existing systems.

The copyright in this information and webpage is vested in Science & Technology B.V. on behalf of the PAASAR consortium. This information may only be reproduced in whole or in part, or stored in a retrieval system, or transmitted in any form, or by any means electronic, mechanical, photocopying or otherwise, either with the prior permission Science & Technology B.V. and the PAASAR consortium in accordance with the terms of ESTEC Contract no 4000108533/13/NL/US.

Challenges

During the design and development phase of the project the baseline PAASAR requirements and design have been developed, extended with a requirement baseline for a full Phased Array MEOLUT station. The following key issues for developing and system integration of the PAASAR prototype have been identified, addressed and implemented in in final PAASAR POC:

Global beam forming algorithms
Clock distribution system
Calibration method: Phase and Amplitude calibration on satellite signal itself.
Digital stream distribution system
Control system
System health management system
EMC environmental analysis

Plan

The baseline PAASAR requirements and design have been developed in the first (design) phase of the PAASAR Project, extended with a requirements baseline for a full MEOLUT. During the following development phase existing available (sub)system components are combined and the algorithms for Beam Forming and Calibration are developed, and in parallel the development and design of all PAASAR components/features to meet the program objectives has taken place. The PAASAR production plan has encompasses a structured build-up to the final functional PAASAR POC, in sequential order:

PAASAR Early Development and Test Setup: controlled signal, not over–the-air
PAASAR Development and Test Setup: 1 antenna tile, over-the-air signals
PAASAR Final Proof of Concept (POC): 5 antenna tiles, over-theair signals

The final functional PAASAR POC was tested and validated for final acceptance. In addition an antenna characterization was performed. A field test of the PAASAR POC also supported the successful verification and acceptance of the PAASAR POC.