European Space Agency



With the AMETHYST program, EADS Astrium continued a long and successful history in the development of geomobile satellite systems, since it has participated in the development of all generations of INMARSAT satellites (MARECS, Inmarsat-2, Inmarsat-3, Inmarsat 4) and is now developing the next one as the prime contractor of the Inmarsat-XL satellite.

One of the key challenges of geomobile system design is the provision of ever-increasing bit-rate performances to mobile users equipped with lightweight terminals. This progress has been permitted in the past thanks to the parallel evolution of satellite technologies and transmission techniques. Based on this guideline, the AMETHYST program was initiated in 2003 to prepare the foundations for the next generation of geomobile systems.


Among the many challenges faced by future mobile satellite network design, some key issues are:

  • Definition and sizing space and ground segment infrastructures allowing the integration of terrestrial satellite & terrestrial services thanks to new types of lightweight, satellite-enabled mobile terminals,
  • Analysis of system design issues with regards to air interface, services, programmatic and technical constraints,
  • Analysis of space segment sizing issue (use of signal diversity, reflector antenna size, feeder link issue, multi-standard compatibility).


AMETHYST Phase 0 identified market opportunities either for early entry mobile payloads in L or S-band, or for integrated terrestrial / satellite geomobile systems.

AMETHYST Phase 1A allowed to develop innovative satellite mobile solutions which have been proposed to mobile satellite operators.

AMETHYST Phase 1B was key to preparing the Inmarsat-XL program.

It also allowed support of the Astrium NEMO initiative, which is an on-going initiative with a stepped approach:

  • Target 1 on existing system capacity (through the lease of capacity on winner candidates of the S-band on-going EC process),
  • Target 2 optimised solution to deliver two-way communication for public safety.


The following figure shows the overall system architecture for an integrated satellite/terrestrial infrastructure.

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Existing mobile products such as those developed for INMARSAT-4 satellites: see below) were considered as initial inputs for this study phase.

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AMETHYST Phase 0 (2003) aimed to catch initial operators' requirements, identify associated system design drivers with respect to existing products and to perform system-level analysis. During this prospective phase, two main directions for further studies were identified, leading to two separated studies in Phase 1 which were targeting different applications but relying on the same technological basis.

  • Phase 1A was a sub-project dedicated to the system and design analysis of Geomobile Networks aiming at the integration of Satellite Networks with Ancillary Terrestrial Components System that will allow the use of new types of satellite-enabled mobile terminals based on the terrestrial standards. The project focused on System Analysis, Satellite & payload Analysis and consolidation of the Telecom Ground Infrastructure. The key purpose of Phase 1A was to devise and then validate new system architectures based on the analysis of the present and future satellite technological limitations.
  • Phase 1B is a second sub-project initiated in April 2004 with INMARSAT. The purpose is to study the possible adaptation of the existing Inmarsat-4 spacecraft design to offer high performance services and integrate the new worldwide MSS spectrum allocation at L-band decided at the WRC-03.

In 2006, an extension of Phase 1A has also been performed in order to assess the end-to-end communication performances of mobile systems using Ground-Based Beam Forming signal processing techniques for different payload configurations. Performances were assessed using an ad-hoc powerful software simulation tool to model the payload transfer characteristics, propagation impairments, and ground-based signal processing degradations.

In 2007 in Europe, the mobile satellites under development at S-band selected On Board-Based Beam Forming technique. Ground-Based Beam Forming technique was still a valid concept (implemented in the US) that may be further investigated for the second generation of mobile satellites.

Considering this context, Astrium proposed to focus the activities of Amethyst in order to investigate the short term opportunities offered by the new S-band mobile satellites to support the Astrium Nemo - New Mobile System - system service, i.e. delivery of communication services to the Public Safety.

Current status

All activities are completed.
The Final Review of the Amethyst Phase 1A CCN7 was successfully held at ESTEC on 4th February 2009.
The Amethyst project is closed.

Status date

Wednesday, November 16, 2011 - 12:25