The European ARTAS tracker is currently undergoing a major development step, taking advantage of new ADS-B, Mode S Enhanced and latest platform technologies. COMSOFT, the EUROCONTROL industry partner for ARTAS is preparing the new generation of ARTAS under an INTEL/LINUX platform.

ARTAS (ATM SuRveillance Tracker and Server) has in the past years become a de facto standard for surveillance data processing in Europe. It is a major enabler for improving the efficiency and reliability of ATM surveillance systems across Europe. Today more than 15 European countries use ARTAS with almost 50 installations throughout the continent.

The system is based on latest tracker technology and comes with an integrated concept for operation, support and maintenance. The CAMOS (Centralised ARTAS Maintenance and Operational Support) service provided by EUROCONTROL in cooperation with COMSOFT is formally installed since 2001 and supports national administrations that use ARTAS.

Functional Enhancements

ARTAS traditionally supports classical primary radars, secondary radars and since the last version also Mode S Elementary surveillance sensors. As part of the EUROCONTROL EATMP (European Air Traffic Management Programme), the agency is now extending the scope of the tracker to new types of data sources, including Mode S Enhanced surveillance and Automatic Dependent Surveillance (ADS).

Primary goal of the ARTAS V7 development is to make use of the additional information available from the cockpit via these technologies. The new version will take advantage in two ways of these so-called Downlink Aircraft Parameters (DAPs):

1. First and of major importance, ARTAS will make these DAPs available to the controller. This will close a gap between traditional surveillance and on-board available information. In the future, the controller will, e.g., be capable to see ACAS alerts and ACAS resolution advisory information from a critical flight on his screen.
2. Second and not less important, the ARTAS tracker will take advantage of the additional information and use the high accuracy of the new sensor types for an improvement of the tracking process.

The two functionalities correspond to two milestones of the ARTAS V7 development project: By 2004 the DAP Store and Forward version of ARTAS will be delivered, followed by a full Mode S Enhanced and ADS tracking version in 2005. Both versions will be operationally validated.

Capacity Enhancements

In addition to the functional enhancements, ARTAS V7.0 will incorporate major capacity improvements of the tracker:

• The ARTAS Domain of Interest (DOI) will be increased from currently 1024 x 1024 to 2048 x 2048 Nautical Miles.
• The ARTAS throughput capacity will be extended to a maximum of 2000 plots/sec and 4000 concurrently supported system tracks.
• The above will be coupled with a range of other capacity expansion measures to prepare the ARTAS tracker for new scenarios.

Tracking Extensions

In case of ADS-only detection, as the case in oceanic areas, ARTAS will initiate a track based on ADS data only. Once the flight gets onto continental airspace, the tracking will continue without interruption using data fusion of classic sensor input and ADS input. For track initiation under a mixed ADS/classical radar coverage track initiation will be considerable accelerated and the subsequent update process will be improved in terms of its accuracy and likelihood of false or split tracks.

Both for track initiation and track continuation, the characteristics of ADS data have to be taken into account in the underlying algorithms. Problematic cases have to be treated, e.g. when ADS data and classical data contradict each other with some of their information. Data fusion technologies, also related to bias estimation and processing are employed in the development. ARTAS will support the major currently employed types of ADS ground stations, namely ES (Extended Squitter), VDL Mode 4 and UAT (Universal Access Transceiver).

Figure 2 gives an overview of the ARTAS architecture for V7. There are two major chains of processing, one for DAP store & forward, the other for the core tracking. Via a global parameter, administrations can choose, whether they want to use ADS input data in the tracking process itself or only take advantage of the DAP parameters.

This dual approach to ADS integration is useful in order to accompany a step-wise migration of ADS into European operational concepts. While initially the DAP parameters may represent valuable auxiliary information to the controller, the use of aircraft-derived data for operational positioning may still have to wait until extended field trials have confirmed ADS reliability and safety aspects (see "ADS-B Evaluation in Europe").

ASTERIX Evolution

As part of the evolution towards Mode S Enhanced and ADS, the universal exchange format for surveillance data, ASTERIX, will be extended in various ways. Table x gives an overview of the ASTERIX categories that have been added or modified to cater for the new requirements.

To support downward compatibility, each ARTAS service can be individually configured to either use the ASTERIX CAT 30 or the new CAT 62 suite of formats.

In parallel to the V7.0 evolution of ARTAS, COMSOFT is upgrading their RAPS (SuRveillance Recording, Analysis and Playback System) to cater for the new categories. RAPS-II is a EUROCONTROL-qualified ASTERIX test tool, employed for analysis and conformance testing against the standards.

ARTAS on LINUX

ARTAS is currently operating on a DEC Alpha DS10 platform under the TRU64 operating system. As part of V7, COMSOFT was contracted by EUROCONTROL to operationally port ARTAS to an INTEL/LINUX platform. This will ensure a mainstream, high performance system basis for the long-term evolution of the tracker. In early 2003, COMSOFT carried out an ARTAS Platform Upgrade Study on behalf of EUROCONTROL. By 2004, the company will deliver a beta version of ARTAS-L(inux), followed by a completely validated operational version of ARTAS-L in early 2005.

ADS-B Evaluation in Europe

Accompanying the ARTAS V7 development, COMSOFT supports the EUROCONTROL AVT (ADS-B/TIS-B Validation Testbed), an infrastructure to perform testing of the new generation of ARTAS under real conditions. In early 2002, the company installed an ARTAS unit in Arlanda, Sweden, which will be fed with live ADS test data from the VDL-M4, Mode S and UAT based technology networks. Using AVT technology, a series of live trials including Malmo, Arlanda, Rome and the EUROCONTROL Experimental Centre in Bretigy are being carried out. Links of this program exist to further European ADS programs, including NUP/NEAN (North European ADS-B Network), and ADS-MEDUP (Mediterranean Update Programme).

Conclusion

COMSOFT will continue to support the ARTAS tracker in all its development, support and operation aspects. Under their framework contract with EUROCONTROL, the company will provide installation, integration, training and fine tuning services and support all administrations employing ARTAS as their system tracker. In the close future, Version 7 of ARTAS will become the major operational baseline for the ARTAS user community. It will deliver another important contribution to the Single European Sky and provide major enhancements for the next decade of Air Traffic Management.