Having passed its main acceptance tests, the UK´s new ERCAMS en route radar control and monitoring system is ready for a countrywide roll-out. Germany's Comsoft reveals the CMS/XA architecture which makes it possible.

How do you manage a large, heterogeneous set of radar stations, each of different size and type, with a multitude of equipment from different manufacturers, of differing age and technology? All hundreds of miles apart from each other - and when safety is the number one issue?

Traditionally this was achieved by specifically - trained local personnel, capable of reacting instantly using one or more local control and monitoring systems. Often these have been dedicated, proprietary supervision stations, requiring a specialist of their own to support radar station diagnosis and trouble-shooting.

UK National Air Traffic Services' goal and vision has been to find a better way: to manage all its radar, communications and navigation stations in a uniform fashion, from one central point in the country.

The safe and expeditious implementation of this policy requires a lot more than the normal equipment replacement programmes. It also requires the development and integration of new management processes and systems - that is, changes in infrastructure requiring new modes of operation, revised policies and procedures, changes to staffing and training.

After proving the concept with navigation systems, NATS is changing the way it manages their radar and communication sites. It's a change requiring a number of new and/or modified systems, including a new remote control and monitoring system for NATS' radar stations. It demands a system, capable of expressing the inherent complexity and volume of the underlying information in an ergonomic and efficient way.

In the autumn of 1998, NATS launched the ERCAMS project. Its Goal: an integrated control and monitoring system for all UK en route and major airport radars. A starting point for a new era of radar infrastructure support. And the endpoint of a long planning, evaluation and pilot phase, concluding in the award of a contract to Germany's Comsoft.

ERCAMS began with a one-year main phase. This period provided the complete infrastructure for all the centres, sub-centres, the countrywide network as well as the equipment for the first monitored radar.

This main phase was concluded in the autumn of 1999 with successful factory- and site-acceptance tests. These included interoperability tests between all installed sites as well as the simulation of sites to be included in the future.

Since December the project has been in its rollout phase and, during a four-year period, ERCAMS will put all 20 en route and major airport radars under the control of the NATS Service Management Centre at Gatwick.

Architecture

ERCAMS is based on the COMSOFT CMS/XA architecture, standing for a new generation of Control and Monitoring Systems. It is an integrated architecture covering on-site data-acquisition technology, remote communications as well as centrally-based processing and visualization.

The Data Acquisition and Control Equipment (DACE) is located at the individual radar sites. It is based on a standardized field bus architecture and allows both central and distributed installation of acquisition and control entities. Particular emphasis is put on catering for a diversity of existing signal types and the on-the-spot replacement of legacy control and monitoring systems.

The Control Centre Equipment (CCE), the central component of the architecture, is located at the NATS Service Management Centre and coordinates all the remote sites. It is mirrored in an identical contingency site, the CSMC, and both are interconnected via a high-speed link. The CCE provides sophisticated rule-based data processing, filtering and visualization technology, gathering all the information an operator requires, in form of graphical support elements, triggers, alarms and historical databases.

A dedicated Control and Monitoring System network based on ASTERIX Category 253 connects all of the components. This network is based on the COMSOFT RMCDE - Radar Message Conversion and Distribution Equipment - technology, used in many environments for the exchange of surveillance-related data in real time.

In addition, there are 5 sub-centres, equipped with MCEs (Monitoring Centre Equipment), each receiving individually filtered monitoring data from the Service Management Center and the CSMC. These sub-centres receive a tailored view of the radars which are of interest for them, and share a limited set of control commands with the main centres. Like all other sites, the MCEs are connected to the countrywide network and follow the same basic architecture as a CCE.

COTS Platform

One major internal design element of CMS/XA, and a pre-requisite for the NATS ERCAMS, is the system's built-in reliance on open and state-of-the-art COTS technology.

This includes the use of an ORACLE relational database, PROFIBUS field bus acquisition technology, a LabVIEW graphical user interface builder, and OSI Layer 1-7 network technology, including ASTERIX as data exchange format.

Scalability, reliability and openness to future extensions can consequently be seen as an almost automatic side effect.

CMS can be seen as a family of systems, rather than a single instance: the system is scaleable - from a local, single-PC based configuration, to a distributed, integrated control and monitoring system with multiple data-acquisition sites, and multiple control centres and sub-centres. Connectivity scales from the use of a few dedicated serial lines to a country-spanning CMS wide-area network and an intra-centre LAN topology based on Ethernet, Fast Ethernet or FDDI.

Reliability

Designed particularly for ATC applications, CMS/XA includes redundancy concepts for its components at hardware, software and networking level. For ERCAMS, all critical components have to be replicated.

In addition, a dual-centre architecture was a fundamental requirement, with both the NATS, SMC and CSMC being continuously and independently fed by all radars.

Based on the dual-centre axis SMC-CSMC, each of the ERCAMS human-machine interfaces, whether connected at the SMC or CSMC, can either connect locally, or - via a 2 Mbps high speed link - remotely to the respective other centre.

This dual feed concept, put in place between radar heads and end-users, brings the overall availability to the required extreme figures.

Adaptability

Perhaps one of the most distinguishing features of the CMS/XA system is its outstanding ability to be customized to different environments. This capability was another pre-requisite for ERCAMS.

With its 20 different radars, hundreds of different signal types and thousands of individual monitoring points - as well as with the equipment's complex interaction scheme which has to be presented to an operator - it just has to be an easy task to make adaptations.

Especially given the two-month rollout rate for the radars which was as required for ERCAMS. All site-dependent adaptations are handled by CMS/XA via configuration rather than code. Configuration changes by the end-user are no longer a complex and error-prone process involving proprietary system details. The architecture makes it is as easy as editing a field of an underlying relational database, to include a new sensor or to modify an alarm condition.

In the same way, designing a screen for data presentation does not require using more than a graphics editor to "drag & drop" respective symbols from a template bar.

Outlook

The world of control and monitoring is changing in air traffic control. The pressure of cost-efficiency today is promoting architecture with a high degree of centralization.

At the same time, vendor-specific, proprietary control and monitoring systems are giving way to open solutions which uniform and flexible handling of a range of systems, including radars, navaids or plants under one and the same regime.

Flexible distributed availability of monitoring data, powerful event-processing and expressive data-presentation techniques are the essentials of tomorrow. NATS is prepared for the future, using CMS/XA as a flexible platform to support their existing and upcoming control and monitoring requirements.