Space

United Kingdom Satellite Communications

Military satellite communications (MILSATCOMS) have been well established for a number of years, and are major features of US, UK, French, Nato and Warsaw Pact communications systems. They are significant in terms of both current investment and associated research and development activities: there is little doubt that military programmes have helped to maintain the commercial industrial base, and in many ways military systems lead the field in terms of % technology development and sophistication.

The United Kingdom was the third entity to operate a telecommunications satellite in GEO, after the United States and INTELSAT. Its Skynet military communications network has been operational since 1974 following abortive starts in 1969 and 1970. A civilian direct broadcasting system, known as Marcopolo or BSB, debuted in 1989, but those assets have recently been sold to Norway and Sweden. The University of Surrey has earned an international reputation for low cost, high quality microsatellites, which have been used by several countries for modest communications tasks.

The ability to communicate beyond line-of-sight is an essential military requirement, since terrain or horizon-masking can restrict radio communications. Satellite communications (SATCOM) relay data and voice transmissions through space, providing the ability to establish communications at any point on the globe. It enables secure communications between UK home bases and deployed forces, even in austere locations with poor infrastructure. It also enables the dissemination of operationally critical ISR data and the control of unmanned or remotely piloted aircraft systems at range. The global reach and effectiveness of UK Armed Forces is therefore dependent on resilient SATCOM.

The UK’s secure SATCOM capability is provided through a private finance initiative with Airbus, which is managed by Joint Forces Command. It provides a secure and resilient communications capability through the Skynet112 series of satellites and other SATCOM resources from other providers. UK partners and allies also use Skynet bandwidth, which bolsters collaborative ties and similarly, lost or degraded capabilities can be replaced by negotiating access to their space services. Commercial bandwidth can provide redundancy for military systems but there are potential security risks if military communications are enabled by commercial satellites, which could also host foreign payloads. There are also risks in using commercial bandwidth because the terms of service provision could be significantly less than that provided through a dedicated military system.

As with civil systems, Milsatcom systems include both space and ground segments, with a range of associated ground terminals, and other ground facilities for Telemetry Tracking & Command (TT&C). Because of the need to operate with existing equipment ("backward compatibility"), and with the vagaries of defence procurement processes, radical changes in system design tend to occur only slowly.

The demands for military usage of Satcoms are continually increasing. This is due partly to increased requirements for communication (especially from small terminals) in the face of enemy threats, and partly to enhanced end-user complexity (eg computers and sensors exchanging quantities of digital information). Such usage may be regarded as part of "C3I" - Command, Control, Communications & Intelligence". One interesting current development is the planned US MILSTAR programme[l], using EHF and spread-spectrum techniques to provide a highly secure service to a select community of users.

Satellite communication is attractive to the military principally because of its wide coverage area, which permits operations at short notice in virtually any part of the world, without reliance on a national communications infrastructure. The traditional carriers of HF and VHF/UHF suffer from major weaknesses of unpredictable propagation and limited range respectively, and Satcoms provide 'high availability' by comparison. Additionally, the bandwidth (BW) and capacity offered is considerable (typically 100's of MHz @ SHF). A disadvantage however is that the satellite itself is highly visible to an enemy, and links may be subject to intercept or disruption. Because-of the overall need for survivability and redundancy, military networks generally aim to use several different modes of communication, and Satcoms may be simply one overlay dimension of (say) a data network with UH1F radio links and fibre-optics also employed. For many tactical scenarios however, Satcoms may represent the only viable means of communication.