Blue-force tracking evolves for the modern battlefield

Two fundamental questions are always in a soldier's mind: "where am I, and where are my friends?", and for his commander: "where are my forces deployed?"

Until about 20 years ago the first was answered by a map and compass, and accuracy depended on the competency of the user. The second was answered by the result being passed over a radio link, usually in voice, upwards to a headquarters, to be plotted by hand on a map. The potential for error, when you add offline encryption/decryption, was enormous, and the presence of obsolete information was always a possibility. It was more than likely that much of the positional information displayed on maps was obsolete or inaccurate.

GPS removed the dependence on a soldier's individual skill, but making that accurate information available to everybody else was still to come - positional information was still transmitted in the old way.

The 1990s US Army digitisation programme provided the first steps in automating the transmission of this information. Specifically it was the Force XXI Battle Command Brigade and Below (FBCB2) system that demonstrated the possibilities.

As originally construed, FBCB2 comprised a battle-management system with application software running on terminals connected to GPS satellite receivers. These were installed in tactical operations centres (TOCs) at battalion and brigade levels, and on weapons platforms and combat vehicles.

In addition to formatted command and control (C2) messages, these terminals were intended to exchange electronic map-based situation awareness (SA) data on enemy and friendly dispositions - based on sightings and automatic GPS-derived position reports - with each other and their affiliated command cells, using a tactical internet. The latter was founded on a two-tier terrestrial radio network comprising specially adapted ITT Single-Channel Ground/Air Radio System (SINCGARS) VHF radios supplemented by Raytheon Enhanced Position Location Reporting System (EPLRS) UHF data radios.

An automatically updating system that shows the location of all friendly forces removes any question over accuracy and, in theory, is always current. Positional data can be automatically filtered and aggregated by sub-unit and unit, so that as the information moves up the command chain, it is shown at a level appropriate to the viewer, and can also be expanded if required. As the data is available to all, in the same time frame, everyone is working to the common operating picture (COP) and misunderstandings should be reduced.

There are, however, drawbacks. A system that relies purely on terrestrial radio communications is affected by range limitations and terrain interference, for when communications are interrupted data is no longer updated. The updating interval or the refresh rate is the planned delay in the system, and most systems rely either on a time or a distance-moved trigger - positional information is either transmitted at specific time intervals or when the transmitting entity has moved a certain distance. The parameters of these triggers can be varied, and may be changed according to the tactical situation. The latency of the system is the unplanned delay or the delay caused by the time it takes to transmit, manipulate and retransmit the data.

These blue-force tracking (BFT) systems therefore do not provide a real-time image of the battlefield. While going a considerable way towards force deconfliction, they do not offer fail-safe combat identification. The reliance on GPS can be a disadvantage in the urban environment, where the system is less effective, particularly at the level of the individual soldier inside a building.

Image: FBCB2 installed in an armoured vehicle. The US FBCB2 programme constituted the first real step towards digitising blue-force tracking. Latest versions feature an aggregated allied force picture (Northrop Grumman) 570 of 3,550 words