Fact file: Link ZA


Link ZA is a digital network protocol developed by Thales Advanced Engineering1, a South African company that should not be confused with Thales, the French multinational. It is now mandatory for all SANDF communications equipment to be Link ZA-compliant.

Explaining the need for Link ZA, Saab Grintek Communications CE Vincent Scholtz told defenceWeb commercial Internet protocols were “enormously inefficient.”

Military standard (MIL-STD) datalinks, by comparison, have to be robust, cope with drop-outs and be incredibly efficient as they are transferring data over military radio frequencies. Whereas a standard Ethernet can carry about 100 million bits a second, radios can only carry about 1000 bits a second – yet the need is the same, namely the speedy delivery of email, voice, files, documents, attachments, images and the like.

Link ZA, which cost “tens of millions of rand” to develop, is owned by the SA National Defence Force. “It allows SA a fair degree of independence with regard the security and control of military communications and data,” Scholtz adds. “We are not tied into foreign vendors and protocols we have no control over. Link ZA is something a lot of other second tier countries wish they had.”

Peter Hanley, one of Link ZA’s developers, says the protocol, as a subject is “incredibly dry, but like an Internet standard, it makes an awful lot of stuff work.” Hanley says South Africa set out to develop Link ZA after efforts to obtain the technology from abroad failed. NATO, the North Atlantic Treaty Organisation, have been using MIL-STD datalinks for some decades but have, to date, refused to provide the technology. “We asked and were told we would never be allowed access” to NATO’s Links 11, 16 and 22, Hanley says. He adds that SA recently obtained the code for Link 11, which is 20 years old, but he didn’t disclose how.

The development of Link ZA started in the early 1990s. “We needed a standard, we could not find one so we set out to develop a Tactical Radio Data Communications Standard,” says Hanley. This only addressed part of the problem, so we developed the Combat Net Interoperability Standard (CNIS), of which Link ZA is part. It is now mandatory for all SANDF communications equipment to be Link ZA-compliant.”

Although the standard is proprietary, it is not parochial. “NATO MIL-STD 188-220 does a lot of what Link ZA does,” he says. Reflecting on the development costs, Hanley says the “development of standards are enormously, ferociously, expensive. It is to be avoided at all costs. Protocols look simple, but they are like icebergs. You only see the top 10% of the cost.”

He reckons it has been worth it for the SANDF. “Watching a communications system work is watching paint dry”. Since the standard stabilised two years ago, the SANDF gained access to a protocol that is fairly low cost from an implementation point-of-view and that can be modified to meet future needs,” Hanley says. “It allows them to easily and seamlessly exchange information which enhances command and control, it shortens the sensor to shooter time loop, thereby enhancing weapon control and it boosts situational awareness by helping answer the critical battlefield questions of ‘where am I?’, ‘where are my buddies?’, ‘where is the enemy?’, and ‘what next?'” For the artillery, it has brought down the time from when an observer spots a target to when the first round is fired at it from six to 10 minutes to just 90 seconds. “You can just about hit a moving truck,” says Hanley.

Hanley expects Link ZA to continue developing. “It will continue to evolve according to user requirements. It tries not to be prescriptive, but anarchy is not allowed either. The ultimate goal is automatic network establishment and network management. “When you log onto the Internet you don’t care how it was established or is managed. You just want it to work. That’s our ultimate goal, to make communications easier, simpler and faster.”

One practical application of Link ZA is as catalyst for the SA Air Force’s BAE Systems Mk 120 Hawk LIFT radar-simulation system (RSS), which uses a radio-frequency network established among as many as eight aircraft engaged in an exercise. Each aircraft constantly transmits its position via a Link ZA datalink, and each aircraft’s mission computer calculates the positions of the other aircraft relative to itself. That picture is displayed as a real-time radar image on one of each pilot’s three multifunction displays (MFD).

Pic: The BAE Syatems Hawk Mk120 lead-in fighter trainer makes use of Link-ZA to carry data to simulate onboard radar.