What are STANAGs and how do they relate to unmanned aerial vehicles?

If we look at how drones, or UAVs, have been used over the last decade, we can see that they are devices with enormous potential that are far from being underutilized. There is growing interest in them (military, economic, infrastructure, environmental, etc.). So much so that many governments in different countries are investing huge amounts of capital in researching, developing, and improving these unmanned aerial vehicles.

This almost explosive increase in the diversity of UAVs inevitably leads to a poorer and more complex level of interoperability between different systems. Here, each developer creates UAV systems on their own, with their own idiosyncrasies and enriched points of view, making it difficult for two independent systems to communicate with each other and exchange information effectively.

"The ability to work together effectively and efficiently is the foundation of NATO’s success, giving the Alliance strength and capabilities beyond the sum of its parts. To carry out multinational operations, countries need to share a common set of standards"

North Atlantic Treaty Organization (NATO)

With the above quote from NATO, I intend to emphasize the importance of establishing standards for carrying out operations involving several countries or entities. NATO defines several documents specifying an agreement between different member countries to implement a standard. From now on, we will refer to these types of standards as STANAG (STANdarization AGreement).

NATO member countries have agreed on hundreds of STANAGs over the years, covering a wide range of technical specifications for common practices and operations. Some of these relate to:

• STANAG 7191: Aerial Refueling Equipment: Boom-Receptacle System And Interface Requirement Recommendations.
• STANAG 4173: 25 mm x 137 Ammunition.
• STANAG 4205: Technical Standards For Single Channel UHF Radio Equipment.
• STANAG 5516: Tactical Data Exchange - Link 16.

Some of those mentioned above have been ratified by the Spanish government. Many more can be found in this public document: STANAGS RATIFIED BY SPAIN.

In addition to the examples described above, there are other standardization agreements related to unmanned aerial vehicles. For instance, the objective of STANAG 4586 is to define the interfaces that must be implemented to achieve the required LOI (Level of Interoperability) between different UAV systems, in order to comply with the requirements defined by NATO countries.

This standardization document identifies five levels of interoperability that aim to accommodate the different operational requirements that may arise:

• LOI 1: Indirect reception and/or transmission of sensor and associated metadata; for example, Key Length Value (KLV) metadata elements from the UAV.
• LOI 2: Direct reception of sensor data and associated metadata from the UAV.
• LOI 3: Control and monitoring of the UAV payload, unless specified as monitoring only.
• LOI 4: Control and monitoring of the UAV, unless specified as monitoring only, except for launch and recovery.
• LOI 5: Control and monitoring of the launch and recovery of the UAV, unless specified as monitoring only.

It should also be noted, as stated in the document, that STANAG 4586 describes a functional architecture for UCS (UAV Control Systems), in which the following elements or interfaces are defined:

• Vehicle Specific Module (VSM):
• It acts as a “translator” between the AV (Active Vehicle) and the CUCS (UAV Control System Core), adapting the information circulating through the DLI (Data Link Interface) to the vehicle's needs.
• It packages/unpacks data to optimize transmission bandwidth.
• It acts as a database.
• It manages interfaces for controlling and monitoring data link messages.
• It manages interfaces for launch and recovery operations.
• It converts sensor data from analog to digital.
• Data Link Interface (DLI): The Data Link Interface is defined between the CUCS and VSM elements. It allows the CUCS to understand and generate specific control and status messages for aircraft and payloads.
• Core UCS (CUCS): The UAV Control System Core provides an interface that allows the operator to conduct all stages of a flight mission. According to the required LOI, this module should:
• Receive, process, and distribute data generated by the UAV and its payload.
• Create mission plans.
• Monitor and control the UAV, its payloads, and data links.
• Support future additional functionalities for both the UAV and the payload.
• Provide the UAV operator with the necessary tools to carry out mission tasks, mission plans, and mission execution.
• Command and Control Interface (CCI): The Command and Control Interface defines the set of standard messages and accompanying protocols. This module aims to cover all types of messages and data that need to be exchanged bidirectionally between the CUCS and the command and control system:
• Before flight: tactical situation, environmental data, mission constraints, and mission plans.
• During flight: status messages, payload data, and progress reports.
• After flight: status messages, payload data, records of information collected during flight.
• Human Computer Interface (HCI): There are no design requirements regarding human factors or ergonomics (number of screens, manual controls, buttons, etc.).
• Command and Control Interface Specific Module (CCISM): The Specific Control and Command Interface Module is primarily designed to communicate with command and control systems that are not directly compatible with the standards, protocols, or physical layers defined by STANAG 4586, and may be housed alongside the UCS. The architecture of the UCS must allow for the integration of a CCISM to ensure interoperability with these systems.

Functional Architecture for UAV Control Systems (UCS) - NATO

This, STANAG 4586, is just one of many standardization documents relevant to UAVs. Others include STANAG 4545: NATO Secondary Imagery Format (NSIF); STANAG 4575: NATO Advanced Data Storage Interface (NADSI); STANAG 4607: NATO Ground Moving Target Indicator (GMTI) format; STANAG 4609: NATO Digital Motion Imagery Standard; STANAG 7023: Air Reconnaissance Primary Imagery Data Standard; STANAG 7024: Air Reconnaissance Tape Recorder Interface; and STANAG 7085: Interoperable Data Links for Imaging Systems.

This post is also available in Spanish at "¿Qué son los STANAG y cómo se aplican a los vehículos aéreos no tripulados?".