SPOC’s Ears

Northrop Grumman USAF SPOC Airborne Radio
The USAF’s SPOC airborne communications system will play an important role in the air force’s move towards multi-domain operations.

The US Air Force’s SPOC airborne communications system moves forward, helping the air force’s realisation of its Airborne Battle Management System concept.

Towards late March, Northrop Grumman announced via a press release that it had performed a flight test of its Software Programmable Open Mission System Compliant multifunction processor. Better known as SPOC, this is a new communications system for the US Air Force (USAF).

In January 2020, Northrop Grumman was awarded a USAF contract for SPOC’s development. The goal of the programme, reports noted, was to create an airborne radio hosting multiple communications links. SPOC carries the Link-16 Tactical Datalink (TDL) using frequencies of 960 megahertz/MHz to 1.215 gigahertz/GHz and the Common Datalink (CDL: twelve gigahertz to 18GHz). Link-16 is primarily used to support air operations. The CDL carries imagery from satellites and airborne platforms to other airborne users, and users on the surface.

SPOC’s Link-16 and CDL capabilities are complemented by its carriage of the Multifunction Advanced Data Link (MADL) and Multiple User Objective System (MUOS). MUOS is a satellite communications link using frequencies of 240MHz to 385MHz while MADL uses similar Ku-band frequencies to the CDL. The latter shares data between Lockheed Martin F-35 Lightning series and F-22A Raptor combat aircraft. Open sources note MADL equips USAF Northrop Grumman B-2A Spirit strategic bombers. US Navy MADL users include the baseline-9 edition of Lockheed Martin’s Aegis combat management system. Ku-band signals are highly directional using narrow beams; characteristics which make them difficult to detect and locate.

Who’s Calling?

SPOC can act as a link translator taking traffic moving across one link and sending it across another. Suppose an F-22A detects a target, but this information needs to be shared with other aircraft lacking the MADL. MADL data could be transmitted from the Raptor to a system within range. This traffic is converted so it can then be carried across a Link-16 network. The traffic is duly sent across the TDL to those who need it. Likewise, a command centre needs to share target information with the Raptor, but at a beyond line-of-sight range. Target data is sent across the MUOS constellation to the same SPOC radio. There, it is converted into a suitable format to move across MADL and reach the aircraft.

Initiatives like SPOC could play a key role in the US Air Force’s Advanced Battle Management System (ABMS). ABMS is part of the US Department of Defence’s (DOD) overarching Joint All-Domain Command and Control (JADC2) initiative. The ABMS aims to create an Internet of Military Things. Much like the prevailing JADC2 philosophy this will network all air force assets deployed to support an operation. These assets will continually share their information upwards and downwards from a combat cloud. Lateral links between the combat clouds of sister and allied services will let information flow betwixt these.

Northrop Grumman told Armada via a written statement that the SPOC flight test was performed in February 2023 using a Bombardier CRJ-900 regional airliner testbed. Although the architecture currently supports the four links mentioned above, the company said the design “replaces multiple federated radios and puts them into one system … (It) is built to support the deployment of new capabilities with speed and agility. Our multifunction processors are designed to easily integrate a wide range of communications and networking capabilities and enable the ability to operate simultaneous waveforms.” The statement continued that SPOC is currently at Technology Readiness Level-7. According to US DOD definitions, this means that a prototype has been tested in an operational environment.

As the DOD’s JADC2 forward march continues, capabilities like SPOC will only grow in importance. This recent news shows that the USAF is moving ahead with the Air Battle Management System. In doing so the force is contributing to the DOD’s overall JADC2 goals.

Northrop Grumman CRJ-900 Testbed
Northrop Grumman’s CRJ-900 testbed was used for the recent SPOC flight tests that were performed from Patuxent River airbase in Maryland in February 2023.

by Dr. Thomas Withington