Navy researchers seek to tame the electromagnetic interference beast plaguing shipboard electronics

April 26, 2016

By John Keller 

THE MIL & AERO COMMENTARY, 26 April 2016. 

Navy surface warships aren't just maneuverable steel islands bristling with weapons; they're complex electromagnetic transmitters and receivers driving applications like radar, combat data links, electronic warfare (EW), and communications systems. Ships also are nests of electromagnetic interference.

Take a look at one of today's Navy Arleigh Burke-class destroyers and you'll see a dense forest of antennas of virtually every size and description, covering the electromagnetic spectrum from high frequency (HF) to extremely high frequency (EHF), and beyond.

The problem with almost any radio frequency (RF) antenna is it doesn't exist in isolation; its RF emissions can influence anything nearby that can transmit or receive a signal.

Now take another look at those densely packed shipboard antennas and you'll appreciate the potential problems of noise and static they can cause for one another in what experts call co-site interference.

It boils down to a monumental headache for Navy program managers, ship designers, antenna makers, and anyone else responsible for any kind of RF and microwave system that goes aboard Navy ships, or the fixed-wing aircraft, helicopters, and unmanned aerial vehicles (UAVs) that operate from Navy ships.

Anything that transmits or receives RF energy that goes aboard ship must be compatible with everything else that does the same. Need to add a new RF system or upgrade an existing one? Good luck. Without painstaking test and evaluation, the potential is great for any new transmitter to cause big and unanticipated problems for those already there.

RF and microwave scientists at the Office of Naval Research (ONR) in Arlington, Va., have been at the forefront of the battle to eliminate or mitigate the problem of shipboard co-site interference.

Among ONR's first major attempts to come to grips with this troublesome problem was the Integrated Topside (InTop) program, which involved many of the nation's largest military RF and microwave companies to develop a scalable suite of electronic warfare, information systems, and line-of-sight communications for naval surface warships.

InTop sought to use open-systems architectures to reduce the number of topside antenna apertures, increase bandwidth, and resolve electromagnetic interference and compatibility issues caused by the large number of shipboard antennas.

Now ONR experts have launched a follow-on initiative to InTop called the Electromagnetic Command and Control (EMC2) program, which will pick up where InTop left off in developing close integration of disparate RF system electronics and antennas to reduce costs and RF interference.

ONR on Monday named 12 defense contractors to work on the 5-year potential $800 million EMC2 program: Lockheed Martin; ArgonST; Northrop Grumman; Raytheon; EOIR Technologies; SI2 Technologies; S2 Corp.; Sea Corp.; Leidos; Rockwell Collins; and TiCom.

The goal of ONR's EMC2 program is to reduce the number of RF and microwave antennas on ships, aircraft, ground vehicles, and land sites to mitigate the effects of RF interference, as well as reduce the costs of military systems that use radio waves.

Although similar to InTop, the EMC2 program seeks to take the next step by developing prototypes that integrate the RF functionality of EW, radar, communications, and information operations into a common set of open-systems antennas, electronics, and software.

The program represents a major departure from the common practice of developing stand-alone RF and microwave systems that each require a separate antenna, which wastes money and space, and threatens co-site interference.

Prototypes should be able to provide several simultaneous and independent RF and microwave beams that can work together to perform EW, radar, communications, and wireless information exchange. Researchers want to integrate these new prototypes with InTop or other RF combat systems.

With EMC2, ONR researchers want the ability to monitor the RF spectrum across a wide range of frequencies and reallocate functions to the best frequency in response to changes in the electromagnetic environment for intelligence gathering, cyber warfare, command and control, EW, situational awareness, and battle management.

Not only will technologies developed in the EMC2 program apply to new ship classes and aircraft, but also should be able to migrate into existing shipboard RF and microwave systems like the Surface Electronic Warfare Improvement Program (SEWIP).

With programs like InTop and EMC2, it sounds like ONR experts are well along in taming the co-site interference beast.