Tag Archives: EMW

Harvesting the Electromagnetic Bycatch

By Tim McGeehan

Most Navy bridge watchstanders have had the experience of adjusting their surface-search radar to eliminate sea clutter or rain. In relation to the task of detecting surface ships, these artifacts represent “noise,” just as when one tunes out unwanted transmissions or static to improve radio communications.

However, information can be gleaned indirectly from unintentionally received signals such as these to yield details about the operating environment, and it may reveal the presence, capabilities, and even intent of an adversary. This “electromagnetic bycatch” is a potential gold mine for the Navy’s information warfare community (IWC) in its drive to achieve battlespace awareness, and represents a largely untapped source of competitive advantage in the Navy’s execution of electromagnetic maneuver warfare (EMW).

Electromagnetic Bycatch

The term electromagnetic bycatch describes signals that Navy sensors receive unintentionally. These signals are not the intended target of the sensors and usually are disregarded as noise. This is analogous to the bycatch of the commercial fishing industry, defined as “fish which are harvested in a fishery, but which are not sold or kept for personal use, and includes economic discards [edible but not commercially viable for the local market] and regulatory discards [prohibited to keep based on species, sex, or size].”1

The amount of fisheries bycatch is significant, with annual global estimates reaching twenty million tons.2 Navy sensor systems also receive a significant volume of bycatch, as evidenced by efforts to drive down false-alarm rates, operator training to recognize and discard artifacts on system displays, and the extensive use of processing algorithms to filter and clean sensor data and extract the desired signal. Noise in the sensor’s internal components may necessitate some of this processing, but many algorithms aim to remove artifacts from outside the sensor (i.e., the sensor is detecting some sort of phenomenon in addition to the targeted one).

U.S. and international efforts are underway to reduce fishing bycatch by using more-selective fishing gear and methods.3 Likewise, there are efforts to reduce electromagnetic bycatch, with modifications to Navy sensors and processing algorithms via new installations, patches, and upgrades. However, it is unlikely that either form of bycatch ever will be eliminated completely. Recognition of this within the fishing industry has given rise to innovative efforts such as Alaska’s “bycatch to food banks” program that allows fishermen to donate their bycatch to feed the hungry instead of discarding it at sea.4 This begs the question: Can the Navy repurpose its electromagnetic bycatch too?

The answer is yes. Navy leaders have called for innovative ideas to help meet twenty-first century challenges, and do to so in a constrained fiscal environment. At the Sea-Air-Space Symposium in 2015, Admiral Jonathan W. Greenert, then-Chief of Naval Operations, called for the Navy to reuse and repurpose what it already has on hand.5 Past materiel examples include converting ballistic-missile submarines to guided-missile submarines; converting Alaska-class tankers to expeditionary transfer docks (ESDs), then to expeditionary mobile bases (ESBs); and, more recently, repurposing the SM-6 missile from an anti-air to an anti-surface and anti-ballistic missile role.6 However, the Navy needs to go even further, extending this mindset from the materiel world to the realm of raw sensor data to repurpose electromagnetic bycatch.

Over The River and To The Moon

The potential value of bycatch that U.S. fisheries alone discard exceeds one billion dollars annually (for context, the annual U.S. fisheries catch is valued at about five billion dollars).7 Likewise, the Navy previously has found high-value signals in its electromagnetic bycatch.

In 1922, Albert Taylor and Leo Young, two engineers working at the Naval Aircraft Radio Laboratory in Washington, DC, were exploring the use of high-frequency waves as new communication channels for the Navy. They deployed their equipment on the two sides of the Potomac River and observed the communication signals between them. Soon the signals began to fade in and out slowly. The engineers realized that the source of the interference was ships moving past on the river.8 Taylor forwarded a letter to the Bureau of Engineering that described a proposed application of this discovery:

If it is possible to detect, with stations one half mile apart, the passage of a wooden vessel, it is believed that with suitable parabolic reflectors at transmitter and receiver, using a concentrated instead of a diffused beam, the passage of vessels, particularly of steel vessels (warships) could be noted at much greater distances. Possibly an arrangement could be worked out whereby destroyers located on a line a number of miles apart could be immediately aware of the passage of an enemy vessel between any two destroyers in the line, irrespective of fog, darkness or smoke screen. It is impossible to say whether this idea is a practical one at the present stage of the work, but it seems worthy of investigation.9

However, this appeal fell on deaf ears; the idea was not considered worthy of additional study. Later, in 1930, after it was demonstrated that aircraft also could be detected, the newly formed Naval Research Laboratory (NRL) moved forward and developed the early pulsed radio detection systems whose successors are still in use today.10 What started as degradations in radio communication signals (owing to objects blocking the propagation path) evolved to being the signal of interest itself. Today that bycatch is used extensively for revealing the presence of adversaries, navigating safely, and enforcing the speed limit. It is known as RAdio Detection And Ranging, or simply by its acronym: RADAR.

Notebook entry of James H. Trexler, dated 28 January 1945, showing calculations for a long-distance communications link between Los Angeles, California, and Washington, D.C., via the Moon. (Courtesy of the Naval Research Laboratory)

During World War II, Navy radar and radio receivers became increasingly sensitive and began picking up stray signals from around the world. Instead of discarding these signals, the Navy set out to collect them. The NRL Radio Division had been investigating this phenomenon since the mid-1920s, and in 1945 NRL established a Countermeasures Branch, which had an interest in gathering random signals arriving via these “anomalous propagation” paths.11 By 1947, it had erected antennas at its Washington, DC, field site to intercept anomalous signals from Europe and the Soviet Union.12 Just the year before, the Army Signal Corps had detected radio waves bounced off the moon. The convergence of these events set the stage for one of the most innovative operations of the Cold War.

NRL engineer James Trexler, a member of the Countermeasures Branch, advocated exploiting the moon-bounce phenomenon for electronic intelligence (ELINT). He outlined his idea in a 1948 notebook entry:

From the RCM [Radio Counter Measures] point of view this system hold[s] promise as a communication and radar intercept device for signals that cannot be studied at close range where normal propagation is possible. It might be well to point out that many radars are very close to the theoretical possibility of contacting the Moon (the MEW [actually BMEWS, for Ballistic Missile Early Warning System] for example) and hence the practicability of building a system capable of intercepting these systems by reflections from the Moon is not beyond the realm of possibility.13

Trexler’s idea addressed a particular intelligence gap, namely the parameters of air- and missile-defense radars located deep within the Soviet border. With an understanding of these parameters, the capabilities of the systems could be inferred. This was information of strategic importance. As friendly ground and airborne collection systems could not achieve the required proximity to intercept these particular radar signals, the moon-bounce method provided a way ahead. All that was required was for both the Soviet radar and the distant collection site to have the moon in view at the same time. What followed were NRL’s Passive Moon Relay experiments (known as PAMOR) and ultimately the Intelligence Community’s Moon Bounce ELINT program, which enjoyed long success at collecting intelligence on multiple Soviet systems.14

Around this time, the Navy grew concerned about ionospheric disturbances that affected long-range communications.15 So the service employed the new moon-bounce propagation path to yield another Navy capability, the communications moon relay. This enabled reliable communications between Washington, DC, and Hawaii, and later the capability to communicate to ships at sea.16 Thus, what started as bycatch led to a search for the sources of stray signals, revealed adversary air- and missile-defense capabilities, and ultimately led to new communications capabilities for the Navy.

Extracting the Electromagnetic Terrain

Signals in the electromagnetic spectrum do not propagate in straight lines. Rather, they refract or bend on the basis of their frequency and variations in the atmospheric properties of humidity, temperature, and pressure. Signals can encounter conditions that direct them upward into space, bend them downward over the horizon, or trap them in ducts that act as wave guides. Knowing this electromagnetic terrain is critical to success in EMW, and can prove instrumental in countering adversary anti-access/area-denial capabilities.

Variation in electromagnetic propagation paths can lead to shortened or extended radar and communications ranges. Depending on the mission and the situation, this can be an advantage or a vulnerability. Shortened ranges may lead to holes or blind spots in radar coverage. This information could drive a decision for an alternate laydown of forces to mitigate these blind spots. It also could aid spectrum management, allowing multiple users of the same frequency to operate in closer proximity without affecting one another. Alternatively, extended radar ranges can allow one to “see” farther, pushing out the range at which one can detect, classify, and identify contacts. Signals of interest could be collected from more distant emitters. However, the adversary also can take advantage of extended ranges and detect friendly forces at a greater distance via radar, or passively collect friendly emissions. Identifying this situation could prompt one to sector, reduce power, or secure the emitter.

As the weather constantly changes, so too does signal propagation and the resultant benefit or vulnerability. Understanding these effects is critical to making informed decisions on managing emitters and balancing sensor coverage against the signature presented to the adversary. However, all these applications rely on sufficient meteorological data, which typically is sparse in space and time. More frequent and more distributed atmospheric sampling would give the U.S. Navy more-complete awareness of changing conditions and increase its competitive advantage.

Luckily, Navy radar sensors already collect a meteorological bycatch. Normally it is filtered out as noise, but emerging systems can extract it. The Hazardous Weather Detection and Display Capability (HWDDC) is a system that takes a passive tap from the output of the SPS-48 air-search radar (located on most big-deck amphibious ships and carriers) and repurposes it like a Doppler weather radar.17 Besides providing real-time weather information to support operations and flight safety, it can stream data to the Fleet Numerical Meteorology and Oceanography Center in Monterey, California, to feed atmospheric models. With this data, the models can generate better weather forecasts and drive electromagnetic propagation models for prediction of radar and communications-system performance.18 The Tactical Environmental Processor (TEP) will perform the same function by extracting atmospheric data from the SPY-1 radar.19

By passively using the existing radar feeds, HWDDC and TEP provide new capabilities while avoiding additional requirements for power, space, frequency deconfliction, and overall system integration that would be associated with adding a new radar, antenna, or weather sensor. There also is the potential to extract refractivity data from the radar returns of sea clutter.20 The multitude of radar platforms in the Navy’s inventory represents an untapped opportunity to conduct “through the sensor” environmental data collection in support of battlespace awareness.

Likewise, the Global Positioning System (GPS) also collects meteorological bycatch. As GPS signals pass through the atmosphere, they are affected by the presence of water vapor, leading to errors in positioning. The receiver or processing software makes corrections, modeling the water vapor effect to compensate, thereby obtaining accurate receiver positions. However, water vapor is a key meteorological variable. If the receiver location is already known, the error can be analyzed to extract information about the water vapor, and by using multiple receivers, its three-dimensional distribution can be reconstructed.21 Instead of dumping the bycatch of water vapor, it can be (and is) assimilated into numerical weather prediction models for improved short-range (three-, six-, and twelve-hour) precipitation forecasts.22

Do Not Adjust Your Set

There is also great potential to harvest bycatch from routine broadcast signals. While a traditional radar system emits its own pulse of energy that bounces back to indicate the presence of an object, passive systems take advantage of signals already present in the environment, such as television and radio broadcasts or even signals from cell towers or GPS.23 These signals propagate, encounter objects, and reflect off. This leads to the “multipath effect,” in which a transmitted signal bounces off different objects, then arrives at the same receiver at slightly different times owing to the varied distances traveled. (This is what used to cause the “ghost” effect on television, in which an old image seemed to remain on screen momentarily even as the new image was displayed.) Variations in this effect can be used to infer the presence or movement of an object that was reflecting the signals.

In a related concept, “multistatic” systems collect these reflections with multiple, geographically separated receivers, then process the signals to detect, locate, and track these objects in real time.24 These systems have proved effective. In a 2002 demonstration, Lockheed Martin’s Silent Sentry system tracked all the air traffic over Washington, DC, using only FM radio and television signal echoes.25 More recently, another passive system went beyond simple tracking and actually classified a contact as a small, single-propeller aircraft by using ambient FM radio signals to determine its propeller rotation rate.26 This level of detail, combined with maneuvering behavior, operating profiles, and deviations from associated pattern-of-life trends, could even give clues to adversary intent.

Passive radar systems have many advantages. They emit no energy of their own, which increases their survivability because they do not reveal friendly platform location and are not susceptible to anti-radiation weapons. They do not add to a crowded spectrum, nor do they need to be deconflicted from other systems because of electromagnetic interference. The receivers can be mounted on multiple fixed or mobile platforms. Technological advances in processing and computing power have taken much of the guesswork out of using passive systems by automating correlation and identification. Moving forward, there is great potential to leverage radar-like passive detection systems.

That being said, operators of the passive radar systems described may require extensive training to achieve proficiency. Even though the systems are algorithm- and processing-intensive, they may require a significant level of operator interaction to select the best signals to use and to reconfigure the network of receivers continually, particularly in a dynamic combat environment when various broadcasts begin to go offline. Likewise, the acquisition, distribution, placement, and management of the many receivers for multistatic systems (and their associated communications links) is a fundamental departure from the traditional employment of radar, and will require new concepts of operations and doctrine for employment and optimization. These efforts could be informed by ongoing work or lessons learned from the surface warfare community’s “distributed lethality” concept, which also involves managing dispersed platforms and capabilities.27

Challenges and Opportunities

Among the services, the Navy in particular has the potential to gain much from harvesting the electromagnetic bycatch. During war or peace, the Navy operates forward around the world, providing it unique access to many remote locations that are particularly sparse on data. Use of ships provides significant dwell time on station without requiring basing rights. Navy platforms tend to be sensor intensive, and so provide the means for extensive data collection. This extends from automated, routine meteorological observations that feed near-term forecasts and long-term environmental databases to preconflict intelligence-gathering applications that include mapping out indigenous signals for passive systems to use later.28 The mobility of Navy platforms allows for multiple units to be brought to bear, scaling up the effect to create increased capacity when necessary.

However, there are many challenges to overcome. The Navy soon may find itself “swimming in sensors and drowning in data”; managing this information will require careful consideration.29 Returning to the fishing analogy, to avoid wasting bycatch fishermen need to identify what they have caught in their nets, find someone who can use it, temporarily store it, transport it back to port, and get it to the customer before it spoils. Likewise, the Navy needs to dig into the sensor data and figure out exactly what extra information it has gathered, identify possible applications, determine how to store it, transfer it to customers, and exploit it while it is still actionable.

This hinges most on the identification of electromagnetic bycatch in the first place. As automation increases, sensor feeds should be monitored continuously for anomalies. Besides serving to notify operators when feeds are running outside normal parameters, such anomalous data streams should be archived and analyzed periodically by the scientists and engineers of the relevant systems command (SYSCOM) to determine the presence, nature, and identity of unexpected signals. Once a signal is identified, the SYSCOM team would need to cast a wide net to determine whether the signal has a possible application, with priority given to satisfying existing information needs, intelligence requirements, and science and technology objectives.30 

History has shown that this is a nontrivial task; remember that the original discovery and proposed application of radar were dismissed. If the unplanned signal is determined to have no current use, it should be noted for possible future exploitation. Subsequent sensor upgrades, algorithm improvements, and software patches then should strive to eliminate the signal from future incidental collection. If there is potential value in the incidental signal, upgrades, algorithms, and patches should optimize its continued reception along with the original signal via the same sensor, or possibly even demonstrate a requirement for a new sensor optimized for the new signal. The identified uses for the electromagnetic bycatch will drive the follow-on considerations of what and how much data to store for later exploitation and what data needs to be offloaded immediately within the limited bandwidth owing to its value or time sensitivity.

The analogy to fisheries bycatch also raises a regulatory aspect. Much as a fisherman may find that he has caught a prohibited catch (possibly even an endangered species) that he cannot retain, the same holds true for electromagnetic bycatch. It is possible that an incidental signal might reveal information about U.S. citizens or entities. Once the signal is identified, intelligence oversight (IO) requirements would drive subsequent actions. Navy IO programs regulate all Navy intelligence activities, operations, and programs, ensuring that they function in compliance with applicable U.S. laws, directives, and policies.31 IO requirements likely would force the SYSCOM to alter the sensor’s mode of operation or develop upgrades, algorithms, and patches to avoid future collection of the signal.

The Role of the Information Warfare Community

The Navy’s IWC is ideally suited to play a key role in responding to these challenges. Its personnel have experience across the diverse disciplines of intelligence, cryptology, electronic warfare, meteorology and oceanography (METOC), communications, and space operations, and assembling these different viewpoints might reveal instances in which one group can use another’s bycatch for a completely different application. IWC officers now come together to make connections and exchange expertise in formal settings such as the Information Warfare Basic Course and the Information Warfare Officer Milestone and Department Head Course. Further cross-pollination is increasing owing to the cross-detailing of officers among commands of different designators. Recent reorganization of carrier strike group staffs under the Information Warfare Commander construct has increased and institutionalized collaboration in operational settings. Restructuring has trickled down even to the platform level, where, for example, the METOC division has been realigned under the Intelligence Department across the carrier force. As a net result of these changes, the IWC has a unique opportunity to have new eyes looking at the flows of sensor data, providing warfighter perspectives in addition to the SYSCOM sensor review described above.

The Navy also can capitalize on the collective IWC’s extensive experience and expertise with issues pertaining to data collection, processing, transport, bandwidth management, archiving, and exploitation. Furthermore, the different components of the IWC share a SYSCOM (the Space and Naval Warfare Systems Command, or SPAWAR); a resource sponsor (OPNAV N2/N6); a type commander (Navy Information Forces); a warfighting-development center (the Navy Information Warfighting Development Center); and a training group (the Navy Information Warfare Training Group will be established by the end of 2017). This positions the IWC to collaborate across the doctrine, organization, training, materiel, leadership and education, personnel, and facilities  (DOTMLPF) spectrum. This will support shared ideas and unified approaches regarding the employment of emerging capabilities such as the machine-learning and “big-data” analytics that will sift through future electromagnetic bycatch. Ultimately, the members of the IWC can forge a unified way forward to develop the next generation of sensors, data assimilators, and processors.


While the Navy might not recognize exactly what it has, its sensors are collecting significant amounts of electromagnetic bycatch. The Navy’s forward presence positions it to collect volumes of unique data with untold potential. The associated electromagnetic bycatch is being used now, previously has yielded game-changing capabilities, and could do so again with future applications. Instead of stripping and discarding it during data processing, the Navy needs to take an objective look at what it can salvage and repurpose to gain competitive advantage. The fishing bycatch dumped every year could feed millions of people; the Navy needs to use its electromagnetic bycatch to feed new capabilities. Don’t dump it!

Tim McGeehan is a U.S. Navy Officer currently serving in Washington.  

The ideas presented are those of the author alone and do not reflect the views of the Department of the Navy or Department of Defense.

[1] Magnuson-Stevens Fishery Conservation and Management Act of 1976, 16 U.S.C. § 1802 (2) (1976), available at www.law.cornell.edu/.

[2] United Nations, International Guidelines on Bycatch Management and Reduction of Discards (Rome: Food and Agriculture Organization, 2011), p. 2, available at www.fao.org/.

[3] Ibid., p. 13; Lee R. Benaka et al., eds., U.S. National Bycatch Report First Edition Update 1 (Silver Spring, MD: NOAA National Marine Fisheries Service, December 2013), available at www.st.nmfs.noaa.gov/.

[4] Laine Welch, “Gulf Bycatch Will Help Feed the Hungry,” Alaska Dispatch News, June 4, 2011, www.adn.com/; Laine Welch, “Bycatch to Food Banks Outgrows Its Beginnings,” Alaska Fish Radio, August 3, 2016, www.alaskafishradio.com/.

[5] Sydney J. Freedberg Jr., “Tablets & Tomahawks: Navy, Marines Scramble to Innovate,” Breaking Defense, April 13, 2015, breakingdefense.com/.

[6] Sam Lagrone, “SECDEF Carter Confirms Navy Developing Supersonic Anti-Ship Missile for Cruisers, Destroyers,” USNI News, February 4, 2016, news.usni.org/; Missile Defense Agency, “MDA Conducts SM-6 MRBM Intercept Test,” news release, December 14, 2016, www.mda.mil/.

[7] Amanda Keledjian et al., “Wasted Cash: The Price of Waste in the U.S. Fishing Industry,” Oceana (2014), p. 1, available at oceana.org/.

[8] David Kite Allison, New Eye for the Navy: The Origin of Radar at the Naval Research Laboratory, NRL Report 8466 (Washington, DC: Naval Research Laboratory, 1981), p. 39, available at www.dtic.mil/.

[9] Ibid, p. 40.

[10] “Development of the Radar Principle,” U.S. Naval Research Laboratory, n.d., www.nrl.navy.mil/.

[11] David K. van Keuren, “Moon in Their Eyes: Moon Communication Relay at the Naval Research Laboratory, 1951–1962,” in Beyond the Ionosphere, ed. Andrew J. Butrica (Washington, DC: NASA History Office, 1995), available at history.nasa.gov/.

[12] Ibid.

[13] Ibid.

[14] Frank Eliot, “Moon Bounce ELINT,” Central Intelligence Agency, July 2, 1996, www.cia.gov/.

[15] Van Keuren, “Moon in Their Eyes.”

[16] Pennsylvania State Univ., From the Sea to the Stars: A Chronicle of the U.S. Navy’s Space and Space-Related Activities, 1944–2009 (State College, PA: Applied Research Laboratory, 2010), available at edocs.nps.edu/; Van Keuren, “Moon in Their Eyes.”

[17] SPAWAR Systems Center Pacific, “Hazardous Weather Detection & Display Capability (HWDDC),” news release, n.d., www.public.navy.mil/; Timothy Maese et al., “Hazardous Weather Detection and Display Capability for US Navy Ships” (paper presented at the 87th annual meeting of the American Meteorological Society, San Antonio, TX, January 16, 2007), available at ams.confex.com/.

[18] Tim Maese and Randy Case, “Extracting Weather Data from a Hybrid PAR” (presentation, Second National Symposium on Multifunction Phased Array Radar, Norman, OK, November 18, 2009), available at bcisensors.com/.

[19] Hank Owen, “Tactical Environmental Processor At-Sea Demonstration,” DTIC, 1998, www.handle.dtic.mil/.

[20] Ted Rogers, “Refractivity-from-Clutter,” DTIC, 2012, www.dtic.mil/.

[21] Richard B. Langley, “Innovation: Better Weather Prediction Using GPS,” GPS World, July 1, 2010, gpsworld.com/.

[22] Steven Businger, “Applications of GPS in Meteorology” (presentation, CGSIC Regional Meeting, Honolulu, HI, June 23–24, 2009), available at www.gps.gov/; Tracy Lorraine Smith et al., “Short-Range Forecast Impact from Assimilation of GPS-IPW Observations into the Rapid Update Cycle,” Monthly Weather Review 135 (August 2007),  available at journals.ametsoc.org/; Hans-Stefan Bauer et al., “Operational Assimilation of GPS Slant Path Delay Measurements into the MM5 4DVAR System,” Tellus A 63 (2011), available at onlinelibrary.wiley.com/.

[23] Lockheed Martin Corp., “Lockheed Martin Announces ‘Silent Sentry(TM)’ Surveillance System; Passive System Uses TV-Radio Signals to Detect, Track Airborne Objects,” PR Newswire, October 12, 1998, www.prnewswire.com/; Otis Port, “Super-Radar, Done Dirt Cheap,” Bloomberg, October 20, 2003, www.bloomberg.com/.

[24] Lockheed Martin Corp., “Silent Sentry: Innovative Technology for Passive, Persistent Surveillance,” news release, 2005, available at www.mobileradar.org/.

[25] Port, “Super-Radar, Done Dirt Cheap.”

[26] F. D. V. Maasdorp et al., “Simulation and Measurement of Propeller Modulation Using FM Broadcast Band Commensal Radar,” Electronics Letters 49, no. 23 (November 2013), pp. 1481–82, available at ieeexplore.ieee.org/.

[27] Thomas Rowden [Vice Adm., USN], Peter Gumataotao [Rear Adm., USN], and Peter Fanta [Rear Adm., USN], “Distributed Lethality,” U.S. Naval Institute Proceedings 141/1/1,343 (January 2015), available at www.usni.org/.

[28] “Automated Shipboard Weather Observation System,” Office of Naval Research, n.d., www.onr.navy.mil/.

[29] Stew Magnuson, “Military ‘Swimming in Sensors and Drowning in Data,’” National Defense, January 2010; www.nationaldefensemagazine.org/.

[30] U.S. Navy Dept., Naval Science and Technology Strategy: Innovations for the Future Force (Arlington, VA: Office of Naval Research, 2015), available at www.navy.mil/.

[31] “Intelligence Oversight Division,” Department of the Navy, Office of Inspector General, n.d., www.secnav.navy.mil/.

Featured Image: ARABIAN GULF (March 4, 2016) Electronics Technician 3rd Class Jordan Issler conducts maintenance on a radar aboard aircraft carrier USS Harry S. Truman (CVN 75). (U.S. Navy photo by Mass Communication Specialist 3rd Class Justin R. Pacheco/Released)

Get Ready For The Spectrum Melee

By Douglas Wahl and Tim McGeehan

A New Era

In 1903, Guglielmo Marconi, the father of modern radio, was demonstrating an improved version of his device for wireless telegraphy at the Royal Institution in London. He had planned to transmit a message in Morse code from 300 miles away in Cornwall to the lecture hall in London, where it would be received and deciphered by an associate in front of the waiting audience. As the demonstration commenced the machine began receiving a signal. It repeatedly spelled the word “rats” before beginning a message that scandalously mocked Marconi: “there was a young fellow of Italy, who diddled the public quite prettily…”1 The press soon reported that someone had made a “deliberate and cowardly attempt to wreck the experiment.”2

This event was sensational because this version of Marconi’s wireless had been advertised as being specially tuned and therefore secure from outside interception or interference. The ‘scientific hooligan’ behind the interference was Nevil Maskelyne, a local magician and wireless competitor, who sought to demonstrate that the radio signals were neither as private nor as secure as Marconi had claimed.3

Although technology has progressed significantly over the last 100-plus years, this episode still has serious ramifications today, as it could be considered the first episode of communications electronic attack (EA) or spoofing. Maskelyne, who had set up his own transmitter nearby, seized control of the electromagnetic spectrum (EMS) and disrupted Marconi’s communications signal by overpowering it and injecting his own signal in its place, thereby delivering the new message to the intended receiver. Maskelyne’s 1903 stunt had also heralded a new era in warfare, where the EMS itself could and would be a contested battleground. Today, both non-state actors and adversary nations seek to use EA to deny the use of the EMS, which has become critical to both our daily lives and military operations. Fortunately, disruptive technologies are emerging to fill the urgent need to sense, characterize, and exploit the EMS, while at the same time deny it to our adversaries.

Our Reliance

As U.S. forces continue to become more technologically advanced, we continue to become more reliant on access to the EMS. Communications, sensor feeds, and command, control, and intelligence data all flow through the EMS and we have become increasingly addicted to the bandwidth available in permissive environments, with applications ranging from routine radio traffic to fire control radars. This demand will only increase.

Now, momentum is building in the drive to decouple sensors from shooters, further increasing reliance and demand on assured access to the EMS. The Naval Integrated Fire Control–Counter Air (NIFC-CA) capability distributes the AEGIS shipboard fire control data across diverse networks of remote sensors. This provides the AEGIS combat system the means to achieve independent engagement of over-the-horizon (OTH) targets with the Standard Missile (SM-6).4 In the future, engagement information will be passively provided to AEGIS from other platforms networked into NIFA-CA. Surface picket ships, aircraft like the E-2D Advanced Hawkeye, and future Unmanned Aerial Vehicles (UAV) will all be threads in the Navy’s kill web. The first generation of NIFC-CA is already here; the USS THEODORE ROOSEVELT Carrier Strike Group completed its deployment as the first NIFC-CA enabled strike group in 2015.5

Net-Enabled Weapons (NEW), like the Tactical Tomahawk that can be launched at a target and then directed inflight to a new, different target, are likewise EMS dependent.6 Future NEW weapons systems will no longer be confined to a set system of dedicated sensors, but will instead draw on the many sensors available in kill webs. These weapons will include swarms of unmanned platforms and loitering munitions that can circle overhead until being directed into a target. Similarly, our existing Tactical Data Links (Link 4A, Link 11, and Link 16) and NIFC-CA are spectrum dependent; they must be able to network, communicate, and exchange data. Our adversaries know this too and are investing in capabilities that which specifically target our access to the EMS itself as part of their Anti-Access/Area Denial (A2/AD) strategies.

In general, the A2/AD model is based on the tenants of both Clausewitz and Mahan in that it is focused on controlling the battlespace and attrition of the adversary’s forces. To counter this the surface Navy continues to develop its “distributed lethality” concept. Distributed lethality explores how dispersing forces could enhance warfighting by “countering A2/AD’s attrition model through maneuver warfare’s intent to probe for weakness” and once found, exploit it, and disable or destroy the adversary’s forces.7 Dispersion creates more room to maneuver, and “strains the anti-access mission and forces the adversary into executing area denial simultaneously.”8 However, distributed lethality will exacerbate the burden on the EMS as the distributed forces must be able to communicate and coordinate in order to mass effects when and where required.

That said, distributed lethality has a role to play in denying the EMS to our adversaries. Sun Tzu placed high value on spies and defeating adversaries before the battle. Distributed forces can test and stimulate adversary intelligence, surveillance, and reconnaissance (ISR) capabilities to determine their scope and breadth in preparation for follow-on operations. Mapping the spectral dependencies of adversary systems before conflict is key to configuring our kill web, disrupting our adversary’s Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance (C4ISR) systems, and breaking their kill chains before weapons are launched.

Spectrum control is not a “future” issue; it is an urgent issue that has been long neglected and must be addressed now – as observed in Russia’s operations in Ukraine. In 2015, then-Deputy Secretary of Defense Bob Work recently summarized the situation stating “Ukrainian commanders reported to us that, within minutes of coming up on the radio net, they were targeted by concentrated artillery strikes…  They [Russian backed separatists] jam GPS signals, causing Ukrainian UAVs to drop out of the sky. And they jam proximity fuses on artillery shells, turning them into duds.”9  Likewise in the recent past, Iran claimed to have hacked into the mission-control system of a Lockheed Martin RQ-170 SENTINEL UAV flying near their Afghan border, taken control of it, and successfully landed it in Iran.10 Tehran claimed that they jammed the UAV’s communications and when it switched to autopilot they spoofed its GPS system with false coordinates, fooling it into thinking it was close to home and landing in Iran.11 Regardless of the veracity of Iran’s version of this story, it illustrates the mindset of our adversaries. We need to ensure that the multiple entry points and data links required to fully realize concepts like “distributed lethality” don’t turn them instead into “distributed vulnerability.” Ukraine is a cautionary tale of real-world vulnerability and the A2/AD investments of potential adversaries signal intent for more of the same. As part of its mandate to ensure All Domain Access, the U.S. Navy must be able to sense, characterize, and exploit a contested EMS, while at the same time deny it to our adversaries – we need to own the spectrum.12

The Technology

Real-Time Spectrum Operations (RTSO) is a new and highly automated capability theorized to provide warfighters the ability to understand and drive their forces’ use of EMS resources. RTSO predictions are based on three mainstays: physics algorithms, sensor characteristics, and numerical weather predictions (NWP). All three must work together for RTSO to transition from theory to reality:

Sense. We need sensors distributed throughout the battlespace to constantly measure the environment and accordingly adjust our weapon systems, continuously tailoring their settings to optimize performance. The “environment” includes both the ambient EM signals and the physical environment through which they propagate. As a forward deployed service, the Navy often operates in data-sparse regions, thus every platform, manned and unmanned, must be a sensor. We need environmental and ES sensors on all of our ships and aircraft from autonomous surface vehicles to UAVs and from logistics ships to strike fighters. All this data has to be collected, processed, and most importantly sent back to our modeling and fusion centers to provide information for optimizing future operations.

Massive amounts of environmental data can also be gathered “through the sensor,” in addition to the actual desired signal.13 This is analogous to the “by-catch” of commercial fishing, where additional marine species are caught in addition to the type of fish targeted by the fisherman. The bycatch is often discarded at sea, resulting in a wasted resource. The same happens during the processing of sensor data, where the extraneous signals are removed. However, this resource can be not only salvaged but used to provide a new capability. For example, Doppler radar weather data can be extracted from SPS-48 air search radars of our big-deck aviation platforms as well as from the SPY-1 radar of the AEGIS weapon system. With the multitude of sensors available there are many untapped sources of environmental data.

We also need to take advantage of commercial off the shelf (COTS) data collection systems, such as the Aircraft Meteorological Data Relay (AMDAR) program that has been adopted by over 40 commercial airlines.14 AMDAR uses existing aircraft sensors, processing systems, and communication networks to collect, process, format, and transmit meteorological data to ground stations where it is relayed to National Meteorological and Hydrological Services to be processed, quality controlled, and transmitted on the World Meteorological Organization’s Global Telecommunications System. The Navy could incorporate a similar system into its platforms to collect and transmit data on both the EMS and physical environment.

Characterize. Once we have the environmental data in hand, we can use it to characterize the environment. In the EMS this includes mapping the frequencies in use by all actors and inferring their operations and intent. For the physical environment it includes incorporating collected data into our NWPs to forecast the future physical environment itself, which can then be fed into the EMS analysis to predict how sensors and receivers will respond to new conditions. To do this effectively we must invest in supercomputing and shared processing. In the future, an advanced version of Consolidated Afloat Networks and Enterprise Services (CANES) and the Navy’s Tactical Cloud may provide the ability to have a supercomputer on each of our large deck surface platforms, enabling this capability even when reach back data-links are degraded or denied.15

SAN DIEGO (Nov. 19, 2013) Information Systems Technician 2nd Class Anthony Pisciotto, right, familiarizes Information Systems Technician Seaman Cameron Treanor with the Consolidated Afloat Ships Network Enterprise Services (CANES) system in the Local Area Network (LAN) Equipment Room aboard the guided missile destroyer USS Milius (DDG 69).  (U.S. Navy photo by Rick Naystatt)

Exploit. Once we understand the environment, we must exploit it by adapting our tactics. We need to “seize spectral high ground” and apply maneuver warfare principles to the spectrum to assure our bandwidth. Understanding the environment better than our adversaries will allow us to evaluate trade-offs and turn Battlespace Awareness into Information Warfare. Only this will allow our forces to have the operational advantage and overmatch our adversaries by fully integrating the Navy’s information functions, capabilities, and resources to optimize decision-making and maximize warfighting effects.

Deny. Finally, we need to deny the spectrum to our adversaries by further developing systems such as the Surface Electronic Warfare Improvement Program (SEWIP) and delivering the Next Generation Jammer. We must expand the HAVE QUICK radio system with the Defense Advanced Research Projects Agency (DARPA) Analog-to-Digital Converter (ADC)16 to provide anti-jam, frequency hopping secure communications that use ultra-high frequency (UHF) and require smaller antennas.

We must also deny our spectral emissions to our adversaries. A good rule of thumb is that if your radar can range 100 nautical miles, the adversary can detect it at least to 200 nautical miles. With an eye toward preventing unwanted detection, we need to revisit how we communicate. With the widespread use of direction finding in World War II, radio silence was a normal operating procedure and information was passed between ships using semaphore. Today, Laser Communication Relay Systems exist that are both extremely secure and have high data rates. As a bonus, these systems use less energy and when paired with satellites, these line-of-sight systems have unlimited potential.

Risks, Barriers, and Integration

There are multiple risks and barriers to integrating these technologies. From the operational aspect, these technologies have to interface with currently fielded systems. Spectrum management and deconfliction are already ostensibly done through Operational Tasking Communications (OPTASK COMMS) and the Afloat Electromagnetic Spectrum Operations Program (AESOP), but we still routinely have electromagnetic interference (EMI) between our systems. The commander of the Air Force’s Space Command said that in the first 11 months of 2015 there were over 261 cases of satellite downlink jamming. When asked how many of these incidents were caused by actual adversaries, he responded “I really don’t know. My guess is zero,” and that the real cause was “almost always self-jamming.”17 In a way, this suggests that the problem might be as much cultural as it is technical. A military workforce that has grown up in the age of unlimited and uncontested bandwidth is less aware of their EMS operations, filling (and over-filling) all available bandwidth with little discipline. This nonchalance will be difficult to overcome, but the fielding of new high-end capabilities must be accompanied by a change in mindset in order to realize maximum benefit.

CAPE CANAVERAL, Fla. (Aug. 19, 2015) The U.S. Navy’s fourth Mobile User Objective System (MUOS) satellite, encapsulated in a 5-meter payload fairing, is mated to an Atlas V booster inside the Vertical Integration Facility at Cape Canaveral’s Space Launch Complex-41. (Photo courtesy United Launch Alliance/Released)

EMI is not confined to just our own systems. Used indiscriminately, military radar systems may be strong enough to interfere with wireless systems, air traffic control radars, and cellphone systems. In the late 1980s, a Dutch naval radar caused the Supervisory Control and Data Acquisition (SCADA) system of a natural gas pipeline near the naval port of Den Helder to open and close a valve, ultimately leading to an explosion.18 Despite a crowded spectrum at home, the U.S. government continues to sell off bandwidth and civil users continue to encroach upon what remains. The net effect is an increasing limitation on the military’s ability to effectively train stateside.

Another barrier to progress in the acquisition and integration of new systems is the U.S. military’s acquisition system itself. It is too slow and vulnerable to espionage and theft. In military acquisitions the mantra is that “we don’t fight the enemy, we fight the budget,” which is often shaped more by political considerations than by the needs of the services. In 2016, Assistant Secretary of the Navy for Research, Development, and Acquisition Sean Stackley testified that Navy needs more authority to spend on experimentation and prototyping (not necessarily programs of record), because “the pace of technology is outpacing” the services’ ability to work their way through the “long and lengthy process” of fielding weapons systems.19

In terms of security, plans to assure access to the EMS should begin before these systems are even fielded. Espionage and theft are rampant from cleared defense contractors, evidenced by the striking similarity of ‘new’ adversary platforms to our own. However, the threat even extends to university and research labs. Today’s high-tech research becomes tomorrow’s classified projects and programs; we need to ensure these capabilities are protected throughout their entire development as an early compromise of one of these technologies gives our adversaries years to either improve upon it or develop a counter.


As we wage the battle of Washington, we need to prioritize investment in the capabilities described above. Roadmaps and plans are aspirational without resources and in this constrained fiscal environment there are many promising programs that will fall “below the cut line” and not be funded. However, capabilities that will enable us to own the spectrum when and where required are just as important, if not more important, than any particular ship or handful of strike fighters. At the cost of $100-plus million dollars per unit, would one F-35 Joint Strike Fighter be missed if the Navy was to reallocate this funding towards a RTSO program? If we lose the battle for the spectrum, many platforms like these will be seriously impaired and vulnerable, if not completely blind, deaf, and dumb and thus defenseless.

Luckily, there have been recent admissions from senior Department of Defense leadership that these types of capabilities are critical as we move forward. This support may help identify funding for rapid transition or similar acquisition “fast track” opportunities to get these technologies to the Fleet quickly. However, the true level of commitment will be clear in the budget.


The spectrum is a battleground whose control is absolutely fundamental to warfare in the information age. The U.S. military must seize upon emerging technologies that will enable it to maintain superiority in this congested and contested environment. To paraphrase Sun Tzu, “Know the enemy, know yourself; your victory will never be endangered. Know the electromagnetic terrain, know the weather; your victory will then be total.”  The spectrum is no longer an “enabler” to military operations; it is the battlefield.

Douglas T. Wahl is the METOC Pillar Lead and a Systems Engineer at Science Applications International Corporation.

Tim McGeehan is a U.S. Navy Officer currently serving in Washington.  

The ideas presented are those of the authors alone and do not reflect the views of the Department of the Navy or Department of Defense.


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14. https://www.wmo.int/pages/prog/www/GOS/ABO/AMDAR/AMDAR_System.html

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17. Syndey Freedberg, U.S. Jammed Own Satellites 261 Times; What if Enemy Did?, Breaking Defense, December 02, 2015, http://breakingdefense.com/2015/12/us-jammed-own-satellites-261-times-in-2015-what-if-an-enemy-tried/

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Featured Image: ARABIAN SEA (June 11, 2011) Operations Specialist 2nd Class Stephen Sittner, from Denver, identifies and tracks air contacts in the Combat Direction Center of the aircraft carrier USS Ronald Reagan (CVN 76).  (U.S. Navy photo by Mass Communication Specialist 3rd Class Alexander Tidd/Released)