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Countering Illegal Jamming

The Department of Homeland Security (DHS) Science and Technology Directorate (S&T) works to combat jamming threats by evaluating the threat, developing and testing mitigation technologies and tactics, working with public safety agencies to update training procedures, and raising awareness of jamming threats and reporting channels. S&T is committed to increasing communications resilience by making first responders safer and more aware of jamming and its potential impact to their communications, safety and ability to execute their mission.

JamX 22

The JamX 22 counter-jamming event was held at White Sands Missile Range in New Mexico from April 25-29, 2022. The event was co-hosted by the DHS S&T Office for Interoperability Technology Center and the Cybersecurity & Infrastructure Security Agency (CISA) Emergency Communications Division, and continued efforts from the 2016 and 2017 First Responder Electronic Jamming Exercises.

JamX 22 logo

There are two parts that occurred simultaneously:

  • Operation Trinity — an exercise with federal and first responder personnel that assessed the effectiveness of Resilient Communications Training for operational and technical personnel.
  • Project Resilience — an experiment with industry, academia and federal partners that assessed tools and technologies that identify, locate and mitigate spectrum interference, including illegal jamming signals, and to measure the impact of that interference on communications networks.

CISA developed the Public Safety Communications and Cyber Resiliency Toolkit to assist public safety agencies and others responsible for communications networks in evaluating current resiliency capabilities, identifying ways to improve resiliency, and developing plans for mitigating the effects of potential resiliency threats.

Communications provide a mission-critical lifeline for America’s first responders and federal law enforcement, ensuring they can do their jobs to protect and serve our citizens, communities and nation. Illegal jamming of communications systems—including jamming of GPS, radio and wireless systems—poses a threat to law enforcement and public safety across the country. Jammers may interfere with public safety communications and can leave responders without vital communications and critical situational awareness. While jamming is a growing threat to public safety communications, many first responders and federal law enforcement officers across the country remain unaware that jammers exist, or that jammers can impede their communications. Federal law prohibits the operation, manufacture, sale, marketing, importation, distribution or shipment of jamming equipment.

The S&T Resilient Communications Portfolio has worked to increase awareness and preparedness for illegal jamming threats over the last six years, including two major counter-jamming exercises and additional research. S&T’s objective is to enable federal, state and local operators to recognize, respond to, report and resolve jamming incidents without compromising the mission or endangering communities.

two participants at JamX 17

In 2016, DHS S&T held the First Responder Electronic Jamming Exercise to assess the impact of jamming on public safety communications systems and mission response and to identify gaps in training.

​Building on the results of the 2016 exercise, the 2017 First Responder Electronic Jamming Exercise (JamX 17) was the next step towards making our country and communities more resilient to jamming threats. During JamX 17, DHS S&T and public safety, law enforcement, private sector and academic partners characterized the impact of jamming on a variety of communications systems and evaluated tactics and technologies to help responders better identify, locate and mitigate the impact of jamming.

Arrows pointing to right: Recognize, Respond To, Report, Resolve, Resilient

The first step to improving communications resilience is recognizing if there is an interference problem. Disruption or failure of wireless communications or mapping equipment—including cellular, LMR or GPS systems—for unknown reasons could indicate jamming. Jamming indicators include all the following:

  • Can’t communicate in areas where there is typically good radio or cell coverage
  • Can’t communicate with normally reliable base radios or repeaters
  • Can’t communicate on multiple communications devices using multiple bands
  • Notice a significant loss of lock or general failure of GPS systems
  • Can significantly improve communications capability by moving a short distance away from a fixed “dead zone”

spectrum analyzer showing narrowband radio signals from JamX 17

In a jamming environment, an emergency response or law enforcement mission may be compromised by the lack or unreliability of communications, and they may not realize there is a problem. Many operators assume that a communications device is simply broken if it isn’t working, rather than considering that jamming could be the source of the problem. Educating operators that jamming is a real issue and ensuring they understand what to do is essential to keeping responders and our communities safe.

The first priority for the responders is to complete the mission while ensuring operator safety. DHS S&T has developed several basic mitigation tactics to ensure responders can continue focusing on their mission while re-establishing communications:

  • Switch Communications Devices or Bands: Try using a different band on radios, a cellular call or text, or disconnect Bluetooth. Many jammers only target certain types of devices, so one device may have connectivity while others do not.
  • Move Away: Move 10-20 feet in any direction to see if coverage improves. If inside, try moving outside and vice versa.
  • Go High: Elevation increases range, so try climbing a flight of stairs, or onto the back of a truck.
  • Shield Yourself: Go around a corner or behind a vehicle. Because jamming is a signal, it can be blocked or weakened by physical barriers, including vehicles or buildings. Heavy materials, such as metal or concrete, work best to shield devices from jammers.
  • Mobiles versus Portables: It is better to transmit on the mobiles and receive on portables to get through jamming. Mobile radios in response vehicles are more powerful, so they can better punch through jamming to send a message, but because they have more sensitive antennas than portable handheld radios, the receiver gets overwhelmed by the jamming noise and can’t receive. Portable radios have poor-quality antennas, so they don’t pick up as much noise.

Once the primary mission is accomplished, it is important to locate the source of the interference and neutralize it. Trained technicians can located jamming devices using spectrum analyzers and direction-finding equipment, which are now available for purchase with grant funding through the FEMA Authorized Equipment List (06CP-07-RFDF - Equipment, RF Direction Finding and 06CP-07-RFSA - Equipment, RF Detection and Spectrum Analysis). Once found, the device should be turned off and disconnected from the power source. One of the tactics that DHS S&T validated at JamX 17 to destroy jammers is covering it with a Mylar emergency blanket—something most responders have in the back of their car. This is an easy and effective way to disable the jammer quickly without touching it directly. Operators should follow all local policies regarding device seizure and evidence collection on and around the jamming device.

For suspected jamming affecting safety of life, first responders and public safety agencies should immediately report to the 24/7 FCC Operations Center:

small jammer sitting on ground at night from JamX 16

For suspected criminal activity involving the use of a jammer, law enforcement and public safety agencies should immediately report to the Homeland Security Investigations (HSI) / U.S. Immigration and Customs Enforcement (ICE) Tip Line:

For all other reports of jamming, SLTT agencies should report to the FCC Public Safety Interference Complaint portal:

Resolving jamming incidents is identifying lessons learned and then applying those to improve an agency’s response to jamming. To better prepare your agency, DHS S&T recommends focusing on education, preparation, and evaluation:

Arrows labeled Education, Preparation, Evaluation point to right
  • Educate operational employees. Training new and incumbent employees is essential to ensure they are aware of jamming threats, symptoms and response protocols. Can they recognize a jammer? Do they know the symptoms of interference? Do they know how to respond to and report incidents?
  • Prepare employees and agency policies. Ensure your agency is prepared by updating policies and interference reporting requirements, understanding what legal actions officers are authorized take to counter jammers, conducting operational exercises, and procuring any needed equipment to detect and locate interference. It is also critical to develop a Primary, Alternate, Contingency, Emergency (PACE) Plan for communications and to train all operators from every local agency on it. If the primary means of communication is disabled by jamming or other issues, all operators will understand what the fallback communications means is and coordination can continue without interruption.
  • Evaluate communications resilience. Assess how well employees are prepared to identify, locate and mitigate interference and evaluate your baseline communications resiliency. If communications vulnerabilities are exposed, address the gaps. Develop after action reports to review how interference incidents were handled and identify lessons learned to incorporate throughout the agency.
Last Updated: 07/17/2024
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