Radio Frequency Interference Best Practices Guidebook, February 2020

RADIO FREQUENCY

INTERFERENCE BEST

PRACTICES GUIDEBOOK

FEBRUARY 2020

Cybersecurity and Infrastructure Security Agency

SAFECOM/National Council of Statewide Interoperability Coordinators

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook i

Executive Summary

Public safety voice and data communications are continuously at risk of radio frequency (RF)

interference, which is defined as “the effect of unwanted energy due to one or a combination of

emissions, radiations, or inductions upon reception in a radio communication system, manifested by any

performance degradation, misinterpretation, or loss of information which could be extracted in the

absence of such unwanted energy.”

RF interference can impact a variety of commonly-used wireless

technologies such as land mobile radio (LMR), Long-Term Evolution (LTE), Bluetooth, Wi-Fi, and

Global Positioning Systems (GPS). Both manmade and natural sources can generate undesired signals

that may cause RF interference capable of disrupting wireless communications, including 911 calls,

essential LMR or LTE communications between first responders, and navigational systems using GPS or

other satellite-based location services.

o mitigate possible risks to public safety communications, SAFECOM and the National Council of

Statewide Interoperability Coordinators (NCSWIC) developed the Radio Frequency Interference Best

Practices Guidebook with the support of the Department of Homeland Security (DHS) Cybersecurity and

Infrastructure Security Agency (CISA) and the Science and Technology Directorate (S&T) to educate

public safety organizations on RF interference threats. Specifically, this Guidebook:

• Provides an overview of the different types of RF interference, illegal jamming operations, and

the implications they pose to public safety communications;

• Summarizes ongoing efforts related to awareness, preparation, mitigation, and current laws

pertaining to RF interference; and

• Offers information on how public safety organizations can best recognize, respond to, report, and

resolve RF interference incidents.

Following a review of the current threats posed by RF interference, SAFECOM, NCSWIC, CISA, and

S&T recommend that public safety organizations:

• Train personnel to recognize and respond to RF interference that is either: (1) unintentionally

caused by naturally occurring or manmade signal sources; or (2) the result of an intentional

attempt to disrupt communications;

• Create and routinely test a Primary, Alternate, Contingency, and Emergency (PACE) Plan to

ensure communications operability and resiliency;

• Familiarize themselves with how to report incidents of RF interference to the Federal

Communications Commission (FCC) and other appropriate authorities; and

• Help legislators and regulators understand the value of RF interference enforcement legislation.

This document does not contain information on specific system requirements, comprehensive operating

procedures, or specific governance considerations, but instead provides general recommendations and

resources for state, local, tribal, and territorial (SLTT) public safety practitioners.

International Telecommunication Union (ITU), “Radio Regulations Chapter I – Terminology and Technical Characteristics” last accessed January 3,

2020.

Examples of known RF interference include: nearby wireless communications transmitters, vehicle ignition systems, jamming devices, lightning, solar

flares, and auroras.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook ii

Table of Contents

Executive Summary ..................................................................................................................... i

Introduction ................................................................................................................................. 1

RF Interference Categories and Symptoms ............................................................................. 2

Internal/Self Interference ........................................................................................................... 2

External Interference ................................................................................................................. 3

Intentional Interference .............................................................................................................. 3

RF Jammers .......................................................................................................................... 3

Meaconing ............................................................................................................................. 4

Legal and Public Safety Responses to RF Interference .......................................................... 5

Federal Law ............................................................................................................................... 5

State Law .................................................................................................................................. 6

RF Interference Mitigation .......................................................................................................... 6

Education .................................................................................................................................. 6

Everyday Preparedness ............................................................................................................ 7

Special Events ........................................................................................................................... 7

RF Interference Mitigation Lifecycle .......................................................................................... 8

Recognize .............................................................................................................................. 8

Respond ................................................................................................................................ 9

Report .................................................................................................................................... 9

Resolve ................................................................................................................................ 11

Resilience ............................................................................................................................ 12

Conclusion ................................................................................................................................ 12

Appendix A: DHS RF Interference Activities ........................................................................ A-1

Appendix B: Acronym List ..................................................................................................... B-1

Appendix C: DHS-FCC Jammer Infographic ........................................................................ C-1

Appendix D: Disclaimer of Liability ....................................................................................... D-1

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Radio Frequency Interference Best Practices Guidebook iii

Figures

Figure 1. RF Jammer Examples ................................................................................................. 4

Figure 2. RF Interference Mitigation Lifecycle ............................................................................. 8

Figure 3. How to Mitigate RF Interference - Recognize .............................................................. 8

Figure 4. How to Mitigate RF Interference - Respond ................................................................. 9

Figure 5. How to Mitigate RF Interference - Report .................................................................... 9

Figure 6. How to Mitigate RF Interference - Resolve ................................................................ 11

Figure 7. How to Mitigate RF Interference - Resilience ............................................................ 12

Tables

Table 1. Internal RF Interference Examples ................................................................................ 2

Table 2. External RF Interference Examples ............................................................................... 3

Table 3. Intentional Interference Examples ................................................................................. 4

Table 4. State Legislation Overview ............................................................................................ 6

Table 5. Authority Contact Information for RF Interference Reporting ...................................... 10

Table 6. DHS S&T Jamming Exercise Contact Information .................................................... A-2

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 1

Introduction

In day-to-day operations, and even

more critically in emergency and

disaster situations, resilient

communications and situational

awareness play a vital part in

supporting the missions of public

safety and protecting the lives of first

responders. Interruption to mission-

critical communications may lead

public safety personnel into dangerous

situations or delay delivery of life-

saving services. To minimize disruption, the public safety community must work together to

address and

mitigate the growing problem of radio frequency (RF) interference.

RF interference is defined as “the effect of unwanted energy due to one or a combination of emissions,

radiations, or inductions upon reception in a radio communication system, manifested by any

performance degradation, misinterpretation, or loss of information which could be extracted in the

absence of such unwanted energy.”

Eff

ects of interference can range from mild disruption or delays in data throughput to a complete loss of

service. All devices that use RF are potentially vulnerable to interference, including radio, cellular, radar,

satellite, Wi-Fi, Global Positioning System (GPS), unmanned aircraft system (UAS) communications and

control systems, and other technologies. While public safety personnel primarily use land mobile radios

(LMR) for emergency communications, the rollout of the Nationwide Public Safety Broadband Network

(NPSBN) by the First Responder Network Authority (FirstNet Authority)

and a wider array of available

mobile communications technologies have required that agencies recognize their current vulnerabilities to

RF interference and prepare to mitigate them appropriately.

According to the International Telecommunication Union’s (ITU) Radio Regulations (RR), there are three

types of RF interference:

• Permissible interference (RR, No. 1.167): “Observed or predicted interference which complies

with quantitative interference and sharing criteria contained in these [ITU RR]…or in ITU

Radiocommunication Sector (ITU-R) Recommendations or in special agreements as provided for

in these Regulations”

;

• Accepted interference (RR, No. 1.168): “Interference at a higher level than defined as

permissible interference and which has been agreed upon between two or more administrations

without prejudice to other administrations”

; and

• Harmful interference (RR, No. 1.169): “Interference which endangers the functioning of a

radio[-]navigation service or of other safety services or seriously degrades, obstructs, or

repeatedly interrupts a radio…communication service operating in accordance with RR”

Ibid, ITU.

The FirstNet Authority is “the first nationwide public safety broadband network dedicated to public safety…ready to help law enforcement, the fire

services, and EMS do their jobs safely and effectively.”

Ibid, ITU.

“A responder’s most important tool is his or her

communication device. It’s what provides the awareness

we need to accomplish our mission when responding to

an emergency. It is ultimately what serves as our lifeline

and determines whether we make it home or not.”

Rodney Reed

Assistant Chief, Operational Support

Fire Marshal’s Office, Harris County, TX

(The Siren, 2017)

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 2

There are two sources that can result in harmful interference:

• Intentional interference sources, which include illegal jamming devices, radios programmed to

use unauthorized frequencies, or other purpose-built solutions; or

• Unintentional interference sources, which include low-quality foreign-made electronics

(e.g., Universal Serial Bus [USB] chargers, baby monitors transmitting on public safety

frequencies); outdated, degraded, or improperly installed signal boosters; lighting ballasts; and

solar flares.

RF Interference Categories and Symptoms

RF interference symptoms include disruption or failure of wireless communications or equipment for

unknown reasons. More specifically, responders may be experiencing interference if they:

• Cannot co

mmunicate in areas where they typically have radio or cell coverage;

• Cannot communicate with normally reliable base radios or repeaters;

• Cannot communicate on multiple communications devices using multiple bands;

• Notice a significant loss of functionality or general failure of GPS systems; or

• Realize communications improve significantly when moving a short distance away from a

specific fixed area, or “dead zone.”

The severity of the interference will depend significantly on the location of the source in relation to the

target. Three categories of RF interference that can affect mission-critical public safety communications –

internal/self-interference, external interference, and intentional jamming – are discussed further below.

The U.S. Government, including the Department of Homeland Security (DHS) Cybersecurity and

Infrastructure Security Agency (CISA) and the Science and Technology Directorate (S&T), have

established programs to encourage education and information sharing around RF interference threats.

Appendix A, DHS RF Interference Activities, outlines more information on these ongoing initiatives.

Internal/Self Interference

Internal or self-interference is a type of unintentional RF interference which occurs when an

organization’s own devices may be operating in a manner that interferes with their internal

communications. Most RF interference can be attributed to internal interference, which may be caused by

the improper or incorrect setup of communications equipment. Internal interference can occur directly

after upgrading equipment, adding new equipment to networks, or changing existing configurations.

Table 1. Internal RF Interference Examples

Internal RF Interference Examples

Equipment problem

Interruptions may be caused by new installations of or updates to

communications technologies. For example, updates to physical infrastructure

(e.g., new additions to a tower or relocation of a receiver), as well as upgrades

of radio consoles or hubs may cause this kind of internal interference.

Receiver

intermodulation

Interruptions may be caused by “non-linear mixing” of external signals inside

the receiver.

Users will usually hear multiple wireless signal emissions at the

same time.

Front-end overload

Interruptions may be caused by inadequate filtering of radio equipment, or

equipment that needs adjustment.

DHS S&T, “GOT COMMS? Recognizing and Mitigating Intentional and Unintentional Interference,” last accessed January 3, 2020.

Jay M. Jacobsmeyer, “800 MHz Interference: What Is It, How Do We Mitigate It and What Does the Future Hold?” November 6, 2017.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 3

External Interference

Table 2. External RF Interference Examples

External RF Interference Examples

Co-channel

Caused by more than one transmitter communicating on the same channel

due to improper frequency coordination, deteriorating or malfunctioning

equipment, or anomalous propagation.

Adjacent channel

Caused by a transmitter operating on an adjacent frequency and its energy

spilling over into the desired receive channel.

For example, adjacent channel

interference occurs along the U.S. Southwest Border where there are reported

difficulties coordinating with local Mexican entities.

Spurious emissions

Caused when a transmitter emits on frequencies on which it is not meant to

operate. This can be observable by poor audio quality or connectivity.

Natural occurrences

Caused by natural events such as solar flares, northern lights, and other

electromagnetic activities.

Natural disasters, including hurricanes and floods,

can also disrupt and damage RF communications infrastructure.

External interference is a type of unintentional RF interference that can result from sources similar to

those associated with internal RF interference but exist outside of an organization’s jurisdiction or

control. External RF interference may result from a neighboring organization’s communication system

affecting another’s frequency, or naturally occurring space weather events, such as solar flares.

Intentional Interference

Intentional interference – or jamming – is performed by an actor with a willful intent to disrupt,

disconnect, or degrade communications. Malicious jamming and nuisance jamming are the two types of

intentional interference. Malicious jamming is conducted by individuals with willful and criminal intent.

The criminal intent may be to prevent public safety personnel from completing their mission, or conceal

an ongoing criminal activity, among other possible motivations.

In contrast, nuisance jammers are willful, but not malicious as they cause interference without criminal

intent.

Common examples include drivers using mobile GPS jammers to avoid GPS tracking and speed

monitoring, and cellular or Wi-Fi jammers used to create “quiet zones” in workplaces, places of worship,

and other locations. Despite the lack of malicious intent, nuisance jamming is dangerous as it could

impact public safety operations (e.g., blocking 911 calls, impacting radio dispatch), and the first

responders should recognize that anyone they interact with daily could be a nuisance jammer, not just

individuals or organizations with criminal intent.

RF Jammers

Jamming is a term used to describe one type of intentional interference, a Denial-of-Service (DoS)

attack,

which can either use a “brute force” method to overwhelm a signal or use relatively low-powered

signals to overwhelm public safety communications systems. Illegal jamming devices are designed to

emit RF signals—or noise—over specific bands to overpower the intended, legitimate signals. Under

Title 47, United States Code (U.S.C.) Sections 302a(a) and 302a(b), the manufacture, importation,

Kenneth Wyatt, “Identifying and Locating Radio Frequency Interference (RFI),” September 7, 2018.

Ibid.

For more on adjacent channel regulation and procedures at U.S. borders, see Manual of Regulations and Procedures for Federal Radio Frequency

Management.

Telecom ABC, “Spurious Emission,” last accessed January 3, 2020.

Jacoba Poppleton, “Solar Storms: A Communication Problem,” Research Matters 2010, last accessed January 3, 2020.

John Merrill, “Ensuring Resilient Communications – Briefing for Position, Navigation & Timing Advisory Board,” May 17, 2018.

United States Computer Emergency Readiness Team (US-CERT), “Understanding Denial-of-Service Attacks,” last modified November 20, 2019.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 4

marketing, sale, shipment, or operation of devices capable of interfering with radio communications (e.g.,

jammers) is illegal in the United States.

Out

side the U.S., RF jamming devices are commercially available, however the cost and supported range

varyies significantly by device. It is difficult to detect the presence of low powered jammers as they are

often cheaply made overseas and emit inconsistent signals. Moreover, these devices, examples of which

are outlined in Figure 1 below, are easily concealed, mobile, and can be effective in concentrated areas.

Figure 1. RF Jammer Examples

Bad actors can obtain illegal jamming devices or utilize their knowledge of RF systems to sufficiently

disrupt public safety communications, as illustrated below in Table 3:

Table 3. Intentional Interference Examples

Intentional Interference Examples

Intentional

interference within

the organization

An internal actor may be causing RF interference through one of the

previously discussed methods or through a jamming device.

Intentional external

interference

An external actor uses equipment, such as a jamming device, to overpower or

send continuous transmissions on communications channels critical for law

enforcement or public safety operations, such as smuggling interdiction.

Meaconing

Meaconing describes a system which receives radio beacon signals and rebroadcasts them on the same

frequency to intentionally confuse navigation. Meaconing stations cause inaccurate bearings to be

obtained by aircraft or ground stations. Meaconing introduces position and altitude errors onto a

navigation system such as a GPS. Meaconing may be extremely difficult to detect as the GPS receiver

may appear to be functioning properly however its position or altitude information is inaccurate.

The threat of intentional interference frequently impacts the public safety community and puts the public

at risk. This delay or disruption of public safety communications can result in the loss of life or property,

as outlined in the following examples:

Examples of Intentional RF Interference to Public Safety Communications

In 2013, police in Suffolk County, New York, arrested a man who, over a nine-month period, repeatedly

interfered with Melville Fire Department’s radio transmissions.

The Federal Communications

Commission (FCC) investigated this complaint and worked closely with local police to resolve this

intentional interference to GPS signals.

Examples of Intentional RF Interference

In 2012, the FCC investigated a Federal Aviation Administration (FAA) complaint regarding interference

to their Ground-Based Augmentation System (GBAS) at Newark Liberty International Airport. FCC

47 U.S.C. § 302a (2013)

Frank Eltman, “2 NY Congressman Propose Law on Fire Radio Jammers,” The Washington Times, March 10, 2014.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 5

agents found the source of interference was coming from an individual using a GPS jammer in his

company vehicle while traveling along the New Jersey Turnpike. Although the individual intentionally

interfered with GPS to avoid detection and tracking of his vehicle, his intent was not to disrupt the GBAS.

The FCC levied a fine of $31,875 against the individual.

Similar

ly, in 2013, the FCC received an interference complaint from a local wireless service provider.

FCC agents investigated and found an individual using a cell phone jamming device in his car during his

daily work commute to and from Tampa, Florida, which caused interference to cellular service along

Interstate 4, and disrupted police communications. The FCC levied a fine of $48,000 against the

individual.

Examples of Federal Government Activity to Counter RF Interference

Agencies along the U.S. Southwest Border face ongoing challenges mitigating unintentional adjacent

channel interference originating from Mexico. Cooperation and coordination on the federal, state, and

local levels are critical to resolving these incidents.

e U.S. Customs and Border Protection (CBP) has jurisdiction to inspect imported goods as they enter

the country via mail facilities and airports, seizing jammers when identified. While these jamming devices

are subject to confiscation if properly identified, it is difficult to estimate how many shipments of illegal

jammers may have entered the country without impediment.

Legal and Public Safety Responses to RF Interference

Federal Law

The FCC enforces provisions from the Communications Act of 1934 (the Act), which expressly prohibits

the marketing, sale, or use of devices designed to intentionally block, jam, or interfere with authorized

radio communications.

More specifically:

• Section 301 states that “no person shall use or operate any apparatus for the transmission of

energy or communications or signals by radio…except under and in accordance with [the] Act

and with a license in that behalf granted under the provisions of this chapter”;

• Section 302(b) states that “no person shall manufacture, import, sell, offer for sale, or ship [non-

compliant] devices or home electronic equipment and systems, or use devices”; and

• Section 333 states that “no person shall willfully or maliciously interfere with or cause

interference to any radio communications of any station licensed or authorized by or under this

chapter or operated by the United States Government.”

In addition to the Act, other applicable provisions under FCC rules include:

• Section 2.803 prohibits the importation, marketing, or sale of these devices within the United

States;

• Se

ction 2.805 prohibits operation of these devices within the United States;

and

• Section 2.807 provides for certain limited exceptions, such as the sale to U.S. Government for

authorized, official use.

Inside Global Navigation Satellite Systems (GNSS), “FCC Fines Operator of GPS Jammer That Affected Newark Airport GBAS,” August 31, 2013.

FCC, “FCC Fines Florida Driver $48k For Jamming Communications,” May 25, 2016.

CISA, “Southwest Border Communications Working Group Fact Sheet,” last accessed January 3, 2020.

FCC, “GPS, Wi-Fi, and Cell Phone Jammers Frequently Asked Questions (FAQs),” last accessed December 20, 2018.

Ibid.

47 C.F.R. § 2.803

47 C.F.R. § 2.805

47 C.F.R. § 2.807

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Radio Frequency Interference Best Practices Guidebook 6

Violators of the Act and associated FCC rules may be subject to the penalties set forth in Title 47, U.S.C.

Sections 501 through 510.

• Section 503 allows the FCC to impose forfeitures for willful or repeated violations of the Act, the

Commission’s rules, regulations, or related orders, as well as for violations of the terms and

conditions of any license, certificate, or other FCC authorization, among other things; and

• Section 510 allows for seizure of equipment used, possessed, advertised, or sold with knowing

intent to violate Title 47, U.S.C. Sections 301 or 302.

State Law

In addition to the prohibitions set forth by the Act, several states have enacted laws that prohibit jamming

and intentional interference.

Table 4. State Legislation Overview

State

Legislation

Penalties

Florida

Statute Chapter 877,

Section 27

A person who violates this Section commits a felony of the

third degree.

Texas

Statute Chapter 38,

Section 152

Violations under this Section are considered a Class A

misdemeanor.

Arizona

Chapter 13, Section 2922

A person who violates Subsection A is guilty of a Class 6

felony and a person who violates Subsection B is guilty of a

Class 1 misdemeanor.

Alabama

Statute Section 13a-10-16

Anyone in Alabama who interferes with public safety

communications is charged with a Class C felony.

In addition, Colorado,

Connecticut,

Illinois,

and Tennessee

have established laws prohibiting the

use of in-vehicle jamming devices.

RF Interference Mitigation

Education

An organization’s technical team, radio support personnel, and Communications Unit Leaders (COML)

are the most qualified staff to recognize if there is a persistent RF interference problem. However, the key

to early detection and data collection is to educate field personnel on the threat and potential mitigation

methods. Additionally, having teams formally trained and accredited in RF interference mitigation

ensures that staff supporting public safety answering points (PSAP) or other public safety agencies are

equipped and trained in mitigation methods. Officials should be made aware that public, state, and local

government agencies, including state and local law enforcement agencies, are also prohibited from using

jammers or any other type of device that blocks, jams, or interferes with authorized communications.

There are many commercially available training opportunities to expand knowledge of RF Interference

Mitigation (RFIM) best practices, as well as courses on RF interference identification and how to use a

spectrum analyzer. One example is the International Certification Accreditation Council (ICAC) which

offers several accredited training courses and certificate programs related to RFIM.

Gaining

competency and certification on RFIM enables public safety technicians to quickly identify, mitigate, and

FCC, “Public Notice DA # 05-1776s,” June 27, 2005.

FL Stat § 877.27 (2016)

Texas Penal Code § 38.152

AZ Rev Stat § 13-2922 (2017)

AL Code § 13A-10-16 (2014)

CO Rev Stat § 42-4-1415 (2017)

CT Gen Stat § 53a-127c (2016)

IL Vehicle Code 625 ILCS 5/12-613

TN Code § 39-16-610 (2017)

Electronics Technicians Association, “RF Interference Mitigation – RFIM Competency Requirements,” last accessed January 3, 2020.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 7

respond to RF interference affecting their communications. Organizations, especially those neighboring

one another, should promote information and resource sharing partnerships to raise awareness of

anomalous and cross-jurisdictional interference activities. Below are additional examples demonstrating

how to mitigate RF interference:

• Train operators to better use radios and switch between channels when communications are not

reliable;

• Consider using RF filters to attenuate adjacent channel traffic; and

• Train personnel on courteous operating procedures, allowing operators to practice using

equipment, switch between channels, and enable automatic gain control (AGC), among other

actions.

Everyday Preparedness

Combining education with everyday preparedness practices further assists RF interference mitigation

from the onset. Public safety organizations should engage legal counsel to better understand state, local,

territorial, and tribal (SLTT) jamming laws that exist in addition to FCC rules and regulations. On some

occasions, the interference is frequency specific. To further minimize impacts, organizations are

recommended to procure communications systems in bands different from their primary system, with a

preference for high frequency (HF), ultra-high frequency (UHF), or very high frequency (VHF) bands

where possible, and change the frequencies in LMRs to mitigate interference. If changing frequency does

not work, changing the band of frequencies may mitigate the interference.

It is crucial that organizations only operate devices that have received FCC grants of equipment

authorization, and maintain transmission systems that are compliant with FCC-issued licenses. Certain

FCC-certified frequency coordinators can receive, investigate, and recommend engineering solutions to

resolve complaints of interference to private LMR licensees. If interference arises, licensees should be

prepared to provide frequency coordinators with the necessary information as expeditiously as possible.

It is also important to ensure that the FCC equipment authorization remains up-to-date by notifying the

FCC of any organizational administrative changes (e.g., entity name, points of contact, address) when

applicable. Organizations should maintain active awareness of construction deadlines and expiration

dates, as operating pursuant to an expired license or one that terminated due to failure to construct would

violate FCC rules and result in the loss of license. Licensees can also face forfeiture for unauthorized

operation, though renewals filed no later than 30 days following expiration are typically granted.

Special Events

Special events are situations where RF interference is more likely to occur, as they bring diverse actors

with diverse intentions into the operational environment, resulting in an increased likelihood for

equipment to be installed or operated improperly. Localities may need to reconfigure their equipment or

make rapid adjustments to equipment to counter the challenges that special events create.

Below are

steps to mitigate RF interference during special events:

• Train security teams, including internal and external stakeholders, on RF interference

identification, mitigation tactics, and reporting procedures;

• Monitor events with spectrum analyzers and direction-finding equipment to locate interfering

signals; and

• Where possible, ensure that each participating stakeholder has communications systems in

multiple bands, and a communications plan to direct back-up procedures (e.g., a Primary,

Alternate, Contingency, and Emergency [PACE] plan).

Some physical modifications could invalidate the equipment authorization and using different equipment may require a Special Temporary Authority

(STA) request, https://www.fcc.gov/applying-special-temporary-authority

. Refer to FCC guidance when modifying equipment.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 8

In addition to these actions, public safety organizations should include knowledgeable staff experienced

with RF interference in their special event operations.

Stakeholders are encouraged to leverage expertise

from federal government entities, such as CISA, FCC, the National Telecommunications and Information

Administration (NTIA), and the Wireless Spectrum Research and Development (WSRD) Interagency

Working Group (IWG)

to support interference identification and resolution.

RF Interference Mitigation Lifecycle

The RF interference mitigation cycle includes five steps: Recognize, Respond, Report, Resolve, and Resilience. In

order to robustly defend against RF interference, public safety organizations must employ these steps continuously. It

is also recommended that organizations consider sharing information on RF interference with neighboring

jurisdictions to further increase resiliency.

Figure 2. RF Interference Mitigation Lifecycle

Recognize

Figure 3. How to Mitigate RF Interference - Recognize

Although public safety agencies may attribute equipment failure to normal wear or general

malfunctioning, disruptions in communications may result from internal or external RF interference. Per

the above figure from S&T,

identifying the source of the RF interference is a crucial step to mitigating

issues and regaining communications capabilities.

S&T offers the following recommendations for public safety network technicians, COMLs, or others

responsible for recognizing and mitigating RF interference:

• Track reports of equipment malfunctions/disruptions in communications:

o If multiple operational assets experience issues simultaneously, or if there are repeated or

escalating issues at or near the same location, investigate.

• C

haracterize the interference using a spectrum analyzer:

o Is there a high noise floor?

Where applicable, agencies should review existing Tactical Interoperable Communications Plans (TICP) and Regional Interoperable

Communications Plans (RICP) at the local, county, regional, state, or territorial levels for the existence of additional information or identified best

practices for interference mitigation.

The WSRD IWG helps coordinate research and development activities in the federal government and with academia and the private sector. For

additional information, visit https://www.nitrd.gov/nitrdgroups/index.php?title=Wireless_Spectrum_Research_and_Development

DHS S&T, “First Responder Electronic Jamming Exercise,” last accessed January 3, 2020.

Technicians troubleshooting RF interference should be aware that narrow band equipment (e.g., 6.25 MHz) requires annual or more frequent

retuning. When out of tune, this equipment is less tolerant of receiving signals and may cause RF interference.

Recognize

Respond

Report

Resolve

RESILIENCE

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 9

o Is there blocking or lack of a control channel? Is the Bit Error Rate (BER) within

reasonable bounds? Is audio disabled or degraded? Is the pattern discernable on a

particular day of the week or at a particular time of day? Use these clues to help diagnose

whether the communications are experiencing RF interference.

Respond

Figure 4. How to Mitigate RF Interference - Respond

As intentional and unintentional disturbances occur in public safety communications nationwide, it is

important to know how to mitigate, capture, and maintain interference incident records. Everyday

preparedness and mitigation for special events are also crucial elements of RF interference protection.

The sections below outline measures agencies can take to mitigate and respond to RF interference.

Immediate Mitigation

• Alert the communications team, commander, and dispatch;

• Attempt rotating the radio antenna element 90°, so the antenna is horizontal to the terrain;

• Switch to tactical channels;

• Switch to a different means of communication, preferably on a different band (e.g., switching

from cellular to UHF or VHF bands or Satellite Communications [SATCOM] could be a potential

course of action);

• Shield the mobile radio behind a wall or large vehicle; and

• Find higher ground.

Capturing and Maintaining Local RF Interference Incident Records

• Report the incident to dispatch;

• After being alerted, dispatch should pass the information to the organization’s internal

Information Technology (IT) or Communications Division;

• The IT or Communications Division should deploy trained technicians to the area with spectrum

analyzers to observe the issue; and

• Technicians should capture, catalog, and record in a local database details of the incident to track

the issue in case of future occurrences in the same area.

Report

Figure 5. How to Mitigate RF Interference - Report

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 10

Capturing and Reporting RF Interference at a National Level

After performing local mitigations, it is important for officials to report RF interference to the appropriate

national-level authorities. Those reporting should be prepared to provide as many details as possible on

the incident, including:

• Complaining party’s name, contact information, agency, date, time, duration, location, and

affected mission or operations;

• Nature of the disruption (e.g., single occurrence, recurring, intermittent, or loss of signal

indication), the affected equipment (e.g., type, model, application) and any devices that continue

to function properly;

• Recordings, spectrum analyzer screenshots, and incident logs with location tagging;

• Environmental conditions (e.g., weather, topography, terrain, time of day);

• Steps taken to improve or regain ability to use equipment; and

• Possible cause of the disruption, information on the suspected interfering/jamming device, and

details on the suspected operator of the illegal equipment (e.g., name, date of birth, vehicle tag).

Public safety organizations should report incidents to the FCC and state and local authorities (where

applicable) both for potential legal action and to ensure that there are consistent records. Without

complete reporting, it is impossible for the FCC, other federal agencies, and state and local authorities to

fully understand the regularity and severity of RF interference incidents. This makes it challenging to

identify trends such as locations, sources, and targeted bands that could help law enforcement enforce or

prevent jamming. Although a few states are beginning to adopt FCC guidance on RF interference rules

into their own legislation, these laws are limited and difficult to enforce. While jamming is illegal under

federal law, state and local law enforcement agencies may not have the authority to confiscate or act

under their laws. Jamming may also be prosecuted as interfering with police business or as cybercrime, in

conjunction with jamming-specific charges.

NTIA is responsible for management of spectrum usage of the federal government. Section 8.2.30 of the

NTIA Manual of Regulations and Procedures for Federal Radio Frequency Management addresses

interference reporting procedures,

and the electronic reporting form is available at their website.

Add

itionally, civilian non-aviation GPS outages can be reported to the U.S. Coast Guard (USCG), civil

aviation GPS outages to the Federal Aviation Administration (FAA), while military and Department of

Defense (DOD) GPS outages can be submitted to the United States Air Force (USAF) at the GPS

Operations Center (GPSOC) for response.

ntact information and links to additional resources are provided below:

Table 5. Authority Contact Information for RF Interference Reporting

Authority

Contact Information

FCC 24/7 Operations

Center

• Website - https://fccprod.service-now.com/psix-esix/

• Phone number - (202) 418-1122

•

Email - [email protected]

Non-Aviation GPS

Outages: USCG

• Website - https://www.navcen.uscg.gov/?pageName=gpsUserInput

Aviation GPS Outages:

FAA

• Website - https://www.faa.gov/air_traffic/nas/gps_reports/

Military GPS Outages

worldwide: GPSOC

• Website - https://gps.afspc.af.mil/ (may not open for non-military users)

NTIA, “Manual of Regulations and Procedures for Federal Radio Frequency Management (Redbook),” last accessed January 3, 2020.

NTIA, “NTIA Interference Report Form,” last accessed January 3, 2020.

The GPS Operations Center (GPSOC) at Schriever Air Force Base, Colorado, is the focal point in the DOD for operational issues and questions

concerning military use of GPS. The GPSOC, part of Air Force Space Command, provides DOD and allied GPS users worldwide with anomaly reports

and other information 24 hours a day, seven days a week.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 11

PIRT Reporting

The Purposeful Interference Response Team (PIRT) is an interagency organization chartered by the

National Security Council (NSC) to facilitate U.S. Government collaboration with commercial owners,

operators, and allies to attribute and resolve satellite interference. The PIRT includes seven core member

agencies: DOD, Department of State (DOS), Department of Commerce (DOC), DHS, Department of

Transportation (DOT), Office of the Director of National Intelligence (ODNI), and the FCC, with several

other conditional member agencies. The FCC is one of the founding members of the PIRT and actively

supports the resolution of domestic and international instances of satellite interference.

Resolve

Figure 6. How to Mitigate RF Interference - Resolve

Once public safety agencies have recognized, responded to, and reported an RF interference incident, they

must resolve it by identifying lessons learned at an agency level so they can apply them to improve future

incident response. To better prepare, an agency should focus on the following:

Educate

As indicated in the previous section, public safety agencies need to educate their operational personnel on

how to best recognize and respond to incidents of RF interference. It is important that personnel can

distinguish the different types of interferences and know which reporting process they should follow.

Prepare

Public safety agencies should update personnel and agency policies, understand interference reporting

requirements, and conduct operational exercises. Agencies should also routinely conduct maintenance,

upgrades, and exchange of transmission system components as they occur, and inspect transmission

system components on a regular basis and after severe weather events.

It is also critical to develop a PACE Plan for communications and train all agency operators on it. The

PACE Plan includes a “waterfall” of communications methods, and regular training will help all operators

know what to do if their primary means of communication is disabled by RF interference or equipment

failure. A PACE Plan allows agencies to pre-set their continuity plans for communications—usually

switching between multiple channels, bands, or devices—ensuring that operators understand what other

avenues and tools are available in case of an interruption and that all operators go to the same back-up

methods in the same order. The PACE Plan should also be routinely tested and exercised to ensure its

effectiveness in maintaining communications operability and resiliency.

Evaluate

Public safety agencies need to evaluate their baseline of communications resiliency by assessing how well

personnel are prepared to identify, locate, and mitigate RF interference. If communications vulnerabilities

are exposed, organizations should address gaps as needed, develop after action reports to review how RF

interference incidents were handled, and identify lessons learned to incorporate throughout the agency.

FCC, “Satellite Interference Monitoring and Resolution,” last modified December 4, 2015.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook 12

Resilience

Figure 7. How to Mitigate RF Interference - Resilience

Applying best practices from this document will help public safety organizations become more resilient to

RF interference. Everyday preparedness through training, developing and implementing standard

operating procedures (SOP) for special events, and educating staff on the threats of RF interference

incidents will enable entire organizations to be vigilant. When more staff learn to recognize, respond to,

report, and resolve RF interference incidents, the organization becomes more resilient and can return to

efficiently operating without disruption.

Conclusion

RF interference is not a temporary communications issue. RF interference, including internal, external,

and malicious sources, will continue to be a threat to key communications systems and mission-critical

communications in public safety.

Public safety organizations may be dealing with daily RF interference, and the effects of unresolved RF

interference may be detrimental to mission-critical communications. Educating and informing members

of the public safety community on best practices and procedures surrounding RF interference will allow

for effective response and mitigation.

The public safety community must continue to share best practices and methods to combat and protect

against RF interference. Public safety organizations must work with legal authorities when responding to

RF interference incidents. Except for a few states that have adopted legislation, local law enforcement

agencies do not have the authority to confiscate RF jamming devices. It is important that key members of

public safety organizations understand their legal and procedural capabilities and limitations associated

with cases of RF interference and to whom they should report these incidents.

The guidance surrounding RF interference in the public safety space is continuing to evolve and improve.

As a result, the community must continue to speak about, educate themselves, and share best practices in

order to strive for communications resilience.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook A-1

Appendix A: DHS RF Interference Activities

The Department of Homeland Security (DHS) has several initiatives to help the public safety community

address radio frequency (RF) interference and communications resiliency. Examples include the

Cybersecurity and Infrastructure Security’s (CISA) RF Testing and Analysis Assistance, the Science and

Technology Directorate’s (S&T) First Responder Electronic Jamming Exercises (JamX),

development

of devices to detect RF interference of communications systems, and purchasing RF interference

detection and spectrum analysis equipment through grants.

CISA RF Testing & Analysis Assistance

Since September 2017, CISA has been assisting agencies with RF coverage testing and analysis, which

plays a critical role throughout the life cycle of a land mobile radio (LMR) system. RF coverage testing

and analysis are used to:

• Define and refine system coverage requirements;

• Supplement baseline coverage studies;

• Provide supplemental information related to Coverage Acceptance Testing (CAT);

• Provide in-building coverage measurement including assistance in locating interfering signals;

and

• Assist with system optimization as well as ongoing maintenance.

The RF Testing and Analysis System is also able to identify interference and signal degradation related to

mobile Long-Term Evolution (LTE) systems.

S&T

2016 and 2017 First Responder Electronic Jamming Exercises

S&T is working to combat RF interference by evaluating jamming’s impact, testing mitigation

technologies and tactics, working with public safety agencies to update training procedures, and raising

awareness of jamming threats and interference reporting channels. First, S&T hosted the 2016 JamX

event, a multi-agency operational exercise at White Sands Missile Range.

The exercise assessed the

impact of illegal jamming on public safety communications systems and mission response, and identified

gaps in training, techniques, and procedures. DHS used illegal commercial-grade jamming devices that

were representative of the types of jammers that public safety agencies may routinely encounter in their

communities. The results proved that jamming threats could significantly impact the communications of

law enforcement and public safety organizations across the country.

JamX 17 was held at the Department of Energy (DOE)’s Idaho National Laboratory (INL) and focused on

strengthening resilience against jamming threats on a community and national level.

During JamX 17,

DHS and public safety, law enforcement, private sector, and academic partners simulated 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.

As a result, S&T and CISA are

working together to provide robust recommendations to law enforcement and public safety agencies on

how to improve their resiliency to jamming and all other forms of RF interference.

In 2020, S&T plans to host JamX 20 to further evaluate how public safety agencies have implemented

DHS communications resiliency recommendations, assess advancements in counter-jamming

technologies, profile non-jamming interference sources, and provide an interference testbed for industry.

DHS S&T, “First Responder Electronic Jamming Exercise,” last accessed January 3, 2020.

DHS CISA, “Interoperable Communications Technical Assistance Program Resources”, last accessed January 3, 2020..

DHS S&T, “2016 First Responder Electronic Jamming Exercise,” July 18, 2016.

DHS S&T, “2017 First Responder Electronic Jamming Exercise,” January 25, 2017.

DHS S&T, “First Responder Electronic Jamming Exercise,” last accessed January 20, 2020.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook A-2

Table 6. DHS S&T Jamming Exercise Contact Information

Authority

Contact Information

S&T

• Website - https://www.dhs.gov/science-and-technology/ngfr

•

Email - Jamming.Exerci[email protected]

Device Research and Development

S&T is partnering with private sector companies to develop a solution to identify RF interference

incidents. An S&T Small Business Innovation Research Program (SBIR) grant identified three companies

to develop a device that can detect RF interference, which completed the SBIR phase I in December

2018.

Subsequently, a SBIR phase II grant was awarded in April 2019 to one of the companies to

continue development of their miniature intelligence spectral analyzer, which will alert first responders to

RF interference so they can carry out back-up mitigation, and reporting procedures.

In addition, S&T is

in development of an innovative solution toward a low-cost portable sensory device that can be used in a

mobile environment to detect impacts resulting from RF signal interference from both intentional or

unintentional RF sources and alert responders to the hazard.

Grants and Purchasing

S&T coordinated with the Federal Emergency Management Agency (FEMA) Grant Programs Directorate

(GPD) to add two new items to the authorized equipment list (AEL) to make it easier for responders to

purchase tools capable of identifying and locating RF interference using grant funding:

• 06CP-07-RFDF – Equipment, RF Direction Finding: Devices (e.g., handheld detectors,

deployable networks, fixed sensor networks) that measure, triangulate, and identify the location

from which signals (including interference signals) are being transmitted;

and

• 06CP-07-RFSA – Equipment, RF Detection and Spectrum Analysis: Devices that detect,

identify, and analyze RF signals from radios, cellular devices, Global Positioning Systems (GPS),

Wi-Fi, and other emitting devices. These devices can be used to identify transmissions from

suspicious or threatening sources, including interference that may be blocking or damaging first

responder communication.

DHS S&T, “News Release: DHS Awards Nearly $3 Million to Small Businesses for Innovative Research,” May 24, 2018.

DHS S&T, “News Release: Nine Small Businesses Awarded $10M to Advance Homeland Security Research Projects,” May 2, 2019.

FEMA, “06CP-07-RFDF - Equipment, RF Direction Finding,” last accessed January 3, 2020.

GovTribe,“Market Survey Report Radio Frequency (RF) Detection, Spectrum Analysis, and Direction Finding Equipment,” last modified June 11,

2018.

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook B-1

Appendix B: Acronym List

Acronym

Definition

AEL

Authorized equipment list

AGC

Automatic gain control

BER

Bit Error Rate

CAT

Coverage Acceptance Testing

CBP

Customs and Border Protection

CISA

Cybersecurity and Infrastructure Security Agency

COML

Communications Unit Leader

DDoS

Distributed Denial-of-Service

DHS

Department of Homeland Security

DOC

Department of Commerce

DOD

Department of Defense

DOE

Department of Energy

DoS

Denial-of-Service

DOS

Department of State

DOT

Department of Transportation

FAA

Federal Aviation Administration

FCC

Federal Communications Commission

FEMA

Federal Emergency Management Agency

FirstNet

First Responder Network Authority

GBAS

Ground-Based Augmentation System

GPD

Grant Programs Directorate

GPS

Global Positioning System

GPSOC

Global Positioning System Operations Center

High frequency

ICAC

International Certification Accreditation Council

ICTAP

Interoperable Communications Technical Assistance Program

INL

Idaho National Laboratory

Information Technology

ITU

International Telecommunication Union

ITU-R

International Telecommunication Union Radiocommunication Sector

IWG

Interagency Working Group

JamX

First Responder Electronic Jamming Exercise

LMR

Land mobile radio

LTE

Long-Term Evolution

NCSWIC

National Council of Statewide Interoperability Coordinators

NPSBN

Nationwide Public Safety Broadband Network

NSC

National Security Council

NTIA

National Telecommunications and Information Administration

ODNI

Office of the Director of National Intelligence

PACE

Primary, Alternate, Contingency, and Emergency

PIRT

Purposeful Interference Response Team

PSAP

Public safety answering point

Radio frequency

RFIM

Radio Frequency Interference Mitigation

Radio Regulations

S&T

Science and Technology Directorate

SATCOM

Satellite communications

SBIR

Small Business Innovation Research Program

SLTT

State, local, tribal, and territorial

SOP

Standard operating procedure

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook B-2

Acronym

Definition

TDoS

Telephony Denial-of-Service

UAS

Unmanned aircraft systems

UHF

Ultra-high frequency

USAF

United States Air Force

U.S.C.

United States Code

USB

Universal Serial Bus

US-CERT

United States Computer Emergency Readiness Team

USCG

United States Coast Guard

WSRD

Wireless Spectrum Research and Development

VHF

Very high frequency

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook C-1

Appendix C: DHS-FCC Jammer Infographic

February 2020 Public Safety Communications – RF Interference

Radio Frequency Interference Best Practices Guidebook D-1

Appendix D: Disclaimer of Liability

The Public Safety Radio Frequency Interference Best Practices Guidebook (hereinafter the “document”)

is provided by the Department of Homeland Security (DHS) and is intended to provide guidance. The

document does not contain or imply any official requirements, policies, or procedures, nor does it

supersede any existing official emergency operations planning guidance or requirements documents.

As a condition of the use of the document, the recipient agrees that in no event shall the United States

Government or its contractors or subcontractors be liable for any damages, including but not limited to,

direct, indirect, special or consequential damages, arising out of, resulting from, or in any way connected

to the document or the use of information from the document for any purpose.

DHS does not endorse any commercial product or service referenced in the document, either explicitly or

implicitly. Any reference therein to any specific commercial products, processes, or services does not

constitute or imply its endorsement, recommendation, or favoring by the United States Government or

DHS.

The views and opinions of authors expressed herein do not necessarily state or reflect those of the United

States Government or DHS and shall not be used for advertising or product endorsement purposes. Rules

and regulations (at all levels of government) related to radio frequency (RF) interference change; it is the

responsibility of the reader to ensure they remain informed and up-to-date of any changes to RF

interference rules, regulations, and available technologies.