Washington, DC 20548 

December 1, 2005 

The Honorable Todd R. Platts 

Chairman 

Subcommittee on Government Management, 

 Finance, and Accountability 

Committee on Government Reform 

House of Representatives 

Subject: Potential Spectrum Interference Associated with Military Land

Mobile Radios 

Dear Mr. Chairman: 

To address homeland defense needs and comply with government 

direction that agencies use the electromagnetic spectrum more efficiently, 

the Department of Defense (DOD) is deploying new Land Mobile Radios to

military installations across the country. The new Land Mobile Radios 

operate in the same frequency range--380 Megahertz (MHz) to 399.9 MHz--

as many unlicensed low-powered garage door openers, which have 

operated in this range for years. While DOD has been the authorized user 

of this spectrum range for several decades, their use of Land Mobile 

Radios between 380 MHz and 399.9 MHz is relatively new. With DOD’s 

deployment of the new radios and increased use of the 380 MHz-399.9 MHz 

range of spectrum, some users of garage door openers have experienced

varying levels of inoperability that has been attributed to interference 

caused by the new radios.1

 Nevertheless, because garage door openers 

operate as unlicensed devices, they must accept any interference from 

authorized spectrum users. This requirement stems from Part 15 of the 

Federal Communications Commission (FCC) regulations.2

 Garage door 

 1

 The garage door openers in question are programmed to operate at 390 MHz. However, 

because the technology employs a wide receiver bandwidth, the openers are also 

susceptible to interference from signals in other parts of the 380 MHz-399.9 MHz range,

with a maximum interference potential from 387 MHz to 393 MHz. 

2

47 CFR §15 (2004). 

Page 1 GAO-06-172R Potential Spectrum Interference
openers and other unlicensed devices are often referred to as “Part 15 

devices.”3

In response to your April 27, 2005, request, we reviewed the potential 

spectrum interference caused by DOD’s recent deployment of Land Mobile 

Radios. Specifically, you asked us to (1) determine the extent of the 

problem of spectrum interference associated with the recent testing and 

use of mobile radios at military facilities in the United States, (2) review 

the efforts made by DOD during the development of its Land Mobile Radio 

system to identify and avoid spectrum interference, and (3) identify efforts 

to address the problem. We briefed your staff on August 30, 2005, on the 

results of our review. This report summarizes that information and makes 

a recommendation to the Department of Defense.

The electromagnetic radio frequency spectrum is the medium that enables 

wireless communications of all kinds, such as mobile phones, radios, and 

satellite-based services as well as low-powered consumer devices such as 

advanced tire pressure gauges, remote entry devices for vehicles, and 

garage door openers. As new spectrum-dependent products are developed 

and deployed, the demand for spectrum, a limited resource, has escalated

among both government and private sector users. The demand for 

spectrum has resulted in direction from the National Telecommunications 

and Information Administration (NTIA)4

 that the U.S. Government foster 

spectrum conserving methods for government radio communications 

systems, including, for land mobile radios, methods for “narrowbanding” 

those systems. In response, DOD issued a policy that all DOD land mobile 

radio systems be modified or, for new systems, procured in conformance 

with the NTIA “narrowbanding” direction by 2008.5

 

Background 

In response to NTIA’s direction to make more efficient use of spectrum, 

DOD recently began rolling out new Land Mobile Radios that comply with 

narrowband requirements in various military installations across the 

United States. The Land Mobile Radio system is a two-way radio system 

 3

The Federal Communications Commission (FCC) is an independent regulatory body that

manages commercial and nonfederal spectrum use. 

4

The Department of Commerce’s National Telecommunications and Information 

Administration manages federal spectrum use. 

5

Narrowbanding involves the modification or implementation of devices that require less

spectrum for their operation. 

Page 2 GAO-06-172R Potential Spectrum Interference 
that provides communications capabilities for law enforcement, force 

protection, fire, transportation management, medical duties, and first 

responders on military installations. The new Land Mobile Radios are also

expected to strengthen homeland defense with such capabilities as 

improved interoperability with other installations. DOD expects the Land 

Mobile Radio system to operate at about 36 locations in 9 states and the 

District of Columbia by the end of fiscal year 2005, and 137 installations in 

28 states and the District of Columbia by fiscal year 2010. 

Since DOD began its rollout of the new Land Mobile Radios in 2004, a 

number of complaints have been reported at several locations near 

military installations—notably, Eglin Air Force Base, Florida; Defense 

Distribution Depot Susquehanna (DDSP) near New Cumberland, 

Pennsylvania; and Ft. Detrick, Maryland. As of August 2005, manufacturers 

had received over 1,300 customer complaints of affected garage door 

openers that they attributed to interference from Land Mobile Radios. One 

major manufacturer also estimated that its distributors had received 

between 7,000 and 10,000 complaints. However, the extent of interference

experienced by users of garage door openers from DOD’s Land Mobile 

Radios is difficult to quantify because interference problems may not be 

reported or may be reported to several different organizations, including 

garage door opener manufacturers and retailers, government agencies, or 

congressional representatives. According to DOD and garage door opener 

manufacturers, the nature of the interference that has occurred varies by

location. In some locations where the radios were rolled out, no 

occurrences of interference have been reported. Where interference has 

been reported, the problems range from intermittent inoperability to 

situations where the garage door may not open at all with the remote 

control device. DOD has reported a decrease of interference complaints. 

They attribute this decrease, in part, to consumer awareness of the 

problem and the completion of the Land Mobile Radio testing phase, at 

each site.6

Summary 

Because DOD is the authorized user of the 380 MHz-399.9 MHz spectrum, 

it was under no obligation, according to the FCC, to identify or mitigate 

potential interference with Part 15 devices that may also be operating in 

that spectrum. Even if DOD had attempted to identify Part 15 devices, 

 6

According to DOD officials, the potential for interference is higher during the testing phase 

when the radio system is transmitting a test tone continuously on a single frequency. 

Page 3 GAO-06-172R Potential Spectrum Interference 
there is no documentation available as to where such devices operate. 

Users of Part 15 devices are not tracked by federal agencies in the way 

that licensed users are tracked. DOD chose to operate the new Land 

Mobile Radio system in the 380 MHz-399.9 MHz spectrum range because 

other bands of spectrum could not accommodate system requirements. 

DOD received NTIA certification in 2003 to operate the new radios in that

spectrum. According to DOD officials, they cannot readily move off of this 

range of spectrum as it would necessitate costly technical changes and

would negatively impact Land Mobile Radio capabilities. 

In early 2005, following reports of interference, NTIA’s Office of Spectrum 

Management and the FCC’s Office of Engineering and Technology 

established a working group with representatives from DOD and the major 

manufacturers of garage door openers to develop short- and long-term 

solutions to the spectrum interference problem. The group has met several 

times, and as a result, DOD and the manufacturers report that progress has 

been made in terms of coordination and information sharing. For example, 

DOD has provided the Land Mobile Radio rollout locations to

manufacturers and the ranges of spectrum to be affected through fiscal 

year 2010. DOD has also conducted analyses showing the likely extent of

potential interference from Land Mobile Radios in several populated areas

where the radios will be deployed and has given the findings to major 

manufacturers. For their part, manufacturers are offering retrofit kits to 

change the frequencies of existing garage door openers that would cost 

consumers $50 to $80, excluding installation. Furthermore, for new 

devices, one manufacturer is moving off of the 390 MHz spectrum range, 

and another plans to go to a multi-frequency approach using 390 MHz and 

other spectrum in order to minimize potential interference problems in the 

future. 

Despite these efforts, for consumers with garage doors that do not 

operate, it can be difficult and costly to sort out the problem and to know 

how to fix it. Information available does not always provide a clear course 

of action to consumers trying to remedy interference problems. Because 

of potential confusion, consumers receiving intermittent interference may

unnecessarily purchase a new opener, not knowing that the interference 

may be temporary. While DOD has provided guidance to local installations 

regarding public relations with the communities potentially affected by the 

Land Mobile Radio rollout, it is largely reactive in nature. Specifically, the 

guidance primarily provides information on how to respond to media 

inquiries and leaves the decision of any community outreach efforts to the 

discretion of local installation officials. The benefits of proactive 

community outreach were demonstrated in one installation we visited 

Page 4 GAO-06-172R Potential Spectrum Interference 
where, among other things, installation officials briefed retail associates, 

and local officials and continued to keep the local media informed of the 

situation. These proactive efforts have helped to resolve complaints, 

according to installation officials. 

DOD officials recently acknowledged the need to improve community 

outreach efforts and told us that they are planning to take steps to more 

proactively inform local communities of potential interference problems. 

For example, DOD and the major garage door manufacturers plan to 

synchronize outreach efforts to ensure communities receive at least 1 

month notification of the Land Mobile Radio rollout. DOD is also creating 

press release templates for local installations to use that will include, 

among other things, information about the radio system, potential 

interference that could occur, and points of contact. In addition, DOD 

officials plan to inform local congressional district offices as appropriate 

of the potential for spectrum interference associated with the rollout of 

Land Mobile Radio systems. These outreach efforts, if carried out, should 

help better inform local communities that may encounter interference 

problems. 

We recommend that the Secretary of Defense document and affirm DOD’s 

current plans for improving community outreach.

DOD provided written comments on a draft of this report. Their 

comments are discussed below and are reprinted in appendix I. Both DOD 

and NTIA provided technical comments which were incorporated where 

appropriate. The FCC had no comments on a draft of this report. 

Recommendation for 

Executive Action 

Agency Comments 

and Our Evaluation 

DOD concurred with our recommendation and indicated that it plans to 

follow through with the outreach effort. DOD noted that the responsibility 

for mitigating potential spectrum interference lies solely with the garage 

door device manufacturers. DOD expressed concern that the 

recommendation could entail a recurring reporting requirement 

throughout the roll-out of the radio system. Our intent with the 

recommendation, however, is not to require DOD to report on outreach 

efforts each time the radio system is fielded at a new location. Rather, the

intent of the recommendation is to have DOD formalize its current plans 

for improving community outreach on future radio deployments. DOD is 

required, however, by 31 U.S.C. §720 to report to Congress on the action 

taken on the recommendation. 

Page 5 GAO-06-172R Potential Spectrum Interference 
To assess the extent of the interference problems associated with Land 

Mobile Radios, DOD’s efforts to identify potential interference and ways to

address it, we interviewed key officials from DOD, FCC, NTIA, and 

representatives of the garage door opener manufacturing industry. We also

reviewed various DOD, FCC, and NTIA documents, reports, and guidance. 

To assess responses by local installations to reports of interference, we 

met with DOD officials from Ft. Detrick, Maryland and New Cumberland, 

Pennsylvania. We conducted our work between June and September 2005 

in accordance with generally accepted government auditing standards. 

Scope and 

Methodology 

We are sending copies of this letter to the Secretary of Defense and 

interested federal agency officials and Congressional committees. We will

make copies available for other interested parties upon request. In 

addition, the letter will be available at no charge on the GAO Web site at 

http://www.gao.gov. 

Please contact me at (202) 512-4841 if you or your staff has any questions

concerning this letter. Other major contributors to this letter were John 

Oppenheim, Ridge Bowman, and Lisa Henson. 

Sincerely yours, 

Paul L. Francis, Director 

Acquisition and Sourcing Management 

Page 6 GAO-06-172R Potential Spectrum Interference 
Page 7 GAO-06-172R Potential Spectrum Interference 

Enclosure: Comments from the Department 

of Defense 
Page 8 GAO-06-172R Potential Spectrum Interference 
(120465) Page 9 GAO-06-172R Potential S

pectrum Interference 
This is a work of the U.S. government and is not subject to copyright protection in the 

United States. It may be reproduced and distributed in its entirety without further 

permission from GAO. However, because this work may contain copyrighted images or 

other material, permission from the copyright holder may be necessary if you wish to 

reproduce this material separately. 

Page 10 GAO-06-172R Potential Spectrum Interference
GAO’s Mission The Government Accountability Office, the audit, evaluation and 

investigative arm of Congress, exists to support Congress in meeting its 

constitutional responsibilities and to help improve the performance and 

accountability of the federal government for the American people. GAO 

examines the use of public funds; evaluates federal programs and policies; 

and provides analyses, recommendations, and other assistance to help

Congress make informed oversight, policy, and funding decisions. GAO’s 

commitment to good government is reflected in its core values of 

accountability, integrity, and reliability. 

The fastest and easiest way to obtain copies of GAO documents at no cost

is through GAO’s Web site (www.gao.gov). Each weekday, GAO posts 

newly released reports, testimony, and correspondence on its Web site. To

have GAO e-mail you a list of newly posted products every afternoon, go 

to www.gao.gov and select “Subscribe to Updates.” 

The first copy of each printed report is free. Additional copies are $2 each. 

A check or money order should be made out to the Superintendent of 

Documents. GAO also accepts VISA and Mastercard. Orders for 100 or 

more copies mailed to a single address are discounted 25 percent. Orders 

should be sent to: 

U.S. Government Accountability Office 

441 G Street NW, Room LM 

Washington, D.C. 20548 

To order by Phone: Voice: (202) 512-6000 

TDD: (202) 512-2537 

Fax: (202) 512-6061 

Contact: 

Web site: www.gao.gov/fraudnet/fraudnet.htm

E-mail: fraudnet@gao.gov

Automated answering system: (800) 424-5454 or (202) 512-7470 

Gloria Jarmon, Managing Director, JarmonG@gao.gov (202) 512-4400 

U.S. Government Accountability Office, 441 G Street NW, Room 7125 

Washington, D.C. 20548 

Paul Anderson, Managing Director, AndersonP1@gao.gov (202) 512-4800

U.S. Government Accountability Office, 441 G Street NW, Room 7149 

Washington, D.C. 20548 

Obtaining Copies of 

GAO Reports and 

Testimony

Order by Mail or Phone 

To Report Fraud,

Waste, and Abuse in 

Federal Programs 

Congressional 

Relations 

Public Affairs 

PRINTED ON RECYCLED PAPER