General Scanning Information
SPECTRUM USE IN THE FIXED AND MOBILE SERVICES
This section summarizes the Federal spectrum use of the various bands
between 75-1400 MHz frequency range allocated for Federal Government fixed
and mobile services. Frequency bands that serve a major common function are
grouped together for convenience of discussion.
The information is based jointly on data provided by the Federal agencies
and the data records contained in the NTIA Government Master File (GMF) of
frequency assignments. While some information is presented in terms of the
number of Federal frequency assignments, it should be noted that the number
of actual radio equipment will exceed, and sometimes far exceed, the number
of assignments in a band, since one frequency assignment may represent many
radio equipment. The Federal assignment data used in the spectrum use
assessment are current as of October 1993.
118-137 MHz BAND
Internationally and nationally, the 117.975-137 MHz frequency range is
allocated to the aeronautical mobile service on a primary basis. Nationally,
the 121.9375-123.0875 MHz, 128.8125-132.0125 MHz and a portion of the 136-137
MHz frequency bands, which represent a total bandwidth of 4.85 MHz, are
exclusively allocated for use by the non-Federal, and the remaining portion of
the overall band is shared by the Federal Government and non-Federal entities
on a co-equal basis. The entire band has a total bandwidth of 19.025 MHz and
13.675 MHz of bandwidth is designated for shared use; no portion of this band
is allocated exclusively for Federal Government use.
Aeronautical mobile service spectrum requirements are accommodated mostly
in the HF (3-23 MHz) and VHF (117.975-137 MHz) portion of the radio spectrum.
The VHF band provides the primary communications mode for Air Traffic Service
(ATS) and Aeronautical Operational Control (AOC) safety communications for all
areas of the world where radio line-of-sight services can be established. In
the United States, this band is used by Federal Aviation Administration to
provide ATS safety communications and by users such as, the airlines, business
aviation, and general aviation to provide AOC safety communications. Each
communications frequency is re-used as often as possible (due to the fixed
number of available frequencies) so that continuous coverage can be established
to support air traffic control systems. The FAA maintains an extensive network
of over 3,050 VHF radio stations giving reliable coverage over the most areas
of the United States.
138-150.8, 162.0125-174, 220-222 AND 406.1-420 MHz BANDS
Federal Government land mobile communication requirements are accommodated
in segments of the following bands which are allocated to the fixed and mobile
services for non-tactical use: 138-144, 148-149.9, 150.05-150.8, 162.0125-174,
220-222, and 406.1-420 MHz. Federal Government agencies use the fixed and
mobile radio systems that operate in these bands to accomplish a variety of
missions that serve the public. The approximately 80,000 frequency assignments
throughout these bands represent over one million Federally-owned radios. Since
the dominant bands used by the Federal agencies for land mobile operations are
the 162.0125-174 MHz and 406.1-420 MHz bands, the list of major users presented
in Table D-1 only accounts for these two bands. The "Others" category includes
Federal agencies with 20 or less assignments.
Federal mobile radio systems use a wide range of equipment types in a
variety of geographic environments for voice and data communications. Common
types of equipment include base and repeater stations, mobile stations, and
hand-held portable stations. In nearly all cases, this equipment is the same
type of off-the-shelf equipment used by local and state public safety agencies.
Mission requirements often lead to worldwide and nationwide, as well as
local service areas that range in natural character from remote to urban.
Federal Government missions are mandated by Congress and the President, and
generally have no counterparts outside the Federal Government. The closest are
the state and local governments with similar missions that own and operate
their own systems. The major differences lie in two areas: (1) the national
security operations and wide area safety services of the Federal Government,
and (2) the geographic areas of communication coverage required.
Table D-1. Major Federal Users of the 162.0125-174 MHz and 406.1-420 MHz
Total Number of Assignments
Federal Agency 162.0125-174 MHz 406.1-420 MHz
-------------- ---------------- -------------
Agriculture 9,154 1,555
Air Force 1,645 1,935
Army 3,351 2,243
Commerce 2,300 1,379
Coast Guard 917 308
Energy 2,420 1,816
Environmental Protection Agency 124 See "Others"
Federal Aviation Administration 4,024 1,336
Federal Communications Commission 114 0
Federal Emergency Management Agency 25 26
Federal Reserve System 22 96
Government Services Administration 73 496
Health and Human Services 285 120
Interior 7,929 1,253
International Boundary Water Commission 55 See "Others"
Justice 17,204 4,358
Labor 52 48
Navy 396 872
National Aeronautics and Space Adm. 215 191
Nuclear Regulatory Commission 215 See "Others"
National Science Foundation 59 See "Others"
State 53 58
Smithsonian Institution 22 See "Others"
Treasury 5,090 1,906
Transportation 238 35
Tennessee Valley Authority 467 285
United States Information Agency See "Others" 71
United State Postal Service 804 896
Veterans Administration 793 343
"Others" 120 513
Federal Government radio systems support agency mission requirements in
the following broad categories: law enforcement, transportation, natural
resources, emergency and disaster services, utilities, medical, and
administrative. Federal Government radio systems are usually multi-purpose
systems; e.g., law enforcement, natural resource, medical, administration,
and utility functions may be supported on the same radio system, thus
increasing their spectrum efficiency. Federal Government land mobile
requirements for each of the above categories are described in the following
Federal law enforcement radiocommunications requirements include everything
from hand-held portable communications between internal security posts to
nationwide/worldwide airborne communications for drug interdiction and
protection of the President. Federal law enforcement radiocommunications must
be immediate; delay is not acceptable.
Effective and reliable radiocommunications are required for safety-of-life
and property protection of Federal building complexes, Federal lands, military
bases, and other types of installations. A major use of dedicated
radiocommunications is the security of current and former Presidents and family
members, as well as the Vice President and family, and other distinguished
persons including foreign heads of state.
Operations requiring high priority communications include movement of
protected individuals, in response to violent crimes (bank robbery or
kidnapping), undercover surveillance, and arrests. Cases involving
counterintelligence, personal crimes, organized crimes, drug interdiction,
fugitives, hostage situations, terrorism, smuggling, guns and explosives,
counterfeiting, fraud, forgery and tax evasion also require immediate
communications. Additionally, portable radios and body transmitters are used
inside prisons for prisoner control activities, and by special agents to
support investigative functions, and in personnel and property security
Most Federal law enforcement agencies have area offices that are
responsible for activities throughout a geographic region. Repeaters and radio
links are installed to obtain the necessary radiocommunications coverage within
that region. Repeater systems are installed throughout urban areas in these
regions to permit necessary portable radiocommunications. Transportable
equipment is provided to respond to impromptu travel requirements in support
of personnel protection or pursuit of criminal cases, special cases, or other
major crises such as Waco, Texas, and the bombing of the New York City World
Trade Center in early 1993.
Federal law enforcement systems require communications with privacy. The
monitoring of clear voice communications by the general public, the news media,
foreign intelligence agents, and criminals has disrupted investigations and
caused life-threatening situations for law enforcement personnel and innocent
victims. Digital encryption, spread spectrum and other techniques are now
utilized to assure transmissions are not compromised.
Installation of radio systems that provide complete coverage of the United
States is not spectrum-efficient. However, the mandated missions of Federal law
enforcement agencies require the capability to deploy and install both
permanent and temporary facilities when and wherever needed, not only
nationwide but worldwide. This is accomplished through agency-dedicated means,
including full and complete control of installations, operations, and
maintenance by the various elements of the law enforcement community.
Federal activities in aviation, maritime, highways, and railroads have a
heavy investment in both fixed and land mobile operations. Aviation-sector
land mobile applications include maintenance, safety, and inspection using
portable and mobile radios, and repeaters and base station facilities; remote
maintenance monitoring equipment; remote control of robot devices at supply
depots; airport runway light control systems and windshear alert systems. These
systems are installed in airports and airway facilities for management and
coordination activities. The systems use both voice and data to: automate
equipment monitoring; perform safety-of-life, anti-terrorist, and air security
functions; integrate air traffic control communications within the centers and
control towers; and conduct various airport and airfield communications as
necessary, tailored to the needs of each airport/airway location.
Federal maritime management coordination, safety, and law enforcement
activities also use radios operating in Federal land mobile bands. These
activities require nationwide implementation, although many operations are
concentrated in seaports, docks, and waterways of the nation's coastal areas,
major rivers, and the Great Lakes region.
Federal surface transportation operations provide a variety of management
and oversight support to coordinate activities at various highway and rail
sites. Many of these functions are mandated by law and nationwide in scope.
The Federal Government manages its natural resource programs using
radiocommunications to accomplish Congressionally-mandated missions. Fixed
stations, mobiles, handheld portables, and transportable repeaters and base
stations make up these radio systems. These operations are spread throughout
the United States and Possessions, in suburban, urban and rural sometimes
remote and almost inaccessible areas. Some systems encompass only a few
buildings in a city or a small wildlife refuge. Others encompass large
geographical areas, such as, the national forests, Indian reservations, and
national parks; multiple counties or states, such as the Tennessee Valley
Authority; or are nationwide in nature.
These systems provide for the safety of the public and Federal Government
personnel; monitoring and distribution of water; management of timber growth
and harvest; protection, operation, and management of our national parks,
national forests, range and grass lands, wildlife refuges; protection and
management of wildlife and fisheries; recreation; surveying and mapping;
protection of Native Americans and protection and management of their lands;
forestry and range management; and assessment of mineral deposits. Wildlife
monitoring and tracking to protect endangered and threatened species and to
control animal damage are performed in these bands with transmitters as small
as dimes or as large as softballs.
Emergency situations such as fires, hurricanes, earthquakes, volcanic
eruptions, etc., place great demands on the existing communication systems
each year and routinely require the use of emergency backup systems. These
emergencies sometimes require a tenfold expansion of communications facilities
in a matter of hours. This separate function is described in greater depth in
the next section.
Emergency and Disaster Services
The Federal Government provides an array of emergency and disaster response
communications capabilities to protect the American public and resources from
natural disasters and technological hazards. This involves a wide range of
missions including prevention, mitigation, preparedness, response and recovery.
These services involve virtually every department and agency of the Federal
government. Where safety of life and property is at risk, communication systems
that can operate reliably even when normal systems are disrupted are essential.
Spectrum-dependent emergency radio systems are the only systems capable of
providing the essential levels of reliability, mobility, and flexibility during
crises. A significant number of the Federal Government emergency and disaster
response communications systems interface with state and local governments as
well as with national volunteer organizations such as the Red Cross, amateur
radio operators and similar groups. An important consideration in managing
these emergency assets is the need to conduct periodic exercises to ensure
they work when required.
Many specialized emergency requirements have unique spectrum-dependent
needs that must also be satisfied by the nationwide dedication of radio
spectrum for that purpose. As an example, Federal, state, and local government
search and rescue teams deploying to the site of a national emergency or
disaster need reliable communications to locate victims in collapsed buildings,
administer medical and lifesaving treatment and relocate them to safety or
Providing the communications needed during major natural and technological
emergencies requires a significant quantity of readily deployable land mobile
radiocommunications. Major natural disasters occur on a continuing basis. Major
disasters, such as Hurricanes Andrew and Hugo, the San Francisco earthquake,
and the recent floods in the Mississippi Valley have required the deployment of
thousands of radios. These have been Federal Government-owned land mobile
radios used to effectively coordinate and provide emergency management during
the readiness, response and recovery phases of major natural and manmade
disasters. Land mobile radios are critical for providing the needed level of
flexibility and survivability required. Dedicated, reliable non-blocked
resources are required to support these time-sensitive, high demand operations
to improve rapid response, to minimize interference, and to safeguard
emergency response personnel and the delivery of life saving services to the
Federal Government utility operations which provide essential services to
both Federal Government and non-Federal users are also supported in these
bands. These operations include generation of electric power at fossil, hydro,
and nuclear power plants; the distribution of electrical energy and the
maintenance of distribution lines; and the distribution of potable and
agricultural waters and the maintenance of these systems.
The distribution of electrical energy from the generating plants to the
load centers and the interconnection of bulk electrical power supply systems
for reliability and adequacy has required the development of complex,
supportive radio systems. Communications must be of the highest level of
reliability, economically and technically feasible, and must be instantly
available for the successful operation of these electrical power systems.
Radiocommunications systems are also vital to the operation and maintenance
of water distribution and sewage systems on military bases, water distribution
systems encompassing aqueducts and canals in arid areas, and dams for the
control of flooding. Radio systems provide for collection of water flow and
salinity data and control of irrigation ditch gates and pumping stations for
the management of vast water distribution systems and the maintenance of these
systems. Dam safety data is transmitted to central processing points to provide
early warning of potential dangers and scheduling of maintenance. Day-to-day
operations of these systems with limited field personnel resources provide for
efficient and timely response to changing customer requirements.
The criticality coupled with the remote areas encompassed by many of these
systems have generally precluded the availability of cost effective support
from commercial communications providers.
The Federal Government provides essential land mobile radiocommunications
for medical facilities. Reliable radiocommunications are required to provide
life-or-death medical care along with the daily operations of a medical center.
Radio paging communications are essential to obtain doctors and nurses during
emergency situations. Two-way radiocommunications are required to interact with
local governments to provide security, fire protection and maintenance.
Reliable radiocommunications are required for local, Federal Government,
civilian, and military medical facilities to interact with each other to
provide essential emergency medical care.
Administrative communications is the descriptive term for various support
type communications used for administrative management of personnel or material
required in performing Federal Government missions. All Federal Government
agencies employ some type of administrative land mobile communications systems
within their respective departments. Examples of these support communication
systems include base stations for VIP management and control of operations and
test-range safety, wireless microphones, maintenance communications, motorpool,
building guards, and paging. These systems use fixed and transportable base
stations and repeaters, mobiles and handheld portables.
The Federal Government fixed uses in these bands include the collection of
seismic, meteorological, and hydrologic data for the forecast of volcanic
eruptions and earthquakes; identification of potential fire danger areas; and
prediction of availability of water for agricultural and public use. These data
are provided to state and local officials for planning and emergency operation
purposes. National Oceanic and Atmospheric Administration (NOAA) Weather Radio,
which provides the public with up-to-date weather information, also operates in
the 162-174 MHz band.
216-220 MHz BAND
The 216-220 MHz band is allocated to the Federal Government and non-Federal
for the maritime mobile service on a shared, primary, co-equal basis. Fixed and
aeronautical mobile services are also shared by the Federal Government and
non-Federal on a secondary basis. Federal Government radiolocation is also
permitted in the band on a secondary basis, but limited to the military
services. Non-Federal government land mobile operations are also permitted in
the band on a secondary basis.
In the 216-220 MHz band, there is a total of 1160 assignments,
approximately 40% of which are for Federal Government operations. Table D-2
shows the major Federal users of the band. Any agency with less than 10
assignments is not included. The Departments of Energy and Interior are the
major Federal users, primarily for telemetry systems in the fixed and mobile
services for low power seismology operations. These systems are deployed
throughout the United States.
TABLE D-2. Major Federal Users of the 216-220 MHz Band.
Freq. Band Federal Government Agencies/Total Number of Assignments
(MHz) Air Force Army Energy Interior Navy NASA Others
---------- --------- ---- ------ -------- ---- ---- ------
216-220 21 12 301 101 12 11 19
225-400 MHz BAND
The 225-400 MHz band consists of several band segments. The 225-328.6 MHz
and 335.4-399.9 MHz are allocated to the Federal Government for fixed and
mobile services on a primary basis. Some portions of these segments are also
allocated for military mobile-satellite use. The segments 328.6-335.4 MHz
and 399.9-400 MHz are allocated to the Federal Government and non-Federal on
a shared, primary basis for aeronautical radionavigation and radionavigation-
satellite services, respectively. Discussions on the latter two services were
presented in Section 2 under the radionavigation category.
There are more than 23,000 frequency assignments currently authorized in
the 225-328.6 MHz and 335.4-399.9 MHz segments of the band. Seventy-five
percent of the total assignments belong to the DoD, as can be seen in Table
D-3. In the Table, the "Others" category includes those agencies with 20 or
less assignments. The FAA, with 23% of the total assignments, is the other
major user of these portions of the 225-400 MHz band. Seventy percent of the
military use are for air-ground-air, air traffic control, shipboard line-of-
sight, and tactical and strategic forces satellite communications. The FAA's
assignments are in direct support to the military air traffic control.
The 225-400 MHz band is the single most critical spectrum resource for the
military tactical forces, both nationally and within NATO. The DoD operates
approximately 75,000 radio equipments supporting its operational requirements
in the band. Extensive peacetime training and alert exercises are conducted by
the military to maintain their combat readiness. The band is standardized with
U.S. military allies in Europe and elsewhere for interoperability during
combined actions and is extensively used for a wide variety of functions,
including forward area tactical radio relay, airborne, land-based and satellite
TABLE D-3. Major Users of the 225-400 MHz Band.
Total Number of Assignments
Federal Agencies 225-328.6 (MHz) 335.4-399.9 (MHz)
---------------- --------------- -----------------
Air Force 4,555 2,076
Army 2,532 1,424
Coast Guard 134 176
Energy 75 20
Federal Aviation Adm. 3,537 1,860
Navy 5,153 1,603
NASA 35 25
Others 46 3
The FAA uses the band for the control of DoD aircraft within the National
Airspace because very few military aircraft have VHF aeronautical band radios.
The Coast Guard also uses this band on all its aircraft to support air-ground-
air communications. On every flight, these aircraft actively use and depend
upon channels provided especially in the 380-399.9 MHz portion of the band. An
estimated 45,000 flights per year is made for missions including search and
rescue operations, drug interdiction and other law enforcement, marine
environmental protection, International Ice Patrol, alien interdiction,
National defense, and support of other Federal Government agencies.
932-935 MHz and 941-944 MHz BANDS
Both bands are allocated to the Federal Government and non-Federal for the
fixed service on a shared primary basis. In addition, Government off-shore
radiolocation operation is permitted on a non-interference basis and limited
to the military services. The 932-935 MHz and 941-944 MHz bands are two of the
few bands supporting fixed low-capacity communication links. Spectrum use for
every agency is similar in both the 932-935 MHz and 941-944 MHz bands. Usually,
a transmit frequency in one band has a corresponding receive frequency in the
other band or a paired channel.
The main users of the bands are listed in Table D-4. As shown, FAA and
Agriculture are the dominant users with an approximate combined 76% of the
total assignments in both bands. The other significant users are Energy and
Interior. The "Others" category includes those agencies with 10 or less
FAA uses these bands for low density communications links (voice and/or
data). The majority of their assignments are authorized for the Low Density
Radio Communication Link (LDRCL) system, which are deployed across the United
States, in support of the National Airspace System. Agriculture's assignments,
however, are concentrated on the West Coast and in the North-central States.
These assignments are in support of their point-to-point, microwave backbone
communications systems. The DOE also operates microwave systems specially in
remote areas of the United States where their operation is not accessible by
telephone. For example, in the control of operation, maintenance, management
and distribution of electric power. In addition, DOE employs telemetering fixed
systems for weather data transfer. These bands also support DOE's emergency
functions. The Interior's backbone microwave systems are directly in support
of law enforcement activities and for their dispatch systems for resource
management and fire suppression.
TABLE D-4. Major Users of the 932-935 MHz and 941-944 MHz Bands.
Total Number of Assignments
Federal Agencies 932-935 MHz 941-944 MHz
---------------- ----------- -----------
Agriculture 158 153
Coast Guard 11 11
Energy 52 48
Federal Aviation Administration 302 305
Interior 44 45
Navy 14 15
Treasury 15 15
Others 10 8
1350-1400 MHz BAND
This band is allocated exclusively to the Federal Government for fixed,
mobile, and radiolocation services on a primary basis. Federal Government
operations in these services are limited to the military forces, although FAA
has few assignments for surveillance radars needed for air traffic control. In
addition, the discrete frequency at 1381.05 MHz is allocated to the fixed and
mobile-satellite services for space-to-Earth relay of nuclear burst data.
The 1350-1400 MHz band is primarily used by the Army for tactical training.
For example, out of the approximately 690 assignments, about 508 assignments
(74%) belong to the Army in support of tactical radio relay systems. The Air
Force also has assignments for tactical radio relay systems but, the major
Air Force system in this band is the Range Applications Joint Program Office
(RAJPO) data link. This system, which cost about $100 million and also operates
in the 1429-1435 MHz band, provides real-time GPS data to designated military
test ranges. RAJPO is currently the only known system to fully support advanced
space weapons systems development like the Strategic Defense Initiative. Other
major systems supported by RAJPO are advance fighter technology integration,
all stealth developments, advanced tactical aircraft, AEGIS, and sonar and
antisubmarine warfare. The RAJPO has a tuning range capability between 1350-
1450 MHz. This system will be deployed at all major military test ranges and
provide, in conjunction with the Global Positioning System, high accuracy
position location, target tracking and other uses.
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© 2005 Jim Fordyce
These pages created by Jim Fordyce.
© 2005 Jim Fordyce