Radars and Spectrum Management
Spectrum management is a combination of administrative and technical procedures which are necessary to ensure the efficient operation of radio communications, taking into account legal, economic, engineering, and scientific aspects for the use of the radio frequency spectrum. Current spectrum management policies are under increasing strain as the public's demand for wireless services grows, and new spectrum-related technologies and applications emerge. In the United States, NTIA is responsible for managing the Federal Government's use of the radio spectrum. Management of the spectrum for the private sector, including State and local governments, is the responsibility of the Federal Communications Commission (FCC).
Spectrum Certification of Federal
NTIA's authority in spectrum management is extensive. The National Telecommunications and Information Administration Act (1) and the Office of Management and Budget (OMB) Circular No. A-11 provide NTIA with the authority to assign frequencies and approve the spectrum use of new systems. Federal users must obtain frequency assignments before they can operate transmitters. OMB Circular No. A-11 requires that Federal users obtain certification of spectrum support from NTIA (certification that new radiocommunication systems are expected to be able to operate compatibly with existing and planned stations) before developing and procuring major systems. Spectrum certification is especially important for radar systems because of their long lead times and large system costs.
In the Federal Government, the identification of spectrum requirements, including radar systems, occurs primarily through two ongoing, but separate, processes at NTIA--the systems review and frequency assignment processes. Two standing subcommittees of the Interdepartment Radio Advisory Committee (IRAC), the Spectrum Planning Subcommittee (SPS) and the Frequency Assignment Subcommittee (FAS), support this effort. Systems review and frequency assignment information is supplemented through NTIA spectrum resource assessments, spectrum occupancy measurements, and preparations for international radio conferences. The collective information available from these sources portray short- and mid-term Federal spectrum requirements.
The systems review process exists to satisfy the spectrum certification requirements of OMB Circular No. A-11.(2) The systems reviewed are "major" systems (including all space radiocommunications systems). A system is considered "major" if it will have a significant impact on existing or potential future use of the portion of the spectrum in which it is intended to operate. The systems review identifies the level of conformity of the system to the spectrum standards and to the U.S. National Table of Frequency Allocations. Systems that do not conform, but are otherwise compatible with existing uses, are generally approved on a secondary or noninterference basis to other systems, current or future, that do conform. Systems that have potential for interference, but are essential for national defense, are reviewed with regard to the coordination and conditions required to allow operation in the United States.
Approximately 36 radar systems are currently under systems review within the SPS. Of the 36 radar systems, the Departments of the Army, Navy, and Air Force have 14, 11, and 8, respectively. The National Aeronautics and Space Administration, Department of Commerce, and Department of Energy each have one. While there has been a trend for radar systems to move into higher frequency bands, it is interesting to note that there are a few radar systems operating in or through the HF and very high frequency (VHF) bands.
Frequency Allocation Overview
Under current regulations, before spectrum can be used, it must first be allocated for a particular use. These regulations are either the FCC's regulations contained in Title 47 of the Code of Federal Regulations, or the regulations governing Federal use of the spectrum contained in the Manual of Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual).(3) At the present time, the radio frequency spectrum in the United States from 9 kHz to 300 GHz is completely allocated to one or more radio services.
As a basic plan for usage, the radio spectrum is allocated to various radio services in blocks of frequencies. The concept of the block allocation system provides for a band of contiguous frequencies dedicated to one or more radio services, depending on the technical and operational characteristics of the service(s). A block so dedicated is said to be allocated to the radio service(s) associated with that block. Further, within a block, the radio services may have a hierarchical structure that grants rights or imposes limitations on the services relative to other services in the same block.(4) Footnotes to the allocation table draw attention to the use of a specific band by providing for an additional allocation, alternative allocation, or a different category of service. Within the United States, the compilation of these spectrum blocks, along with associated footnotes, is called the U.S. National Table of Frequency Allocations,(5) and is used for general spectrum planning. The table also further separates those allocation blocks that are managed by NTIA from those managed by the FCC.(6) For the allocation of frequencies internationally, the world has been divided into three regions as contained in the International Telecommunication Union (ITU) Table of Frequency Allocations of Article 8 of the ITU Radio Regulations. The United States is within Region 2 as shown in the figure below.
There is, however, considerable flexibility in the block allocation system. Footnotes to the allocation blocks may permit operation of additional radio services in the spectrum block, restrict the operation of services allocated in the block, specify or clarify the relative status of services in a block, or stipulate other requirements for operation. Other footnotes may permit multi-mode operation, where the transmitted signal is used for more than one purpose, and would otherwise be separate radio services.
Radio Services Supporting Radars
Radars typically operate in radio frequency bands of the electromagnetic spectrum that are allocated for the radiodetermination, Earth exploration-satellite, and the meteorological aids radio services. Since radars became operational over 60 years ago, the need for management of spectrum for their use became apparent and scores of frequency bands have been allocated for their use. These allocations are contained in the U.S. National Table of Frequency Allocations.
In spectrum management, the term radiodetermination is defined as: "The determination of the position, velocity and/or other characteristics of an object, or the obtaining of information relating to these parameters, by means of the propagation properties of radio waves." In the U.S. National Table of Frequency Allocations, no allocation is listed for the radiodetermination service per se because, in practice, radiodetermination operations are allocated either as the radionavigation service or the radiolocation service, with the radionavigation service also subdivided as aeronautical radionavigation service and maritime radionavigation service.
These radio services are just part of the 34 radio services defined in the NTIA Manual.(7) These six radio services are defined below and are treated as distinct radio services in subsequent sections of this report when considering radar.
a. The radionavigation service is defined as "radiodetermination used for the purpose of navigation, including obstruction warning."(8) The radionavigation service is unique in that it is referred to as a safety service--any radiocommunication service that is used permanently or temporarily in the safeguarding of human life and property.(9)
(1) A subset of the radionavigation service intended for the benefit and for the safe operation of aircraft is defined as the aeronautical radionavigation service(10) and is considered a safety service.
(2) The maritime radionavigation service is a subset of the radionavigation service intended for the benefit and for the safe operation of ships(11) and is also considered a safety service.
b. The radiolocation service is defined as "a radiodetermination service used for the purposes other than those of radionavigation."(12)
c. The meteorological aids service is a radiocommunication service used for meteorological, including hydrological, observations and exploration.(13)
d. The Earth exploration-satellite service is a radiocommunications service between earth stations and one or more space stations, which may include one or more space stations, in which:
(1) Similar information is collected from airborne or earth-based platforms;
(2) Such information may be distributed to earth stations within the system concerned;
(3) Platform interrogation may be included.
This service may also include feeder links necessary for its operation.(14)
Radar Trends: Frequency and Power
Since radars were first developed, it appears that the frequency and power requirements of many radars have been increasing. This may have been the result of users' radar search requirements as well as advancing technology to support greater surveillance distances, placing radars on shipborne and airborne platforms, and accommodating the shrinking available platform space. The following chart shows that radar frequency usage had already expanded by 1960 to the full spectrum available for practical use.(15)
The trends in radar power are similar to those of frequency. By 1960, both peak and average power had reached levels about as high as those used in today's high-power radars.
Frequency Bands Supporting Radar Allocations
Frequency bands that provide the greatest protection for radars are those that have a primary allocation and where radars in that radio service share with no other primary users. Next in the level of protection are the bands that are allocated on a primary basis but share this status with one or more radio services. Less protection is afforded where bands are allocated to the radiolocation, radionavigation, Earth exploration-satellite , or meteorological aids radio services on a secondary basis to other radio services. The frequency bands that support radar operations in the radiolocation, radionavigation aeronautical radionavigation, maritime radionavigation, Earth exploration-satellite, and meteorological aids radio services shown in the U.S. National Table of Frequency Allocations are listed in TABLE 2 below.
U.S. Radar Operating Bands, Radio Services, and Allocation Status
|Meteorological Aids||Earth Exploration- Satellite|
1. This band is used for a DOD space surveillance radar system. Under BBA-97, this band was identified for reallocation on January 2002. The space surveillance radar located at three transmitter sites and six receiver sites will be protected indefinitely. See National Telecommunications and Information Administration, U.S. Department of Commerce, Special Report 98-36, Spectrum Reallocation Report, Response to Title III of the Balanced Budget Act of 1997, (Feb. 97) at iv-v.
2. Allocation for EESS is pending implementation of World Radio Conference 97 changes.
3. The 2385-2390 MHz portion of this band is identified for reallocation on January 2005.
4. Prior to OBRA-93, 3100-3700 MHz was allocated to the radiolocation service on a primary basis. The 3650-3700 MHz portion was identified for reallocation on Jan 1999. Three essential military radar operations will be continued at three sites. See National Telecommunications and Information Administration, U.S. Department of Commerce, NTIA Special Publication 95-23, Spectrum Reallocation Final report (Feb. 1995), at 4-16 to 4-4-21.
Erosion of Radiolocation Spectrum Availability
Spectrum is allocated internationally as a result of international radio conferences held under the auspices of the International Telecommunication Union (ITU). The World Radiocommunication Conferences (WRC's) determine the spectrum allocation to radio services for the three ITU Regions.(16) Many administrations use the international Table of Frequency Allocations as a template for their national frequency allocation tables. For this reason, decisions made at international conferences have a profound effect on worldwide use of specific frequency bands. Many administrations do not have the heavy operational use of radiolocation as the United States, and the potential for commercial use of radiolocation bands creates a pressure to reallocate radiolocation bands to other services. Although the United States has not always followed the ITU allocations when establishing domestic allocations to allow for operation of high-priority systems, a lack of worldwide allocations make it difficult to operate some military systems globally without individual coordination with host countries.
Changes to approximately 3.64 GHz of internationally allocated spectrum supporting radar operations in Region 2 have been effected at three WRC's and are described below:
The World Administrative Radio Conference held in 1979 (WARC-79) revised the international Table of Frequency Allocations and Radio Regulations that affected radar operation status in frequency bands from 200 MHz to 20 GHz. Although the United States may not have implemented all of the changes affecting radiolocation, the following summarizes allocation changes totaling 856 MHz in the Region 2:(17)
a. In the 216-225 MHz band, the primary status of the radiolocation service ceased after January 1, 1990 and after this date, no new radiolocation stations could be authorized, and any existing radiolocation devices were afforded secondary status.(18)
b. In the 420-450 MHz band, radiolocation was downgraded from primary to secondary status in 20 MHz. The 20 MHz includes the 420-430 MHz and 440-450 MHz bands.(19)
c. In the 890-942 MHz, 3400-3700 MHz, 5850-5925 MHz, and 17.3-17.7 GHz bands, radiolocation was downgraded from primary to secondary status.(20)
Reallocations at WARC-92 affected the radiolocation service in two bands: 13.75-14.0 GHz and 17.3-17.8 GHz. Taking into account WARC-79 changes, an additional 350 MHz of spectrum allocation changes affecting radiolocation was made at this WARC. Prior to WARC-92, the radiolocation service enjoyed exclusive primary status in the 13.75-14.0 GHz band. The reallocation at WARC-92 added the fixed-satellite service as co-primary with the radiolocation service. In the 17.3-17.8 GHz band, where the radiolocation service had worldwide secondary status to the fixed satellite service (Earth-to-space), the broadcast satellite service (BSS) allocation was added with a primary status. The BSS allocation is scheduled to be in effect on April 1, 2007.(21)
The WRC-97 affected the radiolocation and radionavigation services in 2,435 MHz of spectrum allocations. In the United States, the radiolocation service was affected by upgrading the secondary allocation of radio services in some of its bands to primary. Either by direct table listing or by footnote, the EESS and space research (SR) services were upgraded in the following bands: 1215-1300 MHz, 3100-3300 MHz (secondary status), 5250-5460 MHz, 8550-8650 MHz, 9500-9800 MHz, 13.4-13.75 GHz, 17.2-17.3 GHz, 35.5-36 GHz, and 94-94.1 GHz. The radionavigation service allocations at 31.8-33.4 GHz were affected with the addition of the fixed service as a co-primary service.
Even within the United States, radiolocation bands have been reduced to make room for emerging commercial services. As a result of the OBRA-93 and BBA-97, changes affecting the radiolocation and the aeronautical radionavigation services in the national table of allocations will be made in the very near future. In approximately 139 MHz of the 255 MHz of spectrum identified for reallocation, future private-sector users may be affected by adjacent-band interference from radars. The bands affected are:
a. 216-220 MHz. Prior to the BBA-97, this band was allocated to the radiolocation service on a secondary basis. This band was identified by NTIA, under the BBA-97, to be reallocated on a mixed-used basis with a scheduled availability date of January 1, 2002. The military space surveillance radar system sites will be protected indefinitely.(22)
b. 1390-1400 MHz. Prior to OBRA-93, the entire 1350-1400 MHz band was allocated to the radiolocation service on a primary basis. Under the OBRA-93, NTIA identified the 1390-1400 MHz for reallocation to the private sector on January 1, 1999.
c. 2300-2310 MHz. This band was identified by NTIA for reallocation, effective August 10, 1995, for exclusive private-sector use under OBRA-93. Any existing Federal Government operations in this band are on a non-interference basis to private-sector operations.
d. 2385-2450 MHz. Under the BBA-97, the 2385-2390 MHz radiolocation band was identified for reallocation for private-sector use effective January 2005. Under OBRA-93, the 2390-2400 MHz and 2402-2417 MHz portions of this band were identified for immediate reallocation, effective August 10, 1994, for exclusive private-sector use. The same was applied to the 2400-2402 MHz band but became effective August 10, 1995. The 2417-2450 MHz was identified for reallocation, effective August 10, 1995, for mixed government and non-government use under OBRA-93
e. 3650-3700 MHz. Prior to reallocation, the entire 3500-3700 MHz band supported radar operations to include radiolocation and aeronautical radionavigation. The 3650-3700 MHz band was identified by NTIA for reallocation, effective 1 January 1999, for mixed government and non-government use under OBRA-93.(23)
Summary of Allocation Changes Affecting Radar Operations
Since 1979, spectrum allocated for radar operations in the United States has seen some erosion of allocations whether it be from changes of its status from primary to secondary, the sharing with non-radar primary radio services, spectrum allocation transfers, or lost allocations. The total amount of spectrum affected is about 3.78 GHz and is depicted in the following table:
Summary of Allocation Changes
|847 MHz||Primary to Secondary Status||WARC-79 (Region 2)|
|9 MHz||Lost Allocation||WARC-79 (Region 2)|
|750 MHz||Share with New Primary Service||WARC-92 (Region 2)|
|2,435 MHz||Share with New Primary Service||WRC-97|
|139 MHz||Allocations Transferred to FCC||OBRA-93, BBA-97|
|Note: In WARC-92, 400 MHz of the 750 MHz indicated above was also changed at WARC-79.|
Summary of Radar Operations
3-30 MHz Band. This band, normally referred to as the high frequency (HF) band, has only a small portion allocated to the radiolocation service and with only a secondary status. Radars operate in various portions in the HF band on a non-interference basis. Typical radars in this band are referred to as over-the-horizon radars or skywave radars.
216-225 MHz Band. This band is allocated on a secondary basis to the radiolocation service and government radiolocation operation is limited to the military services. In this band, the United States operates the Navy space surveillance (SPASUR) radar as part of the North American Air Defense (NORAD) system for space detection and tracking. The SPASUR system detects and tracks satellites as they passes through its fan-shaped radar beams extending from San Diego on the west coast to Fort Stewart, Georgia on the east coast.(24)
420-450 MHz Band. In the United States, this band is allocated on a primary basis to Federal Government radiolocation service operations. Military radar support includes national air defense radar systems for surveillance of spacecraft and ballistic missiles; service-unique ground and airborne early warning radars; battlefield radar systems for search/surveillance, position location; shipborne long and medium-range air search and surveillance radars; and maritime radionavigation. Non-military radars operations support law enforcement, wind profiling, nuclear safety programs, and environmental monitoring.
890-902 MHz Band. In the United States, this band is allocated exclusively to the non-Government for fixed, mobile, land mobile, and aeronautical mobile services. However, Federal Government off-shore radiolocation operation is permitted on a non-interference basis limited to the military services. Radiolocation operation is primarily by the Navy for their shipborne radars.
902-928 MHz Band. In the United States, this band is allocated on a primary basis to Federal Government radiolocation service operations. Federal Government usage include Navy shipborne long-range air surveillance radars, vehicle tracking radars, and mobile range control radars supporting research, development, test, and evaluation (RDT&E) activities.(25)
928-942 MHz Band. In the United States, this band is allocated to the radiolocation service for Government ship stations (off-shore areas) on a non-interference basis to non-Government land mobile stations. Radiolocation operation is primarily by the Navy for their shipborne radars.
1215-1390 MHz Band. In various portions of this band, the radiolocation and aeronautical radionavigation radio services share co-primary status. Primary status for the radiolocation service is in two portions of the band, 1215-1300 MHz and 1350-1390 MHz, and is secondary in the 1300-1350 MHz portion. From 1240-1370 MHz, the aeronautical radionavigation service has primary status. The band 1390-1400 MHz was once allocated to the radiolocation service on a primary status but was identified for reallocation under OBRA-93 (1390-1400 MHz) to the private sector on January 1, 1999. The military services operate many radars in this band that perform such functions as air defense surveillance; military and national test range instrumentation radars; battlefield early warning, surveillance and tracking, man-portable search and target acquisition; shipborne long-range air surveillance; and minimally attended radars. Non-military radars provide air route surveillance; test range safety surveillance radars; and spectral imaging radars. This band has been identified by the FAA as needed for aeronautical surveillance in the modernized air traffic control system.(26) Pending implementation of WRC-97 allocation changes, the EESS shares primary status in the 1215-1300 MHz band. NASA performs Earth observations in this band and operates spaceborne active sensors primarily SAR imaging radars.
2310-2385 MHz Band. The radiolocation service has primary status in this band except for 2320-2345 MHz, in which it is secondary. NASA operates a tri-static planetary and lunar radar in this band supporting space exploration. The National Science Foundation operates a high-power radar in its research and studies of objects beyond the moon.
2417-2500 MHz Band. The radiolocation service has secondary status in the 2417-2450 MHz portion of this band and government radiolocation operation is limited to the military services. Government radiolocation services is permitted in the remainder of the band (2450-2500 MHz) on the condition that harmful interference is not caused to non-Government services.
2700-2900 MHz Band. The aeronautical radionavigation and meteorological aids radio services share co-primary status in this band; however, the radiolocation service is secondary for government radiolocation services. The FAA and military services operate airport surveillance radars for the safe and efficient management of aircraft during approach and departures to/from airports or military airfields. Many Federal agencies operate weather radars in support of the national meteorological operations with the Next Generation Weather Radar (NEXRAD) being the most recently commissioned system. There are approximately 150 NEXRAD commissioned sites belonging to the DOC (National Weather Service), DOD (Air Force), and Department of Transportation (FAA).(27) NASA also operates a range safety surveillance radar to detect aircraft and ships during airborne test operations as well as during space launches.
2900-3100 MHz Band. The maritime radionavigation service has primary status throughout this band; however, it shares co-primary status with the meteorological aids radio service in the 2900-3000 MHz portion of the band. The meteorological aids allocation is limited to government NEXRAD systems where accommodation in the 2700-2900 MHz band is not technically practical.(28) Radiolocation services are secondary in this band. The USCG and the Navy operate numerous shipborne maritime radionavigation and search radars as well as positioning aids to radionavigation. Several NEXRAD radars are supported in this band. This band supports various military radiolocation services such as air base and tactical airfield ATC surveillance radars; medium and long-range battlefield air defense radars; and shipborne long-range air surveillance radars. Non-military radiolocation radars support such functions as atmospheric weather research and studies; marine fisheries; range safety search and surveillance; NASA ships; and law enforcement. This band has been identified by the FAA as needed for aeronautical surveillance as well as for critical aviation support services in the modernized air traffic control system.(29)
3100-3650 MHz Band. The radiolocation service has primary allocation status throughout this band for Government operations and is secondary for non-Government operations. Primary status is shared in the 3500-3650 MHz with aeronautical radionavigation service where it is primary only for Government operations. The military services have radiolocation operations throughout the band in support of air base and tactical airfield ATC search and surveillance; aircrew bombscoring; airborne search and surveillance; battlefield weapons-locating, Doppler radar; shipborne fleet air defense radar systems (search and surveillance, tracking, fire-control, etc.); aircraft carrier precision approach control; and point area defense for small surface ships and patrol craft. Other radiolocation radars support non-military functions at the many national and agency test ranges for search radars for range safety to detect unauthorized transiting aircraft and ships. Pending implementation of WRC-97 allocation changes, the EESS has secondary status in this band. NASA performs Earth observations in this band and operates spaceborne active sensors primarily SAR imaging radars
4200-4400 MHz Band. This band is allocated on a primary basis for aeronautical radionavigation where its only use in this band is for aircraft radar altimeters.
5250-5925 MHz Band. This band contains five radio service allocations supporting radars with many sharing sub-bands. The radiolocation service is primary in the sub-bands 5250-5460 MHz and 5650-5925 MHz. In the 5350-5460 MHz band, the aeronautical radionavigation service is co-primary with the radiolocation service. The radionavigation service is primary in the 5460-5470 MHz band. In the 5470-5650 MHz band, the maritime radionavigation service has primary status and is co-primary with the meteorological aids service in the 5600-5650 MHz portion. Finally, the radiolocation service is primary in the 5650-5925 MHz band and is secondary in the 5460-5650 MHz band. The military services operate numerous radars in the 5250-5925 MHz band in support of national and military test range surveillance and instrumentation operations; airborne radar transponders; battlefield missile surveillance and tracking; weather radar observations; shipborne fire-control of surface-to-air missiles; shipborne surface search radars; shipborne missile and gunfire-control radar; and navigational aids to assist in precise positioning of ships. Non-military government radar operations include support for airborne weather and navigation; missile and rocket target instrumentation radars at test sites and ranges; range safety surveillance radars; radar transponders aboard unmanned airborne vehicles; airborne radionavigation radars; nuclear incidents situations; weather phenomena research and studies; geological and water/shoreline surveys; and airport terminal Doppler weather radars. Pending implementation of WRC-97 allocation changes, the EESS shares primary status in the 5250-5460 MHz band. NASA performs Earth observations in this band and operates spaceborne active sensors such as SAR imaging radars, altimeters, and scatterometers.
8500-9000 MHz Band. The radiolocation service has primary status throughout this band for Government radiolocation services and is secondary for non-Government operations. In the sub-band 8750-8850 MHz, the aeronautical radionavigation service has secondary status. The military services operate numerous radars for such operations as airborne multimode weapons fire-control; airborne search and interception radars; mobile and portable battlefield radars for air search and surveillance; artillery, rockets, and mortar locating radars; airborne anti-submarine warfare radar; shipborne weapons fire-control radars; submarine surface navigation and search radars; and airborne maritime Doppler surveillance radars. Non-military radars are supported in this band for such search and tracking of airborne test/experimental manned and unmanned vehicles; tracking radars supporting nuclear reactor test activities and limited nuclear test band treaty; mobile meteorological radars; and land-based planetary radars. With implementation of WRC-97, the EESS will share the 8550-8650 MHz band on co-primary basis where NASA operates spaceborne active sensors consisting primarily of SAR imaging radars, altimeters, and scatterometers.
9000-9200 MHz Band. The primary radio service in this band is aeronautical radionavigation and the radiolocation service is secondary for Government operations. The users of this band are the military services in support of fixed and mobile base and airfield ATC precision approach radars (PAR); airborne search and rescue radar and law enforcement radars; airborne maritime Doppler navigation and surveillance radars. This band has been identified by the FAA to support a new, low-cost version of an airport surface detection equipment (ASDE) in the modernized air traffic control system.(30)
9200-10550 MHz Band. From 9200-9500 MHz, the maritime radionavigation service is primary from 9200-9300 MHz, radionavigation service is primary from 9300-9500 MHz, radiolocation is secondary from 9200-9500 MHz, and the meteorological aids is secondary from 9300-9500 MHz. Pending implementation of WRC-97 allocation changes, the EESS shares primary status in the 9500-9800 MHz band. NASA performs Earth observations in this band and operates spaceborne active sensors such as SAR imaging radars and plans to operate altimeters and scatterometers. NASA also operates spaceborne active sensors in the 9975-10025 MHz band and plans to operate mainly spaceborne weather radars in this band. The radiolocation service has primary status in the remainder of the band, 9500-10550 MHz. The military services are the primary Federal users of this band with operations such as bomb scoring radars; intrusion detection radars; airborne search and rescue radars; airborne multi-mode weapons fire-control radars; airborne search and interception radars; airborne weather and navigation; airborne beacon rendezvous radar; airborne terrain following and terrain avoidance radars; airborne anti-submarine warfare radars; airborne maritime surveillance radars; mapping and imaging radars; airborne side-looking surveillance radar; airborne reconnaissance and surveillance radars; mobile and portable battlefield radars for air search and surveillance; artillery-, rocket-, and mortar-locating radars; battlefield ATC ground approach control radars; microwave landing system radars; battlefield air defense weapons fire-control radar; base security and area perimeter surveillance radars; weather radars; various shipborne navigation and surveillance radars for ships/boats, aircraft, and submarine periscopes; guided missile fire-control radars; land-based harbor search radars; military and national test range instrumentation radars; and vehicle speed detection radars. Non-military use support airborne weather radars; maritime search and navigation radars; natural resource pulse radar used in the study of fire properties (wind, flame, particle velocities, etc.); entomological radar to study aerial population and flight characteristics of insects and their migration patterns; ground and airborne meteorological research radars; marine sanctuary monitoring radars; land-based radionavigation radar; range safety search, surveillance, and instrumentation radars; airborne radar beacons; cadastral and geological survey radars; atmospheric studies and wind research radars; space shuttle support ships; maritime mobile radars; and vehicle speed detection radars.
13250-14200 MHz Band. The aeronautical radionavigation service is primary in the 13250-13400 MHz portion of this band, the radiolocation service is primary in the 13400-14000 MHz portion, while the radionavigation service is primary in the remainder, 14000-14200 MHz.(31) The predominant users in this band are the military services for airborne and shipborne radars. Airborne radar applications support multimode Doppler navigation and search radars; and navigation and sea search radars. Shipborne radar applications in 13400-14400 MHz band include pulse Doppler search and acquisition radars as well as pulse Doppler weapons system control radars. Non-military applications include airborne ocean wave spectrometer radars that measure ocean surface characteristics. Pending implementation of WRC-97 allocation changes, the EESS shares primary status in the 13250-13750 MHz band. NASA performs Earth observations in this band and operates spaceborne active sensors such as altimeters, scatterometers, and precipitation radars.
15400-17700 MHz Band. The aeronautical radionavigation service is primary in the 15400-15700 MHz portion of this band while the radiolocation service has primary and secondary allocations in the 15700-17300 MHz and 17300-17700 MHz bands, respectively. Pending implementation of WRC-97 allocation changes, the EESS secondary status in the 17200-17300 MHz band will be upgraded to primary. NASA performs Earth observations in this band and operates spaceborne active sensors such as scatterometers and precipitation radars. The military services are the largest users of this band with airborne multi-mode weapons fire-control radars; airborne search and interception radars; airborne weather and navigation radars; airborne terrain following and terrain avoidance radars; battlefield weapons-locating radars; battlefield aircraft approach landing system radars; battlefield mobile and portable ground surveillance radars weapons guidance/control radars; aircraft carrier precision approach and landing system radars; shipborne weapons fire-control radars; shipborne navigational radars; and various national and military test range target tracking and instrumentation radars. Non-military radar applications in this band include microwave landing systems supporting the space shuttle; search radars supporting atmospheric research studies; airport surface detection equipment radars for the control of aircraft and ground vehicles on airport surfaces.
24050-24650 MHz Band. In this band, the sub-band 24050-24250 MHz has primary and secondary status for Government and non-government operations, respectively. In the 24050-24250 MHz band, the EESS operate spaceborne active sensors on a secondary basis. The EESS intends to operate mainly scatterometers and precipitation radars in this band. From 24250-24650 MHz, this sub-band is allocated to the non-government for radionavigation on a primary basis; however, the Government shares co-primary status at 24450-24650 MHz. The predominant Government operations in this band is for the use of vehicle speed detection radars in 24050-24250 MHz. The 24250-24450 MHz band was reallocated on May 1997 (FCC 97-95) by the FCC to the fixed service to support the Digital Electronic Message Service (DEMS) service.
24750-25250 MHz Band. The radionavigation service has primary status in this band and the Government has primary allocation status in only the 24750-25050 MHz band. NTIA could not identify any operational radar usage in this band. The band 25050-25250 MHz was reallocated on May 1997 (FCC 97-95) by the FCC to the fixed service to support the DEMS service.
31800-36000 MHz Band. In this band, the radionavigation service is primary in the 31800-33400 MHz portion and the radiolocation service is primary in 33400-36000 MHz. The military services have radars in this band for airborne navigational and mapping radars; weather avoidance; aircraft radar beacon rendezvous; airborne terrain following and avoidance radars; airborne long-range mapping radars; aircraft carrier precision approach and landing system radars; cloud measurement radars; military and national test range instrumentation radars; and vehicle speed detection radars. NASA, FAA, and the DOD are involved in synthetic vision radar research at around 35 GHz. Non-government radar operations support millimeter wave radar research of atmospheric radiation measurements; multi-mode airborne radar altimeters for profiling topographic features of land and ocean surfaces; and radar measurements of aircraft wake vortices during approach and departures. With implementation of WRC-97, the EESS will share the 35500-36000 MHz band on co-primary basis where NASA plans to operate spaceborne active sensors such as scatterometers and wideband altimeters.
92000-95000 MHz Band. This band is allocated to the radiolocation service on a primary basis. The military operates airborne pulse Doppler fire-control radars and airborne radiometer beacons. NASA, FAA, and the DOD are involved in synthetic vision radar research at around 94 GHz. Additionally, numerous RDT&E is conducted in this band for various radar systems. Non-military operations consist of ground-based CW pulse radars in the high-resolution profiling of clouds and for airborne test and evaluations of cloud detection radars. With implementation of WRC-97, the EESS will share the 94000-94100 MHz band on co-primary basis. NASA performs Earth observations in this band and is planning to operate cloud profile radars.
95000-100000 MHz Band. This band is allocated to the radionavigation service on a primary basis and to the radiolocation service on a secondary basis.
Endnotes: Chapter 2
1. The National Telecommunications and Information Administration Organization Act, Pub. L. No. 102-538, 106 Stat. 3533 (1992) (codified at 47 U.S.C. § 901 et seq.).
2. NTIA Manual, infra note 3, § 8.2.5 at 8-4. OMB Circular A-11, Section 12.4(e) requires that "estimates for the development and procurement of major communications-electronics systems (including all systems employing satellite (space) techniques) will be submitted only after certification by the NTIA that the radio frequency required for such systems is available."
3. National Telecommunications and Information Administration, Manual of Regulations and Procedures for Federal Radio Frequency Management § 1.1, at 1-1 (Sep1995, Jan and May 1997 revisions) [hereinafter NTIA Manual].
4. Radio regulations provide two levels of protection: primary and secondary. Radio services allocated on a primary basis have equal rights within the same band. Secondary services are on a non-interference basis to the primary services.
5. The U.S. National Table of Frequency Allocations is comprised of the U.S. Government Table of Frequency Allocations and the FCC Table of Frequency Allocations. The National Table indicates the normal national frequency allocation planning and the degree of conformity with the ITU Table of Frequency Allocations.
6. Copies of the NTIA spectrum wall chart, the NTIA Manual, the Extract of the NTIA Manual (containing the U.S. National Table of Frequency Allocations) and the FCC Rules (Parts 1 to 19) containing the U.S. National Table of Frequency Allocations are available from the Government Printing Office (GPO) or from the NTIA homepage: www.ntia.doc.gov. For ordering information and GPO address, contact Norbert Schroeder, Vice-Chairman, Interdepartment Radio Advisory Committee (ph: 202-482-3999, fax: 202-501-6198, or email: email@example.com).
7. See NTIA Manual, supra note 3, §, 6.1.1, at 6-1 to 6-16.
8. Id., §, 6.1.1, at 6-12 .
9. Id., §, 6.1.1, at 6-13.
10. Id., §, 6.1.1, at 6-2.
11. Id., §, 6.1.1, at 6-8.
12. Id., §, 6.1.1, at 6-11.
13. Id., §, 6.1.1, at 6-9.
14. Id., §, 6.1.1, at 6-4. The EESS is where SAR imaging, altimetry, scatterometry, precipitation monitoring, and cloud profile monitoring is done.
15. David K. Barton (ANRO Engineering, Inc.), Keynote Address at the 1999 Tri-Service Radar Symposium (June 22, 1999).
16. Previous conferences were known as World Administrative Radio Conferences (WARC's).
17. Similar changes were made in ITU Regions 1 and 3 for the bands discussed.
18. In this band, the DOD operates a national space detection and tracking radar system.
19. The DOD operates in this band a national air defense radar system for surveillance of spacecraft and ballistic missiles as well as other types of airborne shipborne, and battlefield radar systems. These DOD radars are radiolocation systems and the secondary allocation status applies not only in Region 2 but also in Regions 1 and 3.
20. The DOD operates numerous radiolocation radar systems in these bands on a secondary allocation status and, at times, must operate them worldwide.
21. S5.517. NTIA believes that the use of the 17.3-17.7 GHz band by radiolocation may be impractical after 2007.
22. See Balanced Budget Act of 1997, Pub. L. No. 111, Stat. 251 (1997), § 9233(a) (4); see also TABLE 3-2 and Figure 3-2 at 3-18 and 3-19, respectively.
23. Three essential military radar operations will be continued at three sites. See National Telecommunications and Information Administration, U.S. Department of Commerce, NTIA Special Publication 95-23, Spectrum Reallocation Final Report (Feb. 1995), at 4-16 to 4-21.
24. Jane's Information Group Limited, National and International Air Defense Systems, Jane's Radar and Electronic Warfare Systems, 1995-96, at 35 (Bernard Blake ed, 7th ed, 1995).
25. Department of Transportation, Federal Aviation Administration, Radio Spectrum Requirements for a Modernized Air Traffic Control System, July 1997, at 31 [hereinafter FAA Spectrum Requirements]. This FAA report was in response to a recommendation by the White House Commission on Aviation Safety and Security report that the FAA should identify and justify the frequency spectrum necessary for the transition to a modernized air traffic control system.
27. U.S. Department of Commerce, National Oceanic and Atmospheric Administration/OFCM, The Federal Plan for Meteorological Services and Supporting Research, FCM P1-1998, June 1998, at ix.
28. See U.S. Footnote US316, NTIA Manual, supra note 3, § 4.1.3, at 4-113.
29. See FAA Spectrum Requirements, supra note 25, at 31 and 42.
31. At 13250-13400 MHz, primary status of radiolocation applies to Government operations and is secondary for non-government operations.