The amateur service is defined internationally as "A Radiocommunications service for the purpose of self-training, intercommunication and technical investigations carried out by amateurs, that is, by duly authorized persons interested in radio technique solely with a personal aim and without pecuniary interest."[EN574] Radio amateurs are trained and experienced in electronics, propagation theory, and communications techniques.[EN575] Amateurs also respond swiftly and effectively to calls for communications assistance when normal channels are lost. The amateur service has significantly contributed to the development of radio technology. Amateur operators continue to fulfill certain public service radiocommunications requirements, and increase their skills relating to emergency communications. During natural disasters such as hurricanes, floods, and other events, amateur radio communications have been particularly effective, and in many cases have been the sole means of communicating from the scene of a disaster.
The amateur-satellite service was formally created as a result of the 1971 World Administrative Radio Conference for Space Services. At that Conference and the 1979 WARC, both primary and secondary frequency allocations were granted to the service. Many of the secondary allocations are provided as a result of international Radio Regulation 664.
Amateur, or "ham" radio operators, have provided a unique service to the public while enjoying a popular, technical hobby. Many innovative uses of radio systems have been developed by amateurs for use in the amateur bands, such as packet-switched systems and amateur television. It is estimated that there are in excess of 632,000 amateur radio operators in the United States, and over 2.4 million worldwide.[EN576]
Amateur allocations have been based, in part, on the desirability of having a choice of relatively narrow frequency bands with different propagation properties distributed throughout the spectrum. As propagation conditions change in the medium and high-frequency bands, amateur operators can follow the changing maximum usable frequency (MUF) and still be able to communicate. Higher frequency bands have other propagation properties useful for different amateur activities, such as amateur-satellite and short-range land mobile applications. Current amateur allocations start at 1800 kHz and, in narrow bands, extend to 250 GHz.
Amateurs use the HF bands for medium to long-distance communications. The 160 meter band (1.8 MHz) provides good groundwave coverage and is relatively free of propagation anomalies. The higher HF bands have increasing dependance on ionospheric refraction to provide long-distance communications. Time-of-day and sunspot activity are important factors in the ability of the HF bands to support communications beyond the range of groundwave coverage. A good selection of frequencies spread throughout the HF bands is critical to maintaining reliable communications. Amateurs use voice and data communications in the HF bands, operating from base and mobile stations.
Frequencies above 30 MHz provide generally short-range terrestrial communications, and support the use of amateur satellite communications. In the bands above 54 MHz, amateurs rely heavily on a system of radio repeaters to increase the range of amateur communications. However, amateurs are always experimenting with point-to-point systems to push the state-of-the-art in antenna design and solid-state equipment, and to investigate the properties of signal propagation at the higher frequencies. Amateurs use Morse code, voice, packet-switched data, television, and satellite communications in the various frequency bands.
In addition to recreational use, amateurs use the amateur bands to provide public services in a variety of ways. The American Radio Relay League sponsored National Traffic System provides a nationwide network that carries thousands of messages monthly. This system is available in the event that regional or local disasters degrade the public communications systems. The DOD works closely with the amateur community in its Military Affiliate Radio System (MARS) network. Local amateur radio clubs provide communications support for community events, and are a source of trained radio operators to complement state and local communications personnel through the ARES and RACES programs.[EN577]
Amateurs have historically been on the leading edge of radio technology. As new solid-state devices become available, amateurs will use them in radio systems to push the upper limits of practical spectrum usage. It is expected that the current analog systems employing single-sideband, FM voice, and television modulation will be overtaken by digital techniques. The number of amateur radio operators is increasing at a current annual rate of 7.5 percent in the United States,[EN578] and about 7 percent worldwide.[EN579] Growth in the amateur service will require increased use of higher frequencies, and necessitate the use of radio repeaters to overcome the limitations imposed by the propagation characteristics of the higher frequency bands.
Some of the frequency bands shared by amateur operations are becoming heavily used. For example, the 902-928 MHz band will become more used with the increased use of LMS systems and possibly by Federal and non-Federal wind profiler radars. Radiolocation bands, which have been shared with amateurs for years, will become more valuable to military users as new radar systems are deployed and pressure for the bands to be used for non-government purposes increases.
The amateur-satellite service will soon have a new generation of amateur satellites in orbit using all frequency bands allocated to the amateur-satellite service from 29 MHz through 24 GHz.[EN580] The Phase 3D OSCAR (Orbiting Satellite Carrying Amateur Radio) satellite is scheduled to be launched in late 1995. This satellite is designed to be an improvement over current OSCAR satellites in terms of link performance and capabilities. The OSCAR 3D satellite will facilitate the use of gateway earth stations, so that an amateur operator with a hand-held radio will be able to reliably communicate with other amateurs over a distance of several thousand kilometers.
Future spectrum requirements for the amateur and the amateur-satellite services were contained in responses to the Notice provided by the American Radio Relay League (ARRL) and the Radio Amateur Satellite Corporation (AMSAT). The commenters have requested a significant revision of the allocation table to accommodate expanded amateur operations. Table 6-1 lists ARRL's and AMSAT's requested future spectrum allocations for these services.
It should be noted that the frequency ranges 2390-2400 MHz and 2402-2417 MHz, allocated to the amateur service on a secondary basis to Federal Government radiolocation, have been made available for immediate reallocation to the FCC. The range 2300-2310 MHz, also allocated to the amateur service on a secondary basis, may be reallocated to the FCC within two years.
Frequency Band Requested Amateur Allocations Notes ______________ _____________________________ _____ 160-190 kHz New Allocation (Shared) (a,b) 1800-1900 kHz Retain 1900-2000 kHz Retain 3500-4000 kHz Retain, but Add 300 kHz Worldwide (a, c) 5000 kHz New Allocation (Shared) (a,d) 6900-7200 kHz New Allocation: Exclusive, Worldwide (a, e) 10100-10350 kHz New Allocation: Primary, Worldwide (a, f) 14000-14250 kHz Retain 14250-14400 kHz New Allocation (a,g) 18068-18318 kHz New Allocation: Exclusive, Worldwide (a,h) 21000-21450 kHz Retain 24740-24990 kHz New Allocation: Exclusive, Worldwide (a, i) 28.0-29.7 MHz Retain 29.7-30.0 MHz New Allocation (a, j) Between 30-50 MHz New Allocation (a,k) 50-54 MHz Retain; Extend into Region 1 (a, l) 144-146 MHz Retain; Delete RR 605, 606 (a,m) 146-148 MHz Retain; Extend into Region 1 (a) Part of 216- New Allocation (n) 220 MHz 222-225 MHz Retain 420-430 MHz Retain 430-440 MHz Revised Allocation: Exclusive, Worldwide (a,o) 440-450 MHz Retain 902-903 MHz Revised Allocation (Upgrade to (p) Primary) 903-928 MHz Retain (p) 1240-1260 MHz Retain 1260-1300 MHz Revised Allocation (Upgrade to Primary) (a,q) 2300-2310 MHz Retain 2390-2400 MHz New Allocation (Add Amateur-Satellite, Upgrade to Primary) (a, r) 2400-2402 MHz New Allocation (Add Amateur-Satellite, Upgrade to Primary) (a) 2402-2450 MHz Revised Allocation (Upgrade to Primary) (s) 3300-3400 MHz Retain 3400-3402 MHz Revised Allocation (Upgrade Amateur-Satellite to Primary) (a) 3402-3420 MHz Revised Allocation (Upgrade to Primary) (a, t) 3420-3500 MHz Retain 5650-5668 MHz Retain (s) 5668-5670 MHz Revised Allocation (Upgrade Amateur and Amateur-Satellite to Primary) (a) 5670-5848 MHz Retain (u) 5848-5850 MHz Revised Allocation (Upgrade Amateur and Amateur-Satellite to Primary) (a) 5850-5925 MHz Retain 10.00-10.45 GHz Retain 10.45-10.50 GHz Revised Allocation (Upgrade Amateur and Amateur-Satellite to Primary) (a) All above 24 GHz Retain (v) ___________________________________________________________________ Notes: [a]Allocation must also be approved at competent World Radiocommunication Conferences [b]New allocation would be secondary to the fixed and maritime mobile services nationally. Additionally, must share with the broadcasting service in ITU Region 1, and aeronautical radionavigation in ITU Region 3. [c]The requirement is for any common, worldwide exclusive 300 kHz allocation within the 3500-4000 kHz band. [d]Requirement is for about 50 kHz near 5 MHz, on a shared basis. Particularly desirable for communications during solar cycle minima when maximum usable frequencies are below 3.5 MHz. [e]The requirement is for 300 kHz aligned worldwide to reduce sharing with high frequency broadcasting in the 7100-7300 kHz band; 6900-7200 kHz was requested. [f]A modification of the present 10100-10150 kHz allocation, requiring elimination or downgrading of the fixed service internationally. [g]The requirement is for an additional 50 kHz primary, exclusive, worldwide. [h]The requirement is for an additional 150 kHz to the present 18068-18168 kHz allocation. [i]The requirement is for an additional 150 kHz to the present 24890-24990 kHz band allocation. [j]The requirement is for amateur-satellite (space-to-Earth) [k]The requirement is for a number (e.g., five) of narrow bands of frequencies between 30 and 50 MHz. [l]A 2 MHz allocation in ITU Region 1 is requested, with at least 500 kHz being exclusive. [m]The deletion of RR 605 & 606 is requested. These footnotes allow operation other than amateur in certain countries. [n]Amateurs requested access to a portion of the 216-220 MHz band. The ARRL petitioned the Commission for additional access. The Commission (ET Docket No. 93-40, RM-7747) has proposed to allocate the 219-220 MHz band for amateur use. [o]Requested for amateur television, voice and data communications, and Earth-moon-Earth communications. [p]This band presently used by LMS systems, which have priority over amateur operations. The proposed LMS systems would also have priority. Non-government primary allocation is for ISM operations on 915 MHz + 13 MHz. [q]Additionally, the removal of the directional Earth-to-space indicators is requested to increase the flexibility of amateur satellite use. [r]Expand the amateur-satellite allocation by 10 MHz in the 2390-2400 MHz band. [s]Retain amateur-satellite allocation in accordance with RR 664. [t] Amateur-satellite allocations in the 3400-3410 MHz band are to be expanded to ITU Region 1. [u]Retain amateur-satellite allocation in accordance with RR 808. [v]Retain all current amateur and amateur-satellite allocations above 24 GHz.
In general, we believe that current amateur and amateur-satellite allocations should be retained. Amateur requests for international reallocations would be appropriate issues for FCC private sector advisory committees addressing U.S. preparations for future World Radiocommunication Conferences (WRC's). Additional allocations at 160-190 kHz, and near 5 MHz will require technical studies to determine the availability of these bands to support amateur use.
The expansion and upgrading of amateur allocations in the 10 MHz, 14 MHz, 18 MHz and 24 MHz bands are acceptable, but will depend on future decrease of requirements for the aeronautical mobile (R) or the fixed services internationally. The alignment of the amateur 3.5 and 7 MHz bands worldwide will require the inclusion of these issues in U.S. preparations for future WRC's.[EN581]
As noted, FCC rulemaking is in progress for amateur access to the 219-220 MHz band. The request for additional narrow spectrum allocations between 30 and 50 MHz for propagation experimentation (e.g., five, 50 kHz slots) will need to be studied for technical compatibility. Spectrum requirements for the amateur service total 2,180 kHz.
However, any sharing of military radiolocation spectrum (e.g., 430-440 MHz) with the amateur services on a co-primary basis in current Federal radiolocation bands is not feasible because of the potential loss of operational flexibility for military radar systems. Further, the expansion of use in the 902-928 MHz band by Federal and non-Federal users, including the operation of wind profiling radars, may make this band untenable for amateur operations in the future.
Standard Frequency and Time Signal Services
The standard frequency and time signal service is "[a] radiocommunication service for scientific, technical and other purposes, providing the transmission of specified frequencies, time signals, or both, of stated high precision, intended for general reception."[EN582] The standard frequency and time signal-satellite service is "a radiocommunications service using space stations on earth satellites for the same purpose as those of the standard frequency and time signal service. This service may also include feeder links necessary for its operation."[EN583]
The reference signals provided by these services are used in association with scientific research, and as standards for Universal Coordinated Time (UTC) where precise time is required. Reflecting the widespread need for precise and accurate frequency and time information in a great variety of applications, standard time and frequency reference signals are distributed by a variety of techniques. Most users are served, directly or indirectly, by one of a variety of radio broadcasts available in the United States. These include not only the dedicated time and frequency broadcasts from radio stations WWV, WWVB (Ft. Collins, Colorado), and WWVH (Hawaii) operated by the Department of Commerce's National Institute of Standards and Technology (NIST) but also the broadcasts from other radio services, such as electronic navigation aids, which have proven to be highly useful for time and frequency applications.[EN584]
Terrestrial as well as satellite-based transmissions are used for dissemination of additional frequency and time information. The Omega, LORAN-C, and GPS navigation broadcasts are examples of systems that are widely used for time and frequency standards, although they are primarily intended for a different purpose. Time and frequency reference signals are also distributed by dial-up telephone services, such as NIST's Automated Computer Time Service, by telecommunication networks, and by other more special-purpose links.
The various time and frequency dissemination methods and services mentioned above have varying spectrum requirements. In the United States, the only services that operate in frequency bands specifically allocated for time and frequency include the NIST broadcasts from WWV and WWVH in the 2-30 MHz band, and from WWVB in the low frequency (LF) band. Dissemination via the NOAA Geostationary Operational Environmental Satellite (GOES) time-code service is a shared use of spectrum near 469 MHz allocated to the meteorological-satellite service. The Omega, LORAN-C, and GPS broadcasts for time and frequency applications makes use of the existing allocations in the radiodetermination services. Increasing use is also being made of the fixed-satellite service spectrum by exchanging time and frequency signals simultaneously through communication satellite channels to accomplish point-to-point time comparisons at the highest possible accuracy levels of near one nanosecond. Other techniques, such as the dial-up service offered by NIST, do not require direct use of the spectrum.
Current Use at 20 kHz
This allocation was formerly used by radio station WWVL, providing very-low-frequency standard frequency and time signal service operated from Ft. Collins, Colorado. Although this service was discontinued in 1972, primarily due to financial reasons and the impact of the Omega Navigation System coming into operation, the capability to broadcast on 20 kHz still exists at NIST.
Current Use at 60 kHz
Use of this frequency for standard frequency and time signal dissemination is allowed by Radio Regulation 447. NIST's WWVB low-frequency service has used this allocation in the United States since 1963. Approximately 1000 entities from government, private industry, universities, science, and the military have been identified as current users. Primary applications for WWVB are in scientific data monitoring, electric power system operations, standards laboratories, communication system calibrations, and military applications.
Current Use at 2.5 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz, 20.0 MHz, and 25.0 MHz
These are the primary allocations used by many high-frequency services, including WWV and WWVH in the United States. All these allocations have been in use at one time or another by WWV and/or WWVH. Currently, the first five allocations are used by WWV and the first four by WWVH. The WWV service has operated since 1923 and WWVH has served the Pacific Ocean area since 1948. Radio stations WWV, WWVH, and other similar services serve users numbering well into the tens of thousands and provide the main access to time signals accurate to about 1 millisecond and frequency references accurate to about 1 x 10-7. HF standard frequency signals transmitted by WWV and WWVH are used by many communicators, including amateur radio operators. Additional information regarding HF propagation is also transmitted by these stations. U.S. standard frequency and time signal systems are allocated 90 kHz in the National Table of Frequency Allocations.
Current Use at 400.1 MHz
This space-to-Earth satellite allocation was made by the 1971 WARC. The allocation was originally intended for use as a satellite-based replacement for some terrestrial HF time and frequency services. However, no administration has implemented a service using this allocation.
Current Use at 4202 MHz and 6427 MHz
Radio Regulation 791 allows the use of this uplink/downlink pair of frequencies for time and frequency transfer on a shared basis subject to completion of suitable agreements under Article 14 of the Radio Regulations. Although two-way exchange of timing signals simultaneously through communication satellites, for which this allocation was intended, has become rather widely used in the time and frequency community for the highest accuracy time transfers, it has not proven necessary to use this specific allocation. Under present conditions, there are no plans to use these specific 4202/6427 MHz allocations within the United States.
Current Use at 13.4-14.0 GHz and 20.2-21.2 GHz
These two uplink/downlink bands are allocated on a secondary basis for satellite-based time transfers at the highest possible accuracy levels. The relatively large bandwidth should support time transfers at higher accuracy and precision than can presently be achieved by any other method or system. However, to date there has been no activity within the United States involving these frequencies for time and frequency transfer.
Current Use at 25.25-27.0 GHz and 30.0-31.3 GHz
This is a second uplink/downlink allocation intended for development of future, higher accuracy time transfer techniques that would take advantage of the relatively large bandwidth provided. As in the previous case there has been no U.S. or international activity as yet to make use of this allocation pair for time and frequency applications.
The HF and LF services, such as WWV, WWVH, and WWVB, continue to fill important user needs for accuracies that are adequate for most applications. Mutual interference will likely continue to be a problem for use of HF services in some areas, but alternative sources are becoming more widely available and economically feasible. In the long term, it may become possible to replace some or all of the terrestrial HF and LF services with more reliable satellite-delivered services.
However, only limited efforts in this direction have been attempted to date, most notably in the form of the NIST time code service from the NOAA GOES satellite system, and the similar service from the INSAT satellite system in the Indian subcontinent region. The future of the GOES system is somewhat uncertain at this time and cannot be considered as a permanent replacement for any of the existing services.[EN585] Preliminary planning by NIST for future satellite services could affect the long-term need for HF and LF allocations, but for at least the next 10 years no impact on the need for the current allocations is foreseen.
While the continuing need for current HF and LF spectrum during the next 10 years or so is clear, the situation concerning spectrum for satellite-based time and frequency distribution is more uncertain. Recently, there has been a strong trend toward increased reliance on satellite-delivered time and frequency signals for applications requiring timing accuracies of better than 1 millisecond. As many modern time and frequency applications develop requirements for sub-millisecond timing accuracies that can no longer be satisfied by the traditional HF and LF broadcast services, more users are tending to make use of the GPS satellite system. Today's most demanding applications must rely on GPS, or in some cases, the two-way exchange of signals through communication satellites. During the next few years it is also possible that additional high-accuracy time and frequency dissemination alternatives may become available through the use of emerging digital synchronized telecommunication networks and perhaps from the INMARSAT system.
In summary, we believe that spectrum currently allocated to and used by the standard frequency and time signal services needs to be retained and seems adequate for future use and expansion of time and frequency standards for the foreseeable future.[EN586] Further, it would seem that as long as the GPS signals continue to be available to the civilian sector at current accuracy levels and assuming sufficient availability of economical communication-satellite channels for the most demanding needs, there may be little need for specific dedicated satellite frequency allocations for the time and frequency services. On the other hand, if future developments restrict time and frequency providers from efficiently making use of spectrum assigned to other services, then the availability of dedicated space-service spectrum becomes essential. Therefore, spectrum planners should consider the standard frequency and time signal-satellite allocations for alternate uses that can share with the radio services currently allocated in these bands, while not eliminating future use of the bands by the standard frequency and time-signal services.
Meteorological Aids Service
The meteorological aids service is "a radiocommunications service used for meteorological, including hydrological, observations and exploration."[EN587] In the United States, the National Weather Service (NWS) of the Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) is charged with the observing and reporting of weather, issuing forecasts, and warning of weather and flood conditions affecting national safety, welfare and the economy. The equipment employed in the meteorological aids service (e.g., weather radars, radiosondes, and rocketsondes) provide many of these observations and continue to provide critical data used in around-the-clock weather forecasting services, flood warning, and meteorological research studies.[EN588] The collected data is shared among various Federal agencies, state and local governments, academic research programs, private weather-forecasting firms, etc. Because of national and agency-specific meteorological functions and requirements, the Federal Government is the largest user of meteorological aids equipment in the frequency bands depicted.
Of the 13 Federal Agencies that engage in meteorological activities, 10 own and operate meteorological aids equipment. These include the Departments of Commerce, Agriculture, Energy, Treasury, as well as the United States Army, Navy, Air Force, the FAA, NASA, and NSF. Over the next two decades, major emphasis in the research community will be on climate and global changes and the operational meteorological community will have responsibilities in providing most of the observations.[EN589]
Radiosondes and their associated tracking and receiving stations are used in the meteorological aids service for the determination of atmospheric conditions.[EN590] The NWS operates approximately 93 radiosonde stations in the US&P as well as a large number of cooperative stations throughout the Western Hemisphere. Rocketsondes also provide atmospheric readings and are the only means of obtaining adequate data from 25-60 kilometers into the atmosphere for stratospheric monitoring and global warming assessments.[EN591] Both provide accurate readings and are used often to calibrate meteorological satellite readings. The three largest users of these systems are the NWS, the Army, and the Department of Energy.
NOAA currently collects water level data using the Next Generation Water Level Measurement System. This data is collected primarily via the existing GOES Data Collection Platform (DCP) network operating near 402 MHz. Additionally, NOAA operates a network of DCP's aboard ships of opportunity to collect sea surface and subsurface temperatures, with the data being transmitted back via GOES or other meteorological satellites operated by cooperating nations.
The NWS, USAF and FAA are the Federal Agencies having the largest number of ground weather radars. Both the NWS and the FAA operate weather radars in the frequency bands 2700-2900 MHz and 5400-5600 MHz. In addition to these two bands, the USAF also operates weather radars in the 9300-9400 MHz band. The newest weather radar is the WSR-88D, commonly referred to as the Next Generation Radar (NEXRAD), and is the second-generation Doppler, meteorological radar replacing the non-Doppler meteorological radars of the NWS and USAF operating in the 2700-2900 MHz band. The introduction of the NEXRAD radar presented a problem in those areas where the band is heavily used. Consequently, the NEXRAD radar was accommodated in an adjacent band, 2900-3000 MHz, to provide frequency supportability. The United States adopted Footnote US316 to the allocation table that allocated the band 2900-3000 MHz on a primary basis to the meteorological aids service.[EN592] The FAA used technology developed during the NEXRAD program to develop its Terminal Doppler Weather Radar (TDWR). The TDWR operates on a single channel in the 5600-5650 MHz band and serves the immediate vicinity of airport terminal areas to provide warning of wind shear and other weather conditions hazardous to aviation.[EN593]
Unattended remote sensors, while requiring large capital investments, offer low cost per sounding. Large numbers of these can be deployed in networks to obtain needed observations with the frequency, accuracy, and vertical resolution needed to predict severe weather. Of all the promising technologies currently available, wind profiler Doppler radars are the most advanced.[EN594] Propagation characteristics of the atmosphere require that the wind profilers operate in the range 50-1000 MHz. Currently, there are three frequency ranges of particular interest: around 50 MHz, 200-500 MHz, and 1000 MHz, each of which best accommodates a particular application. Most of wind profiler operations to date have been conducted at research facilities for experimental purposes. The concern with wind profilers is the selection of appropriate frequencies for long-term operation, both nationally and internationally. Nationally, the majority of effort has focused around the 200-500 MHz range since NOAA plans to establish a national network. Within this range, the frequency 449 MHz has been authorized for Federal wind profilers. Internationally, papers concerning wind profiler operations have been presented in various scientific fora such as the ITU's Radiocommunication Sector (formerly the CCIR). As a result, the ITU established ITU-R Task Group 8/2 to identify suitable frequency bands for wind profilers.
Non-Federal usage of the meteorological aids bands is in the 400.15-406 MHz and 9300-9500 MHz bands; however, many licensees also use the 5350-5600 MHz band on a non-interference basis. State and local governments primarily use the 400.15-406 MHz band for hydrologic data collection, fire weather forecasting, and water runoff predictions, with the data sent back and collected via the GOES satellite. Many colleges and universities perform research in the areas of carbon monoxide studies and global atmospheric assessments. Many meteorological weather radars operate in the 5350-5600 MHz and 9300-9500 MHz bands and are owned and operated by state and local governments, private weather forecasting businesses, utility companies, Cable television companies, broadcast stations, college/universities, etc.[EN595]
NOAA noted that weather radars and radiosondes are "traditional" methods for the collection of weather observations where spectrum has been set aside for in the United States and throughout the world. Meteorological and hydrologic data collection via the GOES data collection platforms will continue unabated into the foreseeable future.[EN596] The FAA in their comments noted that the NEXRAD radars have added to the congestion in the 2700-2900 MHz bands in many geographic areas of the United States.[EN597] Further, the FAA noted that they plan to implement the full NEXRAD system in the 2900-3000 MHz and 3500-3700 MHz bands when frequencies become unavailable in the 2700-2900 MHz band.[EN598] NOAA stated that both the NEXRAD and the wind profiler required the allocation of new spectrum to support them. In both cases, the impact is minor: the NEXRAD requires shared access to an adjacent radar band in those few areas where its primary band is crowded and the wind profiler can be accommodated in 2 MHz in the upper end of a 30 MHz wide military radar band. NOAA further noted that in both cases, NTIA and NOAA have worked carefully to protect systems operating in these shared bands.[EN599]
Meteorological aids equipment will continue to provide necessary meteorological observations in support of Federal agencies' plans and programs, and to support meteorological research initiatives through the year 2000 and beyond. Their importance in providing for national safety, welfare, and the economy is well documented. As new meteorological aids systems are fielded, attempts to provide for frequency supportability via sharing techniques will be made. We believe the spectrum allocated for the meteorological aids service appears adequate for the foreseeable future.