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SpectrumWiki.com is an aggregate of information about the radio spectrum and its many uses. On a band-by-band basis, SpectrumWiki.com contains:

Allocations
Pertinent regulatory footnotes
FCC rule parts
U.S. spectrum auction revenue
Engineering data

Additional information about the radio spectrum is contributed on a crowd-sourced basis through a wiki environment, including:

Spectrum usage (systems and applications)
Regulatory and legislative actions
Band plans
Spectrum measurements
Historical data

and more. Please see below for more information about contributing to SpectrumWiki.

Latest Wiki Entries

Here are a few of the latest new and modified entries in SpectrumWiki:

NASA Differential GPS (NTIA)

NASA uses this band to provide differential Global Positioning System (GPS) for mission support, and equipment calibration. The systems operate at Edwards AFB, CA; White Sands Space Harbor, NM; and at the Kennedy Space Center, FL. (Information extracted from the NTIA Federal Government Spectrum Use Reports, dated December 1, 2015)

Frequency Bands
Band	Use	Service	Table
328.6 - 335.4 MHz	NASA Differential GPS (CA, NM, FL)	-	F

External Links:

NTIA Spectrum Use Summary 328.6-335.4 MHz

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Federal Search and Rescue Communications on 243 MHz (NTIA)

The footnotes 5.111, 5.199, and 5.256 were adopted by the International Telecommunication Union and are incorporated into the U.S. Table of Frequency Allocations. Among other things, these footnotes provide for the use of the 243 MHz frequency for search and rescue purposes. The frequency 243 MHz is used on the radios onboard most Federal aircraft as a special channel, called a "guard" channel that is used for distress and safety purposes, including search and rescue. The 243 MHz channel is always activated on aircraft and ground systems even though another channel may be in use on a transceiver operating in the band. For example, a military aircraft in distress could make an emergency distress call for assistance on 243 MHz, and all other aircraft or ground stations in the area would hear it immediately and take action. In general, the band 225-328.6 MHz is reserved for military uses by North Atlantic Treaty Organization (NATO), its member nations, and other U.S. allies. The band is harmonized among NATO-member nations for secure communications. (Information extracted from the NTIA Federal Government Spectrum Use Reports, dated December 1, 2015)

Frequencies
Frequency	Bandwidth	Use	Service	Table
243 MHz	25 kHz	Federal Search and Rescue	Mobile	F

External Links:

NTIA Spectrum Use Summary 225.0-328.6 MHz

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Area Common User System (ACUS) (NTIA)

The military agencies use the band 225-328.6 MHz for tactical and non-tactical land mobile and fixed service point-to-point communications. The most extensive use is by the Army's Area Common User System (ACUS), consisting of both land mobile and fixed communications systems. The mobile version uses mobile subscriber equipment (MSE) that functions like a cellular communications network, capable of providing communications to many users. The fixed communications part of the ACUS is a high capacity line-of-sight point-to-point radio system. The radio provides voice and data communications over paths up to 70 miles. The system can use various data rates, with the highest being 34 Mbps, and it has a feature that provides a spectrum scan to detect spectrum congestion to identify frequencies to maximize link availability. In general, the band 225-328.6 MHz is reserved for military uses by North Atlantic Treaty Organization (NATO), its member nations, and other U.S. allies. The band is harmonized among NATO-member nations for secure communications. (Information extracted from the NTIA Federal Government Spectrum Use Reports, dated December 1, 2015)

Frequency Bands
Band	Use	Service	Table
225 - 328.6 MHz	Military land mobile communications	Mobile	F
225 - 328.6 MHz	Military fixed point-to-point communications	Fixed	F

External Links:

NTIA Spectrum Use Summary 225.0-328.6 MHz

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Military Mobile-Satellite Communications (NTIA)

Satellites operating in the mobile-satellite service in this band are used by the military services and the Coast Guard. The military mobile-satellite communications networks in the band serve ships at sea, aircraft, land-based forces, and a variety of other U.S. military fixed and mobile terminals used by mobile users. The bands 225-322 MHz and 335.4- 399.9 MHz are the only bands below 7250 MHz available for Federal Government mobile-satellite communications, and the narrowband satellite links are frequently the only reliable means of communications. The military makes extensive use of the mobile-satellite service operating in this band because the electromagnetic waves can penetrate foliage, inclement weather, and urban terrain including concrete-reinforced buildings. Small antennas can be used at the earth terminals making it easy to transport the stations. There are numerous satellite earth terminals currently in use by the military, many of which are small and portable enough to be carried deep into theaters of operation. The Federal use of the band for mobile satellites was initiated in 1978 with the Navy's Fleet Satellite Communications System (FLTSATCOM), a constellation of five geostationary satellites operating in the band 235-322 MHz, channelized into the downlinks at 243.855-269.95 MHz and corresponding uplinks in the band 292.85- 317.325 MHz. The Navy began upgrading the FLTSATCOM in the 1990s with the UHF Follow-On (UFO) satellites. The UFO satellites offer increased communications channel capacity over the same frequency spectrum used by the previous FLTSATCOM systems. Each UFO satellite has 39 channels with a total 555 kHz bandwidth. The satellite payload comprises 21 narrowband channels at 5 kHz each and 17 relay channels at 25 kHz.3 These channels are used by the military agencies for tactical communications on land, ships, submarines, and aircraft. The Coast Guard also uses channels on the military satellites on some of their ships. The Department of Defense (DOD) Defense Satellite Communications System (DSCS-III) series of geostationary satellites operating in the 7- and 8- GHz bands also carry a transponder in this band called the single channel transponder (SCT) that provides communications for emergency action messages to the forces. The Military, Strategic, and Tactical Relay Satellite (MILSTAR) geostationary satellite also has mobile-satellite capability in this band, with a transponder that provides four Air Force Satellite Communications (AFSATCOM IIR) channels and a fleet broadcast channel. The Navy has launched the next generation mobile satellites, termed the Multiple User Objective System (MUOS) that use the bands 243.525-270.05 MHz and 280-320 MHz. The MUOS is undergoing testing and is not fully operational as of September, 2014. The Navy has awarded contracts for the MUOS, and overall, the MUOS will be $6.4 billion system. The MUOS enables communications to various terminal devices such as handhelds, laptops, and personal communications units. To support legacy systems, the MUOS will use a narrowband system of 64 kbps/channel and below. The MUOS will use wideband-code-division-multiple-access (WCDMA) technology, the same technology as some forms of the third generation (3G) commercial cellphone technology. The capacity is 4 Mbps per antenna beam. In general, the band 225-328.6 MHz is reserved for military uses by North Atlantic Treaty Organization (NATO), its member nations, and other U.S. allies. The band is harmonized among NATO-member nations for secure communications. (Information extracted from the NTIA Federal Government Spectrum Use Reports, dated December 1, 2015)

Frequency Bands
Band	Use	Service	Table
225 - 322 MHz	Military mobile-satellite communications	Mobile-satellite	F
335.4 - 399.9 MHz	Military mobile-satellite communications	Mobile-satellite	F

External Links:

UHF-MILSATCOM frequencies (RadioReference.com)

NTIA Spectrum Use Summary 225.0-328.6 MHz

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Military Aeronautical/ATC Communications and Telemetry (NTIA)

The military agencies, National Guard units, the Coast Guard, and the FAA are the heaviest users of the band 225-328.6 MHz, using the band for critical air-to-ground-to-air communications systems. The military agencies and National Guard units use the band 225-328.6 MHz for various types of aeronautical communications, e.g., for training flights and air-traffic-control functions such as ground control, approach control, enroute aircraft separation, and in-flight refueling services. The Air Force, Army, Navy, and the FAA have thousands of frequency assignments for air-to-ground-to-air communications in the band 225-328.6 MHz. Most of these assignments are to ground stations. The Coast Guard uses the band on its maritime search-and-rescue aircraft and other aircraft for air-to-ground-to-air communications. The military agencies, National Guard units, and the FAA make extensive use of the band 225-328.6 MHz which alleviates possible impact of the national airspace civilian air-to-ground-to-air communications operating in the bands within 117.975-137 MHz. Thus, the Federal use of the band 225-328.6 MHz for aeronautical communications plays an important part in national defense and security, and to control the nation's airspace. The band 225-328.6 MHz is also used for essential communications by a number of other agencies such as NASA, DOE, and DOC. NASA uses the band for aircraft communications, and for International Space Station (ISS) communications during Extravehicular Activity (EVA); and DOC uses the band on National Oceanographic and Atmospheric Administration (NOAA) hurricane-hunter aircraft, and on ground stations to communicate with other hurricane-hunter aircraft. The military agencies use the band 225-328.6 MHz for a major tactical communications system to provide anti-jam, secure, frequency-hopping radio communications for tactical air-to-air and air-to-ground-to-air communications. The uses include coordination and vectoring of aircraft to targets, and large scale training exercises. For example, the major radio communications systems are deployed on all rotary wing aircraft, and are used by all operational aviation units, air traffic services, and units. The radio communications system enables interoperability communications among Air Force, Navy, Army, and NATO units. The Navy makes extensive use of the band for aeronautical telemetry, and DOE also uses the band for this purpose. The Navy uses the band for flight testing of military aircraft. The military agencies also use this band for telemetry systems for rocket testing. In generall, the band 225-328.6 MHz is reserved for military uses by North Atlantic Treaty Organization (NATO), its member nations, and other U.S. allies. The band is harmonized among NATO-member nations for secure communications. (Information extracted from the NTIA Federal Government Spectrum Use Reports, dated December 1, 2015)

Frequency Bands
Band	Use	Service	Table
225 - 328.6 MHz	Military aeronautical communications and telemetry	Mobile	F

External Links:

NTIA Spectrum Use Summary 225.0-328.6 MHz

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