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Multiple Address System (MAS)
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According to the FCC, MAS is defined as "a point-to-multipoint or point-to-point radio communications system used for either one-way or two-way transmissions that operates in the 928/952/956 MHz, the 928/959 MHz or the 932/941 MHz bands" in accordance with section 101.147 of the FCC's rules. Specific rules for MAS are in Subpart O of Part 101.
Limited mobile operations are permitted under MAS, per 101.1307.
According to frequency coordinator Micronet, MAS are "point-to multipoint microwave systems that provide corporations and other institutions with the ability to support their dedicated operations."
Details of the MAS service were established in a 1999 FCC Report and Order (FCC 99-415), which took the following actions:
- Designate the 928/952/956 MHz bands exclusively for private internal services, licensed on a site-by-site basis.
- License the 928/959 MHz bands on a geographic area basis.
- License twenty of the forty paired channels in the 932/941 MHz bands on a geographic area basis.
- Reserve twenty of the forty channel pairs in the 932/941 MHz bands for public safety/Federal Government and private internal services, licensed on a first-come, first-served, site-by-site basis. Designate five of the twenty channels in the 932/941 MHz bands' set-aside exclusively for public safety/Federal Government services.
- Grandfather existing operations on the MAS bands and restrict expansion in the 928/959 MHz bands.
- Establish service areas based on the Federal Communications Commission's definition of Economic Areas (EAs) and on the U.S. Department of Commerce's definition of EAs.
- Establish construction/coverage requirements for EA licensees -- specifically, coverage to at least one-fifth of the population in their service areas or substantial service within five years of the license grant -- and a showing of substantial service within ten years of being licensed.
- Introduce flexibility to the MAS technical rules.
- Allow licensees to provide mobile and fixed operations on a co-primary basis for point-to-point and point-to-multipoint operations.
- Adopt a flexible approach for defining the regulatory status of MAS licensees by allowing the licensee to indicate its regulatory status.
- Lift the suspension on the acceptance of applications for the 928/952/956 MHz bands and the twenty channels in the 932/941 MHz bands designated for public safety/Federal Government and/or private internal services upon the release of this Report and Order.
- Adopt Part 1 competitive bidding rules for MAS spectrum.
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Frequency Bands |
Band | Use | Service | Table |
928 - 929 MHz | Multiple Address System | Fixed | N |
932 - 932.5 MHz | Multiple Address System | Fixed | N |
941 - 941.5 MHz | Multiple Address System | Fixed | N |
952 - 960 MHz | Multiple Address System | Fixed | N |
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Distance Measuring Equipment (DME)
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According to NTIA:
DME and TACAN are very similar in their functional performance. DME systems operate between the bands 962-1213 MHz and are usually co-located with a very high frequency (VHF) Omni-directional Range (VOR) operating in the band 108-118 MHz to provide the distance and azimuth from the aircraft to the DME transmitter. An important requirement is a frequency separation of 63 MHz between the interrogation and the reply frequency. This accommodates the pulse-pair shaping and signal processing bandwidth necessary to achieve individual system integrity. This procedure leaves only 126 possible frequency pairs throughout the band 962-1213 MHz. DME and VOR operate in paired channels so at any given location, both the VOR and DME proposed assignments must “pass” their channel planning criteria. This puts additional constraints on DME assignments.
DME allows aircraft to fly safe, accurate paths during the en-route, terminal, landing, missed approach and departure phases of flight. The system provides aircraft pilots with the slant range to a ground-based transponder station. The ground-based transponder system is air-initiated, with the airborne transmitter interrogating a transponder, and calculating range from the time difference between the initiation of the interrogation and receipt of the reply. The maximum range for high altitude service (18km) is 240 km and for low altitude, service (5.5 km) the distance is 74 km. The maximum range for the standard terminal service is 46 km for an altitude of 3.7 km.
TACAN is a tactical air navigation system for the military services used ashore, afloat, and airborne. TACAN is primarily collocated with the civil VOR stations (VORTAC facilities) to enable military aircraft to operate in the NAS and to provide DME information to civil users. The Navy, Coast Guard, and Military Sealift Command (MSC) operate several hundred sea-based TACAN stations.
The FAA operates approximately 60 VOR, 405 VOR/DME, and 590 VORTAC ground stations, as well as another 30 DMEs. Other Federal agencies, state and local governments, and private entities also own some of these facilities.
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Frequency Bands |
Band | Use | Service | Table |
960 - 1215 MHz | Distance Measuring Equipment (DME) | Aeronautical Radionavigation | F |
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