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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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Airport Surveillance Radar (ASR-11)
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According to the FAA:
Airport Surveillance Radar (ASR-11) is an integrated primary and secondary radar system that has been deployed at terminal air traffic control sites. It interfaces with both legacy and digital automation systems and provides six-level national weather service calibrated weather capability that provides enhanced situational awareness for both controllers and pilots.
The primary surveillance radar uses a continually rotating antenna mounted on a tower to transmit electromagnetic waves that reflect, or backscatter, from the surface of aircraft up to 60 nautical miles from the radar. The radar system measures the time required for radar to echo to return and the direction of the signal. From this, the system can then measure the distance of the aircraft from the radar antenna and the azimuth, or direction, of the aircraft in relation to the antenna. The primary radar also provides data on six levels of rainfall intensity and operates in the range of 2700 to 2900 MHz. The transmitter generates a peak effective power of 25 kW and an average power of 2.1 kW. The average power density of the ASR-11 signal decreases with distance from the antenna. At distances of more than 43 feet from the antenna, the power density of the ASR-11 signal falls below the maximum permissible exposure levels established by the Federal Communications Commission (FCC).
The secondary surveillance radar uses a second radar beacon antenna attached to the top of the primary radar antenna to transmit and receive area aircraft data for barometric altitude, identification code, and emergency conditions. Military, commercial, and some general aviation aircraft have transponders that automatically respond to a signal from the secondary radar by reporting an identification code and altitude. The air traffic control centers uses this system data to verify the location of aircraft within a 60-mile radius of the radar site. The secondary radar also provides rapid identification of aircraft in distress. The secondary radar operates in the range of 1030 to 1090 MHz. Transmitting power ranges from 160 to 1500 watts.
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Frequency Bands |
| Band | Use | Service | Table |
| 1030 - 1090 MHz | Airport Surveillance Radar (ASR-11) secondary radar band | Aeronautical Radionavigation | F |
| 2700 - 2900 MHz | Airport Surveillance Radar (ASR-11) primary radar band | Aeronautical Radionavigation | F |
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