Air-ground radiotelephone service
Encyclopedia
Air-ground radiotelephone service is a method of telephone
communications used by aircraft
pilots and passengers of commercial airline jets
flying over the United States
.
The air-ground radiotelephone service operates on frequencies
designated
by the Federal Communications Commission
.
signal in the 849 to 851 megahertz
range; this signal is sent to either a receiving ground station or a communications satellite
depending on the design of the particular system. If it is a call from a commercial airline passenger radiotelephone, the call is then forwarded to a verification center to process credit card
or calling card information. The verification center will then route the call to the Public Switched Telephone Network
, which completes the call. For the return signal, ground stations and satellites use a radio signal in the 894 to 896 megahertz range.
, was originally reserved for "general" aviation
use (non-airliners) and the 800 MHz range, primarily used for airliner telephone service, which has shown limited acceptance by passengers. AT&T
abandoned its 800 MHz air-ground offering in 2005, and Verizon
AIRFONE (formerly GTE Airfone) is scheduled for decommissioning in late 2008, although the FCC has re-auctioned Verizon's spectrum
(see below). Skytel, which had the third nationwide 800 MHz license, elected not to build it, but continued to operate in the 450 MHz AGRAS
system. Its AGRAS license and operating network was recently sold to Bell Industries (April 2007).
The 450 MHz General Aviation network is administered by Mid-America Computer Corporation in Blair, Nebraska
, which has called the service AGRAS, and requires the use of instruments manufactured by Terra and Chelton Aviation/Wulfsberg Electronics, and marketed as the Flitephone VI Series. Activating or reactivating an existing Flitefone instrument can be accomplished by calling 800-552-4727.
In the 800 MHz band, the FCC defined 10 blocks of paired uplink/downlink narrowband
ranges (6 kHz
) and six control ranges (3.2 kHz). Six carriers were licensed to offer in-flight telephony, each being granted non-exclusive use of the 10 blocks and exclusive use of a control block. Of the six, only three commenced operations, and only one persisted into the 1990s, now known as Verizon Airfone
.
AirFone commenced its service in the early 1980s starting with first-class under experimental licenses; the FCC's formal allocation was in 1990. AirFone handsets were gradually extended to include one unit in each row of seats in economy. The service was always priced extremely high--$3.99 per call and $4.99 per minute in 2006--and has seen less and less use as the ready availability of cellular telephones has increased. In an FCC filing in 2005, the agency noted that 4,500 aircraft have AirFone service, and quoted Verizon AirFone's president stating in a New York Times article that only two to three people per flight make a call.
Verizon added stock tickers and limited information services, but those had little use. In 2003, Verizon partnered with Tenzing Communications
to offer very low-speed email using an on-board proxy server
and limited live instant messaging at rates of 64 to 128 kbit/s on United Airlines
and two other carriers. This service lasted about a year. (Tenzing was merged into a new entity called OnAir
along with investment from Airbus
and SITA
, an airline-owned systems integrator. OnAir will launch satellite-based broadband service in 2006.)
On May 10, 2006, the FCC began Auction 65, which sold off the 4 MHz of spectrum over which radiotelephone calls were made, and required AirFone to revise its equipment within two years of the auction's conclusion on June 2, 2006. Instead of the narrowband approach, with dedicated uplink and downlink for each call, Verizon is required to move its operations to a 1 MHz slice which is expected to provide substantially higher call volume and quality.
AirFone received a non-renewable license to share that 1 MHz until 2010 using vertical polarization with the winner of License D in Auction 65, LiveTV
, a division of the airline JetBlue, which had not announced its plans at the end of the auction. A more broadband-oriented 3 MHz license (License C) was won by AC BidCo, LLC, a sister company of Aircell
. Aircell will deploy in-flight broadband using this license. (License C includes 849.0-850.5 MHz and 894.0-895.5 MHz; License D includes 850.5-851.0 MHz and 895.5-896.0 MHz.)
An interim approach by Aircell was to utilize the existing ground-based cellular network, with highly directional antennas beamed upward. Although initially successful, the widespread conversion to GSM and spread-spectrum by carriers (not all carriers participated) made obsolete the early generation Aircell instruments. Some units were exchanged for satellite-based Iridium equipment, but Aircell's recent acquisition of three MHz of the 800 MHz spectrum at auction at the FCC, will undoubtedly lead to a new generation of products.
Only the 450 MHz AGRAS network continues to operate in its original configuration.
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
communications used by aircraft
Fixed-wing aircraft
A fixed-wing aircraft is an aircraft capable of flight using wings that generate lift due to the vehicle's forward airspeed. Fixed-wing aircraft are distinct from rotary-wing aircraft in which wings rotate about a fixed mast and ornithopters in which lift is generated by flapping wings.A powered...
pilots and passengers of commercial airline jets
Jet aircraft
A jet aircraft is an aircraft propelled by jet engines. Jet aircraft generally fly much faster than propeller-powered aircraft and at higher altitudes – as high as . At these altitudes, jet engines achieve maximum efficiency over long distances. The engines in propeller-powered aircraft...
flying over the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
The air-ground radiotelephone service operates on frequencies
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
designated
Frequency assignment authority
In telecommunication, frequency assignment authority is the power granted an administration, or its designated or delegated leader or agency via treaty or law, to specify frequencies, or frequency bands, in the electromagnetic spectrum for use in systems or equipment.International frequency...
by the Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
.
Design
A U.S. air-ground radiotelephone transmits a radioRadio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
signal in the 849 to 851 megahertz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
range; this signal is sent to either a receiving ground station or a communications satellite
Communications satellite
A communications satellite is an artificial satellite stationed in space for the purpose of telecommunications...
depending on the design of the particular system. If it is a call from a commercial airline passenger radiotelephone, the call is then forwarded to a verification center to process credit card
Credit card
A credit card is a small plastic card issued to users as a system of payment. It allows its holder to buy goods and services based on the holder's promise to pay for these goods and services...
or calling card information. The verification center will then route the call to the Public Switched Telephone Network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
, which completes the call. For the return signal, ground stations and satellites use a radio signal in the 894 to 896 megahertz range.
Frequencies
Two separate frequency bands have been allocated by the FCC for air-ground telephone service. One at 454/459 MHzHertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
, was originally reserved for "general" aviation
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...
use (non-airliners) and the 800 MHz range, primarily used for airliner telephone service, which has shown limited acceptance by passengers. AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
abandoned its 800 MHz air-ground offering in 2005, and Verizon
Verizon Communications
Verizon Communications Inc. is a global broadband and telecommunications company and a component of the Dow Jones Industrial Average...
AIRFONE (formerly GTE Airfone) is scheduled for decommissioning in late 2008, although the FCC has re-auctioned Verizon's spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
(see below). Skytel, which had the third nationwide 800 MHz license, elected not to build it, but continued to operate in the 450 MHz AGRAS
Agras
Agras is a surname. People with this surname include:* William Stewart Agras, American psychologist* Tellos Agras , an officer of the Hellenic Army who played a prominent role during the Greek Struggle for Macedonia-See also:...
system. Its AGRAS license and operating network was recently sold to Bell Industries (April 2007).
The 450 MHz General Aviation network is administered by Mid-America Computer Corporation in Blair, Nebraska
Blair, Nebraska
Blair is a city in and the county seat of Washington County, Nebraska, United States. The population was 7,990 at the 2000 census. Blair is a part of the Omaha-Council Bluffs Metropolitan Statistical Area.- History :...
, which has called the service AGRAS, and requires the use of instruments manufactured by Terra and Chelton Aviation/Wulfsberg Electronics, and marketed as the Flitephone VI Series. Activating or reactivating an existing Flitefone instrument can be accomplished by calling 800-552-4727.
In the 800 MHz band, the FCC defined 10 blocks of paired uplink/downlink narrowband
Narrowband
In radio, narrowband describes a channel in which the bandwidth of the message does not significantly exceed the channel's coherence bandwidth. It is a common misconception that narrowband refers to a channel which occupies only a "small" amount of space on the radio spectrum.The opposite of...
ranges (6 kHz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
) and six control ranges (3.2 kHz). Six carriers were licensed to offer in-flight telephony, each being granted non-exclusive use of the 10 blocks and exclusive use of a control block. Of the six, only three commenced operations, and only one persisted into the 1990s, now known as Verizon Airfone
Airfone
Airfone is a brand of air-ground radiotelephone service offered by Verizon. Airfone allows passengers to make telephone calls in-flight. It was originated by John D. Goeken in the 1970s. Western Union purchased a fifty percent share in Airfone in 1981 and sold to GTE in 1986 for $39 million cash...
.
History
The first recorded air-to-ground radiotelephone service on a scheduled flight was om 1937 on the Chicago-Seattle route by Northwestern Airlines.AirFone commenced its service in the early 1980s starting with first-class under experimental licenses; the FCC's formal allocation was in 1990. AirFone handsets were gradually extended to include one unit in each row of seats in economy. The service was always priced extremely high--$3.99 per call and $4.99 per minute in 2006--and has seen less and less use as the ready availability of cellular telephones has increased. In an FCC filing in 2005, the agency noted that 4,500 aircraft have AirFone service, and quoted Verizon AirFone's president stating in a New York Times article that only two to three people per flight make a call.
Verizon added stock tickers and limited information services, but those had little use. In 2003, Verizon partnered with Tenzing Communications
Tenzing Communications
Tenzing Communications of Seattle was founded in 1999 by software developer Simon "Symonty" Gresham, with the backing of Airbus.The firm had intended to launch in-flight data services, including text messaging, instant messaging, and email using broadband satellite receivers using Inmarsat's...
to offer very low-speed email using an on-board proxy server
Proxy server
In computer networks, a proxy server is a server that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource available from a different server...
and limited live instant messaging at rates of 64 to 128 kbit/s on United Airlines
United Airlines
United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees (which includes the entire holding company United Continental...
and two other carriers. This service lasted about a year. (Tenzing was merged into a new entity called OnAir
OnAir
Incorporated in February 2005, OnAir is a joint venture with SITA and Airbus. OnAir is headquartered in Geneva, Switzerland, and has operations in Seattle and Montreal and sales offices in London, Kuala Lumpur and Dubai....
along with investment from Airbus
Airbus
Airbus SAS is an aircraft manufacturing subsidiary of EADS, a European aerospace company. Based in Blagnac, France, surburb of Toulouse, and with significant activity across Europe, the company produces around half of the world's jet airliners....
and SITA
SITA
SITA is a multinational information technology company specialising in providing IT and telecommunication services to the air transport industry...
, an airline-owned systems integrator. OnAir will launch satellite-based broadband service in 2006.)
On May 10, 2006, the FCC began Auction 65, which sold off the 4 MHz of spectrum over which radiotelephone calls were made, and required AirFone to revise its equipment within two years of the auction's conclusion on June 2, 2006. Instead of the narrowband approach, with dedicated uplink and downlink for each call, Verizon is required to move its operations to a 1 MHz slice which is expected to provide substantially higher call volume and quality.
AirFone received a non-renewable license to share that 1 MHz until 2010 using vertical polarization with the winner of License D in Auction 65, LiveTV
LiveTV
LiveTV is a major provider of airline in-flight entertainment systems. Originally a joint venture of Harris Corporation and BE Aerospace , it is now a wholly owned subsidiary of JetBlue Airways Corporation...
, a division of the airline JetBlue, which had not announced its plans at the end of the auction. A more broadband-oriented 3 MHz license (License C) was won by AC BidCo, LLC, a sister company of Aircell
Aircell
Aircell is a private company started in 1991 developing broadband for both private and commercial aviation. Aircell is the only company in the United States authorized by the Federal Communications Commission and Federal Aviation Administration to use frequencies in the 800 MHz band for...
. Aircell will deploy in-flight broadband using this license. (License C includes 849.0-850.5 MHz and 894.0-895.5 MHz; License D includes 850.5-851.0 MHz and 895.5-896.0 MHz.)
An interim approach by Aircell was to utilize the existing ground-based cellular network, with highly directional antennas beamed upward. Although initially successful, the widespread conversion to GSM and spread-spectrum by carriers (not all carriers participated) made obsolete the early generation Aircell instruments. Some units were exchanged for satellite-based Iridium equipment, but Aircell's recent acquisition of three MHz of the 800 MHz spectrum at auction at the FCC, will undoubtedly lead to a new generation of products.
Only the 450 MHz AGRAS network continues to operate in its original configuration.
External links
- FCC Order for terms of changing 800 MHz Air-Ground Radiotelephone Service (2005)
- FCC Auction 65 details for 800 MHz Air-Ground Radiotelephone Service in May 2006
- Aircell home page
- Verizon AirFone's president's estimate of calls per flight
- FLITEFONE-VI AIR-GROUND TELEPHONE NETWORK
- Verizon Notice re: 800 MHz Magnastar service temporary extension (2007)