A broadcast auxiliary service (BAS) is any

radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the u ...

system used by a

radio station Radio broadcasting is the broadcasting of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based rad ...

TV station A television station is a set of equipment managed by a business, organisation or other entity such as an amateur television (ATV) operator, that transmits video content and audio content via radio waves directly from a transmitter on the earth's ...

, which is not part of its direct

broadcast Broadcasting is the data distribution, distribution of sound, audio audiovisual content to dispersed audiences via a electronic medium (communication), mass communications medium, typically one using the electromagnetic spectrum (radio waves), ...

to listeners or viewers. These are essentially internal-use backhaul channels not intended for actual reception by the public, but part of the

airchain In broadcast engineering for radio or television, the airchain or transmission chain (UK) (sometimes air chain (US) or just chain (UK)) is the path or route an audio or video signal takes on its way through a radio station or television station. ...

required to get those signals back to the broadcast studio from the field. usually to be integrated into a live production. Examples include: *

studio/transmitter link A studio transmitter link (STL) sends a radio station's or television station's audio and video from the broadcast studio or origination facility to a radio transmitter, television transmitter or uplink facility in another location. This is accom ...

(STL) * transmitter/studio link (TSL) *

remote pickup unit A remote pickup unit or RPU is a radio system using special radio frequencies set aside for electronic news-gathering (ENG) and remote broadcasting. It can also be used for other types of point-to-point radio links. An RPU is used to send prog ...

(RPU) *

electronic news gathering Electronic news gathering (ENG) or electronic journalism (EJ) is usage of electronic video and audio technologies by reporters to gather and present news instead of using film cameras. The term was coined during the rise of videotape techno ...

(ENG) Several of these bands exist, but the most frequently used band is the 2 GHz

microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...

BAS band for point-to-point transmission from mobile newsgathering units to mountaintop receivers. Seven 12-MHz wide channels exist in the band. In North America,

DVB-T DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in Fe ...

, precisely the same modulation technique as European Broadcast, is used, using a constellation of

QPSK Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency carrier wave. The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is ...

, 16QAM, or 64QAM, enabling sufficient digital bandwidths at 6 MHz deviation for transmission of an

MPEG The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by International Organization for Standardization, ISO and International Electrotechnical Commission, IEC that sets standards for media coding, includ ...

transport stream at 10 or more megabits per second, producing three "lower", "center", and "upper" overlapping 6 MHz channels within each 12 MHz channel. BAS-2018

2 GHz relocation

In the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

between 2005 and 2010, the

Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, satellite, and cable across the United States. The FCC maintains j ...

(FCC) moved TV channels in the 2 GHz TV BAS band at the request of

Sprint Nextel Sprint Corporation was an American telecommunications company. Before being Merger of Sprint Corporation and T-Mobile US, acquired by T-Mobile US on April 1, 2020, it was the fourth-largest mobile network operator in the United States, serving 5 ...

, so that it could use a portion which was adjacent to PCS frequencies it already uses. The report and order resulting from this

rulemaking In administrative law, rulemaking is the process that executive and independent agencies use to create, or ''promulgate'', regulations. In general, legislatures first set broad policy mandates by passing statutes, then agencies create more de ...

specified that Sprint/Nextel must pay for every TV station using the band to buy and install new BAS equipment to work in the new band structure. Previously, there had been seven analog TV channels, each 17 or 18 MHz wide, between 1990 and 2110 MHz. The new allocation created seven

digital TV Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative adv ...

channels, each 12 MHz wide, from 2025.5 to 2109.5 MHz. (There was also a "narrowed in place" bandplan used as an interim measure, as the two bands overlap.)
Begun in 2005, the relocation was 94% complete as of October 2008, and was expected to be fully complete in mid 2009. After multiple extensions granted by the FCC, it was finally done in July 2010, with the completion of the

Anchorage Anchorage, officially the Municipality of Anchorage, is the most populous city in the U.S. state of Alaska. With a population of 291,247 at the 2020 census, it contains nearly 40 percent of the state's population. The Anchorage metropolita ...

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

TV market. The cleared band is now used for PCS, AWS, and MSS services, including

mobile broadband Mobile broadband is the marketing term for Wireless broadband, wireless Internet access via mobile network, mobile (cell) networks. Access to the network can be made through a portable modem, wireless modem, or a Tablet computer, tablet/smartp ...

External links

''Broadcast Engineering'' article on completion''TV Technology'' article on completion, with insider details
Broadcast engineering {{bcast-stub