Automatic Transmitter Identification System
Encyclopedia
The Automatic Transmitter Identification System (ATIS) is a communications protocol
used for the station identification
of television channel
s carried on satellite TV.
ATIS is only required for analog TV transmission and only via satellites or earth station
s under United States
jurisdiction. It is continuously repeated whilst an earth station is using a transponder
on a satellite. The Federal Communications Commission
(FCC) rules for ATIS are set forth in 47 CFR
§25.281.
ATIS is a Morse code
transmission sent on a subcarrier
of 7.1 MHz and must activate automatically any time the station is transmitting. The center frequency
must be no more than 25 kHz from this nominal value and the frequency deviation
must be no more than 25 kHz peak when being modulated
. Injection must be at a minimum of −26dB
referenced to the unmodulated carrier. The tone
used to modulate the subcarrier is nominally 1200 Hz, but may vary by as much as 800 Hz (400 to 2000 Hz).
The ATIS message is sent at a transmission rate of 15 to 25 words per minute
and must not exceed 30 seconds in its entire length. The message includes the FCC-assigned callsign of the earth station, its telephone number
, a ten-digit random number
which acts as its serial number
, and sometimes other information which is voluntary. The telephone number must immediately connect to personnel who can resolve radio interference and other frequency coordination
issues. The serial number cannot be easily changed.
ATIS encoders must be included in the uplink
airchain
of all transmitters as of March 1, 1991 "in a method that cannot easily be defeated".
Other subcarriers piggybacked on the video
carrier are also included in transmissions, often at 6.2 MHz and 6.8 MHz, just above the bandpass of the video signal (even if scrambled). These carry left and right stereo audio and second audio program
, and sometimes radio station
s or radio network
s which may be unrelated to the TV network. Backhauls are too intermittent for such uses but may carry in-house private audio channels instead. Because all of these, including ATIS, are all audio, they can all be tuned by an analog TVRO receiver
. However, digital TV has overtaken analog because multiple channels can be transmitted on one transponder. These signals carry their station ID as data
instead.
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
used for the station identification
Station identification
Station identification is the practice of radio or television stations or networks identifying themselves on air, typically by means of a call sign or brand name...
of television channel
Television channel
A television channel is a physical or virtual channel over which a television station or television network is distributed. For example, in North America, "channel 2" refers to the broadcast or cable band of 54 to 60 MHz, with carrier frequencies of 55.25 MHz for NTSC analog video and...
s carried on satellite TV.
ATIS is only required for analog TV transmission and only via satellites or earth station
Earth station
A ground station, earth station, or earth terminal is a terrestrial terminal station designed for extraplanetary telecommunication with spacecraft, and/or reception of radio waves from an astronomical radio source. Ground stations are located either on the surface of the Earth, or within Earth's...
s under United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
jurisdiction. It is continuously repeated whilst an earth station is using a transponder
Transponder
In telecommunication, the term transponder has the following meanings:...
on a satellite. 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...
(FCC) rules for ATIS are set forth in 47 CFR
Code of Federal Regulations
The Code of Federal Regulations is the codification of the general and permanent rules and regulations published in the Federal Register by the executive departments and agencies of the Federal Government of the United States.The CFR is published by the Office of the Federal Register, an agency...
§25.281.
ATIS is a Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
transmission sent on a subcarrier
Subcarrier
A subcarrier is a separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. More technically, it is an already-modulated signal, which is then modulated into another signal of higher frequency and bandwidth...
of 7.1 MHz and must activate automatically any time the station is transmitting. The center frequency
Center frequency
In electrical engineering and telecommunications, the center frequency of a filter or channel is a measure of a central frequency between the upper and lower cutoff frequencies...
must be no more than 25 kHz from this nominal value and the frequency deviation
Frequency deviation
Frequency deviation is used in FM radio to describe the maximum instantaneous difference between an FM modulated frequency and the nominal carrier frequency...
must be no more than 25 kHz peak when being modulated
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
. Injection must be at a minimum of −26dB
Decibel
The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...
referenced to the unmodulated carrier. The tone
Pure tone
A pure tone is a tone with a sinusoidal waveshape.A sine wave is characterized by its frequency, the number of cycles per second—or its wavelength, the distance the waveform travels through its medium within a period—and the amplitude, the size of each cycle...
used to modulate the subcarrier is nominally 1200 Hz, but may vary by as much as 800 Hz (400 to 2000 Hz).
The ATIS message is sent at a transmission rate of 15 to 25 words per minute
Words per minute
Words per minute, commonly abbreviated wpm, is a measure of input or output speed.For the purposes of WPM measurement a word is standardized to five characters or keystrokes. For instance, "I run" counts as one word, but "rhinoceros" counts as two...
and must not exceed 30 seconds in its entire length. The message includes the FCC-assigned callsign of the earth station, its telephone number
Telephone number
A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...
, a ten-digit random number
Random number
Random number may refer to:* A number generated for or part of a set exhibiting statistical randomness.* A random sequence obtained from a stochastic process.* An algorithmically random sequence in algorithmic information theory....
which acts as its serial number
Serial number
A serial number is a unique number assigned for identification which varies from its successor or predecessor by a fixed discrete integer value...
, and sometimes other information which is voluntary. The telephone number must immediately connect to personnel who can resolve radio interference and other frequency coordination
Frequency coordination
Frequency Coordination is a technical and regulatory process which is intended to remove or mitigate radio-frequency interference between different radio systems which utilize the same operational frequency....
issues. The serial number cannot be easily changed.
ATIS encoders must be included in the uplink
Uplink
A telecommunications link is generally one of several types of information transmission paths such as those provided by communication satellites to connect two points on earth.-Uplink:...
airchain
Airchain
In broadcast engineering for radio or television, the airchain or transmission chain is the path or route an audio or video signal takes on its way through a radio station or television station.The airchain begins with cameras, microphones, CD players, turntables, telephone hybrids, video tape...
of all transmitters as of March 1, 1991 "in a method that cannot easily be defeated".
Other subcarriers piggybacked on the video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
carrier are also included in transmissions, often at 6.2 MHz and 6.8 MHz, just above the bandpass of the video signal (even if scrambled). These carry left and right stereo audio and second audio program
Second audio program
Second audio program , also known as secondary audio programming, is an auxiliary audio channel for analog television that can be broadcast or transmitted both over the air and by cable TV.-Usage:...
, and sometimes radio station
Radio station
Radio broadcasting is a one-way wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both...
s or radio network
Radio network
There are two types of radio networks currently in use around the world: the one-to-many broadcast type commonly used for public information and mass media entertainment; and the two-way type used more commonly for public safety and public services such as police, fire, taxicabs, and delivery...
s which may be unrelated to the TV network. Backhauls are too intermittent for such uses but may carry in-house private audio channels instead. Because all of these, including ATIS, are all audio, they can all be tuned by an analog TVRO receiver
Receiver (radio)
A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...
. However, digital TV has overtaken analog because multiple channels can be transmitted on one transponder. These signals carry their station ID as data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
instead.