Glossary / Skylark field guide
The acronyms, translated.
A glossary to dip into when a guide starts assuming you already know the guide.
- 1090ES
- 1090 MHz Extended Squitter, the ADS-B link to investigate first for an Ireland-oriented receiver. Reference ↗
- 978 UAT
- Universal Access Transceiver on 978 MHz, relevant to the US receiving ecosystem. It needs suitable hardware and software. Reference ↗
- ADS-B In
- Equipment's receiving function. Different from the function that broadcasts the aircraft's own information. Reference ↗
- ADS-B Out
- The aircraft's broadcasting function. A home receive-only station listens to broadcasts; it does not install ADS-B Out in an aircraft. Reference ↗
- ADSB.im
- An image and management project for compatible receiving hardware, backed by adsb-feeder-image. Reference ↗
- ADSR
- A rebroadcast of ADS-B information from another data link. Keep it distinct from a direct reception source. Reference ↗
- Antenna gain
- Antenna performance depends on direction. Do not confuse an antenna specification with the receiver's electronic gain control. Reference ↗
- Barometric altitude
- An altitude based on pressure, not automatically a height above your terrain or garden. Preserve the producer's units and reference. Reference ↗
- Beast format
- A receiver-message transport format used by compatible decoders and clients. Use the documented port and source; a format is not authentication. Reference ↗
- Callsign
- An identification field, not necessarily a complete commercial flight-number or route record. Reference ↗
- Coax
- Coaxial cable between radio-frequency components. Use attenuation specified for the actual frequency and length when estimating loss.
- dB
- A logarithmic ratio. For power, a loss of L decibels leaves a fraction 10 to the power of minus L divided by 10.
- dBFS
- A signal level relative to full scale in the digital receiver. It is not interchangeable with an absolute power measurement in dBm. Reference ↗
- Decoder
- Software that recognises radio messages and interprets their contents. It can be separate from the local map and the feed client. Reference ↗
- Feeder
- A program or station that sends observations to a network. Check which observations, which destination and whose terms. Reference ↗
- Filter
- A radio-frequency component with a passband. Read both what it rejects and its insertion loss; it is not an amplifier.
- Gain
- Amplification in part of the receiving chain. Higher settings are not a universal guarantee of better decoded reception. Reference ↗
- GNSS
- Global Navigation Satellite System. A position source used in the ADS-B system, not a requirement that your household receiver itself be a satellite receiver. Reference ↗
- Ground speed
- Speed relative to the ground. Do not substitute it for indicated or true airspeed. Reference ↗
- Hex address
- A commonly displayed form of a 24-bit aircraft address. Keep it distinct from registration and callsign. Reference ↗
- ICAO
- International Civil Aviation Organization. In receiver discussions, an "ICAO address" usually means the aircraft's 24-bit address. Reference ↗
- JSON
- A structured text format. aircraft.json is a data file, not proof that the observations inside it are current or valid. Reference ↗
- MLAT
- Multilateration. A position calculation from arrival-time differences across several receiving sites. Reference ↗
- Mode S
- The wider transponder-message family encountered by 1090 MHz decoders. Not every received message supplies an ADS-B position. Reference ↗
- Nautical mile
- A distance unit equal to 1,852 metres. The calculators explicitly label kilometres and nautical miles rather than writing an ambiguous "miles".
- PiAware
- FlightAware's feeding client; the name is also used for its complete receiver image. Check which meaning an instruction uses. Reference ↗
- Provenance
- Where a field came from: direct observation, a network calculation, a rebroadcast or a database. Keep those distinctions in exports. Reference ↗
- SDR
- Software-defined radio. In a typical hobby station, a USB radio supplies samples to receiving software. Reference ↗
- seen_pos
- In the documented JSON format, seconds between the last position update and the snapshot's now timestamp. Not the age of the last message. Reference ↗
- Snapshot
- One view of known aircraft at a recorded time. It is not a complete flight history. Reference ↗
- tar1090
- A browser interface for compatible aircraft data. It is a map layer, not a replacement for a decoder. Reference ↗
- TIS-B
- Traffic information broadcast from ground infrastructure. Label its provenance rather than passing it off as direct aircraft reception. Reference ↗
- Track
- Direction of travel over the ground. Heading, the direction an aircraft points, is a different quantity. Reference ↗
- Uptime
- Time a system or service has been running. Useful, but insufficient to establish that it is delivering fresh accepted observations.