How it works

ADS-B means Automatic Dependent Surveillance–Broadcast. An equipped aircraft broadcasts information including its position, altitude and ground speed. The position comes from onboard navigation equipment, commonly GNSS such as GPS. Nearby receivers can decode those transmissions.

What reaches the radar?

ADS-B Out sends information; ADS-B In receives it. On a tracking website, software turns received reports into symbols and flight details. The map is a presentation of available data, so a missing aircraft does not prove that the sky is empty.

Where ADS-B.Pro fits

Our feeder guides explain how to connect a receiving station to the network. VRS X and RadarView provide separate browser interfaces for exploring live traffic.

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ADS-B.Pro offers two live radar interfaces: VRS X is the Modern experience, while RadarView is the Classic interface. Each opens its own application.

A radar interface presents data

The receiver gathers signals; the software presents available aircraft reports on a map. VRS X also has a self-hosted installation path, documented in the Operator’s Handbook. Its Closed Beta access is restricted to eligible ADS-B.Pro feeders. RadarView is the Classic service hosted by ADS-B.Pro.

Viewing and installing are different

Opening the live VRS X radar does not install a server on your computer or grant a Closed Beta licence. Use the handbook for installation and the Closed Beta guide for eligibility and activation.

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A Mode S transmission does not automatically provide an ADS-B position. Multilateration (MLAT) can locate an aircraft using the time differences between the same signal reaching several receivers at known locations.

Why several receivers matter

The network solves for a location that fits those arrival-time differences. Receiver timing and geometry matter: hearing the signal at several stations is necessary, but does not by itself guarantee an accurate result. This is a timing-based calculation, not a comparison of signal strength.

How to interpret it

An MLAT position is calculated by the receiving system; an ADS-B position is reported by the aircraft. This explains the general technology. It is not a claim that every ADS-B.Pro feed provides MLAT results.

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Aircraft exchange operational messages as well as tracking data. ACARS is an aircraft communications and reporting system; VDL Mode 2 is a digital VHF data link. They describe different parts of the communications chain and are not interchangeable names.

Messages need a transport

ACARS traffic can be carried over VDL Mode 2 using ACARS over AVLC (AOA). VDL Mode 2 also supports Aeronautical Telecommunication Network (ATN) services. Receiving a data-link message is therefore a different task from decoding a position broadcast for a tracking map.

In this guide

This material introduces the technology. It does not announce an ACARS/VDL2 feed, decoder or public message archive in ADS-B.Pro. Check the product documentation for supported inputs.

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FLARM devices use GPS measurements to predict a flight path and exchange information by radio. Nearby FLARM devices compare that information with their own trajectory to identify potential conflicts.

The Open Glider Network (OGN) is a tracking network. Its project documentation describes support for aircraft equipped with FLARM, OGN trackers and ADS-L devices. FLARM is a technology used aboard aircraft; OGN brings tracking observations into a network.

What a web map tells you

Online tracking and an onboard collision warning system serve different purposes. A web map cannot be assumed to show every nearby aircraft or provide onboard warning functionality. This overview does not announce an OGN or FLARM integration in ADS-B.Pro.

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A METAR describes observed conditions at an aerodrome. A TAF describes expected conditions over a specified period. Neither should be confused with a precipitation radar image. A weather interface combines data products; it does not make them equivalent.

What the weather engine does

A decoder turns coded reports into readable values such as wind, visibility, cloud layers and pressure. The VRS X handbook documents its METAR decoder, NOAA weather data and the airport database used to associate reports with locations.

Always check the timestamp

A newly refreshed page can still contain an older observation. Read the observation time or forecast validity, not just the page refresh time. This guide describes the documented METAR feature; it does not imply that every forecast or precipitation layer is available in VRS X.

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A feeder connects a receiving setup to ADS-B.Pro. The antenna and receiver collect radio signals, decoding software extracts messages, and a network connection forwards data through the configured feeding method.

Choose the right installation path

The ADS-B.Pro documentation provides Linux and Windows guides, plus the classic Virtual Radar Server Push Feed method. Follow the instructions for your setup; a receiving station and a browser used to view the radar have different roles.

Coverage means observations

A receiver does not cover an unlimited area. In VRS X, the documented Coverage tool explores where enabled merged feeds actually observed aircraft. Its result should not be read as a theoretical antenna range or a promise of continuous coverage.

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