Automatic Dependent Surveillance

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Portable ADS-B receiver from Garmin

Automatic Dependent Surveillance - Broadcast ( ADS-B ; German about automatic transmission of associated / dependent observation data ) is an air traffic control system for displaying aircraft movements in the airspace.

function

The aircraft determine their position independently, for example using satellite navigation systems such as GPS with the European Geostationary Navigation Overlay Service and GLONASS . The position and other flight data, such as flight number , aircraft type, time stamp, speed, altitude and planned flight direction are broadcast continuously - typically once per second - in an undirected manner at 1090 MHz. This is why the process is called ADS- B (broadcast) , also known as ADS-B out for out put . Shipping on request is also possible. The system is then called ADS- C (contract) or ADS- A (addressed) .

Flight control receives the participants' data and prepares them graphically. This information is clearly superior to that obtained from ground penetrating radar. If all the traffic data is then transmitted to the aircraft via ADS-B in ( in put ), pilots have the same overview of air traffic as air traffic controllers, on the so-called Cockpit Display of Traffic Information (CDTI).

The range of ADS-B broadcasts is up to 200 nautical miles (370 km) to reception points on the ground. ADS-B signals can also be received via satellites in Low Earth Orbit (LEO) , a service offered by Aireon via the Iridium Next system. Since a single satellite has a range of up to 2000 nautical miles (3700 km), the entire earth can be effectively covered, including areas over the oceans or polar regions that have not been monitored so far.

technology

ADS-B in its standardized form uses the so-called 1090 Extended Squitter Datalink, which is based on the existing Mode S technology. Accordingly, ADS-B shares many characteristics: The frequency is also 1090 MHz, the modulation is a pulse-pause modulation, the bandwidth is 1 Mbit / s and the length of the messages is 112 bits. There is no collision prevention beyond a primitive random backoff process, which leads to high loss rates in heavily used airspaces.

use

ADS-B is primarily used by air traffic control to locate and monitor aircraft to increase safety through improved information for the pilot about the aircraft environment . ADS-B causes lower costs than conventional radar and increases the quality of the positioning of aircraft thanks to a higher update rate compared to radar. ADS-B is now used in regions where there is no area-wide radar surveillance, e.g. B. Alaska or Australia . Another area of ​​application is the use as a replacement for ground penetrating radar to monitor aircraft and, at the same time, ground vehicles on the apron and taxiways of airports .

Some web services such as B. Flightradar24 also evaluate this data.

ADS-B transponders are standard equipment on many newly delivered commercial aircraft.

Every Iridium NEXT satellite is equipped with an ADS-B receiver. Satellite-based ADS-B enables air traffic control in regions that are not covered by air traffic control radar today. Thanks to the ADS-B receivers on the Iridium-NEXT satellites, global, seamless reception of ADS-B signals is possible.

Schedule for the introduction of ADS-B

The schedule for the introduction of ADS-B is determined by the equipment of ADS-B transponders in the aircraft, the costs of the equipment, the assumed benefits and the regulations of the aviation authorities. The cost of equipping aircraft with ADS-B transponders is relatively low and offers a number of advantages for air traffic control and airspace users. Nevertheless, the upgrade speed lags behind expectations. The current schedule in Europe (through Eurocontrol ) and in the USA (through the Federal Aviation Administration ) calls for ADS-B equipment for aircraft in monitored airspace by 2020 and industry observers already fear that this schedule is too tight .

Directive 1207/2011 of the European Community of November 22, 2011 stipulates that aircraft with a take-off weight of more than 5.7 tonnes or a speed of more than 250 nautical miles per hour must be equipped with ADS-B transmitters by January 2, 2020 must be equipped on the basis of Mode S transponder technology. The prescribed frequency is 1090 megahertz. Attempts to enforce an upgrade obligation for smaller or slower aircraft failed in 2017. The concerns that too many Mode S transponders could clog the 1090 frequency were too great. For general aviation there will be no obligation to send broadcast signals on the frequency 1090 MHz. There are considerations to use the frequency 978 megahertz for such purposes. (ADS-B UAT)

Short-term developments (2006–2008) During these years ADS-B field tests were carried out and an increasing number of older commercial aircraft were retrofitted with ADS-B avionics.

  • Sweden . The Swedish Aviation Authority built a comprehensive system of 12 ground stations between 2006 and 2007.
  • Australia . Australia is conducting field trials in Queensland to test the feasibility of ADS-B as an alternative to radar-based surveillance systems. It is expected that ADS-B will result in cost savings and increased security, especially in areas that have not yet been fully covered by radar.

Medium-term developments (2008–2015) In addition to the further spread of ADS-B transponders in commercial aircraft, it is to be expected that a larger number of ground stations will be put into operation.

Long-term effects (from 2016)

  • The almost complete equipping of the airlines' fleets will enable the advantages of ADS-B to be used to a greater extent.
  • A greater accuracy of the airspace monitoring could make it possible to introduce lower graduation minima and thereby increase the capacity of the airspace.
  • ADS-B aims to achieve greater "situation awareness". If pilots know of the existence of other road users, they can better assess the situation.
  • Especially when flying over regions that are not covered by radar, the position of the aircraft can still be determined because ADS-B signals are received and forwarded by satellites.
  • This eliminates expensive investments in satellites or shortwave communication devices for transmitting the position in the aircraft, since ADS-B only means a software extension of an existing transponder with Mode-S.

Related systems

Voice-based VHF radio systems for air traffic management will reach their capacity limits in the near future. Among other things, the EU project SESAR makes a selection of data-based systems. The Traffic Alert and Collision Avoidance System could be expanded. The expansion of the secondary radar by Mode S Extended Squitter (ES) will probably not be pursued in the future in favor of VDL Mode4 in the Self Organizing TDMA procedure (STDMA).

An ADS-B concept called FLARM was implemented especially for the needs of small-scale aviation (high aircraft density, frequent flight path changes, cost-effective, space and energy-saving) . It has spread rapidly worldwide since its introduction in 2004, although it is based on a proprietary radio protocol. In mid-2014, almost 25,000 systems were in use. The short range of FLARM (<5 km) does not allow a larger overview of the airspace. In addition, there are (for this reason) no ground stations that provide an overview of e.g. B. could offer outside the traffic. FLARM is a collision warning device, originally intended for gliders .

In shipping, the AIS works on a similar technical principle as ADS-B. A system similar to the CDTI for the visualization of the data obtained on board is the ECDIS in shipping .

Web links

Individual evidence

  1. ^ Woodrow Bellamy III: Space-based ADS-B: Going Live in the North Atlantic Airspace. Avionics International, accessed October 26, 2019 .
  2. ↑ Implementing Regulation (EU) No. 1207/2011 of the Commission of 22 November 2011 laying down the requirements for the performance and interoperability of surveillance in the Single European Sky
  3. ↑ Dr. Michael Erb: The future of ADS-B in Europe. AOPA Germany, April 4, 2019, accessed on October 26, 2019 .
  4. ^ Sweden Announces Plans for Nationwide ADS-B Network - Swedavia. Airport Technology, September 26, 2006, accessed October 26, 2019 .