ADS-B; A GUIDE TO CONNECTING GPS-DEVICES, ADS-B RECEIVERS, MODE-S TRANSPONDERS AND DISPLAYS...page 2

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ADS-B EXPLAINEDADS-B

ADS-B stands for Automatic Dependent Surveillance-Broadcast. This technology provides data-communication between aircraft as well as between aircraft and ground stations. ADS-B OUT means data collection and transmission. ADS-B IN means data reception and processing. All kinds of data can be transmitted (e.g. weather, traffic, flight information), the most important data however concerns aircraft positions. These position data can be used to generate traffic display on radar screensby by air taffic control as well as or on navigation systems in gliders and other aircraft (e.g. LX80X0- or LX90X0-series, Oudie, Flarm-displays). Several types of data links exist, but for recreational aviation in Europe ADS-B via mode S transponder signals is the logical choice. Using mode S transponders also allows relatively simple receivers on the ground to create real time flightracking systems.


This movie made by Garmin gives a good explanaition of ADS-B, however it is made with the Garmin products and the US regulations in mind (several differences with the situation in Europe exist): http://youtu.be/W5_TsUb4AlI

Flarm and ADS-B

There are some parts where Flarm and ADS-B overlap in functionality, however they are completely different technologies.

  • Flarm can only warn for Flarm traffic, Flarm equipment will always send ánd receive
  • Flarm signal strength is very low compared to transponder signals (ADS-B)
  • Flarm transmission and reception quality is extremely dependent on the type of installation, location of the antenna and the presence of surrounding objects (e.g. carbon fuselage, instruments, metal parts)
  • Flarm ranges are normally between 3 and 10km, transponder range theoretically is line of sight.
  • ADS-B IN solutions can warn only for aircraft using ADS-B OUT (GPS-position data sent by mode S transponder)
  • Some ADS-B IN solutions can also warn for mode A/C/S traffic with limited accuracy
  • Mode S transponders are tested when installed and during regular inspections
  • ADS-B IN solutions combined with Flarm and/or traffic displays are available
Before we continue with the technical part of this guide please take note of this important message:
ALWAYS PROGRAM YOUR ICAO 24-BIT TRANSPONDER CODE AS FLARM ID IN YOUR FLARM and/or ADS-B receiver! 
This will prevent warnings generated by your own transponder, and double warnings displayed in other aircraft.

 

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