ADS-B

ADS-B or Automatic Dependent Surveillance - Broadcast

For most of the world (including New Zealand) ADS-B will use an extended squiter (ES) portion of the Mode S (1090MHz) Transponder signal to transmit the aircraft's position to ATC.

The aircraft's position is determined from an on board WAAS GPS receiver.  This can be a panel mounted GPS system like a Garmin GTN625 or a remote (blind) mounted receiver like the Free Flight Systems 1201.  It must be a WAAS capable receiver that meets TSO C145a, you can not use an older model (Non WAAS) GPS like the GNC250XL etc.  Non WAAS receivers do not contain the correct Data Words in the ARINC 429 outputs.  

In New Zealand there are currently no plans to use the Universal Access Transceiver (UAT) system of ADS-B.  This system is in use in the USA for operations below 18,000 ft.  It operates on a different frequency (980 MHz) and is intended to decrease the amount of traffic on the 1090 MHz band.   Much of the cheaper 'Data Link' ADS-B equipment advertised on the internet is using this UAT system.  There are also no plans at the moment to provide uplink data to aircraft.  In the future, we are hopeful that Airways will make use of the TIS-B system to provide real time traffic data and the FIS-B for weather data, both of which can be displayed on an MFD.