ADS-B Technology Overview

Marc Ramsey

marc@ranlog.com

PASCO Safety Seminar

Oakland, California

November 4, 2006

Topics• What is ADS-B?• How Does ADS-B Work?• Why Ground Stations?• Broadcast Services• Current Continental US ADS-B Coverage• Expanded Coverage: 2008 to 2010?• Universal Access Transceivers• Will ADS-B Replace Transponders?• Why Should We Care?• What Can We Do?

What is ADS-B?

• Automatic– Periodically transmits information with no pilot or

operator input

• Dependent– Position and velocity data derived from Global

Positioning System (GPS)

• Surveillance– Determines position of aircraft, vehicles, or ground

obstructions

• Broadcast– Transmitted data available to anyone with

appropriate receiving equipment

How Does ADS-B Work?

• ADS-B transmitter periodically transmit:– Unique identifier– 3D Position and velocity vector from GPS

• Altitude from pressure sensor and/or GPS

• ADS-B receiver receives:– Data from nearby ADS-B transmitters– Traffic and weather data from ground stations

• ADS-B transceiver transmits and receives• Two types of ADS-B devices

– Mode S/ES (Extended Squitter) at 1090 MHz– UAT (Universal Access Transceiver) at 978 MHz

• Intended for General Aviation use

Why Ground Stations?

• Receive position/velocity data from ADS-B (both UAT and S/ES) equipped aircraft

• Pass received data to ATC system• Obtain traffic data from ATC system for other

ADS-B and transponder equipped aircraft• Broadcast composite traffic data• Broadcast weather and airspace data• Each station has a range of 100 to 150 miles

Who Can See Who?

ADS-B UAT ADS-B ES Mode A/C/S

ADS-B UAT IN YES via GS via GS

ADS-B ES IN via GS YES via GS

TCAS NO Maybe YES

ATC via GS via SSR/GS via SSR

–GS Ground Station–SSR Secondary Surveillance Radar

Broadcast Services: TIS-B

• Traffic Information Service• Provides real-time position reports

– ADS-B equipped aircraft– Mode B/C equipped aircraft from secondary surveillance

radar data

Broadcast Services: FIS-B• Flight Information Service• National Weather Service products

– NEXRAD

• Special use airspace– Temporary flight restrictions (TFRs)

Current Continental US ADS-B Coverage

Expanded Coverage: 2008 to 2010?

Universal Access Transceiver

• Transmits current state vector (3D position/velocity) once per second

• Receives TIS-B and FIS-B• Low transmit power requirements

– Low power (limited to 18,000 feet) 7 to 18 watts– Medium power (no alt. Restriction) 16 to 40 watts– Short transmit duty cycle (0.03%)

• Garmin GDL 90– Only UAT currently certified– $8000 without display– $16,500 with color display

Will ADS-B Replace Transponders?

• Short answer: eventually…– Most air transport aircraft equipped by 2020– Most other aircraft equipped by 2030

• Advantages– Precise position data on all aircraft in ATC system– UAT transceivers will eventually be smaller,

lighter, and use less current than Mode C– ADS-B ground stations less expensive and cover

wider area than primary/secondary radar systems

• What’s holding it up?– Lack of integration with TCAS– Lack of ground stations

Why Should We Care?

• Potential benefits– Allow gliders, paragliders, hangliders, etc. to be

fully integrated into future ATC system– Ultimately much lower power requirements than

existing Mode C or S transponders– Integrated collision avoidance– Real-time glider tracking for contests, etc.

• Potential Issues– Short term lack of suitable units– Competition

• UAT equipped gliders can be tracked by competitors • Weather data available to UAT equipped competitors

What Can We Do?

• Push for short term installation of ground station in Reno area

• Propose pilot program involving subsidized installation of UATs in Reno area gliders

• Ask for waiver allowing occasional use of low power UATs in wave windows

• Can we interest someone in developing low cost, low power UAT using PDA as display?

• Other ideas?

Winch Launch Update

• Recent trip to UK– Lasham– Bicester– Cambridge– Remember to get your medical form

• BGA transition training– 2 to 4 normal launches– 2 high failures– 2 medium failures– 2 low failures

• Any interest?– Contact me