A possible transition to an ADSB based surveillance system

1
A possible transition to an ADS-B based
surveillance system

• SCRSP WG/B meeting in Langen, October 2002
• WP 4-23, prepared and presented by Mikaël Ponnau,
  STNA

2
Presentation items

• Proposals for a  sweet  transition
• Technical means for a  sweet  transition
• Extended squitter processing by a Mode S sensor
• A communication protocol between ADS-B et Mode S
  sensors
• A phased deployment of ADS-B sensors

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Proposals for a sweet transition (1/2)

• Current situation an independent SSR based
  surveillance consisting of monopulse and Mode S
  sensors
• Envisaged situation an ADS-B based surveillance
  system depending of the navigation system
• ICAO recommendations for any new surveillance
  system (Doc 9684 chapter 10 extracts)
• At least the same level of performance as the
  former system
• A fall back system to get positional data

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Proposals for a sweet transition (2/2)

• To meet the recommendations, it is proposed
• To enhance the existing SSR coverage with ADS-B
  sensors (gap filling application)
• Completing the coverage where there are detection
  holes cone of silence, terrain screening, masks
• The first deployed ADS-B sensors will complete
  the existing SSR coverage
• To deploy progressively the next ADS-B sensors
  until the SSR coverage is completely redounded
  with an ADS-B coverage
• The ADS-B based surveillance system can then be
  the primary mean for surveillance
• To keep maintaining some of the SSR sensors which
  will constitute the fall-back system in case the
  positional data of ADS-B sensors is felt
  erroneous or is missing
• Both systems become complementary

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Technical means for a sweet transition (1/4)

• Extended squitters processing by a Mode S sensor
  
• Type of extended squitters
• Position squitters (05 or 06) contains the same
  information as a Mode S All Call reply used to
  acquire Mode S aircraft
• Other extended squitters contain airborne
  parameter
• Expected benefits to process extended squitters
  in a Mode S sensor
• Surveillance of aircraft on the ground (aircraft
  will directly be interrogated selectively)
• No need for All Call period in a 100 ADS-B
  environment more time for Roll Call period to
  interrogate more aircraft or to perform more data
  link
• Local tracking enhancement (to maintain or
  enhance existing tracks) thanks to extended
  squitter data
• Surveillance coverage enhancement when the sensor
  receives extended squitters from a remote ADS-B
  sensor strategically located

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Technical means for a sweet transition (2/4)

• Extended squitters processing by a Mode S sensor
  (continue)
• Technical means to acquire extended squitters
• Using the reception channel of the Mode S sensor
  (though the ? diagram of the rotating antenna or
  though an omni antenna installed on the same
  tower) ? a feasibility study is undergoing
• Using an external interface the Mode S sensor
  receives surveillance data delivered by a remote
  ADS-B sensor ? similar interfaces exist for
  clustering operation

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Technical means for a sweet transition (3/4)

• A communication protocol between ADS-B and Mode S
  sensors
• ADS-B sensors or the multi sensor tracker can
  request support to the Mode S sensor for some
  aircraft
• Support is requested when positional data is
  doubtful or is missing
• The Mode S sensor maintains a list of aircraft
  thanks to the surveillance data it receives from
  ADS-B sensors (the sensor is client of the
  surveillance server)
• When support is requested it selectively
  interrogates the aircraft and sends back the
  measured position to the ADS-B sensor or the
  multi sensor tracker (whichever made the request)
• Such interfaces and protocols already exist for
  the operation of a Mode S cluster

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Technical means for a sweet transition (4/4)
Mode S sensor
ADS-B station
List of aircraft
? Diagram
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Phased deployment of ADS-B sensors (1/3)

• Phase 1
• The primary surveillance mean is the SSR
  surveillance system
• ADS-B sensors complete the Mode S coverage
• The Mode S sensor process the squitters thanks to
  
• the added ADS-B sensors
• its own ? diagram
• The surveillance system is enhanced

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Phased deployment of ADS-B sensors (2/3)

• Phase 2
• Progressive deployment of ADS-B sensors
• The primary surveillance mean remains the SSR
  surveillance system
• New sources of surveillance information for the
  ATC system

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Phased deployment of ADS-B sensors (3/3)

• Phase 3
• The primary surveillance mean is the ADS-B
  surveillance system
• Some Mode S sensors are maintained for the
  fall-back mode
• Note taking a 250 NM range for a Mode S sensor
  and a 60 NM range for an ADS-B sensor, this
  (very) simple drawing shows that 15 ADS-B sensors
  are required to almost complete the same
  surveillance coverage ! 5 more would be required
  if the ? diagram was not used.