CAAC TEDC WAM/MLAT and ADS-B Security

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CAAC TEDC WAM/MLAT And ADS-B Security

• 
  2012.04.26

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WAM/MLAT Algorithm

• WAM algorithm  is  a
  hyperbolic positioning algorithm, the
  basic equation shown at right. If the number of
  base stations over four, the basic equation for
  thesuper-set equation to convert non-overdetermine
  d equation by the least squares method.

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WAM/MLAT Algorithm

• Theoretical derivation can be drawn,
  multi-point positioning precision and accuracy of
  time difference relationship for the approximate
  linear relation, matrix G directly influences the
  positioning precision, while the matrix G by the
  site location and positioning point position is
  decided jointly.
• According to GPS positioning theory,
  can introduce HDOP / VDOP factor to describe the
  MLAT/WAM error distribution.
• According to statistics, ultimately
  need to get 95 confidence level error, can be
  expressed as
• EPU 1.96HDOP d

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TEDC WAM/MLAT

• TEDC ADSB-2000A provides two types of
  Multilateration model
• WAM mode used for time synchronization methods,
  through the GPS ( the future use of the COMPASS)
  time, by base stations (time synchronization
  accuracy needs to be controlled within 100ns ).
• Surface monitoring Multilateration using
  independent transmitter with high precision
  timing, the TEDC ADSB-2000A device can provide
  the highest 1ns timing precision (theoretical
  value of up to 0.3 meters), taking into account
  the crystal temperature drift, base station
  position measurement error, baseband pulse
  measurement and other reasons, the system in the
  best condition base station layout, the design
  accuracy requirements for RMS 10 metres.

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TEDC WAM/MLAT
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TEDC WAM

• TEDC WAM based on TEDC ADSB-2000A receiver
  equipment R D, consists of the following
  components
• The ADSB-2000A receiver (3 above )
• 10W 1090ES transmitter
• Central processing computer
• Data output interface device
• The optional 1030MHz rotary inquiry machine

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TEDC WAM

• TEDC has carried on many times the
  multilateration test, the car station in Beijing
  Daxing District, Hebei Xiongxian, Hebei Cangzhou,
  Hebei Dingzhou built four remote multilateration
  station.
• Test contains the 1090MHz ModeS, Mode A / C and
  ADS-B ( out ) frame .

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TEDC WAM
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TEDC WAM
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TEDC WAM
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ADS-B Security

• ADS-B data security is the basic problem
• Air Ground transmission reliability (
  transmission delay, crosstalk, interweaves wait
  for a problem )
• False target and electronic jamming.
• GNSS system integrity loss / failure and ADS-B
  Out alternative surveillance technology.

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ADS-B Security
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ADS-B Security
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ADS-B Security
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ADS-B Security
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ADS-B Security

• ADS-B data security problems
• ADS-B data reliability.
• ATC systems fusion model.
• ADS-B data transmission and usability problems.

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ADS-B Security

• ADS-B data reliability problems
• Airborne ADS-B apparatus is provided to position
  the confidence degree ( NUCp ) may not be
  entirely reliable, different aircraft in the same
  region of the same moment may have a different
  location confidence value.
• As a result of airborne equipment and firing
  pattern of inconsistency, leading to ADS-B
  position data is not accurate

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ADS-B Security
From the statistics, NUCp value mainly
concentrated in the5,6,7, but a large proportion
of the data NUCp 0, NUCp 0means that the ADS-B
position data is invalid.
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ADS-B Security

• ATC system security issues (for processing ADS-B
  data)
• Unproven ADS-B track directly into the automated
  system position accuracy and transmission delay
  of dual risk.
• Position risk is airborne equipment NUCp
  inconsistency, may lead to some lost tracks, or
  to produce incorrect track.
• Transmission delay will lead to automatic
  velocity tracking system instability condition,
  serious cases will affect the tracking accuracy.

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ADS-B Security

• Extended ADS-B ground station, through the
  regional centralized processing can solve the
  ADS-B security problems.
• ADS-B ground station should provide precise
  timing function, the use of precision timing,
  without changing the construction scale of the
  circumstances, can greatly improve the security
  questions of ADS-B data.
• Regional centralized processing is the current
  ADS-B construction is necessary and urgent
  problem, through the regional centralized
  treatment, can improve the ADS-B ground station
  network capacity, and provides additional
  functionality.

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ADS-B Security

• ADS-B Corroboration

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ADS-B Security

• ADS-B Security in H15

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ADS-B Security
ADS-B Security in H15
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ADS-B

• Thanks!
• Li Gang
• CAAC TEDC
• 2012.04.26