GUILDANCE MATERIAL ON GENERATION, PROCESSING & SHARING OF ASTERIX CATEGORY 21 ADS-B MESSAGES Jointly...

GUILDANCE MATERIAL ON GENERATION, PROCESSING & SHARING

OF ASTERIX CATEGORY 21 ADS-B MESSAGES

Jointly Presented by Australia and Hong Kong, China

ADS-B SITF/11

April 2012

Civil Aviation Department Hong Kong, China

Introduction

• “All Purpose Structured Eurocontrol Surveillance Information Exchange” (ASTERIX) Category 21

– A data format standard globally accepted by the Air Traffic Management (ATM) system manufacturing industry for sharing of ADS-B data with ATM automation systems

– Used to convey ADS-B data from ADS-B ground stations to ATC processing and display system


ASTERIX Cat 21 in Asia Pacific (APAC) Regions

• During the 16th APANPIRG Meeting held in August 2005

– ASTERIX Category 21 version 0.23 which has incorporated DO260 standard was adopted as

• the baselined ADS-B data format for deployment of ADS-B ground stations

• sharing of ADS-B data in the APAC Regions

– DO260A and DO260B standards have yet been fully defined during that period


Evolution of ASTERIX Cat 21


November 2003

August 2008

May 2011

Version 0.23(Incorporated

DO260 standard)

Version 1.0(incorporated

DO260A standard)

Version 2.1(incorporated

DO260B standard)

August 2005

16th APANPIRG adopted Version 0.23 as baselined version for APAC

• Asterix standard has been developed over many years • Undergone continuous revisions to incorporate the

latest ADS-B link technology

Choice of ASTERIX Version Number

• Asia Pacific decided to use V0.23 as the version for sharing ADS-B data between States in 2005

• V0.23– Provides adequate information for ATC operational

services– Can be used with DO260, DO260A and DO260B

ADS-B avionics/ground stations to provide ATC operational services

– Cannot fully support all enhanced capabilities offered by DO260A and DO260B


Choice of ASTERIX Version Number


V2.1V0.23

• Nearly all V0.23 data items can be reconstructed from a received V2.1 data stream

• Most of the special DO260A and DO260B data items cannot be reconstructed from a V0.23 data stream

(V2.1 as representation of ASTERIX CAT 21 Version after V0.23)

Support of DO260A/B using ASTERIX Cat 21 V0.23

• V0.23 does not directly support DO260A/B

• Ground station software can generate useful V0.23 Asterix data from DO260A/B reports using some techniques (e.g. generation of NUC value based on pre-defined table on combination of SIL, NIC and NAC)

• A more recent version of Cat 21 is needed if there is a particular need for the ATC system to access to NIC/NAC or SIL or other data items that exist in DO260A/B

• States are encouraged to review and determine additional DO260A/B fields beneficial to warrant adoption of newer versions of Asterix Cat 21


Specification of ASTERIX Message Processing

• ASTERIX Cat 21 specification:

– Defines characteristics of data on the interface including items as optional and mandatory on the interface

– It does NOT specify the behaviour of the transmitting ground station nor behaviour of the receiving ATM automation system



• ADS-B ground station specification:

– Defines the Asterix standard to be adopted for outputting data and which optional Asterix data items are required to be delivered on the Asterix interface

– indicates how the ground station processes and outputs every received DO260, DO260A and DO260B data element into an Asterix data element/field

– indicates which and how each Asterix data element and field presented at the output are populated



• ATM automation system specification:

– Defines which received Asterix data element and fields are processed and how they are processed

– Defines which Asterix optional data fields are required by the ATM automation system



• ANSPs that specify ADS-B ground stations and ATM automation systems to consider carefully what they need to achieve

• Specification which simply require compliance with a particular ASTERIX standard will be inadequate in most circumstances



• ANSPs together with suppliers should:– Specify the Asterix standard version to be used

• Defines the message formats that are placed on the link between ADS-B ground station and ATM automation systems

– Specify the ADS-B ground station behaviour• When data is received from the aircraft, the ground station is

required to fill appropriate optional Asterix data fields

– Specify the ATM automation system behaviour and syntax checks applied to the Asterix data, including any triggers for the system to discard data


Generation of ASTERIX at an ADS-B Ground Station

• Group 1 (Mandatory) – an Asterix Cat 21 message should not be transmitted unless the mandatory data items defined below are all present:

Data Items Description V0.23 V2.1 Remarks

I021/010 Data Source Identification

X X Identifies source of data. Important if validity checks are performed as an anti spoofing capability

I021/030 Time of Day X Data received with a Time of Day too far in the past should be discardedI021/071 or

I021/073Time of applicability of Position or Time of Message reception for position

X




I021/040 Target Report Descriptor X X Indicates if report is a duplicate, on the ground, is a simulated target, is a test target. This needs to be checked by ATC system prior to processing.

I021/080 Target Address X X Included in all 1090ES downlink messages, so always available. Used for report/report linkage in ATC tracking.

I021/090 Figure of Merit/Quality Indicators

X X Position cannot be used without quality indicator

I021/130 Position in WGS-84 co-ordinates

X X Report cannot be used without position


Group 1 (Mandatory)


• Group 2 (Operationally Desirable) - should always be transmitted whenever data are received by the ground station from aircraft (if allowed by relevant Asterix standard chosen):


I021/008 Aircraft operational Status

X TCAS capability, Target state reporting capability, CDTI capability, Single/dual aircraft antenna

I021/020 Emitter Category X X Aircraft or vehicle type

I021/140 Geometric Altitude/Height

X X Useful for RVSM monitoring

I021/145 Flight Level X X Flight level is an important information to ATC




I021/155 Barometric Vertical Rate

X X Used for predictive tools and safety nets.

I021/157 Geometric Vertical Rate

X X

I021/160 Ground Vector X X Provides excellent vector to support extrapolation of positional data to time of display

I021/170 Target Identification X X This is the callsign/Flight ID is extremely useful for ATC and matching to the flight plan (if any)

I021/200 Target Status X X This is the emergency type and is highly desirable


Group 2 (Operationally Desirable)


• Group 3 (Optional) – remaining data items belong to this Group which may need to be transmitted depending on availability of such data from aircraft and/or other specific operational needs

• Specification for ADS-B ground station should take into account: – Transmission of all Group 1 (Mandatory) and Group 2 (Operationally Desirable) data items – Whether Group 3 (Optional) data items will be transmitted should be configurable on item-by-item basis depending on specific operational needs and link bandwidth availability


Processing of ASTERIX ADS-B Data at ATC System


• An Asterix Cat 21 message should not be accepted by the ATC System for processing unless it includes at least all Group 1 data items

• The ATC system should process all received Asterix Cat 21 message data items that bring operational benefits. The ATC System should appropriately process those Group 2 data items depending on operational need

• Whether the ATC system will process Group 3 optional data items will depend on specific operational needs

Data Sharing of ASTERIX ADS-B Data

• Data items that should be included in data sharing:– Group 1 (Mandatory)– Group 2 (Operationally Desirable)when such data are received from aircraft

• Subject to mutual agreement between the two data sharing parties concerned, Group 3 (Optional) data items needs to be shared


ADS-B Format Conversion and Filter System

• Evolution of 1090ES ADS-B link technology and avionics standards will continue

• Asterix standards will continue to evolve

• ATC systems need to be adaptable and be able to cope with new functionality requirements and new message standards


ADS-B Format Conversion and Filter System

• Provides ADS-B format conversion between domestic and foreign ADS-B systems

• Allows data meeting agreed sharing criteria to be passed through

• Cost-effective way to provide the necessary protection and flexibility to adapt to new message standards



ADS-B Ground StationAsterix CAT 21

Version “XA”

ADS-B Format Conversion & Filter System- Asterix Format Converter : Domestic: Ver XA / Ver YA ; Foreign: Ver XA / Ver YB - Pass only data that meet sharing criteria - Security features

Agreed sharing format

ATM Automation System

Asterix CAT 21Version “YA”

ANSP “A”

ADS-B Ground StationAsterix CAT 21

Version “XB”

ATM Automation System

Asterix CAT 21Version “YB”

Ver “XA” Ver “YA”

Ver “YA”

Ver “YB” Ver “XB”

Ver “YB”

ADS-B Format Conversion & Filter System- Asterix Format converter : Domestic: Ver XB / Ver YB ; Foreign: Ver XB / Ver YA - Pass only data that meet sharing criteria - Security features

ANSP “B” Domestic Data

Foreign Data

Conclusion

• To recognize differences between DO-260, DO260A, DO260B for ADS-B ground stations and Asterix Cat 21

• To agree on proposed mandatory, desirable and optional ADS-B data fields for sharing of ADS-B data in Asterix Cat 21 format to ensure system interoperability and harmonize ADS-B implementation in APAC Regions

• To take note of possibility of deploying ADS-B format conversion & filter (ADS-B FC&F) system in overall design and integration of ATM automation systems and ADS-B ground stations

• To adopt this “Guidance Material on Generation, Processing and Sharing of Asterix Category 21 ADS-B Messages” for use by APAC States/Administrations


Thank you


GUILDANCE MATERIAL ON GENERATION, PROCESSING & SHARING OF ASTERIX CATEGORY 21 ADS-B MESSAGES Jointly...

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