ASTERIX

ASTERIX is a European aviation network protocol.

History

Until the 1980s, every National Administration developed its own format for delivering radar data to Air Traffic Control Centres. This resulted in duplicate effort and made exchange of radar data across borders a complicated issue. The need for a common European data format became apparent and an example of what a standard format could look like was presented by Maastricht UAC in 1984.

The All purpose STructured Eurocontrol SuRveillance Information eXchange format (ASTERIX) was born, the ASTERIX Users Group was created to work on a common European definition which led to ASTERIX's official approval by the RSSP in its 15th Meeting held on 1/4 July 1986.

In 1988, the ASTERIX Manual was presented, describing the initial structure of ASTERIX and providing a set of "data items" to cover monoradar and weather data.

This initial structure was enhanced in 1991 to provide more flexibility, and the ASTERIX Manual was replaced by the first draft of what is now the ASTERIX Structure Document which is the Standard Document to be used for implementing ASTERIX (this document can be found under section ASTERIX Categories).

In 1994, the responsibilities of the former RSSP were taken over by the Surveillance Team, and the Surveillance Task Force for Radar Data Exchange (STFRDE) was created to continue the work of the ASTERIX Users Group (now renamed ASTERIX Maintenance Group). Since then, the application domain of ASTERIX has constantly expanded, and ASTERIX has now been adopted world-wide as the standard format for exchanging data from primary, secondary, monopulse, Mode S and weather radars, and also for carrying multiradar data, data-link, SMGCS, control & monitoring, etc...

Source: http://www.eurocontrol.int/services/asterix

Protocol dependencies

Example traffic

ASTERIX packet, Category 062
    Category: 62
    Length: 786
    Asterix message, #01, length: 98
        FSPEC
        010, Data Source Identifier
            SAC: 147
            SIC: 100
        015, Service Identification
            SI: 2
        070, Time Of Track Information
            [s]: 46011,320
        105, Calculated Position In WGS-84 Co-ordinates
            LAT[deg]: 45,5832624435425
            LON[deg]: 16,8090444803238
        100, Calculated Track Position (Cartesian)
            X[m]: 180193
            Y[m]: -43716
        185, Calculated Track Velocity (Cartesian)
            Vx[m]: 172,5
            Vy[m]: -123,75
        060, Track Mode 3/A Code
            ..0. .... .... .... = CH: No Change (0)
            .... 0100 1001 0101 = SQUAWK: 02225
        380, Aircraft Derived Data
            FSPEC
            #1: Target Address
                Aircraft Address: 0x4ba742
            #2: Target Identification
                Aircraft Identification: BER3044
            #3: Magnetic Heading
                MH[deg]: 118,30078125
            #5: True Airspeed
                TAS[knot]: 444
            #10: Communications/ACAS Capability and Flight Status reported by Mode-S
                000. .... .... .... = COM: No communications capability (surveillance only) (0)
                ...0 00.. .... .... = STAT: No alert, no SPI, aircraft airborne (0)
                .... .... 1... .... = SSC: Yes (1)
                .... .... .1.. .... = ARC: 25 ft resolution (1)
                .... .... ..1. .... = AIC: Yes (1)
                .... .... ...1 .... = B1A: 1
                .... .... .... 0110 = B1B: 6
        040, Track Number
            TN: 4154
        080, Track Status
            0... .... = MON: Multisensor (0)
            .0.. .... = SPI: default value (0)
            ..0. .... = MRH: Barometric altitude (Mode C) more reliable (0)
            ...1 10.. = SRC: default height (6)
            .... ..0. = CNF: Confirmed track (0)
            .... ...1 = FX: Extension into next extent (1)
            0... .... = SIM: Actual track (0)
            .0.. .... = TSE: default value (0)
            ..0. .... = TSB: default value (0)
            ...0 .... = FPC: Not flight-plan correlated (0)
            .... 0... = AFF: default value (0)
            .... .0.. = STP: default value (0)
            .... ..1. = KOS: Background service used (1)
            .... ...1 = FX: Extension into next extent (1)
            0... .... = AMA: track not resulting from amalgamation process (0)
            .00. .... = MD4: No Mode 4 interrogation (0)
            ...0 .... = ME: default value (0)
            .... 0... = MI: default value (0)
            .... .00. = MD5: No Mode 5 interrogation (0)
            .... ...1 = FX: Extension into next extent (1)
            0... .... = CST: Default value (0)
            .1.. .... = PSR: Age of the last received PSR track update is higher than system dependent threshold (1)
            ..0. .... = SSR: Default value (0)
            ...0 .... = MDS: Default value (0)
            .... 1... = ADS: Age of the last received ADS-B track update is higher than system dependent threshold (1)
            .... .0.. = SUC: Default value (0)
            .... ..0. = AAC: Default value (0)
            .... ...0 = FX: End of data item (0)
        200, Mode of Movement
            00.. .... = TRANS: Constant Course (0)
            ..00 .... = LONG: Constant Groundspeed (0)
            .... 00.. = VERT: Level (0)
            .... ..0. = ADF: No altitude discrepancy (0)
        295, Track Data Ages
            FSPEC
            #1: Measured Flight Level Age
                MFL[s]: 2,75
            #4: Mode 3/A Age
                MDA[s]: 2,75
        136, Measured Flight Level
            Measured Flight Level[FL]: 390
        340, Measured Information
            FSPEC
            #1: Sensor Identification
                SAC: 34
                SIC: 26
            #2: Measured Position
                RHO[NM]: 140,4921875
                THETA[deg]: 94,833984375
            #4: Last Measured Mode C Code
                0... .... .... .... = V: Code validated (0)
                .0.. .... .... .... = G: Default (0)
                HEIGHT[FL]: 390
            #5: Last Measured Mode 3/A Code
                0... .... .... .... = V: Code validated (0)
                .0.. .... .... .... = G: Default (0)
                ..0. .... .... .... = L: MODE 3/A code as derived from the reply of the transponder (0)
                .... 0100 1001 0101 = SQUAWK: 02225
            #6: Report Type
                010. .... = TYP: Single SSR detection (2)
                ...0 .... = SIM: Actual target report (0)
                .... 0... = RAB: Report from target transponder (0)
                .... .0.. = TST: Real target report (0)
        Special Purpose Field

Wireshark

ASTERIX dissector is now part of the Wireshark package. The code is written to support any ASTERIX category. However, not all categories are being dissected at present. To properly dissect the category the program needs its definition. Authors did not include all categories in the source because they don't have the access to samples of each category. To enter definition without ability to check and debug seems useless.

To add a category there is no need to change dissecting code. Only definition of the category has to be put in source so dissecting code will be able to use it for dissecting. Anybody who wants the dissector to be able to dissect other categories too, is welcome to enter definition in the source. We can also input definitions if you provide sample of traffic to be able to see the results and debug the code.

There is also a plugin (but never submitted to Wireshark for inclusion). There is no information whether it is being maintained. See here for more information (most of the pages are in French but a few are in English).

Preference Settings

The support for various Asterix versions can be set in preference settings. The dissector can not guess which version of asterix category is used. User has to set the preferences for Asterix version to be used in dissector in Edit->Preferences->Protocols->ASTERIX.

Example capture file

Sample file.

Display Filter

Filter can be used to display asterix packets. For instance asterix.category == 62 displays only messages with category 62.

Capture Filter

You cannot directly filter ASTERIX protocols while capturing. However, if you know the UDP port used (see above), you can filter on that one.

Discussion

It is interesting to note that the developers of the (external) ASTERIX plugin developed (yet another) code generator to generate the dissector.

ASTERIX (last edited 2014-03-04 12:44:29 by MarkoHrastovec)