asterix specification

Asterix category 009 - Composite Weather Reports

category: 009

edition: 2.1

date: 2014-10-22

Preamble

Surveillance data exchange.

Description of standard data items

I009/000 - Message Type

definition: This Data Item allows for a more convenient handling of the messages at the receiver side by further defining the type of transaction.

Element

bit size: 8

Values:

2:
Cartesian vector
253:
Intermediate-update-step message
254:
Start-of-picture message
255:
End-of-picture message

I009/010 - Data Source Identifier

definition: Identification of the radar station from which the data are received.

Group

I009/010/SAC - System Area Code

Element

bit size: 8

Raw Content

I009/010/SIC - System Identification Code

Element

bit size: 8

Raw Content

Note:

The defined SACs are on the EUROCONTROL ASTERIX website (www.eurocontrol.int/asterix)

I009/020 - Vector Qualifier

definition: This Data Item defines the orientation of the following sequence of Cartesian vectors, their intensity level and the relevant coordinate system.

Extended

I009/020/ORG

Element

bit size: 1

Values:

0:
Local Coordinates
1:
System Coordinates

I009/020/I - Intensity Level

Element

bit size: 3

Unsigned integer

I009/020/S - Shading Orientation with Respect to North

Element

bit size: 3

Values:

0:
0°
1:
22.5°
2:
45°
3:
67.5°
4:
90°
5:
112.5°
6:
135°
7:
157.5°

(FX) - extension bit

For polar vectors "S-bits" are meaningless and shall be set to zero.

I009/030 - Sequence of Cartesian Vectors

definition: Sequence of weather vectors in local or system Cartesian coordinates.

Repetitive

Regular, 1 byte(s) REP field size.

Group

I009/030/X - X-coordinate

Element

bit size: 16

Signed integer

Adjust with scaling factor '080/F' 2exp (-6+f), where f is the scaling factor applied, modifying the standard quantisation unit. Range:-2exp (9+f) =<X<2exp (9+f) NM.

I009/030/Y - Y-coordinate

Element

bit size: 16

Signed integer

Adjust with scaling factor '080/F' 2exp (-6+f), where f is the scaling factor applied, modifying the standard quantisation unit. Range:-2exp (9+f) =<Y<2exp (9+f) NM.

I009/030/L - Vector Length

Element

bit size: 16

Unsigned integer

Adjust with scaling factor '080/F' 2exp (-6+f). Max. range = 2exp (9+f) NM.

'F' shall be incorporated as a parameter in the SOP message.

I009/060 - Synchronisation/Control Signal

definition: This Data Item provides the serial Step Number.

Extended

I009/060/SN - Step Number

Element

bit size: 6

Unsigned integer

Spare bits: 1

(FX) - extension bit

I009/070 - Time of Day

definition: Absolute time stamping expressed as UTC time.

Element

bit size: 24

Unsigned quantity

LSB = 1/27 s ≈ 7.8125e − 3 s

unit: "s"

The time of day value is reset to zero each day at midnight.

I009/080 - Processing Status

definition: Processing status of the Track Server.

Extended

I009/080/F - Scaling Factor

Element

bit size: 5

Signed integer

I009/080/R - Current Reduction Stage in Use

Element

bit size: 3

Raw Content

I009/080/Q - Processing Parameters

Element

bit size: 15

Raw Content

(FX) - extension bit

I009/090 - Radar Configuration and Status

definition: Current radar configuration and status of all operational radars.

Repetitive

Regular, 1 byte(s) REP field size.

Group

I009/090/SAC - SAC of Radar Concerned

Element

bit size: 8

Raw Content

I009/090/SIC - SIC of Radar Concerned

Element

bit size: 8

Raw Content

Spare bits: 3

I009/090/CP - Circular Polarisation

Element

bit size: 1

Raw Content

I009/090/WO - Weather Channel Overload

Element

bit size: 1

Raw Content

I009/090/R - Reduction Step in Use By Radar Concerned

Element

bit size: 3

Raw Content

I009/100 - Vector Count

definition: Total number of vectors defining a complete weather picture.

Element

bit size: 16

Unsigned integer

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