asterix specification

Asterix category 048 - Monoradar Target Reports

category: 048

edition: 1.30

date: 2021-11-02

Preamble

Surveillance data exchange.

Description of standard data items

I048/010 - Data Source Identifier

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

Group

I048/010/SAC - System Area Code

Element

bit size: 8

Raw Content

I048/010/SIC - System Identification Code

Element

bit size: 8

Raw Content

Note:

I048/020 - Target Report Descriptor

definition: Type and properties of the target report.

Extended

I048/020/TYP

Element

bit size: 3

Values:

0:
No detection
1:
Single PSR detection
2:
Single SSR detection
3:
SSR + PSR detection
4:
Single ModeS All-Call
5:
Single ModeS Roll-Call
6:
ModeS All-Call + PSR
7:
ModeS Roll-Call +PSR

I048/020/SIM

Element

bit size: 1

Values:

0:
Actual target report
1:
Simulated target report

I048/020/RDP

Element

bit size: 1

Values:

0:
Report from RDP Chain 1
1:
Report from RDP Chain 2

I048/020/SPI

Element

bit size: 1

Values:

0:
Absence of SPI
1:
Special Position Identification

I048/020/RAB

Element

bit size: 1

Values:

0:
Report from aircraft transponder
1:
Report from field monitor (fixed transponder)

(FX) - extension bit

I048/020/TST

Element

bit size: 1

Values:

0:
Real target report
1:
Test target report

I048/020/ERR

Element

bit size: 1

Values:

0:
No Extended Range
1:
Extended Range present

I048/020/XPP

Element

bit size: 1

Values:

0:
No X-Pulse present
1:
X-Pulse present

I048/020/ME

Element

bit size: 1

Values:

0:
No military emergency
1:
Military emergency

I048/020/MI

Element

bit size: 1

Values:

0:
No military identification
1:
Military identification

I048/020/FOEFRI

Element

bit size: 2

Values:

0:
No Mode 4 interrogation
1:
Friendly target
2:
Unknown target
3:
No reply

(FX) - extension bit

Notes:

  1. For Mode S aircraft, the SPI information is also contained in I048/230.
  2. To bits 3/2 (FOE/FRI): IFF interrogators supporting a three level classification of the processing of the Mode 4 interrogation result shall encode the detailed response information in data item M4E of the Reserved Expansion Field of category 048. In this case the value for FOE/FRI in I048/020 shall be set to “00”. However, even those interrogators shall use I048/020 to encode the information “No reply”.
  3. To bit 6 (XPP): This bit shall always be set when the X-pulse has been extracted, independent from the Mode it was extracted with.
  4. To bit 7 (ERR): This bit set to “1” indicates that the range of the target is beyond the maximum range in data item I048/040.In this case – and this case only - the ERR Data Item in the Reserved Expansion Field shall provide the range value of the Measured Position in Polar Coordinates.

I048/030 - Warning/Error Conditions and Target Classification

definition: Warning/error conditions detected by a radar station for the target report involved. Target Classification information for the target involved.

Repetitive

With FX extension bit.

Element

bit size: 7

Values:

0:
Not defined; never used
1:
Multipath Reply (Reflection)
2:
Reply due to sidelobe interrogation/reception
3:
Split plot
4:
Second time around reply
5:
Angel
6:
Slow moving target correlated with road infrastructure (terrestrial vehicle)
7:
Fixed PSR plot
8:
Slow PSR target
9:
Low quality PSR plot
10:
Phantom SSR plot
11:
Non-Matching Mode-3/A Code
12:
Mode C code / Mode S altitude code abnormal value compared to the track
13:
Target in Clutter Area
14:
Maximum Doppler Response in Zero Filter
15:
Transponder anomaly detected
16:
Duplicated or Illegal Mode S Aircraft Address
17:
Mode S error correction applied
18:
Undecodable Mode C code / Mode S altitude code
19:
Birds
20:
Flock of Birds
21:
Mode-1 was present in original reply
22:
Mode-2 was present in original reply
23:
Plot potentially caused by Wind Turbine
24:
Helicopter
25:
Maximum number of re-interrogations reached (surveillance information)
26:
Maximum number of re-interrogations reached (BDS Extractions)
27:
BDS Overlay Incoherence
28:
Potential BDS Swap Detected
29:
Track Update in the Zenithal Gap
30:
Mode S Track re-acquired
31:
Duplicated Mode 5 Pair NO/PIN detected
32:
Wrong DF reply format detected
33:
Transponder anomaly (MS XPD replies with Mode A/C to Mode A/C-only all-call)
34:
Transponder anomaly (SI capability report wrong)

Notes:

  1. It has to be stressed that a series of one or more codes can be reported per target report.

  2. Data conveyed in this item are of secondary importance, and can generally also be derived from the processing of mandatory items.

  3. Definitions can be found in SUR.ET1.ST03.1000-STD-01-01 Radar Sensor Performance Analysis.

  4. Values 25 to 30 have been defined to comply with the updated European Mode S Specification (EMS) and to provide the possibility to report the following information:

    • Code 25: the maximum number of permitted re-interrogations to acquire the surveillance information has been reached;
    • Code 26: the maximum number of permitted re-interrogations to extract BDS Registers has been reached;
    • Code 27: inconsistency detected between the contents of the message and the BDS register overlayed;
    • Code 28: a BDS swap has been detected and the respective information has been discarded;
    • Code 29: the track has been updated while being in the zenithal gap (also referred to as “Cone of Silence”);
    • Code 30: the radar had lost track of an aircraft and subsequently re-acquired it.

I048/040 - Measured Position in Polar Co-ordinates

definition: Measured position of an aircraft in local polar co-ordinates.

Group

I048/040/RHO

Element

bit size: 16

Unsigned quantity

LSB = 1/28 NM ≈ 3.90625e − 3 NM

unit: "NM"

< 256.0

I048/040/THETA

Element

bit size: 16

Unsigned quantity

LSB = 360/216 ° ≈ 5.4931640625e − 3 °

unit: "°"

Notes:

  1. In case of no detection, the extrapolated position expressed in slant polar co-ordinates may be sent, except for a track cancellation message. No detection is signalled by the TYP field set to zero in I048/020 Target Report Descriptor.
  2. This item represents the measured target position of the plot, even if associated with a track, for the present antenna scan. It is expressed in polar co-ordinates in the local reference system, centred on the radar station.
  3. In case of combined detection by a PSR and an SSR, then the SSR position is sent.
  4. For targets having a range beyond the maximum range the data item “Extended Range Report” has been added to the Reserved Expansion Field of category 048. The presence of this data item is indicated by the ERR bit set to one in data item I048/020, first extension. The ERR data item shall only be sent if the value of RHO is equal to or greater than 256NM. Please note that if this data item is used, the Encoding Rule to data item I048/040 still applies, meaning that the extra item in the Reserved Expansion Field shall be transmitted in addition to data item I048/040. If the Extended Range Report item in the Reserved Expansion Field is used, it is recommended to set the value of RHO in data item I048/040 to its maximum, meaning bits 32/17 all set to 1.

I048/042 - Calculated Position in Cartesian Co-ordinates

definition: Calculated position of an aircraft in Cartesian co-ordinates.

Group

I048/042/X - X-Component

Element

bit size: 16

Signed quantity

LSB = 1/27 NM ≈ 7.8125e − 3 NM

unit: "NM"

>= −256.0

<= 256.0

I048/042/Y - X-Component

Element

bit size: 16

Signed quantity

LSB = 1/27 NM ≈ 7.8125e − 3 NM

unit: "NM"

>= −256.0

<= 256.0

I048/050 - Mode-2 Code in Octal Representation

definition: Reply to Mode-2 interrogation.

Group

I048/050/V

Element

bit size: 1

Values:

0:
Code validated
1:
Code not validated

I048/050/G

Element

bit size: 1

Values:

0:
Default
1:
Garbled code

I048/050/L

Element

bit size: 1

Values:

0:
Mode-2 code as derived from the reply of the transponder
1:
Smoothed Mode-2 code as provided by a local tracker

Spare bits: 1

I048/050/MODE2 - Mode-2 Code in Octal Representation

Element

bit size: 12

Octal string (3-bits per char)

Note:
  • Bit 15 has no meaning in the case of a smoothed Mode-2 and is set to 0 for a calculated track.

I048/055 - Mode-1 Code in Octal Representation

definition: Reply to Mode-1 interrogation.

Group

I048/055/V

Element

bit size: 1

Values:

0:
Code validated
1:
Code not validated

I048/055/G

Element

bit size: 1

Values:

0:
Default
1:
Garbled code

I048/055/L

Element

bit size: 1

Values:

0:
Mode-1 code as derived from the reply of the transponder
1:
Smoothed Mode-1 code as provided by a local tracker

I048/055/MODE1 - Mode-1 Code

Element

bit size: 5

Raw Content

Notes:

  1. Bit 7 has no meaning in the case of a smoothed Mode-1 and is set to 0 for a calculated track.
  2. The values of the bits for V, G, L, A4, A2, A1, B2 and B1 shall be identical to the values of the corresponding bits in subfield #5 of data item “MD5 – Mode 5 Reports” and in subfield #5 of data item “MD5 – Mode 5 Reports, New Format” in the Reserved Expansion Field.

I048/060 - Mode-2 Code Confidence Indicator

definition: Confidence level for each bit of a Mode-2 reply as provided by a monopulse SSR station.

Group

Spare bits: 4

I048/060/QA4

Element

bit size: 1

Values:

0:
High quality pulse A4
1:
Low quality pulse A4

I048/060/QA2

Element

bit size: 1

Values:

0:
High quality pulse A2
1:
Low quality pulse A2

I048/060/QA1

Element

bit size: 1

Values:

0:
High quality pulse A1
1:
Low quality pulse A1

I048/060/QB4

Element

bit size: 1

Values:

0:
High quality pulse B4
1:
Low quality pulse B4

I048/060/QB2

Element

bit size: 1

Values:

0:
High quality pulse B2
1:
Low quality pulse B2

I048/060/QB1

Element

bit size: 1

Values:

0:
High quality pulse B1
1:
Low quality pulse B1

I048/060/QC4

Element

bit size: 1

Values:

0:
High quality pulse C4
1:
Low quality pulse C4

I048/060/QC2

Element

bit size: 1

Values:

0:
High quality pulse C2
1:
Low quality pulse C2

I048/060/QC1

Element

bit size: 1

Values:

0:
High quality pulse C1
1:
Low quality pulse C1

I048/060/QD4

Element

bit size: 1

Values:

0:
High quality pulse D4
1:
Low quality pulse D4

I048/060/QD2

Element

bit size: 1

Values:

0:
High quality pulse D2
1:
Low quality pulse D2

I048/060/QD1

Element

bit size: 1

Values:

0:
High quality pulse D1
1:
Low quality pulse D1

I048/065 - Mode-1 Code Confidence Indicator

definition: Confidence level for each bit of a Mode-1 reply as provided by a monopulse SSR station.

Group

Spare bits: 3

I048/065/QA4

Element

bit size: 1

Values:

0:
High quality pulse A4
1:
Low quality pulse A4

I048/065/QA2

Element

bit size: 1

Values:

0:
High quality pulse A2
1:
Low quality pulse A2

I048/065/QA1

Element

bit size: 1

Values:

0:
High quality pulse A1
1:
Low quality pulse A1

I048/065/QB2

Element

bit size: 1

Values:

0:
High quality pulse B2
1:
Low quality pulse B2

I048/065/QB1

Element

bit size: 1

Values:

0:
High quality pulse B1
1:
Low quality pulse B1

I048/070 - Mode-3/A Code in Octal Representation

definition: Mode-3/A code converted into octal representation.

Group

I048/070/V

Element

bit size: 1

Values:

0:
Code validated
1:
Code not validated

I048/070/G

Element

bit size: 1

Values:

0:
Default
1:
Garbled code

I048/070/L

Element

bit size: 1

Values:

0:
Mode-3/A code derived from the reply of the transponder
1:
Mode-3/A code not extracted during the last scan

Spare bits: 1

I048/070/MODE3A - Mode-3/A Reply in Octal Representation

Element

bit size: 12

Octal string (3-bits per char)

Notes:

  1. Bit 15 has no meaning in the case of a smoothed Mode-3/A code and is set to 0 for a calculated track. For Mode S, it is set to one when an error correction has been attempted.
  2. For Mode S, bit 16 is normally set to zero, but can exceptionally be set to one to indicate a non-validated Mode-3/A code (e.g. alert condition detected, but new Mode-3/A code not successfully extracted).

I048/080 - Mode-3/A Code Confidence Indicator

definition: Confidence level for each bit of a Mode-3/A reply as provided by a monopulse SSR station.

Group

Spare bits: 4

I048/080/QA4

Element

bit size: 1

Values:

0:
High quality pulse A4
1:
Low quality pulse A4

I048/080/QA2

Element

bit size: 1

Values:

0:
High quality pulse A2
1:
Low quality pulse A2

I048/080/QA1

Element

bit size: 1

Values:

0:
High quality pulse A1
1:
Low quality pulse A1

I048/080/QB4

Element

bit size: 1

Values:

0:
High quality pulse B4
1:
Low quality pulse B4

I048/080/QB2

Element

bit size: 1

Values:

0:
High quality pulse B2
1:
Low quality pulse B2

I048/080/QB1

Element

bit size: 1

Values:

0:
High quality pulse B1
1:
Low quality pulse B1

I048/080/QC4

Element

bit size: 1

Values:

0:
High quality pulse C4
1:
Low quality pulse C4

I048/080/QC2

Element

bit size: 1

Values:

0:
High quality pulse C2
1:
Low quality pulse C2

I048/080/QC1

Element

bit size: 1

Values:

0:
High quality pulse C1
1:
Low quality pulse C1

I048/080/QD4

Element

bit size: 1

Values:

0:
High quality pulse D4
1:
Low quality pulse D4

I048/080/QD2

Element

bit size: 1

Values:

0:
High quality pulse D2
1:
Low quality pulse D2

I048/080/QD1

Element

bit size: 1

Values:

0:
High quality pulse D1
1:
Low quality pulse D1

I048/090 - Flight Level in Binary Representation

definition: Flight Level converted into binary representation.

Group

I048/090/V

Element

bit size: 1

Values:

0:
Code validated
1:
Code not validated

I048/090/G

Element

bit size: 1

Values:

0:
Default
1:
Garbled code

I048/090/FL

Element

bit size: 14

Unsigned quantity

LSB = 1/22 FL ≈ 0.25 FL

unit: "FL"

Notes:

  1. When Mode C code / Mode S altitude code is present but not decodable, the “Undecodable Mode C code / Mode S altitude code” Warning/Error should be sent in I048/030.
  2. When local tracking is applied and the received Mode C code / Mode S altitude code corresponds to an abnormal value (the variation with the previous plot is estimated too important by the tracker), the “Mode C code / Mode S altitude code abnormal value compared to the track“ Warning/Error should be sent in I048/030.
  3. The value shall be within the range described by ICAO Annex 10
  4. For Mode S, bit 15 (G) is set to one when an error correction has been attempted.

I048/100 - Mode-C Code and Code Confidence Indicator

definition: Mode-C height in Gray notation as received from the transponder together with the confidence level for each reply bit as provided by a MSSR/Mode S station.

Group

I048/100/V

Element

bit size: 1

Values:

0:
Code validated
1:
Code not validated

I048/100/G

Element

bit size: 1

Values:

0:
Default
1:
Garbled code

Spare bits: 2

I048/100/MODEC - Mode-C Reply in Gray Notation

Element

bit size: 12

Raw Content

Spare bits: 4

I048/100/QC1

Element

bit size: 1

Values:

0:
High quality pulse C1
1:
Low quality pulse C1

I048/100/QA1

Element

bit size: 1

Values:

0:
High quality pulse A1
1:
Low quality pulse A1

I048/100/QC2

Element

bit size: 1

Values:

0:
High quality pulse C2
1:
Low quality pulse C2

I048/100/QA2

Element

bit size: 1

Values:

0:
High quality pulse A2
1:
Low quality pulse A2

I048/100/QC4

Element

bit size: 1

Values:

0:
High quality pulse C4
1:
Low quality pulse C4

I048/100/QA4

Element

bit size: 1

Values:

0:
High quality pulse A4
1:
Low quality pulse A4

I048/100/QB1

Element

bit size: 1

Values:

0:
High quality pulse B1
1:
Low quality pulse B1

I048/100/QD1

Element

bit size: 1

Values:

0:
High quality pulse D1
1:
Low quality pulse D1

I048/100/QB2

Element

bit size: 1

Values:

0:
High quality pulse B2
1:
Low quality pulse B2

I048/100/QD2

Element

bit size: 1

Values:

0:
High quality pulse D2
1:
Low quality pulse D2

I048/100/QB4

Element

bit size: 1

Values:

0:
High quality pulse B4
1:
Low quality pulse B4

I048/100/QD4

Element

bit size: 1

Values:

0:
High quality pulse D4
1:
Low quality pulse D4

Notes:

  1. For Mode S, D1 is also designated as Q, and is used to denote either 25ft or 100ft reporting.
  2. For Mode S, bit-31 (G) is set when an error correction has been attempted.

I048/110 - Height Measured by a 3D Radar

definition: Height of a target as measured by a 3D radar. The height shall use mean sea level as the zero reference level.

Group

Spare bits: 2

I048/110/3DH - 3D Height, in Binary Notation. Negative Values Are Expressed in Two's Complement

Element

bit size: 14

Signed quantity

LSB = 25 ft ≈ 25.0 ft

unit: "ft"

I048/120 - Radial Doppler Speed

definition: Information on the Doppler Speed of the target report.

Compound

I048/120/CAL - Calculated Doppler Speed

Group

I048/120/CAL/D

Element

bit size: 1

Values:

0:
Doppler speed is valid
1:
Doppler speed is doubtful

Spare bits: 5

I048/120/CAL/CAL - Calculated Doppler Speed, Coded in Two's Complement

Element

bit size: 10

Signed quantity

LSB = 1 m/s ≈ 1.0 m/s

unit: "m/s"

I048/120/RDS - Raw Doppler Speed

Repetitive

Regular, 1 byte(s) REP field size.

Group

I048/120/RDS/DOP - Doppler Speed

Element

bit size: 16

Unsigned quantity

LSB = 1 m/s ≈ 1.0 m/s

unit: "m/s"

I048/120/RDS/AMB - Ambiguity Range

Element

bit size: 16

Unsigned quantity

LSB = 1 m/s ≈ 1.0 m/s

unit: "m/s"

I048/120/RDS/FRQ - Transmitter Frequency

Element

bit size: 16

Unsigned quantity

LSB = 1 MHz ≈ 1.0 MHz

unit: "MHz"

I048/130 - Radar Plot Characteristics

definition: Additional information on the quality of the target report.

Compound

I048/130/SRL - SSR Plot Runlength

description: SSR plot runlength, expressed as a positive binary value.

Element

bit size: 8

Unsigned quantity

LSB = 360/213 ° ≈ 4.39453125e − 2 °

unit: "°"

I048/130/SRR - Number of Received Replies for (M)SSR

description: Number of Received Replies for (M)SSR

Element

bit size: 8

Unsigned integer

I048/130/SAM - Amplitude of (M)SSR Reply

description: Amplitude of (M)SSR Reply

Element

bit size: 8

Signed quantity

LSB = 1 dBm ≈ 1.0 dBm

unit: "dBm"

I048/130/PRL - Primary Plot Runlength

description: Primary Plot Runlength, expressed as positive binary value

Element

bit size: 8

Unsigned quantity

LSB = 360/213 ° ≈ 4.39453125e − 2 °

unit: "°"

I048/130/PAM - Amplitude of Primary Plot

description: Amplitude of Primary Plot

Element

bit size: 8

Signed quantity

LSB = 1 dBm ≈ 1.0 dBm

unit: "dBm"

I048/130/RPD - Difference in Range Between PSR and SSR Plot

description: Range (PSR-SSR)

Element

bit size: 8

Signed quantity

LSB = 1/28 NM ≈ 3.90625e − 3 NM

unit: "NM"

I048/130/APD - Difference in Azimuth Between PSR and SSR Plot

description: Azimuth (PSR-SSR)

Element

bit size: 8

Signed quantity

LSB = 360/214 ° ≈ 2.197265625e − 2 °

unit: "°"

Notes:

  1. The total range covered is therefore from 0 to 11.21 °.
  2. Negative values are coded in two's complement form.
  3. The total range covered is therefore from 0 to 11.21 °.
  4. Negative values are coded in two's complement form.
  5. Negative values are coded in two's complement form.
  6. The covered range difference is +/- 0.5 NM.
  7. Sending the maximum value means that the difference in range is equal or greater than the maximum value.
  8. Negative values are coded in two's complement form.
  9. The covered azimuth difference is +/-360/2 7 = +/- 2.8125 °.
  10. Sending the maximum value means that the difference in range is equal or greater than the maximum value.

I048/140 - Time of Day

definition: Absolute time stamping expressed as Co-ordinated Universal Time (UTC).

Element

bit size: 24

Unsigned quantity

LSB = 1/27 s ≈ 7.8125e − 3 s

unit: "s"

< 86400.0

Notes:

  1. The time of day value is reset to 0 each day at midnight.
  2. Every radar station using ASTERIX should be equipped with at least one synchronised time source

I048/161 - Track Number

definition: An integer value representing a unique reference to a track record within a particular track file.

Group

Spare bits: 4

I048/161/TRN - Track Number

Element

bit size: 12

Raw Content

I048/170 - Track Status

definition: Status of monoradar track (PSR and/or SSR updated).

Extended

I048/170/CNF - Confirmed Vs. Tentative Track

Element

bit size: 1

Values:

0:
Confirmed Track
1:
Tentative Track

I048/170/RAD - Type of Sensor(s) Maintaining Track

Element

bit size: 2

Values:

0:
Combined Track
1:
PSR Track
2:
SSR/Mode S Track
3:
Invalid

I048/170/DOU - Signals Level of Confidence in Plot to Track Association Process

Element

bit size: 1

Values:

0:
Normal confidence
1:
Low confidence in plot to track association

I048/170/MAH - Manoeuvre Detection in Horizontal Sense

Element

bit size: 1

Values:

0:
No horizontal man.sensed
1:
Horizontal man. sensed

I048/170/CDM - Climbing / Descending Mode

Element

bit size: 2

Values:

0:
Maintaining
1:
Climbing
2:
Descending
3:
Unknown

(FX) - extension bit

I048/170/TRE - Signal for End_of_Track

Element

bit size: 1

Values:

0:
Track still alive
1:
End of track lifetime(last report for this track)

I048/170/GHO - Ghost Vs. True Target

Element

bit size: 1

Values:

0:
True target track
1:
Ghost target track

I048/170/SUP - Track Maintained with Track Information from Neighbouring Node B on the Cluster, or Network

Element

bit size: 1

Values:

0:
No
1:
Yes

I048/170/TCC - Type of Plot Coordinate Transformation Mechanism:

Element

bit size: 1

Values:

0:
Tracking performed in so-called 'Radar Plane', i.e. neither slant range correction nor stereographical projection was applied
1:
Slant range correction and a suitable projection technique are used to track in a 2D.reference plane, tangential to the earth model at the Radar Site co-ordinates

Spare bits: 3

(FX) - extension bit

I048/200 - Calculated Track Velocity in Polar Co-ordinates

definition: Calculated track velocity expressed in polar co-ordinates.

Group

I048/200/GSP - Calculated Groundspeed

Element

bit size: 16

Unsigned quantity

LSB = 1/214 NM/s ≈ 6.103515625e − 5 NM/s

unit: "NM/s"

I048/200/HDG - Calculated Heading

Element

bit size: 16

Unsigned quantity

LSB = 360/216 ° ≈ 5.4931640625e − 3 °

unit: "°"

Notes:

I048/210 - Track Quality

definition: Track quality in the form of a vector of standard deviations.

Group

I048/210/SIGX - Sigma (X)) Standard Deviation on the Horizontal Axis of the Local Grid System

Element

bit size: 8

Unsigned quantity

LSB = 1/27 NM ≈ 7.8125e − 3 NM

unit: "NM"

I048/210/SIGY - Sigma (Y)) Standard Deviation on the Vertical Axis of the Local Grid System

Element

bit size: 8

Unsigned quantity

LSB = 1/27 NM ≈ 7.8125e − 3 NM

unit: "NM"

I048/210/SIGV - Sigma (V)) Standard Deviation on the Groundspeed Within the Local Grid System

Element

bit size: 8

Unsigned quantity

LSB = 1/214 NM/s ≈ 6.103515625e − 5 NM/s

unit: "NM/s"

I048/210/SIGH - Sigma (H)) Standard Deviation on the Heading Within the Local Grid System

Element

bit size: 8

Unsigned quantity

LSB = 360/212 ° ≈ 8.7890625e − 2 °

unit: "°"

Notes:

  1. The standard deviation is per definition a positive value, hence the range covered is : 0<= Sigma(X)<2 NM
  2. The standard deviation is per definition a positive value, hence the range covered is : 0<= Sigma(Y)<2 NM
  3. The standard deviation is per definition a positive value, hence the range covered is: 0<=Sigma (V)<56.25 Kt
  4. The standard deviation is per definition a positive value; hence the range covered is: 0 <= sigma (H) < 22.5 degrees.

I048/220 - Aircraft Address

definition: Aircraft address (24-bits Mode S address) assigned uniquely to each aircraft.

Element

bit size: 24

Raw Content

Note:
  • The Encoding Rule for Data Item I048/220 has been relaxed in Edition 1.30 for the “End of Track Message”. In order to prevent interoperability problems it is recommended that systems sending I048/220 in an “End of Track Message” continue to do so.

I048/230 - Communications/ACAS Capability and Flight Status

definition: Communications capability of the transponder, capability of the on-board ACAS equipment and flight status.

Group

I048/230/COM - Communications Capability of the Transponder

Element

bit size: 3

Values:

0:
No communications capability (surveillance only)
1:
Comm. A and Comm. B capability
2:
Comm. A, Comm. B and Uplink ELM
3:
Comm. A, Comm. B, Uplink ELM and Downlink ELM
4:
Level 5 Transponder capability

I048/230/STAT - Flight Status

Element

bit size: 3

Values:

0:
No alert, no SPI, aircraft airborne
1:
No alert, no SPI, aircraft on ground
2:
Alert, no SPI, aircraft airborne
3:
Alert, no SPI, aircraft on ground
4:
Alert, SPI, aircraft airborne or on ground
5:
No alert, SPI, aircraft airborne or on ground
7:
Unknown

I048/230/SI - SI/II Transponder Capability

Element

bit size: 1

Values:

0:
SI-Code Capable
1:
II-Code Capable

Spare bits: 1

I048/230/MSSC - Mode-S Specific Service Capability

Element

bit size: 1

Values:

0:
No
1:
Yes

I048/230/ARC - Altitude Reporting Capability

Element

bit size: 1

Values:

0:
100 ft resolution
1:
25 ft resolution

I048/230/AIC - Aircraft Identification Capability

Element

bit size: 1

Values:

0:
No
1:
Yes

I048/230/B1A - BDS 1,0 Bit 16

Element

bit size: 1

Raw Content

I048/230/B1B - BDS 1,0 Bits 37/40

Element

bit size: 4

Raw Content

Note:
  • This item shall be present in every ASTERIX record conveying data related to a Mode S target, except for an “End of Track Message” (i.e. I048/170, First Extension, Bit 8 is set to “1”) in which this Data Item is optional. If the datalink capability has not been extracted yet, bits 16/14 shall be set to zero.

I048/240 - Aircraft Identification

definition: Aircraft identification (in 8 characters) obtained from an aircraft equipped with a Mode S transponder.

Element

bit size: 48

ICAO string (6-bits per char)

Notes:

  1. This data item contains the flight identification as available in the respective Mode S transponder registers.
  2. The Encoding Rule for Data Item I048/240 has been relaxed in Edition 1.30 for the “End of Track Message”. In order to prevent interoperability problems it is recommended that systems sending I048/240 in an “End of Track Message” continue to do so.

I048/250 - BDS Register Data

definition: BDS Register Data as extracted from the aircraft transponder.

Repetitive

Regular, 1 byte(s) REP field size.

Group

I048/250/MBDATA - Mode S Comm B Message Data

Element

bit size: 56

Raw Content

I048/250/BDS1 - Comm B Data Buffer Store 1 Address

Element

bit size: 4

Raw Content

I048/250/BDS2 - Comm B Data Buffer Store 2 Address

Element

bit size: 4

Raw Content

Notes:

  1. For the transmission of BDS Register 2,0, Data Item I048/240 is used.
  2. For the transmission of BDS Register 3,0, Data Item I048/260 is used. In case of ACAS Xu (as defined in [3]), the Resolution Advisory consists of two parts (BDS Register 3,0 and BDS Register 3,1). BDS Register 3,1 will be transmitted using Data Item I048/250. For the detailed definition of BDS Register 3,0 and 3,1please refer to [2] Tables B-3-48a and B-3-49.
  3. In case of data extracted via Comm-B broadcast, all bits of fields BDS1 and BDS2 are set to 0; in case of data extracted via GICB requests, the fields BDS1 and BDS2 correspond to the GICB register number.
  4. The Encoding Rule for Data Item I048/250 has been relaxed in Edition 1.30 for the “End of Track Message”. In order to prevent interoperability problems it is recommended that systems sending I048/250 in an “End of Track Message” continue to do so.

I048/260 - ACAS Resolution Advisory Report

definition: Currently active Resolution Advisory (RA), if any, generated by the ACAS associated with the transponder transmitting the report and threat identity data.

Element

bit size: 56

Raw Content

Notes:

  1. Refer to ICAO Draft SARPs for ACAS for detailed explanations.
  2. In case of ACAS Xu, the Resolution Advisory consists of two parts (BDS30 and BDS31). BDS31 will be transmitted using item 250.

I048/RE - Reserved Expansion Field

definition: Expansion

Explicit (ReservedExpansion)

I048/SP - Special Purpose Field

definition: Special Purpose Field

Explicit (SpecialPurpose)

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