Asterix expansion 021 - ADS-B Target Reports Expansion

category: 021

edition: 1.4

date: 2018-03-08

Description of asterix expansion

Compound item (fspec=8 bits)

I021/BPS - Barometric Pressure Setting

I021/BPS/(spare)

4 bits [....]

I021/BPS/BPS - Barometric Pressure Setting

12 bits [............]

unsigned quantity

unit: “hPa”

LSB = 1/10 hPa ≈ 0.10 hPa

value > = 0 hPa

value < = 819/2 hPa

remark

Notes:

BPS is the barometric pressure setting of the aircraft minus 800 hPa

A value of “0” indicates that in the aircraft a value of 800 hPa or less has been selected.

A value of “409.5” indicates that in the aircraft a value of 1209.5 hPa or more has been selected.

I021/SH - Selected Heading

I021/SH/(spare)

4 bits [....]

I021/SH/HDR - Horizontal Reference Direction

1 bit [.]

values:

0: True North
1: Magnetic North

I021/SH/STAT - Selected Heading Status

1 bit [.]

values:

0: Data is either unavailable or invalid
1: Data is available and valid

I021/SH/SH - Selected Heading

10 bits [..........]

unsigned quantity

unit: “°”

LSB = 45/2⁶ ° ≈ 0.70 °

remark

On many aircraft, the ADS-B Transmitting Subsystem receives Selected Heading from a Mode Control Panel / Flight Control Unit (MCP / FCU). Users of this data are cautioned that the Selected Heading value transmitted by the ADS-B Transmitting Subsystem does not necessarily reflect the true intention of the airplane during certain flight modes (e.g., during LNAV mode).

I021/NAV - Navigation Mode

I021/NAV/AP - Autopilot

1 bit [.]

values:

0: Autopilot not engaged
1: Autopilot engaged

I021/NAV/VN - Vertical Navigation

1 bit [.]

values:

0: Vertical Navigation not active
1: Vertical Navigation active

I021/NAV/AH - Altitude Hold

1 bit [.]

values:

0: Altitude Hold not engaged
1: Altitude Hold engaged

I021/NAV/AM - Approach Mode

1 bit [.]

values:

0: Approach Mode not active
1: Approach Mode active

I021/NAV/(spare)

4 bits [....]

remark

This data-item should only be transmitted if an ADS-B indication has been received that the mode bits have been “actively populated”.by the avionics (1090 ES version 2 (as defined in I021/210) BDS 6,2, subtype 1, bit 47: “Status of MCP / FCU Mode Bits”)

I021/GAO - GPS Antenna Offset

8 bits [........]

raw value

remark

The value of this field is copied from the respective bits 33-40 of version 2 (as defined in I021/210) of 1090 ES BDS register 6,5 (Aircraft Operational Status)

I021/SGV - Surface Ground Vector

Extended item.

I021/SGV/STP

1 bit [.]

values:

0: Aircraft has not stopped
1: Aircraft has stopped

I021/SGV/HTS

1 bit [.]

values:

0: Heading/Ground Track data is not valid
1: Heading/Ground Track data is valid

I021/SGV/HTT

1 bit [.]

values:

0: Heading data provided
1: Ground Track provided

I021/SGV/HRD

1 bit [.]

values:

0: True North
1: Magnetic North

I021/SGV/GSS - Ground Speed

11 bits [...........]

unsigned quantity

unit: “kt”

LSB = 1/2³ kt ≈ 0.12 kt

(FX)

extension bit

0: End of data item
1: Extension into next extent

I021/SGV/HGT - Heading/Ground Track Information

7 bits [.......]

unsigned quantity

unit: “°”

LSB = 45/2⁴ ° ≈ 2.81 °

(FX)

extension bit

0: End of data item
1: Extension into next extent

I021/STA - Aircraft Status

Extended item.

I021/STA/ES

1 bit [.]

values:

0: Target is not 1090 ES IN capable
1: Target is 1090 ES IN capable

I021/STA/UAT

1 bit [.]

values:

0: Target is not UAT IN capable
1: Target is UAT IN capable

I021/STA/(spare)

5 bits [.....]

(FX)

extension bit

0: End of data item
1: Extension into next extent

I021/TNH - True North Heading

16 bits [................]

unsigned quantity

unit: “°”

LSB = 360/2¹⁶ ° ≈ 5.49e − 3 °

remark

Magnetic Heading is defined in I021/152.

I021/MES - Military Extended Squitter

Compound item (FX)

I021/MES/SUM - Mode 5 Summary

I021/MES/SUM/M5

1 bit [.]

values:

0: No Mode 5 interrogation
1: Mode 5 interrogation

I021/MES/SUM/ID

1 bit [.]

values:

0: No authenticated Mode 5 ID reply/report
1: Authenticated Mode 5 ID reply/report

I021/MES/SUM/DA

1 bit [.]

values:

0: No authenticated Mode 5 Data reply or Report
1: Authenticated Mode 5 Data reply or Report (i.e any valid Mode 5 reply type other than ID)

I021/MES/SUM/M1

1 bit [.]

values:

0: Mode 1 code not present or not from Mode 5 reply/report
1: Mode 1 code from Mode 5 reply/report

I021/MES/SUM/M2

1 bit [.]

values:

0: Mode 2 code not present or not from Mode 5 reply/report
1: Mode 2 code from Mode 5 reply/report

I021/MES/SUM/M3

1 bit [.]

values:

0: Mode 3 code not present or not from Mode 5 reply/report
1: Mode 3 code from Mode 5 reply/report

I021/MES/SUM/MC

1 bit [.]

values:

0: Flightlevel not present or not from Mode 5 reply/report
1: Flightlevel from Mode 5 reply/report

I021/MES/SUM/PO

1 bit [.]

values:

0: Position not from Mode 5 report (ADS-B report)
1: Position from Mode 5 report

remark

Notes:

The flag M2 refers to the contents of Subfield #6 below, M3, MC refer to the contents of data items I021/070 and I021/145 respectively. The flag M1 refers to the contents of Subfield #3 below (Extended Mode 1 Code in Octal Representation).

If a Mode 5 reply/report is received with the Emergency bit set, then the Military Emergency bit (ME) in Data Item I021/200, Target Status, shall be set.

If a Mode 5 reply/report is received with the Identification of Position bit set, then the Special Position Identification bit (SPI) in Data Item I021/200, Target Status, shall be set.

If a Mode 5 report (ID or Data) is received and fullfill the autentication criteria the corresponding authentication bit shall be set.

I021/MES/PNO - Mode 5 PIN / National Origin

I021/MES/PNO/(spare)

2 bits [..]

I021/MES/PNO/PIN - PIN Code

14 bits [..............]

raw value

I021/MES/PNO/(spare)

5 bits [.....]

I021/MES/PNO/NO - National Origin Code

11 bits [...........]

raw value

I021/MES/EM1 - Extended Mode 1 Code in Octal Representation

I021/MES/EM1/V

1 bit [.]

values:

0: Code validated
1: Code not validated

I021/MES/EM1/(spare)

1 bit [.]

I021/MES/EM1/L

1 bit [.]

values:

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

I021/MES/EM1/(spare)

1 bit [.]

I021/MES/EM1/EM1 - Extended Mode 1 Code in Octal Representation

12 bits [............]

Octal string (3-bits per digit)

remark

Notes:

Subfield #1 is present, the M1 bit in Subfield #1 indicates whether the Extended Mode 1 Code is from a Mode 5 reply or a Mode 1 reply. If Subfield #1 is not present, the Extended Mode 1 Code is from a Mode 1 reply.

If Subfield #3 is not present the Mode 1 Code was not reported or all Code Bits were equal to 0.

The valid bit is set if the Code was only reported once for that target.

I021/MES/XP - X Pulse Presence

I021/MES/XP/(spare)

2 bits [..]

I021/MES/XP/XP - X-pulse from Mode 5 PIN Reply/report

1 bit [.]

values:

0: X-Pulse not present
1: X-pulse present

I021/MES/XP/X5 - X-pulse from Mode 5 Data Reply or Report

1 bit [.]

values:

0: X-pulse set to zero or no authenticated Data reply or Report received
1: X-pulse set to one (present)

I021/MES/XP/XC - X-pulse from Mode C Reply

1 bit [.]

values:

0: X-pulse set to zero or no Mode C reply
1: X-pulse set to one (present)

I021/MES/XP/X3 - X-pulse from Mode 3/A Reply

1 bit [.]

values:

0: X-pulse set to zero or no Mode 3/A reply
1: X-pulse set to one (present)

I021/MES/XP/X2 - X-pulse from Mode 2 Reply

1 bit [.]

values:

0: 0 X-pulse set to zero or no Mode 2 reply
1: X-pulse set to one (present)

I021/MES/XP/X1 - X-pulse from Mode 1 Reply

1 bit [.]

values:

0: X-pulse set to zero or no Mode 1 reply
1: X-pulse set to one (present)

remark

Within Mode 5 reports, the X-Pulse can be set for the following cases:

1. In a combined Mode 1 and Mode 2 report: in this case the X5 bit and the X2 bit shall be set;

2. In a combined Mode 3 and Mode C report: in this case the X5 bit and the X3 bit shall be set;

3. In a Mode 5 PIN data report: in this case the X5 bit and the XP bit shall be set. The X1 bit and the XC bit are meaningless as in Mode 1 and Mode C replies/reports the X Pulse is not defined. They are kept for compatibility reasons.

I021/MES/FOM - Figure of Merit

I021/MES/FOM/(spare)

3 bits [...]

I021/MES/FOM/FOM - Figure of Merit

5 bits [.....]

raw value

I021/MES/M2 - Mode 2 Code in Octal Representation

I021/MES/M2/V

1 bit [.]

values:

0: Code validated
1: Code not validated

I021/MES/M2/(spare)

1 bit [.]

I021/MES/M2/L

1 bit [.]

values:

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

I021/MES/M2/(spare)

1 bit [.]

I021/MES/M2/MODE2 - Mode 2 Code in Octal Representation

12 bits [............]

Octal string (3-bits per digit)

remark

If Subfield 6 is not present the Mode 2 Code was no reported or all Code Bits were equal to 0.

remark

Notes:

The Reserved Expansion Field is optional. When used to transmit MES, it shall be sent when the targets are represented by Mode 5 Level 2 reports.

The information contained in this data item is specific to 1090MHz Extended Squitter messages transmitted by military aircraft (Mode 5 Level 2 squitter).