Asterix category 023 - CNS/ATM Ground Station and Service Status Reports

category: 023

edition: 1.3

date: 2021-09-27

Preamble

Surveillance data exchange.

Description of standard data items

I023/000 - Report Type

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

Structure:

• 8 bits [........]

• values:

  1: Ground station status report
  2: Service status report
  3: Service statistics report

NOTES:

1. In applications where transactions of various types are exchanged, the Report Type Data Item facilitates the proper report handling at the receiver side.
2. All Report Type values are reserved for common standard use.

I023/010 - Data Source Identifier

Definition: Identification of the Ground Station from which the data is received.

Structure:

I023/010/SAC - System Area Code

• 8 bits [........]
• raw value

I023/010/SIC - System Identification Code

• 8 bits [........]
• raw value

Note:

• The up-to-date list of SACs is published on the EUROCONTROL Web Site (http://www.eurocontrol.int/asterix).

I023/015 - Service Type and Identification

Definition: Identifies the type of service being reported.

Structure:

I023/015/SID - Service Identification

• 4 bits [....]
• raw value

I023/015/STYP - Type of Service

• 4 bits [....]

• values:

  1: ADS-B VDL4
  2: ADS-B Ext Squitter
  3: ADS-B UAT
  4: TIS-B VDL4
  5: TIS-B Ext Squitter
  6: TIS-B UAT
  7: FIS-B VDL4
  8: GRAS VDL4
  9: MLT

Note:

• The service identification is allocated by the system.
• The service identification is also available in item I021/015.

I023/070 - Time of Day

Definition: Absolute time stamping expressed as UTC time.

Structure:

• 24 bits [........................]
• unsigned quantity
• unit: “s”
• LSB = 1/2⁷ s  ≈ 7.81e − 3 s

Notes:

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

I023/100 - Ground Station Status

Definition: Information concerning the status of a Ground Station.

Structure:

Extended item.

I023/100/NOGO - Operational Release Status of the Data

• 1 bit [.]

• values:

  0: Data is released for operational use
  1: Data must not be used operationally

I023/100/ODP - Data Processor Overload Indicator

• 1 bit [.]

• values:

  0: Default, no overload
  1: Overload in DP

I023/100/OXT - Ground Interface Data Communications Overload

• 1 bit [.]

• values:

  0: Default, no overload
  1: Overload in transmission subsystem

I023/100/MSC - Monitoring System Connected Status

• 1 bit [.]

• values:

  0: Monitoring system not connected or unknown
  1: Monitoring system connected

I023/100/TSV - Time Source Validity

• 1 bit [.]

• values:

  0: Valid
  1: Invalid

I023/100/SPO - Indication of Spoofing Attack

• 1 bit [.]

• values:

  0: No spoofing detected
  1: Potential spoofing attack

I023/100/RN - Renumbering Indication for Track ID

• 1 bit [.]

• values:

  0: Default
  1: Track numbering has restarted

(FX)

• extension bit

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

I023/100/GSSP - Ground Station Status Reporting Period

• 7 bits [.......]
• unsigned quantity
• unit: “s”
• LSB = 1 s
• value  >  = 1 s
• value  <  = 127 s

(FX)

• extension bit

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

Notes:

1. A time source is considered as valid when either externally synchronised or running on a local oscillator within the required accuracy of UTC.
2. Bit 8 (NOGO), when set to “1” indicates that the data transmitted by the GS is not released for operational use.
3. Bit 2 indicates that the allocation of Track-IDs (Item I021/161) was re-started.

I023/101 - Service Configuration

Definition: Information concerning the configuration of a Service.

Structure:

Extended item.

I023/101/RP - Report Period for Category 021 Reports

• 8 bits [........]
• unsigned quantity
• unit: “s”
• LSB = 1/2 s  ≈ 0.50 s

I023/101/SC - Service Class

• 3 bits [...]

• values:

  0: No information
  1: NRA class
  2: Reserved for future use
  3: Reserved for future use
  4: Reserved for future use
  5: Reserved for future use
  6: Reserved for future use
  7: Reserved for future use

I023/101/(spare)

• 4 bits [....]

(FX)

• extension bit

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

I023/101/SSRP - Service Status Reporting Period

• 7 bits [.......]
• unsigned quantity
• unit: “s”
• LSB = 1 s
• value  >  = 1 s
• value  <  = 127 s

(FX)

• extension bit

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

I023/110 - Service Status

Definition: Information concerning the status of the Service provided by a Ground Station.

Structure:

Extended item.

I023/110/(spare)

• 4 bits [....]

I023/110/STAT - Status of the Service

• 3 bits [...]

• values:

  0: Unknown
  1: Failed
  2: Disabled
  3: Degraded
  4: Normal
  5: Initialisation

(FX)

• extension bit

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

I023/120 - Service Statistics

Definition: Statistics concerning the service. Provides counts of various ADS-B message types that have been received since the report was last sent.

Structure:

Repetitive item, repetition factor 8 bits.

I023/120/TYPE - Type of Report Counter

• 8 bits [........]

• values:

  0: Number of unknown messages received
  1: Number of too old messages received
  2: Number of failed message conversions
  3: Total Number of messages received
  4: Total Number of messages transmitted
  20: Number of TIS-B management messages received
  21: Number of Basic messages received
  22: Number of High Dynamic messages received
  23: Number of Full Position messages received
  24: Number of Basic Ground messages received
  25: Number of TCP messages received
  26: Number of UTC time messages received
  27: Number of Data messages received
  28: Number of High Resolution messages received
  29: Number of Aircraft Target Airborne messages received
  30: Number of Aircraft Target Ground messages received
  31: Number of Ground Vehicle Target messages received
  32: Number of 2 slots TCP messages received

I023/120/REF - Reference from which the Messages Are Countered

• 1 bit [.]

• values:

  0: From midnight
  1: From the last report

I023/120/(spare)

• 7 bits [.......]

I023/120/CV - 32-bit Counter Value

• 32 bits [................................]
• raw value

I023/200 - Operational Range

Definition: Currently active operational range of the Ground Station.

Structure:

• 8 bits [........]
• unsigned quantity
• unit: “NM”
• LSB = 1 NM

Notes:

1. Maximum value indicates “maximum value or above”.

I023/RE - Reserved Expansion Field

Definition: Expansion

Structure:

Explicit item (RE)

I023/SP - Special Purpose Field

Definition: Special Purpose Field

Structure:

Explicit item (SP)

User Application Profile for Category 023

• 1. I023/010 - Data Source Identifier
• 2. I023/000 - Report Type
• 3. I023/015 - Service Type and Identification
• 4. I023/070 - Time of Day
• 5. I023/100 - Ground Station Status
• 6. I023/101 - Service Configuration
• 7. I023/200 - Operational Range
• (FX) - Field extension indicator
• 8. I023/110 - Service Status
• 9. I023/120 - Service Statistics
• 10. (spare)
• 11. (spare)
• 12. (spare)
• 13. I023/RE - Reserved Expansion Field
• 14. I023/SP - Special Purpose Field
• (FX) - Field extension indicator