AS 680/682
Description, Operation and Maintenance Supervisor Operation
ADS−B
5−27Ed. 10.07
Only extended squitter being compliant with the given versions DO260 or DO260A determined with
the ’DO260A Filter’ are considered by the Ground Station.
The ’Mandatory Field Check’ enables the check for the presence of data items, which are mandatory
for generation of valid Asterix target reports. Mandatory fields are e.g. the target position (longitude
and latitude), the time of day, the target ICAO 24−bit address.
The Asterix CAT21 mandatory fields are:
− Data Source Identification
− Target Report Descriptor
− Time of Day
− Position in WGS 84 Coordinates
− Target Address
− Figure of Merit.
The ’Cover Range’ of the Ground Station is given in nautical miles (NM). If set, any position reports
beyond that range are ignored by the Ground Station. The ’Cover Range’ is disabled setting the value
’–1’.
A minimum and maximum flight level threshold, given in Flight Level (1 FL = 100 ft), cause the Ground
Station to discard any target reports outside the given range.
FOM/PA Restriction can be enabled/disabled. When enabled, a Target’s PA value (Position Accuracy)
can be limited depending on the FOM/PA Restriction table which can be uploaded/downloaded on
the software page (see section 5.4.13).
5.4.11.2 Age Filters
The ’Track’ age, given in seconds, is the maximum age of a track since its last valid update, before
it becomes invalid.
’Position’ defines the maximum age of a valid position in seconds. Obsolete positions are not consid-
ered, when Asterix reports are generated.
If the last update of the identification is older than the last position update minus relative ’Target Identi-
fication’ age in seconds or more recent than the last position update plus the relative ’Target Identifica-
tion’ age, then the identification for the respective target is declared invalid.
If the last update of the velocity is older than the last position update minus the relative ’Velocity Squit-
ter’ age in seconds or more recent than the last position update plus the last ’Velocity Squitter’ age,
then the velocity data for the respective target is declared invalid.
If the last update of the aircraft status is older than the last position update minus the relative ’Target
Status Squitter’ age in seconds or more recent than the last position update plus the relative ’Target
Status Squitter’ age, then the aircraft status for the respective target is declared invalid.
If the last update of the aircraft operational status is older than the last position update minus the rela-
tive ’Aircraft Operational Status’ age in seconds or more recent than the last position update plus the
relative ’Aircraft Operational Status’ age, then the operational status for the respective target is de-
clared invalid.
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