AS 680/682
Supervisor Operation Description, Operation and Maintenance
ADS−B
5−26 Ed. 10.07
5.4.11 Page ’ADSB Filter’
This page, see Fig. 5−15, defines parameters and filter settings used during CPR decoding of incom-
ing extended squitters.
Fig. 5−15 Page ’ADSB Filter’ (example)
5.4.11.1 Extended Squitter and CPR Decoding
The parameter ’Position Type’ defines the extended squitter filter setting for airborne targets or targets
on the ground. It is possible to let the Ground Station consider only airborne, only surface or airborne
and surface positions.
It is possible to determine a certain method of the compact position reporting algorithm (CPR) for
airborne or surface position squitters.
The globally unique position decoding needs two airborne position extended squitters. One of these
must be decoded with the even decoding technique, the other one with the odd decoding technique
to get a worldwide (in case of surface position squitters almost worldwide) unique target position.
Selecting ’global’, the Ground Station needs always an odd and even airborne position squitter to
calculate a target position.
Selecting ’local’, the first position of a target is calculated with the global decoding method. All subse-
quent position squitters are decoded with the help of a reference position being the position of the
Ground Station or the previously decoded position of the target. This depends on the setting of the
’Last Target Position as Ref.’ parameter.
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