AS 680/682
Record and Replay Description, Operation and Maintenance
ADS−B
4−76 Ed. 10.07
S Check on AP/PI field: If this check is activated, the AP field (Address/Parity field) or PI field (Parity/
Interrogator identifier) or the extended squitters of downlink format 17, 18 and 19 (if available) are
checked. This field is represented by the last three bytes in the telegram. If the AP or PI field is 0,
then the telegram is correctly transmitted, else the squitter is damaged and will be ignored.
S Check on the coverage range: If the check on the coverage range is activated, it is possible to
enter a distance in Nautical Miles, beyond which no targets are considered. This coverage range
check is only applicable within the boundaries of uniqueness, i.e. within a range of 170 nautical
miles around the Ground Station for airborne positions and 45 Nautical Miles around the Ground
Station for surface positions. Telegrams that fail the check will be ignored. If this check is disabled
and telegrams arrive from beyond the range of 170 NM for airborne position squitters or from be-
yond the range of 45 NM for surface position squitters, then the targets will always be tried to get
located with the respective global decoding mode.
S Check on the distance of two consecutive positions of a target by using the maximal target veloc-
ity in Nautical Miles per Second and the maximal age of the track position in seconds (refer to sec-
tion 4.6.5.3). If this check is activated, it is possible to enter a maximal target velocity in Nautical
Miles per second. In the case that two consecutive positions of a target exceed the maximal dis-
tance limit, got from the product of maximal target velocity and maximal position age, then the ATP
subfield of the target report descriptor is set to 0 for the concerned target. Once set to 0, this ATP
subfield will be overwritten after 10 seconds. The indication ATP equal to ’Non Unique Address’
(=0) indicates that the ICAO address, assigned to the target, is not unique or that the target sends
some faulty telegrams causing deserting plots of the track.
S Check on maximal altitude of a target. If this check is activated, it is possible to enter an altitude
in Flight Level. If the height of target exceeds the maximal altitude, then the corresponding tele-
gram is ignored.
S Check on minimal altitude of a target. If this check is activated, it is possible to enter an altitude
in Flight Level. If the height of a target remains under the minimal altitude, then the corresponding
telegram is ignored.
If some checks fail, then the corresponding notes can be received on ’Screen Output’, if the ’Detailed
telegram decomposition’ mode is activated (refer to section 4.6.5.2).
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