AS 680/682
Description, Operation and Maintenance Supervisor Operation
ADS−B
5−21Ed. 10.07
5.4.7.2 Raw Data Optional Items
Raw data are the data contained in the telegram received from targets. Unlike the Asterix Standard
Fields, raw data is not decoded. It is possible to switch off the sending of the raw data.
Optional values that can be sent over the raw data interface are:
S the time of day (TOD), based on the system time of the Ground Station, when the respective tele-
gram has been received.
S the time of arrival (TOA), based on the Ground Station’s internal clock, when the respective tele-
gram arrived.
S the enabling of ’loop back’ telegrams (HW generated telegram) adds the loop back telegrams to
the output stream. These loop back telegrams are used for test purposes.
S the confidence bits, indicating the number of bad bits in the telegram. It is an indicator of the quality
of the telegram data
S the signal amplitude, being an indicator, how strong the telegram signal is received.
NOTE: The time of arrival has a very much higher resolution than the time of day, but it cannot
be synchronized with usual clocks, because its range is less than 3000 seconds. The TOA
is not considered in ADS−B applications.
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