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Old 24th Mar 2019, 11:41
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Grummaniser
 
Join Date: May 2001
Location: UK
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Parity bits

Originally Posted by EDLB

Can you verify this? This would be very crude early 1970th technology and with a Haming distance of 1 only protect against single bit failures. A two bit failure would create the next valid data. And there is no guarantee that any interference will only disturb 1 bit. Equaly likely is, that a sequence of bits are disturbed.
I still wonder where the 20 degrees constant offset in the Lion Air AOA sensor came from. See preliminary report. That’s not a stuck sensor.
If the Ethiopian will show a similar offset then there is another problem burried in their flight control system.


It doesn't take a double bit error to lose one bit of data - somewhere in the system between the RDVT fixed to the AoA vane and the bus, is an analogue to digital converter chip (or array of them) which will not itself be creating any error checking. The error checking will be added further downstream (quite possibly by the chip next to the A-D). A fault in the actual A-D chip could produce single bit errors which could only be identified by duplicating the A-D process.
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