PPRuNe Forums - View Single Post - AF 447 Search to resume (part2)
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Old 17th May 2011, 17:04
  #1636 (permalink)  
GarageYears
 
Join Date: Jun 2009
Location: VA, USA
Age: 58
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Why so long to synchronize?

Specifically, the investigation team has yet to synchronize readings from the data recorder with voice recordings taken from the cockpit, a crucial process expected to take several weeks.
I don't understand this?

From the CVR System Description Note:

The SSCVR is synchronized with the 2nd aircraft recorder (SSFDR) by means of an audio signal corresponding to the GMT sent by the FDIU to the audio system and received by the SSCVR on the third occupant channel.
Therefore the necessary time encoding information is embedded with the audio data. Having worked with several different synch systems (in particular IRIG B per Boeing data packages) and understanding the replay mechanisms to support reading the SSCVR would implicitly include the necessary decoding of the synch data, and would assume the same time stamping is available for all the SSFDR data, how can this "synch" task take several weeks???

Sorry, but I just do not buy that.
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