Decoding ARINC 717

[SrinivasAluri]

I have an ARINC 717 file in binary format. I know the Syncwords, there are Teledyne format. I have all the parameter addresses both analog and binary. I am using Matlab to open the binary file by specifying that its a 12 bit word. The sync words for each subframe are 4018 words apart, it should be 1024 x 4 = 4096 words apart if the sub-frame has 1024 words. I can't figure out why this is happening. Also, is it common that sometimes frame are not recorded properly?

 

[WKTaylor]

SA... RELUCTANTLY...

NOTE1.
Your issue/question 'implies' that You might be working with raw ARINC 717 FDR data from a 'real-world investigation'... without support of the FDR manufacturer or any agency experienced with interpreting FDR/CVR data. This questionable... and could be a minefield.

The data stored on the ARINC 717 will be model/aircraft-date-of-manufacturing 'specific'.

Refer-to the following documents… may contain clues...

NTSB FDR [FLIGHT DATA RECORDER] HANDBOOK
FAA AC20-141 AIRWORTHINESS AND OPERATIONAL APPROVAL OF DIGITAL FLIGHT DATA RECORDER SYSTEMS
FAA TSO-C124 FLIGHT DATA RECORDER SYSTEMS
MIL-HDBK-2124 FLIGHT DATA RECORDER FUNCTIONAL STANDARDS FOR
ICAO 10104 MANUAL ON FLIGHT RECORDER SYSTEM MAINTENANCE (FRSM)
ARINC 647 FLIGHT RECORDER ELECTRONIC DOCUMENTATION (FRED)

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[SrinivasAluri]

I am not trying to do any accident investigation, I just want to use the data for data analytics. When I import the binary file assuming 12bit word the syncwords are 1027 words apart instead of 1024, I can't figure out why this is happening.

 

[kontiki99]

The way it works at my current airline, we maintain a report that defines the data format for each like fleet and subfleet. I think without something like that you are going to have a very hard time figuring out which bits are discrete one bit inputs, what the word length is for the longer parameters, how it is coded, even what the size and structure of the overall format is.

We have one model fleet with a small sub fleet of oddball airplanes. Most of them have a 128 word subframe format, the oddballs have a 256 word subframe format. They are similar but, so different. Even if you had the wrong report, I can't imagine there is any way you could use it to unwind the other one. Good luck.

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