COMPONENT MAINTENANCE MANUAL
AVIATION PRODUCTS
Model FA5000
Rev. 02 Page 7
July 21/17
Description and Operation
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task will keep a circular buffer for data being stored. As a minimum, the most recent 2
hours of audio data and DataLink messages will be kept.
The Model FA5000 CVR uses the Analog Devices VDK as its operating system. The com-
munication mechanisms that are used here are consistent with the normal communication
mechanisms of the VDK operating system. This includes messages for sending com-
mands and small amounts of data between tasks and shared memory for sending large
amounts of data between tasks.
The VDK operating system uses timer interrupts to increment its kernel timers. Kernel
timers are used to dispatch execution of a particular function (called a ’timer handler’) at a
specified time in the future. This is used to coordinate which tasks are running at any giv-
en time.
The Model FA5000 CVR will be able to be loaded via the TCP/IP interface used by the
GSE task. This task will report a checksum of the loaded code to ensure the integrity of
the newly loaded software.
There will be no user-modifiable software and multiple-version dissimilar software in the
design of the Model FA5000 CVR.
The partitioning of the software is based on the functionality of each of the recorder types.
Each recorder type has its own set of CSCs that are dependent on the processes needed
for the recorder. The tasks that drive each of the CSCs will be described in more detail
below.
Cockpit Voice Recorder
CSC
Comments
DataLink
DataLink Management Task
CVR
CVR Management Task
Data Storage
Data Storage Management Task
BITE
Fault Management Task
GSE
GSE Interface Task
4. SOFTWARE MODULE DESCRIPTION
This section describes each of the tasks that comprise the software running on the Model
FA5000 CVR recorder.
A.
CVR Task
The CVR Task gets digital Audio from each of the four audio channels and if the recorder
is using the CSMU, then it compresses the data using the g.726 Voice Compression Algo-
rithm.
The CAM channel is compressed using the g.726 algorithm running on the BF527, packe-
tized, and the resulting packet is sent to the CAM partition on the CSMU. A packet head-
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