posted on Dec, 18 2009 @ 03:32 AM
First of all, I'd like to get some stuff of my mind before getting into the technical
part of this thread. According to some people, I'm the guy to blame for what
happened regarding the FLT_DECK_DOOR 'incident'
If anyone has a problem with me for the recent uproar, I'd like to know your
thoughts. Tell me what you think in general about my actions, and your side
of the story. Please use the U2U feature to keep the thread clean.
FYI: I haven't changed 'sides', nor have I stopped researching. I simply choose
to associate myself with other organizations and people during my studies.
Next, I'd like to clear up some misconceptions about how the flight data is extracted
from the Flight Data Recorder [FDR] and transposed into a format such as an
I'll try to keep the terminology simple for all to understand, and use real world
examples whenever possible. As time permits, my intention is to upload a video
to show how a digital circuit (much like the one used on the cockpit door) triggers
signals which are recorded by the FDR.
First off, it's probably best to mention that I'm not an FDR technician so i wont
get into any details about how to interpret the data; we're just going to discuss
how the bits are recorded and then pulled into a software file.
How is the data stored? Much like your computer's hard drive, the flight data
is recorded on a device that translates electrical pulses from sensors to binary
logic levels. In the case of the FDR, it uses a computer chip as opposed to
moving parts that you would find in a typical home desktop PC.
The computer chip inside the FDR does not have any moving parts and therefore
is not susceptible to write errors from bumps and turbulence, or things of that
nature. The data is written using logic gates and electricity only. Logic gates
for this particular device are known as the "Floating" type that you will find in
FLASH EEPROM (look it up on Google. Please note the difference between EPROM
and FLASH EEPROM).
Due to this fact, a logic state of only zero (0 = logic low, low voltage) , or one
(1 = logic high, higher voltage) may be stored. There is no "in between",
and there is no exception. The gate is either conducting, or it is not.
At times you will read about "missing bits", or "blank cells", etc. This has nothing
to do with the Flight Data Recorder. We are talking about the lowest level in the
chain (the computer chip), not data you see in Excel spreadsheets.
I'll stop there for now, and continue in my next post. While you're waiting, check
your understanding of how data is carried on a wire:
#1. An entire word is presented on a data line at any given point in time.
IE: 0000 1101 0101
#2. Only one bit is present on a data line at any given point in time.
#3. Sometimes no data is present on a data line, and therefore nothing is
[edit on 18-12-2009 by turbofan]