Military Communications and Information Technology: A Trusted ...

96 Military Communications and Information Technology...
according to specific instrument is the scale, and of course the program running
inside the microcontroller.
The fourth part is the data storage block. It mainly serves to store measured
flight data parameter into the memory card and thus could serve to two primary
goals. Since this is in particular a very cheap instrument, we can basically assume
that it will be primary used on board of ultra-light aircraft where no flight data
recorder is present [3]. The flight data recorder in case of accident is thus the first
possibility. The second possibility is to serve as flight documentation. Every piece
written to the memory contains not only value but also a time stamp of the event.
It’s easy than to read when some specific event occurred and its value, e.g. crossing
the maximum of speed limit or G‐force. The memory is divided into two parts.
One is permanent holding those specific events and the second part which is acting
as an infinite loop erasing the oldest data, when the maximum capacity is reached.
This part is still under development and at this moment presented by an SD memory
card as can be seen in Figure 4.
Figure 4. SD card storage evaluation board
The last part is the BITE (Built In Test Equipment) block. This block is basically
a second instrument integrated in one PCB (Printed circuit board), running at much
lower speed, which checks out some of the functions of the whole instrument. In case
that the instrument gives too different results then BITE, the instrument is disconnected
and an error flag is transmitted into the system, keeping the rest of the system
untouched by this error. In most cases this block could be the same for more instruments,
but with different I/O ports connected, as well as the program running inside.
Since the whole system is network (bus) based the network capability is the essence
of the whole system
III. Network capability
The proposed instrument is integrated into the on-board aircraft electronic
system, which acquires data from sensors and provides them to the NEC environment
[6, 16]. The whole system consists of two control modules and individual
modules providing aircraft and flight parameters.