Why don't voice radio communications use FM?

Bob Noel writes:

There are versions of VxWorks that are certifiable to DO-178B level A.
Kind of hard to do that while allowing full run of the memory.

Why?

um, not always. the complexity of the OS could dominate the complexity
of the app, especially if the OS provides protection for the app (e.g.,
partitioning).

In mission-critical systems, all of the software works as an
integrated whole; you don't just load arbitrary code off a CD and run
it. If you are running untrustworthy code, you're also running
uncertified/unvalidated code, which is dangerous.

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Stefan writes:

Windows is nothing more than a copyrighted name, and Microsoft is free
to sell anything they want under this name. If they decide to call that
stripped, reliable code Windows, then yes, it *is* Windows.

But then it's not a desktop or server Windows, which is what most
people have in mind when they use the adjective.

Windows is not copyrighted, it's trademarked, as an adjective.

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"Grumman-581" writes:

You would send a particular formated TCP/IP message via a
socket connection to a particular controller that would then change the
intensity of the LEDs in the specified zone...

Seriously? Is it an aircraft or a video game?

And people think I'm being extreme in suggesting FM radio instead of
AM radio?

Quite a bit of the
communication between the various devices was handled via TCP/IP
communication... I believe that Rockwell had been granted a patent on that
approach...

A patent on TCP/IP? Would anyone really want to steal something based
on TCP/IP?

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"Mxsmanic" wrote in message
...
Seriously? Is it an aircraft or a video game?

Yeah, I'm very serious... In fact, it cuts down on the wiring... Think of
multiple control stations aboard an aircraft being able to control various
pieces of hardware... With the typical analog controls like you have for
lights in your house, you would be running 110VAC all over everywhere...
With this sort of system, you run power to the actual device and use lower
gauge wires for sending signals to the controller for that device... Think
of it as every device that you want to possibly control having a particular
IP address and port number... You format a command and send it to the
device... Perhaps this one controller handles multiple physical devices and
the format of the message indicates which device is to be controlled or
queried with respect to its current status... Would you rather hligh voltage
running all around the aircraft or just where it was really needed and
basically the equivalent of phone (i.e. CAT-5/6) wire running everywhere
else? In addition to this, the controls for the cabin entertainment system
also were TCP/IP based... Even the video and audio that was piped throughout
the cabin went over a TCP/IP connection -- UDP, actually...

And people think I'm being extreme in suggesting FM radio instead of
AM radio?

Well, that's because FM doesn't provide any real benefit as compared to AM
for aircraft communications... As I've shown in the above aircraft, using
TCP/IP for communication / control of various devices aboard an aircraft can
definitely provide a certain benefit...

A patent on TCP/IP? Would anyone really want to steal something based
on TCP/IP?

No, a patent on the idea of using TCP/IP for communication between various
systems aboard an aircraft... Or maybe it's a copywrite... Whatever...

Mxsmanic,

If they are stripped enough to be certifiably safe, they are not
longer Linux or Windows.


If the manufacturer calls it Windows, it is Windows, period. Man, this
is really simple...

--
Thomas Borchert (EDDH)

Mxsmanic,

Then they aren't Windows.


You are wrong. Again.

--
Thomas Borchert (EDDH)

On 2006-09-08, Grumman-581 grumman581@DIE-SPAMMER-SCUM wrote:
No, a patent on the idea of using TCP/IP for communication between various
systems aboard an aircraft... Or maybe it's a copywrite... Whatever...

It could be either or both. The code would be copyrighted by default,
and the method itself could be patented. However, just like most patents
issued by the USPTO today, it's barely worthy of a patent because it's
just so obvious to control devices using data passed down some data
connection (such as TCP/IP). I suspect they used TCP/IP rather than
concocting their own control protocol because TCP/IP (for all its warts)
is well understood and TCP/IP stacks are ubiquitous on virtually any
device (including microcontrollers) with even trivial amounts of
processing power - thus reducing development costs.

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Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de

[snip]
to understand morse written as you've done above. Just for fun I tried
to decode your characters, took me a 2-3 minutes to make sense of it.
Much easier to understand as a sequence of musincal type tones :-)

I'll admit I cheated a little. Go to
http://www.onlineconversion.com/morse_code.htm and you can paste the
dots and dashes in and get a english translation. Works the other way
too.

Randy

Mxsmanic wrote:
Perhaps this is a naive question, but: Why don't voice radio
communications for aviation use FM radio instead of AM radio?

FM offers better quality that AM when signal is relatively strong (or
signal to noise ratio is high). As the signal strength decreases, there
is a point when the quality is identical in both cases and then the
quality of FM deteriorates _rapidly_, while AM is still usable.
So, it might be a safety issue - using FM would effectively filter out
the weakest stations that could be heard if AM was used. Just a theory
;-)

Bartek

"Grumman-581" writes:

Yeah, I'm very serious... In fact, it cuts down on the wiring...

Which means that a single break in a single wire disables multiple
aircraft systems. Brilliant.

Think of
multiple control stations aboard an aircraft being able to control various
pieces of hardware... With the typical analog controls like you have for
lights in your house, you would be running 110VAC all over everywhere...

I could never find a justification for those home remote control
systems that used house wiring, and they weren't always reliable,
anyway.

Well, that's because FM doesn't provide any real benefit as compared to AM
for aircraft communications... As I've shown in the above aircraft, using
TCP/IP for communication / control of various devices aboard an aircraft can
definitely provide a certain benefit...

It makes things cheaper, I suppose. I'm not sure I see a safety
benefit, and there might even be a reduction in safety.

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