A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Piloting
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Why don't voice radio communications use FM?



 
 
Thread Tools Display Modes
  #1  
Old September 7th 06, 05:46 PM posted to rec.aviation.piloting
Jim Logajan
external usenet poster
 
Posts: 1,958
Default Avidyne Avionics Are Running Windows OS (Was: Why don't voice radio communications use FM?)

Dylan Smith wrote:
Like car crashes, most Windows crashes are caused by bad drivers.


The same is true of all operating systems; I once had a Sun Solaris system
crash because the tape driver had a bug.

It's been a while since I worked on any RTOS, but I seem to (probably
incorrectly) recall that applications running on VxWorks (the OS used on
the Mars Explorer, among other spacecraft) generally have full run of the
memory. That is, there is no distinction between the app and the OS as far
as access privileges to memory or I/O.

And I'll admit it eventually doesn't matter how reliable the OS is once it
passes a certain reasonable level, since the application(s) are always
going to be less reliable. If your app crashes, you may not get a "blue
screen" but the end result for the pilot is the same: they have to restart
the app somehow, and a cold restart is generally the easiest. (Though if
the OS is running okay it can tell when the app dies and do a warm restart
on the pilot's behalf.)
  #2  
Old September 7th 06, 11:20 PM posted to rec.aviation.piloting
Mxsmanic
external usenet poster
 
Posts: 9,169
Default Avidyne Avionics Are Running Windows OS (Was: Why don't voice radio communications use FM?)

Jim Logajan writes:

It's been a while since I worked on any RTOS, but I seem to (probably
incorrectly) recall that applications running on VxWorks (the OS used on
the Mars Explorer, among other spacecraft) generally have full run of the
memory. That is, there is no distinction between the app and the OS as far
as access privileges to memory or I/O.


It makes sense, since anything used in a truly mission-critical
environment has to be error-free for the mission to succeed.
Protecting the OS against applications serves no purpose, because any
error in the applications will negatively impact or destroy the
mission, anyway. In other words, even if the OS is protected against
an application bug, the mere fact that there is a bug is going to
prevent the mission from being carried out, so one gains nothing by
protecting the OS.

Ultimately you end up with a system that is entirely OS, with
everything being privileged. A system that enforces restricted user
privileges just does so to protect against poorly-written software;
but you cannot afford poorly-written software to begin with in
mission-critical systems, so such restrictions are too little, too
late, if something goes wrong.

And I'll admit it eventually doesn't matter how reliable the OS is once it
passes a certain reasonable level, since the application(s) are always
going to be less reliable.


And vice versa. If it's all mission-critical, there's no reason to
restrict any of it, because it all has to be 100% trustworthy to begin
with.

--
Transpose mxsmanic and gmail to reach me by e-mail.
  #3  
Old September 8th 06, 01:05 AM posted to rec.aviation.piloting
Bob Noel
external usenet poster
 
Posts: 1,374
Default Avidyne Avionics Are Running Windows OS (Was: Why don't voice radio communications use FM?)

In article ,
Jim Logajan wrote:

It's been a while since I worked on any RTOS, but I seem to (probably
incorrectly) recall that applications running on VxWorks (the OS used on
the Mars Explorer, among other spacecraft) generally have full run of the
memory. That is, there is no distinction between the app and the OS as far
as access privileges to memory or I/O.


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.


And I'll admit it eventually doesn't matter how reliable the OS is once it
passes a certain reasonable level, since the application(s) are always
going to be less reliable.


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).

--
Bob Noel
Looking for a sig the
lawyers will hate

  #4  
Old September 8th 06, 03:02 AM posted to rec.aviation.piloting
Mxsmanic
external usenet poster
 
Posts: 9,169
Default Avidyne Avionics Are Running Windows OS (Was: 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.

--
Transpose mxsmanic and gmail to reach me by e-mail.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
UAV's and TFR's along the Mexico boarder John Doe Piloting 145 March 31st 06 06:58 PM
Air Force One Had to Intercept Some Inadvertent Flyers / How? Rick Umali Piloting 29 February 15th 06 04:40 AM
terminology questions: turtledeck? cantilever wing? Ric Home Built 2 September 13th 05 09:39 PM
I Hate Radios Ron Wanttaja Home Built 9 June 6th 05 05:39 PM
AirCraft Radio Communications [email protected] Rotorcraft 0 November 13th 03 12:48 AM


All times are GMT +1. The time now is 07:05 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 AviationBanter.
The comments are property of their posters.