Brian Reay wrote:
"Mike Gathergood (G4KFK)" wrote in message
oups.com...

Radium wrote:
What is FEC?

Forward Error Correction. Google it :-)


Just to add to Mike's comment, FEC works by send the same message several
times- in simple terms, in the hope that one with get through correctly. It
is simple to implement, your recieving system just needs to be able to
identify a correct message and use it, not spot a bad message and initiate
either a request for resend or applly some sort of correction method
(assuming there is error correcting code in the message).


--
73
Brian
www.g8osn.org.uk

These comms are in one direction, so you don't resend a packet as there
is no way to make such a request. In practice, the codes have both
error detection and correction capabilities, so to the degree the
coding allows, the signal can be corrected with the bits that were
received. Note nobody mentioned a modulation scheme for sending this
data.

As a bit of trivia, Reed Solomon encoding was invented without a way to
decode it. That's what you get when you let mathematicians run wild.
For absolutely nothing of any value other than bragging rights, name
the guy who invented the decoding scheme for Reed Solomon. [Hopefully
this isn't wikied someplace. I did one class in grad school on error
detection and correction, and it was a pain in the ass if you get into
the theory. Implementation is quite simple.]

wrote:
As a bit of trivia, Reed Solomon encoding was invented without a way to
decode it. That's what you get when you let mathematicians run wild.
For absolutely nothing of any value other than bragging rights, name
the guy who invented the decoding scheme for Reed Solomon. [Hopefully
this isn't wikied someplace. I did one class in grad school on error
detection and correction, and it was a pain in the ass if you get into
the theory. Implementation is quite simple.]

It makes sense. The encoding software had to be ready to put into a probe
before the launch date. Once it was up it could not be changed.

Decoding software was another matter. Since they had years, maybe even decades
to decode the data, and it did not have to be real time, they could continue
to work on it.

All they had to do is not loose the tapes. :-(

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 Fax ONLY: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/

Geoffrey S. Mendelson wrote:
wrote:
As a bit of trivia, Reed Solomon encoding was invented without a way to
decode it. That's what you get when you let mathematicians run wild.
For absolutely nothing of any value other than bragging rights, name
the guy who invented the decoding scheme for Reed Solomon. [Hopefully
this isn't wikied someplace. I did one class in grad school on error
detection and correction, and it was a pain in the ass if you get into
the theory. Implementation is quite simple.]

It makes sense. The encoding software had to be ready to put into a probe
before the launch date. Once it was up it could not be changed.

Decoding software was another matter. Since they had years, maybe even decades
to decode the data, and it did not have to be real time, they could continue
to work on it.

All they had to do is not loose the tapes. :-(

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 Fax ONLY: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/

I'm not sure what you mean by the "probe". The deal with Reed Solomon
is it is a non-binary code, which was a big deal at the time. The
buzzword is Galois mathematics. There wasn't any hardware that could
handle the code when it was invented.