Need help with error correction.

[Steve Rooke]

In article <steve.665748651 at paddy>, steve at gapos.bt.co.uk (Steve Rooke) writes:
> I have two sites, one sending a file, the other receiving.  There is a lot
> of corruption at the receiving end caused by line noise.  I am not able to
> use any standard form of error correction on the line but I can request
> retransmission of the file, as many times as needed, over another link.
> 
> I need to be able to compair these files and reconstruct the original with
> reasonable confidence.  By that I mean that if two, or more, files have the
> same text at a certain point then I am reasonably confident that the text
> is OK.
> 
> Has anyone tried to do this sort of thing before and how did you do it,
> please?  Solutions based upon diff would do, I guess, for a majority of
> the time.

Thanks for all your initial replys about using file xfer protocols, kermit
and such, checksuming of the file at each end and splitting the file into
short line lengths to enable diff to at least produce some matches.

I guess I should have expanded on the real problem.  As I stated, I cannot
use any standard xfer protocols which is due to the sending and receiving
equipment being dumb (ie LIKE telex [no flames please!]).  The file is
then passed onto a U*IX system where it is checked and actioned upon.
The feedback path, for error retransmission, is by voice as, up to now,
a human has checked the file and pieced the contents together from a
number of transmissions.

As you can see I have no way of runing kermit (or the like), checksums
or altering the standard xmission of the file but I can request a resending
as many times as necessary.  The only way, I can see, for rebuilding the
correct contents is to compair sets of files and select matching sub-strings
in them.

If you have any further ideas or some code fragments then please let me
know.

Thanks again,
Steve
-- 
Steve Rooke  steve at gapos.bt.co.uk  (...mcsun!ukc!gapos!steve)  UK + 394 693595
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