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Re: [RTTY] RTTY Cut Numbers

To: Kok Chen <rtty@w7ay.net>
Subject: Re: [RTTY] RTTY Cut Numbers
From: Jeff Stai <wk6i.jeff@gmail.com>
Date: Sun, 10 Jan 2016 12:32:17 -0800
List-post: <rtty@contesting.com">mailto:rtty@contesting.com>
Once upon a time I designed error correcting codes for solid state disks.
It was a lot of fun and I would love to jump into it again... But putting
ECC onto a RTTY contest exchange seems a little to me like adding a
gasoline engine to a horse drawn wagon. It might make it more efficient and
reliable, but if you have a horse drawn wagon it's probably because you
just enjoy being pulled around by a horse.

73 jeff wk6i

On Sun, Jan 10, 2016 at 11:51 AM, Kok Chen <rtty@w7ay.net> wrote:

> On Jan 10, 2016, at 11:28 AM, G3YYD wrote:
> > If the checksum character is in error?
> Send "AGN?" of course :-).
> You can even automate the "AGN?", but with poor propagation, the back and
> forth could end up sounding like Packet Radio :-).
> Sending the serial number twice is a form error detection, that is why we
> use it today, but it is rather inefficient.   And the response to an error
> is similarly, either "I don't need that mult," or sending "AGN?"
> Sending the exchange 3 times allow a single error to be corrected, but,
> like repeating something twice, is also inefficient.  Even the rudimentary
> Hamming code is better for correcting single errors.
> The "3 copies" methodology has even been used in hardware in spacecrafts.
> Avizienis at JPL called it "Triple Modular Redundancy."  Nowadays, in the
> same vein as error correction codes like the Hamming code (the grand pappy
> of them all), Arithmetic Codes are much more efficient hardware
> implementation than triple modular redundancy.
> Happy New Year 2016, David!
> Chen, W7AY
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Jeff Stai ~ wk6i.jeff@gmail.com
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