On 01/29/99 19:23:17 you wrote:
>
>
>>Well Dale, we will have to respectfully disagree with each other. The
>>difference in copyabiltiy between CW and Pactor when they are down in
>>the noise is simple: Pactor knows when an error has been made, CW
>>doesn't. If you send dit-dit-dit-dah and noise or QRM causes you to
>>miss a dit and copy it as U instead of V, you have no way of knowing
>>you got it wrong.
>
>Yes, I do. Let's say the V was the start of the word Very. When I hear
>Uery, I know that I got it wrong. I have error correction.
>
>Pactor just sits there trying and trying and trying and trying and trying
>and trying. By the time it gets a good resend, I'm way ahead of it.
>
>> Pactor not only knows, it automatically asks for a
>>repeat and will keep on asking until it gets it right. You can not
>>fool it - it either gets it perfect or not at all (see note below).
>>
>
>That's right. And if it gets hung up it can be completely lost for good.
> If some CW pieces get lost, usually, sense can still be made out of what
>is said. The fact is you don't need error free communication. That's
>why error free modes aren't generally used in contests and DXpeditions.
>It takes too long to get everything correct.
>
>>Also, digital signal processing can be done on a Pactor signal which
>>can actually pull an uncopyable signal out of the noise - one the
>>human ear literally can not even hear. I'm not saying your KAM can do
>>that, but it is technically possible given the proper equipment and
>>software. The times they are a-changin'.
>
>Well, I've heard this, but my KAM certainly can't do it. I know that I
>can put my Timewave DSP599-zx on digital signals and pull out stuff out
>of the noise that I couldn't otherwise hear, but I have a hard time
>believing that anything can be pulled out BELOW a noise floor. That's
>why it is called the noise floor. Maybe the DSP helps to move that
>lower, but there is still a noise floor where the signal becomes
>unintelligible from the back ground white nosie. The DSP can give you
>some more dynamic range over the human ear. It can't work magic.
>
>73,
>
>Jon
>KE9NA
>
>
>
>-------------------------------------
>Jon Ogden
>KE9NA
Jon, you hit the nail on the head. I keep hearing about digital mode prowess,
and after
investing a ton of money in it, it sure doesn't beat CW. Lot's of people told
me it would, but I
have yet to see it.
In my opinion, there is nothing that compares to the human brain for error
correction.
Dale
KC8FAQ
"Digital-Another Urban Legend."
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|