--- Robert Chudek - K0RC <[EMAIL PROTECTED]> wrote:
> Andy,
>
> Regarding matching the RTTY tones... matching a tone
> is difficult for some people and easy for others.
> For example, some people sing off key! Were you good
> at matching the note of the pitch pipe in music
> class? :-)
>
> You said some RTTY signals did not sound the same as
> yours. I heard this as well, and one was so blatant
> I had to look at my scope! The reason for this
> dissimilar sound is because some fellows overdrive
> their transmitter audio input when using AFSK. This
> generates distortion, harmonics and secondary
> signals. I hear this during every RTTY contest and
> last weekend was no exception. A bad soundcard or
> driver could be a potential problem as well, but not
> as likely as excessive mic gain.
>
> If a RTTY signal is generated by AFSK and the audio
> is not pure, it will sound different from good 2125
> and 2295 tones. It's the same principle that a
> middle C note on a violin sounds different than the
> same note on a clarinet. Both instruments produce
> the same fundamental frequency, but each has its
> unique signature of harmonics and overtones that
> allow you to easily distinguish between them.
>
> So now you know why a lot of RTTY operators say this
> mode is "music to their ears"! But why are they
> called "green keys"? A piano is black and white.
>
> 73 de Bob - KØRC in MN
>
If the tones are not pure sine waves for RTTY when fed
into the audio of a transmitter, it is probably not
legal. They will generate all sort of junk on the
bands just as you mentioned. Even more so if the
audio is overdriven.
As far as the green keys, the computer boys will never
know unless someone takes the time to explain the
mechanical teletype machines have keys that are
acutally collored GREEN.
DE KU4PT
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