[RTTY] I had a reply in the contest from a fellow using cw forrtty

[Kok Chen]

On Feb 10, 2013, at 6:22 PM, Gary AL9A wrote:

> Just because the radio has some ridiculous functionality put into the rig by the marketing department doesn't mean the owner has to use it!

I'm afraid this is not the case of bad marketing, but IMHO, bad engineering, or not remembering history (like why is it we started to use diddles).

The way it failed is because once you start paddling in a character, it will not put out a diddle.  Even when it is time to output the next character, the rig waits for you, while transmitting in Mark state until you are done with paddling in the current Morse character.

Up until the K3, unless a modem is broken, all modems that have diddles switched on will insert a diddle (Baudot LTRS character) *immediately* when a character is not ready at the instant the next character frame comes up.  One of the most important things this does is to keep the character rate absolutely constant (and why RTTY is such a soothing sound to listen to).

It is a trivial change of firmware.  Probably a single line of code.

RTTY modems can, and have been taking advantage of constant character rates to recover character sync even when the stop bit is corrupted.  It has been around at least since RITTY in what Brain K6STI called the "Digital Flywheel."  And as more people turn from MMTTY to using 2Tone, they will find that 2Tone also takes advantage of constant character rate to maintain character sync even when the start bit is corrupted.

Prolonged Mark also causes ATC circuits to fail.  When you don't keep sending at least some Space tone, the modem can no longer guess what the Space amplitude is in the presence of selective fading.

73
Chen, W7AY