[RTTY] Unshifted Numbers

[Kok Chen]

On Feb 14, 2005, at 2:01 PM, NB1B wrote:

> What mechanism makes some programs send the letters instead of the 
> numbers?
> I don't think the problem was on my rx end when someone would send me 
> "TOO
> PPQ PPQ", I'd ask for the number, and he would repeat the same string 
> of
> letters a second time.   What actually clued me in to this was a 
> station
> would send "599 PQP 010", so I'd ask for the number, and he'd send 
> "599 010
> PQP" back.

Baudot does not have separate codes for numbers and alphabets, since 5 
bitsof information can only handle a total of 32 combinations.

What Baudot does is to send a "shift" character (kinda like caps lock 
on your keyboard) that switches between two separate sets of characters.

If you didn't know what the shift was (e.g., you'd tuned in in the 
middle of a QSO), or the shift was misinterpreted through the QRN and 
QRM (happens all the time in contests), then you will be printing the 
"other" character set.

"1234567890" of the NUMS character set are mapped to "QWERTYUIOP" in 
the LTRS character set.

And, in case you think I have a good memory, I didn't memorize that 
sequence. I simply typed the top two rows of keys on my standard 
keyboard .

That's right, Baudot's mapping exists on our modern ASCII keyboards.

Next time you see a "TOO WER", just look above the T key to find the 5, 
the O key to find the 9, etc, etc, and decode it into the "599 234" 
that was sent.

I will now let W6WRT explain for the thousanth time why USOS plus using 
spaces between exchanges reduces the chances for repeated exchanges to 
be received in the wrong shift. . :-)

There are some other mappings that are not on the QWERTY... row of the 
keyboard that is worth remembering.  For example, if you see  "--5-7" 
on your screen, it is Don calling you.


UE,
Chen, W7AY