Fwd: [RTTY] funny exchanges

[Kok Chen]

I think Roberto intended this for the entire Reflector (there is good 
info in there), so I am forwarding.

(Those who have received a QSL card from me can also decode that image 
of a Baudot tape on the card.  Yes, there is a real message in there, 
HI.)

73
Chen, W7AY


Begin forwarded message:

> From: Roberto <ea2ry at ea2ry.com>
> Date: February 16, 2004 7:06:04 PM PST
> To: Kok Chen <chen at mac.com>
> Subject: Re: [RTTY] funny exchanges
>
> That single one works in the system of QWERTY keyboards,
> the French for example use ACERTY keyboards.
>
>
> The Baudot code is a 5 bit code and those of you who are familiar with
> Binary Notation will know that the maximum number of values we can 
> have with
> 5 bits is 32. That means that each unit of transmission, one keystroke 
> if
> you like, can contain any one of 32 possible values. If you look up a 
> table
> of Baudot codes you will see there are 32 values listed, one code for 
> each
> letter of the alphabet plus a few other codes for other things such as 
> a
> space and a Carriage Return. But, what if we want to send a number 
> such as
> "9" or a question mark? These are not mentioned in that table because 
> all 32
> codes are already used.
>
> The solution is rather similar to the Typewriter or Computer Keyboard 
> where
> we have the Shift key to get various additional codes from the 
> keyboard.
> Most keys will produce a different result if we hold down the Shift 
> key as
> we type. Well, one of those original 32 codes is a special code known 
> as
> FIGS (for Figures Shift). The convention is that when we want to send a
> number or some other special character such as a punctuation mark, we 
> can do
> that by firstly transmitting a FIGS code.
>
> Then instead of using that original table of 32 codes, we have a second
> table of codes to use, and that second table includes all ten numeric 
> digits
> and various punctuation marks. Provided both sides of the conversation
> observe the convention, the sender can send a FIGS and start using the
> second table; the receiver will see the FIGS code and it too will 
> interpret
> all data that follows from the second table.
>
> With just 5 bits of data we then have almost 64 different codes we can 
> send
> and receive. (I say almost because there is some duplication in the two
> tables, including a space and a Carriage Return but that is not 
> important
> here). Even that many codes is not enough to handle all 26 letters of 
> the
> alphabet in both UPPER and lower case, so RTTY systems always operate 
> in
> upper case only.
>
> If we wanted to type a big number (say "13579") we don't have to send 
> FIGS
> before every digit. We send that code only once and the receiver then 
> will
> take EVERYTHING we type from now as if it belongs in the second table. 
> When
> we want to revert to the normal alphabetic table of codes we can send
> another special code, this one called LTRS (for Letters Shift). Then
> everything goes back to normal, using the original alphabetic table of
> codes.
>
> Normally we don't have to concern ourselves with these FIGS and LTRS 
> codes.
> Our computing equipment will take care of those things for us. We just 
> type
> away and rely on the system to generate and send those codes when 
> necessary.
>
> It is quite possible to lose bits here and there when receiving a RTTY
> signal, whether it be because of fading, interference, frequency 
> drift, or
> whatever. One of the big problems with lost data is the possible loss 
> of a
> FIGS or LTRS code! Say we had sent "13579" and then typed "HAPPY 
> BIRTHDAY".
> Our equipment would have sent a LTRS code before the first "H" but 
> what if
> the receiver did not copy the LTRS code we sent? Can you imagine what
> happens? As far as the receiver is concerned we are still sending 
> numbers or
> other codes from the numeric table! So our "HAPPY BIRTHDAY" is going 
> to come
> out looking something like "#-006 ?845#$-6". And EVERYTHING we type 
> from
> then on is going to look just as strange until we happen to send 
> another
> LTRS code later. It is for this reason that many systems include an 
> option
> to "Un-shift on space". If you have a multi mode TNC capable of 
> handling
> RTTY, you will probably have this option in your TNC. If that option 
> is ON
> then your receiving system will imply a LTRS code every time it 
> receives a
> space. So if you seem to be copying lots of funny numbers from a 
> strong,
> well tuned signal, try setting that option ON.
>
>
>
> this information is not mine, as I not to express itself to me in 
> English
> have copied the text of the page NB6Z Web, I hope does not get upset.
>
> You can see the interesting one I articulate in:
> http://home.teleport.com/~nb6z/rtty.htm
>
> Saludos de Roberto EA2RY
> http://www.ea2ry.com
> ea2ry at ea2ry.com
> Correo revisado con Norton Internet Security 2004
> e-mail reviewed with Norton Internet Security 2004
> ----- Original Message -----
> From: "Kok Chen" <chen at mac.com>
> To: "RTTY Reflector" <rtty at contesting.com>
> Cc: "WI8W" <rtty at comcast.net>
> Sent: Tuesday, February 17, 2004 3:37 AM
> Subject: Re: [RTTY] funny exchanges
>
>
>> On Feb 16, 2004, at 6:26 PM, Kok Chen wrote:
>>
>>> Look at the first two rows of your keyboard.  You will find that W is
>>> diagonally below 2, I is diagonally below 9 and U is diagonally below
>>> 7.  He has sent you QSO number 297.
>>>
>> Whoops, I is below 8, not 9.  Sorry.
>>
>> Start with 1->Q,  2->W, 3->E, etc.
>>
>> UE,
>> Chen, 27-6
>>
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>>
>
>