The *BARTG High Speed Sprint* might be an existing (recently introduced)
contest to make the transition?
73 de Bob - KØRC in MN
------------------------------------------------------------------------
On 6/27/2012 3:43 PM, Paul Stoetzer wrote:
> Somebody should set up an ASCII contest. That would be interesting.
>
> Paul, N8HM
>
> On Wed, Jun 27, 2012 at 4:36 PM, Kok Chen <chen@mac.com> wrote:
>> On Jun 27, 2012, at 12:47 PM, Alex Malyava wrote:
>>
>>> Why don't we just invent/introduce some new RTTY standard -
>>> the one with 6 bits instead of 5 - covering whole alphabet and digits
>>> without any FIGS/LTRS and speed it up a little bit to compensate an extra
>>> bit?
>> There is no need to introduce another "mode du jour" even.
>>
>> 7-bit ASCII (CCITT ITA-5) RTTY has been FCC approved (see part 97.309(c))
>> for a long time now. fldigi supports it, so does MultiPSK and cocoaModem,
>> among others.
>>
>> In a discussion (a year or even longer ago) on this reflector, I had shown
>> that for most RTTY contest exchanges, ASCII RTTY beats out Baudot RTTY in
>> speed, even when both are running 45.45 baud.
>>
>> You get rid of the FIGS/LTRS confusion (thus problem with USOS
>> incompatibility either; USOS is a Baudot problem), allows lower case, and it
>> still beats out Baudot in contesting speed. It is when sending paragraphs
>> of upper case text that Baudot wins over ASCII.
>>
>> Because of the Teletype Models 33/35, the popular speeds for running ASCII
>> RTTY was 110 baud. At that speed, it will wipe the floor with Baudot RTTY.
>>
>>> Or drop one stop bit to save the length? Or use 3 frequency FSK -
>>> shift left is "0", shift right is "1" and middle is sync/start/stop ?
>> 3FSK may not be a good idea. The reason is that the equalizer to compensate
>> for selective fading will be at best very complex to build.
>>
>> 2FSK has the very unique ability to fight selective fading with a very
>> simple thresholding scheme. Once you add more tones, you can no longer
>> build simple ATC circuits.
>>
>> For that reason, you will find that there is nothing in MFSK16 (16 tones),
>> DominoEX (18 tones) or Olivia that explicitly fixes the selective fade
>> problem -- they all use long interleaved codes to fight QSB in general --
>> and you may not want to use long interleavers with short contest exchanges;
>> the latency will need to be over 1 second to be effective. You will need to
>> add latency to the exchange time. Selective fading happens quite often.
>> You can almost not avoid it with a Rayleigh path.
>>
>> Anyhow, the solution is already at your fingertips, and the FCC has blessed
>> it for years now. It is called ASCII. And 110 baud with 170 Hz shift is a
>> breeze.
>>
>> 73
>> Chen, W7AY
>>
>>
>>
>>
>> _______________________________________________
>> RTTY mailing list
>> RTTY@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rtty
> _______________________________________________
> RTTY mailing list
> RTTY@contesting.com
> http://lists.contesting.com/mailman/listinfo/rtty
>
_______________________________________________
RTTY mailing list
RTTY@contesting.com
http://lists.contesting.com/mailman/listinfo/rtty
|