[RTTY] PSK31 is faster (Was FD RTTY Question)

[Paul Stoetzer]

No answers yet. I'm still there.

On 6/27/2012 9:05 PM, Alex Malyava wrote:
> Hi Paul,
> Any progress? Anybody answered in 30 minutes?
>
> K2BB
>
> On Wed, Jun 27, 2012 at 8:39 PM, Paul Stoetzer <n8hm at arrl.net 
> <mailto:n8hm at arrl.net>> wrote:
>
>     Anybody want to try ASCII? I've never made a QSO. I'm calling CQ at
>     14.088.5 MHz.
>
>     Paul, N8HM
>
>     On 6/27/2012 8:33 PM, Robert Chudek - K0RC wrote:
>     > 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 at mac.com
>     <mailto:chen at 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
>     >>>
>     >>>
>     >>>
>     >>>
>     >>> _______________________________________________
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>     >>> http://lists.contesting.com/mailman/listinfo/rtty
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>     >>
>     >
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