/"Some developers understand that there is more than one operating //
//paradigm and that all approaches have their merit. Others become //
//religious zealots and show no respect to historical techniques and //
//those who have transceivers that are designed around those traditional //
//techniques."/
Joe, do you really believe this type of rhetoric is a convincing
argument that will help convince someone to change their mind? I don't
think so. In my private discussions with David regarding the initial
release of 2Tome, I found him responsive and open to suggestions that
would make his new product more user friendly. It is my belief with the
positive acceptance of 2Tone, it might only be a matter of time that
David reconsiders supporting an FSK keying solution.
I also remember when Tom, N1MM was very vocal that there would never be
a 'cut numbers' feature in his Logger. Not long thereafter, the feature
'mysteriously' appeared in the options without fanfare. There have been
other features he (personally) believed to be good, but had his mind
changed by rational discussion from the user community.
Stop the name calling.
73 de Bob - KØRC in MN
------------------------------------------------------------------------
On 9/17/2012 2:09 PM, Joe Subich, W4TV wrote:
For transmitting? -- well, we are back at Bill's dilemma -- how to
key the FSK input of a transmitter from a sound card based software
modem.
And here's where we are at the mercy of the software developer -
he/she can either provide support for a traditional UART, provide
on/off keyed tone that can be converted to "dry contact" for the
transceiver, or provide a fixed tone pair mode that can be used to
drive a regenerator (microcontroller a la K4DSP, NE565 or XR2211
or an old TU). If the software author insists on "all AFC, all
the time" then Bill's dilemma is essentially unsolvable.
Some developers understand that there is more than one operating
paradigm and that all approaches have their merit. Others become
religious zealots and show no respect to historical techniques and
those who have transceivers that are designed around those traditional
techniques.
Bill has discovered another apparent reason to use FSK (RTTY mode)
instead of AFSK ("Data" mode) with Icom transceivers. It appears
that there is no way to adjust the center frequency of the "DATA"
filters. One can narrow (and save) the bandwidth but the filters
are fixed at 1500 Hz unless the passband shift is used each time.
Although I am no an Icom user, I can understand how frustrating
(and inconvenient) that must be.
73,
... Joe, W4TV
On 9/17/2012 1:33 PM, Kok Chen wrote:
On Sep 17, 2012, at 6:41 AM, Frank wrote:
Now anyone want to admit that this entire thread was an April fools
joke?
AFSK to FSK converter indeed!
Scoff as much as you like, but K4DSP originally had the same problem
that Bill describes. He simply wanted some way to use a software
modem with older rigs. And indeed, he had used an old discarded TU
for just such a converter.
You can see him describe it right on this very reflector:
http://lists.contesting.com/_rtty/2005-03/msg00035.html
The FSKit makes use of a $2 programmable Atmel AVR chip instead of an
old clunky TU that few people have in their junk boxes anymore.
Engineers design schemes to solve other people's problems. Good
engineers design schemes before others even know they need the
solution (think Edwin Armstrong). Over time, a regenerator like the
FSKit might become the best solution out there for keying an FSK
transmitter.
Also for a couple of bucks, an Exar XR-2211 outperforms an ST-6, but
that is neither here nor there since for this purpose, the
demodulator only needs to decode signals that has SNR in excess of 60
dB (the transmit AFSK tones from a sound card). Time moves on, and a
tiny SOIC chip outperforms a rack full of tubes.
With an SDR tarnsmitter that starts with in-phase and quadrature
baseband signals, you don't really need direct keyed FSK anymore
since the distinction between FSK and AFSK pretty much melts away
(the same can be said of the old keyed AFSK rigs, such as the
FT-1000D; there is no difference between using AFSK and FSK in those
rigs, either).
There is another style of FSK-AFSK conversion too, but sort of in
reverse. TUs such as the ST-8000 and Timewave DSP-599-zx support a
FSK Regenerator mode that turns the demodulated RTTY pulses from the
receiver back into a 2215/2295 AFSK tone pair.
Some of us used to depend on that flavor of regeneration because HAL
and Timewave did not support Mac OS. We simply fed the regenerated
AFSK tone pair into some TNC (e.g., KAM Plus) that can run under Mac
OS. The regenerated tone pair again has very high SNR and the second
(inferior) TU does not throw any extra error. The regenerated tones
includes the errors from the front end (superior) TU, and the entire
TU chain functions as if it is just the superior TU running by
itself.
That second flavor of FSK regeneration is also exactly the way you
can receive with an ST-8000 in the modern word. You turn on the
ST-8000 regenerator and feed the regenerated tones into the sound
card of a modern modem. Not that you would want to, since a whole
bunch software modems today wipe the floor with the ST-8000 if you
have set a decent sound card up properly. For transmitting? -- well,
we are back at Bill's dilemma -- how to key the FSK input of a
transmitter from a sound card based software modem.
73
> Chen, W7AY
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