John,
I would think the first step should be to add a reactance modulator and
simple interface to a computer sound card, ala the psk20, to the KX1 and
use it with an ordinary computer, running a program like MixW. Mixw
supports FSK31 by sending an FM modulated signal via the computer sound
card to the mike input of a transceiver. For example, I can operate FSK31
on my K2 now; I just have to select it in MixW. I have a simple interface
made up. Anyone can do this with any rig that operates on PSK31. The only
difference is that the KX1 finals would operate class C, and the other rigs
finals would operate class AB or some other linear mode. Of course that
means you carry a LapTop with you when you go portable, but some have
stated that isn't a problem. To have Elecraft to make a small keyboard and
display that would plug into a KX1 type radio and allow if to transmit and
receive FSK31, seems to be reinventing the computer. HP, Dell, etc do it
pretty well, Yes I'd like to have one, but from Elecraft's point of view
I'm not sure there is much of a market for that. Also, I'm not sure who
you would talk to, as I have never seen FSK31 used, but maybe we could
start an Elecraft net.
73,
Chas, W1CG
At 01:35 AM 10/8/2004, John, KI6WX wrote:
The original PSK31 implementation included an option for FSK31.
Theoretically, PSK31 should provide a 2-3 dB improvement in signal to noise
ratio over FSK31. In practice, it is necessary to back off the power
amplifier by a few dB to keep from generating an excessively wide signal,
whereas FSK31 can be run in a class C amp at full power (as long as your
amplifier can handle transmitting a continuous carrier). This difference
can negate the improved SNR of PSK31. Since may of the digital mode
software products support FSK31, it would be an interesting experiment to
test its efficiency in a real communication system.
A KX1 could trivially generate a FSK31 signal. Decoding it might require a
more powerful processor, but is doable. The interesting question is how you
interface the input and output to the operator. A display and keyboard
would require a larger package or a separate module that plugged into a KX1.
There are some small keyboards and displays that would work for this type of
application.
So perhaps we ought to ask Elecraft to make a small keyboard and display
that would plug into a KX1 type radio and allow if to transmit and receive
FSK31. It would even be a nicer option if you could plug it into a K2 and
transceive both FSK31 and PSK31.
-John
KI6WX
----- Original Message -----
From: "wayne burdick" <[EMAIL PROTECTED]>
However, it may be possible to operate the KX1 in any low-data-rate,
dual-tone FSK mode. This is compatible with a class-C final amp, and
should require only a firmware change. The KX1's key jack would serve
as the data input/output port for connection to a computer.
Unfortunately FSK (e.g. traditional RTTY) is not quite as popular as
PSK31 for QRP use, even though good reliability is possible with some
variants.
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