[Elecraft] Re: KX1 PSK31? [how about FSK?]

[Charles Greene]

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" <n6kr at elecraft.com>
>
>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.