[Elecraft] [KX3] ADC/DAC access, keyer input

Fri Aug 19 20:09:21 EDT 2011

What we are talking about is moving the ADC in the PC sound card (or external USB sound card if you will) to the rig.  It would not encumber the DSP, the stages are the same as what it does today. Analog stereo could even exist for 1mm on the board trace.

What you are describing is far more complicated than that.

Trouble is today that 192 KHz USB sound cards are hard to come by (although the chipsets are widely available) and the same is true for a 192KHz sound card in the laptop/PC unless we are talking high end (=power hungry) hardware.

Oh well. Screams for an aftermarket gadget.

-----Original Message-----
From: Jessie Oberreuter
Sent: Friday, August 19, 2011 5:54 PM
To: Edward R. Cole
Cc: Elecraft at mailman.qth.net
Subject: Re: [Elecraft] [KX3] ADC/DAC access, keyer input

      Yes, the I/Q data is already in digital form inside the KX3, so -- in 
theory -- it should be easy to just pump it to the outside world in 
digital form.  The challenges are with the standards for that transfer.
      If you could accept real-time digital data at the same speed the DSP 
is running at (say, via an optical port), this would be a no-brainer. 
Were such a protocol common-place, Elecraft may well have used it.
      Unfortunately, it isn't.  USB, ethernet, S/PDIF, etc. all have some 
sort of data framing, which means the KX3 would need to have additional 
buffer and protocol circuitry to negotiate the link and then frame the 
otherwise real-time I/Q data into packets that would then need to be 
transfered at considerably higher than audio rates to prevent drop-outs.
      As a designer, you have three choices: you can create your own ad-hoc 
lossless real-time digital protocol that almost no one will be able to 
use, you can dramatically increase costs and complexity by implementing to 
a more complex standard that many people still won't be able to use, or 
you can take advantage of a commonly available protocol for transfering 
real-time audio data that's perfectly adequate for the expected 
applications: analog stereo.

On Fri, 19 Aug 2011, Edward R. Cole wrote:

> HUGE FAILURE TO COMMUNICATE, guys!!!
>
> The originator wanted a IF, shorthand for interface.  He should have
> written it I/F and then all this extraneous e-mail would have been avoided.
>
> The KX3, like the K3 is a SDR, meaning it has a IQ mixer to produce
> the quadrature data streams for the internal micro-processor to use
> for recovering modulation of multiple kinds of modes.  He is just
> wanting access at the digital level to the IQ data for use outside
> the radio.  This is what is not available in the K3 design.
>
> I understand the K3 was designed several years ago and wasn't
> intended to run anything but Elecraft's proprietory sw.  But times
> they do change - its 2011 and a whole lot is changing on the SDR
> scene if you really look.  What some of us are asking is for it to be
> able to run other sw outside the box.  It should not be that
> complicated to provide a digital port for exporting the IQ signal
> pair to an external computer.  No body wants more soundcards...the
> request is exactly to avoid them.
>
> The other wish for a keyboard port would be nice for a lot of us that
> might use the KX3 for CW and internally supported DATA modes (Psk,
> RTTY are a couple that come to mind).  I haven't read up on details
> that are out on the KX3, but now seems a good time to get any last
> minute design wishes expressed (for a radio going into production in 5-mo.).
> -----------------
> I am still on the fence on what direction I want to go regarding the
> KX3.  I have a FT-817 which was bought expressly for use as a 144-MHz
> IF for portable mw operations.  It also can operate on ham
> satellites, though not crossband duplex, which is desirable.  I may
> decide to sell off my FT-817 and some other stuff to raise cash for a
> KX3+2m transverter (embedded would be a nicety).  But I l already
> have a 144-28 transverter for using my SDR-IQ, which can be used with
> the KX3.  Only problem is it outputs 20mw for mw transverter I/F, so
> an upgrade would be needed for 5w.  I am assuming the KX3 will have a
> transverter I/F.
>
>
>
> 73, Ed - KL7UW, WD2XSH/45
> ======================================
> BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
> EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-60w, 3400-?
> DUBUS Magazine USA Rep dubususa at gmail.com
> ======================================
>
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