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

[Jessie Oberreuter]

      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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