[Elecraft] KX3 I/Q SDR questions

[Tony Estep]

On Mon, Nov 7, 2011 at 3:32 PM, Richard Fjeld <rpfjeld at embarqmail.com>wrote:

> ...I have been trying to run PSDR-IF on an HP with a P4 at 3 GHz.  with a
> 96
> KHz SoundBlaster card.  The image problem makes it unusable. Yet WinRad
> displays fine....

========
Hi Richard,

Yeah, I can believe that. PSDR is buggy software. There's a saying in
computer science that as time goes to infinity, the number of bugs goes to
one. In the case of PSDR, that may be overly optimistic.

My post was not meant to be a recommendation of PSDR, but rather to reflect
on the differences between a dedicated SDR, an analog radio with outboard
IQ circuitry feeding a panadapter, and the KX3 design which does the
detection and filtering in on-board computing gizmos and then hands off the
IQ for those who like a PC-based panadapter.

On the topic of images: PSDR is supposed to tune out its on-screen image,
and this actually has worked for me. To make it work, you need to feed it a
steady S9+ carrier offset from the center frequency. It can help to tweak
the relative channel amplitudes while watching the image amplitude; on my
laptop I use an EMU 0202 sound card, which has knobs for this purpose. My
desktop has a built-in 192K sampling sound card, and its control software
has a slider.

However, this is a side issue relative to my original point, which is that
I'm betting that the KX3 design will be very influential in the future of
ham rigs, and will spell the end of the knobless SDRs we see today, which I
believe are a dead-end diversion in the evolution of ham radio.

73
Tony KT0NY

-- 
http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352