KX3 I/Q SDR questions

[Tony Estep]

On Mon, Nov 7, 2011 at 3:32 PM, Richard Fjeld <[hidden email]>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
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[N8LP]

The E-MU 0202 was $99, and if you can find one, should still be in that
price range. Its replacement, the E-MU 0204 is $140, but it should drop
soon since it has been out for some months. The Infrasonic Quartet is
$90 and still available at auzentech.com. The two older cards also
appear periodically on eBay for even less.

Larry N8LP



On 11/7/2011 8:23 PM, [hidden email] wrote:

> Date: Mon, 7 Nov 2011 15:32:09 -0600
> From: "Richard Fjeld"<[hidden email]>
> Subject: Re: [Elecraft] KX3 I/Q SDR questions
> To: "elecraft posting"<[hidden email]>
> Message-ID:<F5837842E184478FA3A133B789FCA8EC@BIOSTAR>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=response
>
> Thanks Dave,
>
> My comments were to address only the pan-adapter aspect.  The SDR-IF
> receiver was the means to achieve a seemingly low cost computerized
> pan-adapter. (I acknowledge that the SDR receiver offers unique features. No
> argument.) I will be interested to see where a 192 KHz card can be bought
> for $120.
>
> 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. I've used both a Softrock and an LP-PAN.
>
> I have a friend, and I read about others, who are trying to make it work on
> other radios with the same problem.  We can't find the solution. I have been
> told that others are successful. Perhaps it lies with the Video Card which
> you omitted in your cost estimates.
>
> Dick, n0ce

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[Richard Fjeld]

My thanks to the many answers to this subject, and in the Elecraft Digest Vol 91, Issue 9

Good stuff.  I will cut and paste the answers for future reference.

Because the current subject is shown for the KX3, I wish to change the subject to simply 'SDR-IF and I/Q questions' as it could include topics common to one, or both technologies.

I still have a question or two.  See you under that subject.

Richard Fjeld, n0ce
[hidden email]
I'd rather be learning.


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