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Re: KX3 I/Q SDR questions

Posted by Nr4c on Nov 07, 2011; 9:13pm
URL: http://elecraft.85.s1.nabble.com/KX3-I-Q-SDR-questions-tp6960402p6972108.html

Folks, are you assuming the P3 will plug into the KX3?  If so, I think it
will be while until such an adapter is offered.  The P3 accepts input from
the IF out connector on the KXV3(a) board.  I don't think the KX3 even has
an IF to output.  It outputs I/Q signals which are audio level outputs for
direct input into a computer sound card.

...bill  nr4c




-----Original Message-----
From: David Gilbert [mailto:[hidden email]]
Sent: Monday, November 07, 2011 3:14 PM
To: [hidden email]
Subject: Re: [Elecraft] KX3 I/Q SDR questions

"I have to ask what type of soundcard and computer you are using to
accomplish this?
Also, would you include the total value of your package if I were to
purchase the same?"

That's kind of like figuring in the cost of your shack, tower, or antennas.
If you already have a decent computer and sound card, the relevant answer
would be zero additional cost since there is some very competent free SDR
software out there and the KX3 isn't going to require anything else except
an inexpensive cable.  I'm not sure any of that will be any more difficult
to install than doing P3 and K3 firmware updates.  Worst case, if I didn't
already have them, I might factor in the cost of a high end sound card, a
video card with outputs for two monitors, and a second monitor.

But just for the sake of argument, a dedicated computer with great software
flexibility can be purchased new (or factory refurbished) for less than
$300; a low noise, high dynamic range sound card capable of 192 KHz band
coverage for maybe $120 (see N8LP's list of suggested models); and a
dedicated monitor with much larger size and resolution than the P3 for
around $100.

To each his own, but I think KT0NY is totally correct and I think Elecraft
has done an admirable thing by including I/Q outputs in the KX3.  If the KX3
turns out to be significantly less susceptible to mushing of multiple low
level in-band signals than the K3, the combination of that and the I/Q
outputs might even be enough to make me sell my K3 and buy a KX3.

Dave   AB7E



On 11/7/2011 12:34 PM, Richard Fjeld wrote:
> I have included Tony's comments below.  I agree with paragraph one.
>
> However, in paragraph two I take issue.  I am considering the ease and
convenience
> of using a P3. Plus the bandwidth is wider. It is plug and play. No
computer
> issues of hardware, software, and soundcards.
>
> I have used PSDR-IF. I would like to be able to run PSDR-IF, but I am not
alone
> in experiencing mirrored images. Yes, my I&  Q signals are balanced. Yet
WinRad and
> HDSDR works with no images.
>
> I have to ask what type of soundcard and computer you are using to
accomplish this?
> Also, would you include the total value of your package if I were to
purchase the same?
>
> Thank you,
> Richard Fjeld, n0ce
> ______________________________________________________
>
> I would add to Richard's comment that the KX3 design appears to me to be
an
> ideal implementation of SDR for amateur purposes. I have played around
> quite a bit with SDRs. I've owned 2 Flex radios and have 2 Softrocks, and
> that experience has convinced me that the actual signal detection, DSP
> filtering and processing, etc. should all be done inside the radio, not by
> a general-purpose PC. Today's SDRs are an interesting proof of concept,
but
> as operating ham rigs they have insuperable flaws that result mainly from
> trying to get a PC to do tasks that would be much better done by a
> special-purpose computing system with a suitable OS and tailored data
paths.
>
> The computerized panadapter is quite neat and I have found it to be even
> more useful than the very useful P3 (I use PSDR-IF, but there are many
> more; see the LP-Pan home page and/or many other SDR pages for samples).
> However, to use it with an analog radio like the K3, you need extra
> gadgetry and complexity in the shack. I'm really looking forward to
getting
> my hands on a KX3. Perhaps after it hits the market, ham rigs will start
to
> provide I-Q output as standard equipment. That would be a step forward for
> ham radio, and another chapter in Elecraft's history of innovations in the
> industry.
>
> 73,
> Tony KT0NY
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