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SDR-IF and I/Q questions

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Richard Fjeld

SDR-IF and I/Q questions

Larry,
Thank you for the suggestion. That could be possible. I'd hate to remove the Z10,000
Buffer/Amp to change out a SMD component, but that may be what I will have to do.
My Z10,000 is set for 0 dB gain at present. I just e-mailed the Google PSDR-IF group
a question about an observation I have made. It may be totally in the wrong pew, but
you may want to look for it. And, it may reveal something I am doing wrong.

Thanks,

Dick, n0ce
_________________________
Dick, if some programs work, then your levels may be low. PowerSDR/IF
and NaP3 use an algorithm developed by Flex Radio called WBIR (Wide Band
Image Rejection). It does a phenomenal job of eliminating images (>80dB)
but is sensitive to levels, requiring a minimum amount of total signal
power in the display to work. Since you say that other programs work,
your issue may be levels.
_____________________________-

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Richard Fjeld

SDR-IF and I/Q questions

In reply to this post by Richard Fjeld

Whoops, apparently I do not have permission to post to the Google groups, yet. So it will be awhile before I can.

So, FWIW, I will say it here, until then.

I have a K3 with a SoftRock Lite II IF receiver , and I have to use SDR-1000 in the setup. When I do the Image Rejection Calibration, I notice the software tunes my radio to WWV at 10 MHz, and then changes it to 9.982 MHz. It looks like it is trying to calibrate for the SDR-1000, but the SoftRock has a 24 KHz offset.

Could this be the problem, or not?

I set things up according to the best info I could find at the time.

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

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Richard Fjeld

SDR-IF and I/Q questions

In reply to this post by Richard Fjeld

Dave,
I can see your point. One of my earlier posts referred to the problem of
finding an acceptable arrangement to have a pan-adapter for a KX3 using
the I/Q leads, as the IF isn't brought out. I apologize for not making that
distinction in the subject line. That may have thrown others off as well.

However, I am using a SoftRock receiver with a K3, so I have many of the
same problems as we would have with the KX3, only it would not need the
SoftRock.

I don't like to express my likes and dis-likes, but since you asked, I will give
you my personal opinion about the following programs. Others may dis-agree.
Please don't sent me hate mail.

You asked about NaP3. Yes, I tried it, and yes I like it, however I have the
same mirrored image problem as I do with PSDR-IF as they are similar. YMMV.

I think I have tried everything I could find that would be an acceptable matchup,
thinking of it for a KX3. I was trying to find something similar to having a P3 in quality.

You mentioned TRX-Pan. Yes, I tried it. I should maybe give it another try, but
I was not impressed with how it looked. Perhaps I could get used to it. As I remember,
it had a big spike in the center which seemed larger than that of WinRad.

WinRad and HDSDR, are very sensitive on receive, and have no images. If WinRad provides
control, I did not have info on how to use it. HDSDR does, using OmniRig, but control quit
working after awhile. Perhaps I did not have time to learn how to set it up properly.
One thing I did not like is that it seems to only look upward in spectrum from where the
radio is tuned to. But it has other pluses. Both programs show the phase angle, and
they record as well. The ZAP feature is nice for cw.

Rocky works, but I find it to be more of a tool. It displays the signal strength of the L and R
signals (I/Q). That is useful. Rocky can be used, but still not like a P3.

I tried SDR-Radio also. I think it may be new in the offering, and more developments may
coming. Like HRD, it has many add-ons. It wasn't what I was looking for, but a consideration.

All during this time, I have been preparing to give a presentation on SDR to our local club,
so could not devote a lot of time to each one, and it would be nice if that was not necessary.
Unlike plug and play.

I agree with your intended use. I know that SDR offers advantages, but if you have a K3,
you will be satisfied with it's performance.

Some of the comments I received seemed to be polarized with my appreciation of the P3.
The main beef seems to be the screen size. It sure has been adequate for these old eyes.
It is plug and play, and fast to use. I have it programmed up for quick button selections for
the way I operate, and I like it. If the screen was larger, it would not match the radio. Yes,
the addition of a monitor will be nice. I hope we don't lose the ability of looking at the P3 screen
when a monitor is used, but we can't expect to have everything. Time will tell.

SDR is fun to play around with as a learning tool, and will be rewarding to achieve a beautiful
pan-adapter. When I said I was giving up on SDR, I should have said 'for now', as I spoke of
the need to correct the problem of mirrored images.It is not just me, as many are having that
problem. I was trying to find a pattern among those users who were either successful, or unsuccessful. I didn't get the info I requested.

73,
Dick, n0ce
____________________________________________________
The thread title didn't say anything about being restricted to the KX3,
and your comment simply stated that you were giving up on SDR in general
... hence my comment. Whatever rig you've been having your problems
with (I assume a K3), it certainly wasn't a KX3.

I'm curious which programs you have tried that didn't have good rig
control. Do you include TRX-Pan and NaP3 in that group? I'm interested
because those are the programs I intend to try with my K3. By the way,
my intended use would be for spectrum display and point/click QSY. I'm
perfectly happy to rely on the rig for actual reception, filtering,
demodulation, gain control, etc. Your needs may be different than mine.

Dave AB7E

______________________________________________

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

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N8LP

Re: SDR-IF and I/Q questions

I think that the Image Rejection CAL screen only works with SDR-1000
hardware. It was removed in NaP3.

Larry N8LP

On 11/15/2011 11:01 PM, [hidden email] wrote:

> Date: Tue, 15 Nov 2011 13:32:11 -0600
> From: "Richard Fjeld"<[hidden email]>
> Subject: [Elecraft] SDR-IF and I/Q questions
> To: "elecraft posting"<[hidden email]>
> Message-ID:<929717600FA246A7AEA27697ADF1FEB3@BIOSTAR>
> Content-Type: text/plain; charset="Windows-1252"
>
> Whoops, apparently I do not have permission to post to the Google groups, yet. So it will be awhile before I can.
>
> So, FWIW, I will say it here, until then.
>
> I have a K3 with a SoftRock Lite II IF receiver , and I have to use SDR-1000 in the setup. When I do the Image Rejection Calibration, I notice the software tunes my radio to WWV at 10 MHz, and then changes it to 9.982 MHz. It looks like it is trying to calibrate for the SDR-1000, but the SoftRock has a 24 KHz offset.
>
> Could this be the problem, or not?
>
> I set things up according to the best info I could find at the time.
>
> Richard Fjeld, n0ce
> [hidden email]
> I'd rather be learning.
>

______________________________________________________________
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N8LP

Re: SDR-IF and I/Q questions

In reply to this post by Richard Fjeld

You might want to consider buying an XG2 test generator kit from
Elecraft. It would help a lot to have a signal of known level to adjust
your overall gain. It would also help with image rejection adjustment,
although a single carrier at S9 is a tad low for WBIR to work reliably.
WBIR assumes a lot of medium strength signals. As the number of signals
goes down, the required strength of the signals goes up. We use -50dBm
(S9+23dB) in the shop to check out LP-PANs before shipping. WBIR takes
about 10 seconds to find an initial null at this level. The image drops
to about -130dBm. If you set your overall gain so that you get a -73dBm
blip with the K3 preamp OFF, that would give you about -62dBm with the
preamp ON. You can get the extra gain by changing the gain setting
resistor on the Z10000, or increasing the sound card gain. If your K3
does not have the buffer mod, that would be a good idea to add as well.

73,
Larry N8LP

On 11/15/2011 11:01 PM, [hidden email] wrote:

> Date: Tue, 15 Nov 2011 13:21:24 -0600
> From: "Richard Fjeld"<[hidden email]>
> Subject: [Elecraft] SDR-IF and I/Q questions
> To: "elecraft posting"<[hidden email]>
> Message-ID:<423B456D46A04B79A8646FDD9820B2B2@BIOSTAR>
> Content-Type: text/plain; charset="Windows-1252"
>
> Larry,
> Thank you for the suggestion. That could be possible. I'd hate to remove the Z10,000
> Buffer/Amp to change out a SMD component, but that may be what I will have to do.
> My Z10,000 is set for 0 dB gain at present. I just e-mailed the Google PSDR-IF group
> a question about an observation I have made. It may be totally in the wrong pew, but
> you may want to look for it. And, it may reveal something I am doing wrong.
>
> Thanks,
>
> Dick, n0ce

Richard Fjeld

SDR-IF and I/Q questions

In reply to this post by Richard Fjeld

Larry,
I think you are correct. This now makes sense.

Thanks,
Dick, n0ce

_____________________________________________-
Message: 10
Date: Wed, 16 Nov 2011 09:21:58 -0500
From: Larry Phipps <[hidden email]>
Subject: Re: [Elecraft] SDR-IF and I/Q questions
To: [hidden email]
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I think that the Image Rejection CAL screen only works with SDR-1000
hardware. It was removed in NaP3.

Larry N8LP

On 11/15/2011 11:01 PM, [hidden email] wrote:

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

______________________________________________________________
Elecraft mailing list
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Richard Fjeld

SDR-IF and I/Q questions

Larry, (Reply to message 12, 16 Nov 2011)

Yes, I have the XG2 generator for portable use, and another gen in a IFR1500 I can use.

I wrote down the test levels when I tested the SoftRock w/Z10,000 but
I don't remember them. I hope I can find the notes easily.

I found this interesting: ("As the number of signals goes down,
the required strength of the signals goes up")

I DO understand the last part of the paragraph,
but I have a question about this: ("We use -50dBm (S9+23dB) in the
shop to check out LP-PANs before shipping")

What is the ratio of input to output level? And better yet, what is the input level
you expect to see from the IF of a radio on average? I'm curious.

Thanks again,
Dick, n0ce

____________________________________________-
You might want to consider buying an XG2 test generator kit from
Elecraft. It would help a lot to have a signal of known level to adjust
your overall gain. It would also help with image rejection adjustment,
although a single carrier at S9 is a tad low for WBIR to work reliably.
WBIR assumes a lot of medium strength signals. As the number of signals
goes down, the required strength of the signals goes up. We use -50dBm
(S9+23dB) in the shop to check out LP-PANs before shipping. WBIR takes
about 10 seconds to find an initial null at this level. The image drops
to about -130dBm. If you set your overall gain so that you get a -73dBm
blip with the K3 preamp OFF, that would give you about -62dBm with the
preamp ON. You can get the extra gain by changing the gain setting
resistor on the Z10000, or increasing the sound card gain. If your K3
does not have the buffer mod, that would be a good idea to add as well.

73,
Larry N8LP

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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