SDRuno Settings with K3 IF

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SDRuno Settings with K3 IF

Post by Nj5n » Wed Jul 20, 2016 7:34 pm

I have been working with SDRuno utilizing my K3 IF output and everything is interfaced into the DXLab logging program. I am somewhat new to SDR software so I have been climbing the learning curve to try and understand how to achieve the most effective way to use the software.

I recently wrote SDRplay support with some questions and their reply was helpful to me so I thought I would put the information here so if there are others with similar configurations this might help.
I have changed to to the LOWIF setting in the Control window which has eliminated the DC Spike issue. I also set the IF BW to .6 in the Control menu even though the IF from the K3 is around 200 khz, this seems to give me a good view.
I normally leave the AGC off and just adjust it according to band conditions, as you will note in the reply I received there is a known bug with the AGC.
SDRplay support has responded to my questions very promptly when I have emailed them with questions which is greatly appreciated.
Message body
Hello Chris,
If you only want to work in Zero IF mode then I would stick to the main window. It's really one or the other. Setting the visual bandwidth on the main window configures the RSP in ZeroIF mode and will pick the appropriate IF BW and sample rate for the amount of spectrum you want to see. If you click the PERF button, which I see you have, that will pick the highest sample rate and use decimation to bring the final sample rate as close to the wanted visible amount of spectrum as possible.
If you start to then use the ADV panel, this overrides anything you set in the visual bandwidth on the main window and ignores the PERF setting. In the ADV panel you can specify the 3 parameters manually rather than have them calculated by the visual bandwidth on the main window.
I hope that makes sense. Basically I would suggest pick one way or the other and stick to it. If you only want to view 200kHz of spectrum, then there is no problem specifying that in the visual bandwidth field.
In Zero IF mode there will be a DC component at the LO frequency you set the RSP to. The slightly confusing thing about SDRuno is that you program the LO frequency using the RX control panel and then any clicks in the spectrum display do not reprogram the LO so you need to be careful where you think the centre is.
By default the DC/IQ button should be lit and that will ensure that the DC offset elemet is removed. You will see this by toggling the button on/off
Please note that there is a bug in the AGC in SDRuno where it may have a tendancy to "bounce" between values - this will be fixed in the next release. I can't really read how much gain reduction you have.
You can always try LowIF mode (only available in the ADV panel) which will have no DC component and compare the two modes to suit your needs.
Hope that helps,
Best regards,
SDRplay Support

On 20/07/2016 00:21, Chris Bradford wrote:

I have a couple of questions I hope you can provide some direction on:

1. In setting the BW sampling rate on the Main menu I am not sure what I should use as I am using an IF feed from my K3 which is around 200khz however when I use 200khz I seem to get a lot of mirroring of signals. It seems to work better at 600khz and then I set the IF BW in the RSP control menu to 200khz. Does this make sense as I am not really sure what the difference is in the two settings.

2. As you can see in the attached when I set the above settings as I described the "DC Spike" ends up in my area of interest. In this case it is showing up at around 14.012 and tends to block out that area from being able to see signals. Is there away to have the DC Spike offset from my tuned frequency to insure that it does not appear where I am tuning?

3. It almost seems the DC Spike is based on the frequency where I initially start SDRuno, so possibly I should start it out of band?

I really do like the modular design of SDRuno allowing me to size and place the important screens to work within the rest of the programs I am running.

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Re: SDRuno Settings with K3 IF

Post by DanubeBCL » Thu Jul 21, 2016 9:37 am

Is there a way to have the DC Spike offset from my tuned frequency
you only can click into the waterfall/spectrum window next to the center. Then every tuning will take place with an offset and you can avoid the center soundcard spike. But at next start SDRuno returns to the center and you are in the spike again unless you click off center once more.
Some SDR apps allow to use a constant offset when tuning to avoid the center spike which really makes reception distorted there. Some even allow the separate tuning of offset frequency and reception frequency in their plugin, CAT or TCP interface (like SDR#, SdrDx, even ELAD although they have no "spike" in the center).
But you are lucky with SDRPlay. Have you ever tried to receive an FM wide station with a Funcube pro dongle? The Funcude only covers appr. 192 kHz of bandwidth, which means every FM wide signal is affected by the center spike and reception is heavily distorted.
BTW: These DC spike compensation algorithms in the softwares do not help. The make the spike visually disappear but the payload signal is also "corrected" at this place and remains distorted.
I am talking about general tuning. I do not know if the Elecraft K3 IF usage needs special treatment. I do not have this setup. But in general this center spike is a problem with all soundcard based SDRs.
73, Heinrich
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Re: SDRuno Settings with K3 IF

Post by n9seo » Thu Sep 01, 2016 4:29 pm


The kx3 has an "RX Shift" option in the menu that can adjust the IQ to be 8KHz off. What I've noticed is the Main settings offset doesnt seem to take effect when you toggle it as expected here. Maybe a bug or maybe Im doing this in the wrong spot?
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Re: SDRuno Settings with K3 IF

Post by n9seo » Fri Sep 02, 2016 1:40 pm

Well I got the KX3 side at least acccurately measuring the difference in offsets in sdruno.

The problem in the last post is that i did not notice that 8000Hz does not save when you close the main settings panel out. Im not sure if that is by intention, or just a limitation in the code? The KX3 has a standard 0Hz offset or a 8khz one if you enable it in RX shift menu setting. It will move the IQ LO down 8000 so the rig will still be on freq and the DC point on IQ will be down 8000Hz. So this doesnt behave how I expected.

Whats worked so far is that i cannot use RX settings -> Orig to sync LO. Only the VRX->RIG and RIG->VRW work. You must manually tune sdruno this way to set sdr receive filter range on the desired freq.

E.G. If you tune to 10Mhz WWV, the LO base freq will be -8000Hz or 9.992Mhz in sdruno until you manually correct this in uno.

HDSDR has option to in the omnirig menu to set convertor offset but i suspect that is just not working in the menu I posted previously.
Hope this makes sense, only on first cup of coffee.
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Re: SDRuno Settings with K3 IF

Post by on6dp » Sun Sep 04, 2016 7:57 pm

I have also the same problem to receive the signal from my FT-2000D
Which values I must put in SDRUno to can also run on HF band
The IF frequ is 69,450 Mhz
Thanks in advance to explain me exactly the right parameters for my FT-2000D
73 de Paul, ON6DP
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73 de Paul, ON6DP / OP0P

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