SDR Console with W11

Chris van Lint

Sorry Simon,

Hope that this fixes that issue


-------- Forwarded Message --------
Subject: Re: [SDR-Radio] SDR Console with W11
Date: Sun, 31 Jul 2022 05:31:36 +0000
From: Chris van Lint <chrisvanlint@...>

Thank you for your input. I think I understand what you are getting at, but with all due respect it does not really solve the mystery as to what happens when I change frequency using the mouse on the numerical tuner in the DPS.

I have replaced the RTL820 dongle with my Airspy HF+ and that works perfectly fine. Noting that he Airspy HF+ will only allow a BW of 768kHz, I re-inserted the RTL820 and changed the BW to 750kHz. This did not solve the problem. The RTL820 works fine on the SDR-C I have installed on my Laptop running W10. IMHO it would appear that the problem is due to some miscommunication between this particular system and the dongle. I cannot help but conclude that I am flogging a dead horse and I will just have to accept that this is one of mysteries of life and move on and simply use the Laptop.

I know that Simon is allergic to videos, so just in case someone has a flash of inspiration, I have taken a few successive screenshots which will hopefully provide a graphic record of what is happening.

This is the screen when I start SDR-C:

All this looks normal as expected. I now advance the tuner 3.0MHz to 121.2:

All looks quite normal. Now watch what happens when I increase the tuner by another 1.0MHz;

Even though the vertical tuning bar #1 (if that is what it is called) appears to be at 121.3MHz the received signal does not conform with that frequency and the 120.9MHz signal remains at the centre of the display.
If I now reverse the tuning back to 120.9MHz the received signal is lower than the 120.9 Peak, which remains in the centre:

Now if I advance tuning by 7.0MHz to what on the DSP is displayed as 121.6MHz the display looks like this and the tuning bar is to the right of the 120.9MHz signal, which is still in the centre:

Now if I move the frequency shown on the DSP to backwards to 121.5 I receive the 120.9MHz signal again!

If I adjust the frequency display in the DSP to 120.9MHz I get this:

All mysterious stuff !
The only way I can get the 120.9MHz signal to correspond with what is shown in the DSP panel is to Stop SDR-C and re-start
Cheers, Chris

On 30/07/2022 12:03, jdow wrote:

That little keyboard changes the front end's tuned frequency. Since it is 10 MHz wide and you made a small change the receiver can both remain active and as expected on the same frequency. All that little keyboard does is change where your receiver is within (or outside of) the front end's 10 MHz bandwidth. You can define multiple receivers each with a different tuned frequency. That is you can listen to repeaters on 448/060MHz and 448.000 MHz and 446.040 MHz all at the same time if your front end is (nominally speaking) anywhere between 443.060 MHz (about 443.6 MHz to avoid strange effects) and 451.060 MHz (again 450.4 MHz would be better). All three receivers would remain running on their tuned frequency. One thing you will notice is the bottom of the waterfall will show a shift in its frequencies an the active bandwidth when you tune with the little keyboard. That would show the effect I mean.

I don't know if I found the right words to explain. If not I'll try again.


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