RF Gain & NR w/ RSPDuo


n6vl
 

Using a new RSPDuo with V3 and having trouble with RF Gain and Noise Reduction. I've been listening to SSB and CW signals on 40 meters and trying new emulate my ham HF transceiver. I'm used to lowering RF Gain to get a better signal to noise ratio. Also the same with Noise Reduction.
But this isn't happening with SDR Console V3 for me. I have a little better success with SDRUno with noise reduction. But I like Console so much better, especially for an ergo perspective.

Bottom line: I get fatigued trying to copy signals with my RSPDuo.
Any ideas? de Steve N6VL


oldjackbob@...
 

Steve,

I've always optimized S/N ratio in SDR Console by adjusting the Receiver AGC Threshold.

Mark



jdow
 

I see a little bit of a problem here. On 40 meters the RF Gain control cannot change the actual SNR due to all or most of it coming in on the antenna wire. And as a practical matter I've seen a front end that actually developed a lower noise figure with increased AGC action It had other defects that made it undesireable. So I am not sure what effect you are experiencing on your transceiver.

That said on the left you will see an AGC tab. Click to expand it. Then click the off button. The "Gain" slider then behaves like an RF gain control. But it will behave the same as the audio level control for SSB and CW. For AM you may see a difference. I suspect it will not be big. Note that an SSB or CW receiver without AGC is basically a direct frequency conversion to audio frequency from RF with filters and no other audio conditioning. So going from maximum gain downwards can only increase the noise level relative to the signal level.

In general you get the best SDR or ham transceiver performance with the gain set at the point the signal to noise stops improving with increased gain. You can increase the gain usefully until you see spurious signals more or less explode onto your spectrum display. You cannot do better usefully.

{^_^}

On 20210722 09:28:06, n6vl via groups.io wrote:
Using a new RSPDuo with V3 and having trouble with RF Gain and Noise Reduction. I've been listening to SSB and CW signals on 40 meters and trying new emulate my ham HF transceiver. I'm used to lowering RF Gain to get a better signal to noise ratio. Also the same with Noise Reduction.
But this isn't happening with SDR Console V3 for me. I have a little better success with SDRUno with noise reduction. But I like Console so much better, especially for an ergo perspective. Bottom line: I get fatigued trying to copy signals with my RSPDuo.
Any ideas? de Steve N6VL


jdow
 

That is another way to do it. (And the volume control can probably help, too.)

{^_^}

On 20210722 13:13:07, oldjackbob@... wrote:
Steve,

I've always optimized S/N ratio in SDR Console by adjusting the Receiver AGC Threshold.

Mark




n6vl
 

Thanks Mark!

This solution does the trick!. The only caveat is that I can't do this w/o actually going into the AGC settings and change it. Also there are 3 possible AGC settings: Fast, Med, & Slow each with a separate Threshold slider.

In the end it's exactly what I'm looking for. It's the closest thing in SDR Console to an RF Gain knob on a ham transceiver.

The NR function is another matter. I like NR3 with lower settings under 10 dB. It works okay on SSB. On CW I prefer to disable all NR and use narrower filters.

Steve


n6vl
 

Replying to jdow

You have the same solution as oldjackbob above. The only difference is there is NO gain slider in my installation. I think you meant the Threshold slider instead. See the photo in message #63478 above.

Steve


jdow
 

Turn AGC off to get the slider I meant. There are some CW ops who hate AGC and run MGC all the time. So I suggested it. If you like the threshold control operation you might benefit from a long hang time on the AGC. On my R-390A I put in a hang agc that as a by product raised gain maybe 10-20dB fairly rapidly, hung there for a second or so, and then fairly quickly raised gain to max I had set with its "threshold control", the old MGC control modified somewhat. I grew to really like that action. Weak signals trying to break in got a tiny boost and my ears got a rest for a second before the noise came up. Experimenting with that is on my RF bucket list.

{^_^}

On 20210723 09:48:37, n6vl via groups.io wrote:
Replying to jdow

You have the same solution as oldjackbob above. The only difference is there is NO gain slider in my installation. I think you meant the Threshold slider instead. See the photo in message #63478 above.

Steve


n6vl
 

Replying to jdow,

My bad, I didn't catch turning AGC off, you did mention it the first time. Thanks for the clarification.

I'm  more of a CW listener than operator. Trying to get SDRC with my SDRPlay approximate my FTDX3000 on receive, which is a tall order. Want to use the SDR as a second receiver. The transceiver and the SDR are very different receive in usage.

Steve


jdow
 

With AGC the threshold control nicely approximates an effective RF gain control that raises the signal level at which the AGC becomes effective. However, do remember you can note some values that seem to work in notepad and make more changes to them all. A little experimentation can let you know what the controls do. The notepad reference is a way to get back to settings you like.

That's probably the best way to learn all the features. Some will be "Oh, I see what it does. Why do I want that?" Some will be (showing my age) "Nifty". And some will need some use to see what they do for you. (That's how I learn commercial or military surplus equipment. It even led me, as a teenager, to dig into the "crystal notch filter" within the NC-109 I had.)

Listen to the CW ops here. I have enough dyslexia learning the code just doesn't work for me. I did get to 35 WPM without ever really learning the code by sounds. I just followed a mental decoding tree in my head aided by context. It was a heavy duty strain. For me CW is not fun. And that table is long gone, now.

{^_^}

On 20210723 19:42:28, n6vl via groups.io wrote:
Replying to jdow,

My bad, I didn't catch turning AGC off, you did mention it the first time. Thanks for the clarification.

I'm  more of a CW listener than operator. Trying to get SDRC with my SDRPlay approximate my FTDX3000 on receive, which is a tall order. Want to use the SDR as a second receiver. The transceiver and the SDR are very different receive in usage.

Steve


Max
 

On Sat, Jul 24, 2021 at 03:42 AM, n6vl wrote:
I'm  more of a CW listener than operator. Trying to get SDRC with my SDRPlay approximate my FTDX3000 on receive, which is a tall order.
Hi Steve

Sorry to say, if your primary need is HF then you possibly did not make the best choice with an SDR Play receiver. It's a good all round tool for sure, especially if you want to receive up in the VHF/UHF/SHF area all in one receiver, but if your primary need is HF then there are (far) superior options. Don't get me wrong, I have a RSP2Pro and it has its uses, but I generally avoid using it on HF due to all its foibles. For HF I think most will agree that Airspy HF+ Discovery is the better option but for very little more cost you can buy the Hermes Lite HL2 which is a true direct sampling HF SDR (and also a transceiver!). It's superb and no hassle with all of these RF/IF/AGC gain issues, RF images etc etc that you get with the old front end mixer designs. Anyway, as I say, only my opinion (having used all three..... to me, no contest):

http://www.hermeslite.com/
https://www.makerfabs.com/search.html?&search=hermes
Currently out of stock but should be back soon.

Of course you can try out many HF+ and other radios (sadly no HL2 I don't think but maybe one or more on there?) around the world using the SDRC server feature, so don't take my word for it, go and try one out yourself. Takes about two minutes to set up!

https://www.sdr-radio.com/server

(Skip down the page until you get to the heading "Add Definition")

Max


Max
 

On Sat, Jul 24, 2021 at 09:07 PM, Max wrote:
Hi Steve

Sorry to say, if your primary need is HF then you possibly did not make the best choice with an SDR Play receiver.
OK Steve (and anyone else reading), so now time for me to eat some humble pie! I didn't want to make an unfair post so I spent quite a lot of time after posting the above to take a look at many reviews of the later SDR Play receivers. It seems Jon Hudson and the team have gone to considerable effort to improve the later models and now indeed (having watched quite a few YouTube video comparisons too) it seems there really is very little in it between the latest RSPdx receiver and the HF+ Discovery. The newer RSPs do seem to be much improved in terms of front end filtering to prevent images etc. That's what my RSP2 Pro suffers from in abundance, and believe it's not a small issue. It's pretty terrible, which is probably why I've been a bit hard on the RSP brand, but as far as the later models go now I can see unjustifiably so. Apologies for jumping the gun.

From what I can make out the Duo stands somewhere between the RSP1/1a/2 and the RSPdx in terms of overall performance.

However, as per my last post what  do stand by is that for amateur bands HF use, the Hermes Lite 2 is still a superb performer for not disimilar money and has the major advantage of being direct sampling (and it's a transceiver!). It really is pretty much a "turn on and go" rig instead of having to fiddle about with this and that gain setting, HDR mode, blah blah to optimise for each band. It honestly "just works".

Anyway, at the end of the day I also strongly suggest getting the SDRC Server radios a go as I mentioned in my last post and trying all the different available brands that have kindly been made available for remote use by their owners.

Also you might like to read this post from the man himself, Jon Hudson. Throws more light on the design philosophy of the RSP receivers:
https://sdr-radio.groups.io/g/main/message/53341

73

Max