Date   

Re: Fo Max: Re: Re: [SDR-Radio] RF Gain & NR w/ RSPDuo

Barry Jablonski
 

Hi Joanne,

Good information. Too bad it is not mentioned in the Airspy documentation.

Barry
WB2ZXJ


Re: RSPDuo and SDRC

Simon Brown
 

No,

 

It isn’t. The new radio is coming, sometimes things take longer. COVID and the silicon supply chain really doesn’t help.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Waldemar
Sent: 26 July 2021 05:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] RSPDuo and SDRC

 

I sure hope this isn't the new super SDR you've been mentioning, Simon! I know you mentioned having sealed lips, but I've looked at the Malahit (real, not clone), the Hermes 2, and some other tempting units and decided to wait because I didn't want to be kicking myself when the unit I REALLY wanted was released!

cheers,
Waldemar, KI7VYJ

On Wed, Jul 21, 2021 at 05:40 PM, Simon Brown wrote:

Seriously, were there a radio with 4 or more channels I could be very interested, sadly one which was being developed will no longer be released to the public.

Simon Brown, G4ELI

https://www.sdr-radio.com


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: RSPDuo and SDRC

Waldemar
 

I sure hope this isn't the new super SDR you've been mentioning, Simon! I know you mentioned having sealed lips, but I've looked at the Malahit (real, not clone), the Hermes 2, and some other tempting units and decided to wait because I didn't want to be kicking myself when the unit I REALLY wanted was released!

cheers,
Waldemar, KI7VYJ


On Wed, Jul 21, 2021 at 05:40 PM, Simon Brown wrote:

Seriously, were there a radio with 4 or more channels I could be very interested, sadly one which was being developed will no longer be released to the public.

Simon Brown, G4ELI

https://www.sdr-radio.com


Re: Fo Max: Re: Re: [SDR-Radio] RF Gain & NR w/ RSPDuo

jdow
 

However, you cannot have both antennas hooked up at once. There is too much leakage between them. A coax switch is about the only good way to switch antennas. (SMA connectors are NOT made for frequent disconnections and reconnections. At the VERY least use a pigtail with SMA on one end and whatever you want on the other. Change antennas at that end of the pigtail. The gold plating wears off easily. Once that happens connections can easily appear solid and still be flakey.)

{^_^}

On 20210725 05:02:09, Barry Jablonski wrote:
Hi Bob,

The original Airspy HF+ does have two antenna ports.  I think it's still available.

     https://airspy.com/airspy-hf-plus/

Barry
WB2ZXJ






Re: Fo Max: Re: Re: [SDR-Radio] RF Gain & NR w/ RSPDuo

Gedas
 

Hi Bob, having both radios you are in a good position to comment on their actual on the air performance. Can you share your observations on their use on HF and lower, in particular BC and VLF?

Gedas, W8BYA EN70JT

Gallery at http://w8bya.com (under repair)
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 7/25/2021 6:20 AM, rmrrgs wrote:

Hi,

Interesting comments.

I have a RSPdx and the HF+ Discovery.

The only thing I will add is that for the Airspy, they should have put
two ant. spigots on it.  One for the HF range, and the other (which requires a different/separate ant.
of course), for the vhf.

Really inconvenient having to use switches to do it.
Also, I really don't want to have to spend additional $ to purchase, and incorporate, a Diplexer.

Would be so simple with two inputs, like for the RSPdx, and switch in the software.
Can't imagine why they didn't ?

Really a nice product, though.

Regards,
Bob





Re: Fo Max: Re: Re: [SDR-Radio] RF Gain & NR w/ RSPDuo

Barry Jablonski
 

Hi Bob,

The original Airspy HF+ does have two antenna ports. I think it's still available.

https://airspy.com/airspy-hf-plus/

Barry
WB2ZXJ


Re: Fo Max: Re: Re: [SDR-Radio] RF Gain & NR w/ RSPDuo

rmrrgs
 

Hi,

Interesting comments.

I have a RSPdx and the HF+ Discovery.

The only thing I will add is that for the Airspy, they should have put
two ant. spigots on it. One for the HF range, and the other (which requires a different/separate ant.
of course), for the vhf.

Really inconvenient having to use switches to do it.
Also, I really don't want to have to spend additional $ to purchase, and incorporate, a Diplexer.

Would be so simple with two inputs, like for the RSPdx, and switch in the software.
Can't imagine why they didn't ?

Really a nice product, though.

Regards,
Bob


Re: Fo Max: Re: Re: [SDR-Radio] RF Gain & NR w/ RSPDuo

Max
 

On Sat, Jul 24, 2021 at 10:34 PM, rmrrgs wrote:
Hi,

What, specifically, do you like better with the AirSpy HF+ Discovery compared to the SDRPlay units as you mention ?

Hi Bob

Please see my latest post in the original thread where I have to admit I take back a lot of my criticism of the newer RSP receivers. Seems after some research the RSPdx is actually far improved from the original RSP1 &2. I do think, however, the RSPs seem to cause a lot of issues from the posts I read in terms of having to be very careful with gain settings/HDR modes etc. in order to get a decent result. I do think the HF+ is much less fussy to operate in this regard. and Joanne's post in this thread  seems to confirm that the HF+ is a great little receiver.

Best

Max


Re: RF Gain & NR w/ RSPDuo

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


Re: Fo Max: Re: Re: [SDR-Radio] RF Gain & NR w/ RSPDuo

jdow
 

All of the above. It is more sensitive, which allows for smaller than usual antennas. It has a higher number of bits per sample than most of the other front ends in its class. It has an exceptionally good dynamic range. It is functional in two useful frequency ranges one of which is around 10-20 kHz through 31 MHz. (Officially coverage begins at 500 kHz.) The other band is 60 MHz through 260 MHz. And it is plug and play with no fussing around with installing USB drivers.

The downside main is that it is best used with its internal AGC so that large signals outside the bandwidth allowed  by its sample rate do not cause problems. This front end AGC renders the S-Meter calibration more questionable than most. Another downside is no US 6 meters coverage. On large antennas some of its outstanding features are mooted by the HF reality, there is far more noise from external natural sources than almost any HF receiver you can find. So it's excellent noise figure remains but is totally swamped when using large antennas. The cheap little "YouLoop" is tailor made for it giving you enough antenna to work well without overwhelming the front end with natural noise sources. It also gives you some nulling capability for local unnatural noise sources. If you get one you may need to acquire an adapter for its SMA antenna connector.

Most people who get one fall in love with it.

{^_^}

On 20210724 14:34:12, rmrrgs wrote:
Hi,

What, specifically, do you like better with the AirSpy HF+ Discovery compared to the SDRPlay units as you mention ?

Performance ?    How ?
"Better" chip ?
etc. ?

Best regards,
Bob





Fo Max: Re: Re: [SDR-Radio] RF Gain & NR w/ RSPDuo

rmrrgs
 

Hi,

What, specifically, do you like better with the AirSpy HF+ Discovery compared to the SDRPlay units as you mention ?

Performance ? How ?
"Better" chip ?
etc. ?

Best regards,
Bob


Re: RF Gain & NR w/ RSPDuo

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


Re: RF Gain & NR w/ RSPDuo

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


Re: RF Gain & NR w/ RSPDuo

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


Re: RF Gain & NR w/ RSPDuo

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


Re: RF Gain & NR w/ RSPDuo

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


Re: RF Gain & NR w/ RSPDuo

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


Re: RF Gain & NR w/ RSPDuo

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




Re: RSPDuo and SDRC

jdow
 

I knew somebody would ask that. You have to get into the design for frequency synthesizers to understand the effect. An example is the rtlsdr dongle synthesizer. It works on the basis of the average frequency being correct as it dithers between two "exact" settings. If you are simply listening there's no big problem. (Although SSB could sound "odd".) Two dongles set the same will still wander up and down with respect to each other enough to foul up efforts to perform RDF or nulling functions. There have been discussions of this on rtlsdr.com. Getting the dividers in the synthesizers in the same phase as each other takes some effort. Apparently when done, however, they have had success with techniques that require two receivers on two antennas that are tuned to EXACTLY the same frequency with no phase dither between them.

Was I clear enough, I hope. I want to be clear without wandering too far into the weeds.

{^_^}

On 20210722 10:31:11, Bob Dengler wrote:
At 7/22/2021 03:05 AM, you wrote:
If it has separate synthesizers then you can take it to the bank you will have synchronization problems for nulling applications and the like. For average listening it ought to be "Pluto level" good. {^_^} 
If the 2 synths are locked to the same reference, why would they drift w.r.t. each other?  Isn't that the definition of "phase locked"?

I can recall one instance where two commercial synthesizers locked to the same reference did drift w.r.t. each other over time, maybe 10° or so per minute.  But the outputs of both were multiplied up to ~500 GHz.

<O_O>

Bob NO6B 







Re: RF Gain & NR w/ RSPDuo

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

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