Re: coexist SDRuno 1.41.1 with SDRconsole3.1 with RSPdx?


jdow
 

That sounds VERY much like auto-mute is turned on.
{^_^}

On 20220222 06:18:55, Kurt Hechler wrote:
Hi Folks,

did now a no antenna test like jdow suggested.

But first of all, if I switch the AGC to on  the SDR RX went quiet and no spectrum/waterfall is displayed.   So all further test are made with AGC off!  RSPdx Bandwith at start is 2MHz

Do not have a good signal generator just a Elecraft XG3 with -107dBm, -73dBm and -33dbm

First test:
Signal -73 dBm  //  IF-Gain -50 // Visual Gain 0.  Adjusting RF-Gain to 20 to show S-Meter S9.   Now putting signal to -107dBm  S-Meter shows S2 and signal is hardly heard.

Now putting signal to -33dBm  (s9 +40)  SDRconsole stop to work  (means no RX no spectrum and waterfall. Putting back to -73dBm everything RX is working spectrum and waterfall too.


My point of view:  dynamic range is bad and I can not explain why that happen now  after my update.

Repeat my measurement within SDRuno without any problem.   XG3 seems to be not so accurate.  Measure -108dBm(snr 6dB),    -75dBm(snr 40dB) and     -35dBm(snr 75dB)

My first idea HW should be okay. 

Test are made on 3520.0 kHz  (80m)

Any ideas???

As I asked:  Can I go back to 3.0.27  to do these test there?  Or do I run in trouble when if downgrade to 3.0.27. Is version 0.27 working with SDRuno 1.41.1 ???

73
Kurt





Am 21.02.2022 um 23:58 schrieb jdow:
There is a mute setting. Overload usually means you are transmitting. This prevents feedback. In your case the antenna switch made sufficient signal level change that it looked like you were transmitting. At least that's by guess.

And one important note should be appended here. If you connect the antenna and the receiver noise level goes up 6 dB. If it goes up more than 6 dB you are simply wasting dynamic range.  Add front end attenuation. That's the rule for traditional receivers.

For SDRs you can squeak out a little more dynamic range by performing the no antenna test with a signal generator giving you a fairly weak signal. SDRs are sort of magic. They can interpolate between levels. A big signal can put a signal not making 1/2 ADC step can pop out when another signal at say 3 ADC steps. How many times does it hit 2 vs 3 vs 4? You average and there is your 1/2 level signal.

The final trick is purely subjective although SDRC's SNR meter helps. Select a very weak constant signal, SNR maybe 20 dB with the gain up high. Reduce the gain until the SNR drops a couple dB. You'll be set almost perfectly. Then if you connet an antenna with a whole lot more gain, an attenuator is the appropriate fix on HF. At low HF frequencies you can get a natural noise level equivalent to a  40 dB noise figure receiver.

It is hard to accidentally make a receiver that bad. I have done that, though, for a test. Now I run my apparently deceased ProII with 30 dB of attenuation on all the time when on 75 meters. I get the same SNRs as without the attenuation. And the strong 1590 kHz or so signal a couple miles away does not overload anything.

{^_^}    (ProII is about to become an organ donor - it's RF chassis is still just fine.)

On 20220221 12:57:43, Kurt Hechler wrote:
Hi Simon,

from my understanding is the USBpower sufficent.  See attached files.

Maybe I found the problem.  If I was for example on 40m I have to move RF Gain to round about 18 to see the SSB signals. If I go now to 80m and switch from the short dipole to the LW the Console is in overload and does not show spectrum as well the RX is quiet.  If I now minimize the RF gain to round about 10 the Console comes back.  IF Gain is -45, AGC off.   I do not know such a behavior from the early version. Even with the minimized settings the RX is sometimes switching on/off.  Bay the way SDRuno do not show that behavior.

73
Kurt
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