SDR-Console Peak in center

[Manu1981]

Hello,

apologies if I'm not right here. Maybe somene can help me out. In SDR-Console I always have a noisy peak in the center no matter where I go (frequency, band...). Unfortunately I didn't find a possibility to get rid of it.
In Cubic SDR the peak is not there but SDR-Console fits better to my requirements.... if that peak weren't there...!

Anybody knows how to get rid of it?

My Setup:
TRX: Yaesu FT 911a with IF Out
SDR: MSI SDR (RSP1)
Raspberry PI 4B with RSP_TCP Server running
Win 10 Notebook with SDR Console v3 connected to RSP_TCP Server and OmniRig for Frequency and Mode Sync

Any hints appreciated!

Best regards
Manuel

[KA1GJU]

In SDR language, that's usually referred to as a "DC Spike". Google it and you will find lots of info! But, here's some info on the groups site:
https://sdr-radio.groups.io/g/main/topic/5928569

I run SDRC servers, and don't have any issue with the DC spike on the RSP1A. So maybe something with using the Raspberry Pi server? Any old laptop (W7 and higher) will work as a server. Even the little Window 7 Netbooks with Atom processors!

SDRC automatically reduces the DC spike, and you can watch it slowly disappear on my SDR-iq. But my RSP1A, never an issue with the DC spike.

73 Kriss KA1GJU

[Simon G4ELI]

Hello,

apologies if I'm not right here. Maybe somene can help me out. In SDR-Console I always have a noisy peak in the center no matter where I go (frequency, band...). Unfortunately I didn't find a possibility to get rid of it.
In Cubic SDR the peak is not there but SDR-Console fits better to my requirements.... if that peak weren't there...!

Anybody knows how to get rid of it?

My Setup:
TRX: Yaesu FT 911a with IF Out
SDR: MSI SDR (RSP1)
Raspberry PI 4B with RSP_TCP Server running
Win 10 Notebook with SDR Console v3 connected to RSP_TCP Server and OmniRig for Frequency and Mode Sync

Any hints appreciated!

Best regards
Manuel

Please add a screenshot.

[Max]

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

Best

Max

[Manu1981]

@KA1GJU: Tnx fr ur 1st reply. I was reading the group but there was no info that was helping me. I changes the sample rate but there was no effect. Since I had a laptop running as a server all the time (for other things) I don't want it anymore. In addition the laptop has no WoL function which is pertty important for my needs. So the Raspberry is a good choice I think. As I said Cubic SDR works fine. There's no peak and it gets it's data also from the Raspberry. So I would exclude that as the source of error.

@G4ELI & Max: Also many thanks to you guys! I now add a screenshot.....

73's de Manuel

[PD3LK]

This way we can't see what bandwith your using... please add screenshots of a running radio.
Try a BW of 2MHz or lower...

[jdow]

Show all the windows so we know your gain settings and so forth.

More Than You Probably Want To Know But Less Than Rigorous
=======================================

With SDRConsole around here the presence of the noise spike in the middle is a really good indication I need to increase the front end's gain. Tune in a fairly weak signal. Increase front end gain. If the signal lifts out of the noise (SNR improves) repeat until the noise and signal lift by the same amount. if the signal gets very large compared to the noise move to a weaker signal. Repeat this until the noise and signal lift by the same amount. As a general rule I then back off one gain step if the steps are fairly small. By the time this dynamic range setup is done I'd expect that noise pip to be very much smaller.

There is a way to reduce it further. But it introduces a discontinuity in your tuning range at the notched out "DC" peak. That peak is basically made up of noise multiplied by a copy of eh same noise, local oscillator self-conversion, once the basic balancing act is performed.

Devices that use one single A/D converter for both I and Q signals by sampling at twice the intended I/Q sample rate are inherently balanced for all but the zero point with some slight imbalance from internal stray signals. Zero point balance is easy to achieve. Devices that use two separate A/D converters have many balance terms to setup. There is the same zero point balance times two. Both A/D converters must be balanced out. The A/D converter gain differences must be balanced out. And the 90 degree sampling phase shift must be balanced out. The gain differences are also easy to balance out in SW. Gain and offset form the center pip. Then you have the difficult balancing act, phase. If the sampling phase is not precisely 45 degrees within small fractions of a degree you get ghost signals for strong signals. The ghost signals are precisely as far from the center pip as the strong signal but on the other side of the pip. That requires some sophisticated auto-correlation nulling tricks. SDRSharp and Linrad do this. I am pretty sure Simon plays with that somewhere in SDRConsole but don't know for sure.

{^_^}

[CBaltazar]

Tuve el mismo problema, hace tiempo intene solucionarlo en todos los fors posibles, recien hoy porbe algo que esta en este foro:
http://sdrplay.com/community/viewtopic.php?t=82

[jdow]

Hm, I see a brain fart in that message. I believe I sand 45 degrees when I meant 90 degrees. But it seems you understood what I meant anyway.
{o.o}