Interference from PC - What is it causing?

Great Idea :slight_smile: Thanks!

I got a v3, v2 and v1 laying around xD So i dont have to use the v3 from the kit :wink:

Is there a Windows version as well? I only have Linux on Servers in the moment.
Would be nicer as setting up a new vm.

UPDATE: found something :slight_smile: Will try it later today.

regards,
Manuel

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yes, not as good as the linux one but exists something: GUI for rtl_power download | SourceForge.net

Hello again, i finally got some time yesterday to install and use a spectrum analyzer.

I used a RTL-SDR v2 (metal case) with the supplied antenna. In my first test, i placed the antenna next to the Outernet Receiver.

PC OFF:

PC ON:

You can see that there is a signal from the pc between 1,6ghz and 1,62ghz.

I the placed the Antenna on my Desk (1m from the pc that stands on the desk) in my second Test.

PC OFF:

PC ON:

I also tested if the interferance gets stronger if my GPU is at full load. You can see that there is more noise from 1,3ghz to 1,5ghz, but the signal mentioned before doesen’t get stronger.

I also shielded the antenna with a thin carbon sheet that reduced the signal loss. I will test some more shieling soon.
The ferrites also arrived yesterday, but the don’t seem to effect the signal when clamped around the USB cables and Antenna cable.

regards,
Manuel

That is what you get for putting a plastic window in the case…
Replacing the lid with the optional closed version (usually available) could help a lot.
But of course such a case is clearly not designed by an RF shielding expert so it probably has many
other leaks as well (like covers without metal contact every few cm). You know, the "contact fingers"
or even spungy metal you find in a professional case.

Nah…A case with a window is nice :slight_smile:

Also the metal looks like it’s anodised, so there is no perfect RF shielding. But thats not the purpose of a pc case, it has too look good and must be stable.

I think shielding the case of Outernet, that i planned to print, will be enough.
even the not grounded Carbon helps to reduze the noise quite well.

regards,
Manuel

Apparently different people have a different opinion on what the function of a PC case is…
In itself that is not bad, but you clearly are affected by the problems resulting from using a beauty case
instead of a functional case. So then you should start thinking about it…

A functional case would be a brick of metal with some cutouts for ait and the ports.

But that’s another topic, i will shield my planed Outernet case with some alu foil inside, that should be enough.

Of course not! The interference that has leaked out of your PC will enter the Outernet receiver at
the antenna, and you cannot shield that. The only thing that could help is to increase the distance
between the PC and the Outernet system.

The back of the Antenna is pointing into the room where the PC sits, so i can shield it from the back. The antenna is pointed away from the PC.

I already shielded the back of the antenna with a carbon sheet that leans against the Antenna. An it works! I get much less interference from my PC, then before.

I tested the SNR change between shielded Antenna (from the back) with alu foil glued to cardboard vs none.

Without shielding: ~3,5db
shielded:~6,5db

So it seems to filters a lot of noise that comes from my PC.

Where is the spectrum SS with plyers?

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Ahhh…there is no space for plyers in front of the Antenna :frowning:
But there is a Aluminium windows frame near the Receiver as a replacement for the plyers :wink:

I tested if the interference is leaking out only from the window.

And it’s not… also on the opposit site of the case, where it is closed with a metal side panel, the signal is as strong as on the window side.

I already wrote above, your case is probably crap. It has lots of other leaks than the window.
A long slot, e.g. where a side panel meets the case frame without proper electrical contact every
few cm by use of contact fingers or similar will leak as much as a window does.

Unfortunately a case like that can often be sold, especially as separate part for later integration by
the customer, no matter if it meets basic requirements for RFI.

Now that you are a victim yourself you notice this, but normally PC owners are not aware that their
equipment is causing real interference in real life, and will wave comments away. And their neighbors
often lack the technical knowledge to know that some interference they have may be due to the PC
nextdoor.

wait wait wait…it’s not “Crap” only because it doesn’t shield the RFI :angry:

My case is realy sturdy and has a lot of room for hdds and ssd etc. It looks nice to me and has good cooling (A lot of Fan mounts) and Dust filters. That are some of the aspects that matter for a PC case. RFI shielding is not one of them!

Also it can not cause interferance for any of my neighbors. Even in the next room the interference is not there anymore :wink:

So there is no problem with the lacking RFI shielding, if you don’t use outernet or similar in the same Room.

Please stop raging on PC cases…also what case are you using or would use that is RFI shielded?

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How about a oil filled metal box with heat fins and shielded/sealed ports. Great for overclocking and for RFI as well. :slight_smile:

My method od shielding my Antenna from behind seems to work very well :slight_smile:

In the graph below you can easily see that the SNR drops (black border) when my pc was on, are now gone (red border).

regards,
Manuel