Sources of broad-band noise-bursts?

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JEL
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Joined: Wed Feb 07, 2018 2:08 am

Sources of broad-band noise-bursts?

Post by JEL » Fri Aug 24, 2018 2:56 am

What might be sources of broad-band noise-bursts, like the one seen in this screen-grab?

(It's the horizontal line from 120 to 210 MHz)

The antenna is sitting in a corner in a living-room, and isn't near any obvious electrical installations (Nor is the antenna-cable)
It is in an apartment-building though, so it's obviously a noisy environment.
spectrumspy-2018_08_24__04_47_41.png
spectrumspy-2018_08_24__04_47_41.png (232.35 KiB) Viewed 752 times

rtlsdrblog
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Re: Sources of broad-band noise-bursts?

Post by rtlsdrblog » Fri Aug 24, 2018 4:57 am

Light switches sometimes give of wideband noise bursts, but this looks to be in a defined area, so more likely to be something else.

JEL
Posts: 98
Joined: Wed Feb 07, 2018 2:08 am

Re: Sources of broad-band noise-bursts?

Post by JEL » Sat Aug 25, 2018 12:03 am

rtlsdrblog wrote:
Fri Aug 24, 2018 4:57 am
Light switches sometimes give of wideband noise bursts, but this looks to be in a defined area, so more likely to be something else.
That's what puzzles me too.

I get a lot of them.
Most seem to be about 10 MHz wide, but occasionally these huge ones show up.
They're never on the same frequency (At least not straight after each other, but perhaps over time they cycle through a loop. I haven't gone that deep into them yet)

I have checked out bursts from lightning-strikes and what I think may be electrical appliances, and light-switches and so on, being switched ON and OFF, but they always show up below about 50 MHz and they always appear to have power-spectrums that are bottom-heavy and gradually taper off the higher the frequency.

While the ones I get up here seem to be more linear in terms of power vs frequency (Same power across the hole frequency)

They do look, in their nature, a bit like some of the bursts seen around 433 MHZ (All those SRDs that sends data around there)

So wondering if perhaps this is some kind of data-transmission, although I don't know how much data you could realistically fit into an almost 100 MHz wide burst-signal that isn't even broadcasting for a full second)

rtlsdrblog
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Re: Sources of broad-band noise-bursts?

Post by rtlsdrblog » Sun Aug 26, 2018 12:56 am

It could certainly be data, eg telemetry monitoring something. Does your country have an accessible frequency data base? I'd suggest looking up that frequency range to see what companies have registered in those bands. Then you might be able to figure it out.

JEL
Posts: 98
Joined: Wed Feb 07, 2018 2:08 am

Re: Sources of broad-band noise-bursts?

Post by JEL » Sun Aug 26, 2018 5:07 am

Well, the one I got in the image stretches across aviation, maritime and enterprise bands... all at once :)

We do have a national list of assigned frequencies (Owners, wattage, transmitter-locations, etc), but no single user is listed as having access to a 100 MHz wide band. Not even 10 MHz wide bands.

The widest broad-band users listed are those of BCFM stations.

I will investigate further and see if I can make sense of it.

I thought it might perhaps be data-traffic from cell-phones, going back and forth to the tower (There is one about a 100 meters away, so fairly powerful), which perhaps are powerful enough to scatter mirror-images all over the frequencies.
I don't know if that's possible, and I can't really check it since I obviously don't have access to all nearby cell-phones (As said; it's an apartment-building, so there are bound to be quite a few phones and tablets nearby)

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