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  #1 (permalink)  
Old 07-08-2014, 2:12 PM
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Default interference

hwy guys i use an SDR Dongle to Receive Amateur-radio and i have huge interference (Picture).
So hat could that be?!
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Old 07-08-2014, 8:50 PM
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Quote:
Originally Posted by Your_account View Post
...So (W)hat could that be?!
It's hard to say. It could be almost anything with a switching power supply and/or microprocessor. You didn't give us enough information to even speculate.

Is this audio baseband? IF? What frequency? The display says 437.2203 MHz. Really? Does it go away if you remove the antenna? What is the antenna? Is anything grounded? Is it grounded properly? What is the bandwidth of the waterfall display? The on-off pulses almost look like Morse code... equal sign or hyphen? More likely a micro processor type noise.

Details please. The picture is utterly useless without the narrative that should have come with it.
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Old 07-08-2014, 10:01 PM
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Yes, the picture is useless. It could be almost literally a million things. You gave us no information to go on.

If I were to take a wild guess, it looks like your computer might be struggling with the program. Never mind all of the random interference lines, from the looks of the horizontal shifting lines, it seems to me that the program itself is struggling. Might be a problem with too little RAM, other programs clogging up CPU resources, or a faulty dongle. But really it could be anything, but my suspicion is with your computer.
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Old 07-09-2014, 4:49 AM
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Quote:
437.2203 MHz. Really?
yes...
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What is the antenna?
Indoor for aircraft freq.
Quote:
Is anything grounded?
i dont know but the dongle via usb yes?!
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What is the bandwidth of the waterfall display?
2mhz
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Does it go away if you remove the antenna?
i have to check

other frequency +/- 10mhz work perfect.
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Old 07-09-2014, 11:29 AM
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Can you post a screen shot with a spectrum analyzer type display instead of the waterfall display? With an indoor antenna, you're quite likely getting interference from the computer.
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Old 07-09-2014, 2:01 PM
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Aliens. It's gotta be aliens.



It could be a TV giving off RFI. When my living room plasma TV is on, 445.575 on my radio gets a ton of noise. Turn off the TV and the noise is gone.
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Old 07-09-2014, 2:02 PM
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i never use any TV...
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Old 07-09-2014, 2:20 PM
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A thousand different things from poor shielding in absolutely
anything and everything cheaply engineered that generates RF,
to RF traveling along cables - ethernet, audio, home wiring.
Maybe a dimmer, fluorescent light, poor ground on powerco
xfmr, cheap CATV amp, loose or improperly installed
cable tv cables, blah, blah, blah.

Routers and ethernet cables are super common sources of
interference along with loose or improperly installed cable tv
coax fittings. They spew out all kinds of noise.

The tough part is that it could be in any of your neighbor's homes, too.

If only on one or several freqs,
Have you put that freq in a handheld and done a walk around???????

Are you using a laptop or PC with UPS?
If so turn off the AC main at the house.
That will eliminate many possible sources.

I'd bet you'd find all kinds of ideas on how to solve
interference problems by using the search feature
in the RR forums.
It's been discussed hundreds of times.


Good luck.
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Last edited by mikepdx; 07-09-2014 at 2:25 PM..
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Old 07-09-2014, 2:22 PM
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Quote:
Have you put that freq in a handheld and done a walk around???????
i dont have any but when i shutdown my pc i can put the antenne on my tablet pc and check.
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Old 07-09-2014, 3:03 PM
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Had a similar problem. Try using an outside antenna.
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Old 07-09-2014, 3:09 PM
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I am on the 1Floor and i cant use an Outside Antenna.
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Old 07-09-2014, 5:08 PM
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Quote:
Originally Posted by Your_account View Post
I am on the 1Floor and i cant use an Outside Antenna.
Can you try putting one outside the window, or making a stealth antenna?
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Old 07-09-2014, 5:15 PM
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when i use the small antenna outside its the same noise.
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Old 07-09-2014, 5:29 PM
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Cable-TV channel 59 perhaps (due to leakage from a nearby CATV cable).
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Old 07-10-2014, 7:47 AM
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so i check it yesterday and my pc make that noise.
the huge problem is a cant close that pc the case is rubbish....
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Old 07-10-2014, 9:35 AM
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Maybe try wrapping it in aluminum foil (keeping the vent holes uncovered) to form a Faraday cage?
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Old 07-10-2014, 9:38 AM
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i mean the case is full open!
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Old 07-10-2014, 1:29 PM
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So, now you know... computers generate RF noise. Placing a receiver right next to an open computer is going to cause the receiver to pick up noise. You need to do two things... separate the antenna from the computer, and close up or otherwise suppress the noise radiating from the computer.

In the snippets of sentence fragments you've provided us, we've managed to discern that you're on the first floor, can't use outside antennas, and are using an SDR dongle adjacent to the computer that has some sort of undefined "rubbish" open case issue.

Sounds like a recipe for failure to me, and you're not giving us much to work with to come up with suggestions. Good luck to you!
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Old 07-10-2014, 8:33 PM
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Try a ground loop isolation transformer. You can get them for around twenty bucks on the internet or you can make your own if you have some ferrite cores hanging around. The output of my computer had terrible noise on it when plugged into my stereo system, and this was completely eliminated by the transformer.
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Old 07-10-2014, 8:39 PM
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assuming this is the pc that you're using with your sdr dongle, maybe you should read some reviews and shop around for a quieter pc? it's not a point that you'll see mentioned in most reviews, but that screenshot looks pretty terrible if you ask me, and if it's generating that much noise, it's obviously not much good to try and use it with your dongle?
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