Help identifying noise..

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Help identifying noise..

Post by DavidB445 » 17 Sep 2018, 12:40

Evening folks.
I'm getting some strange noise on SDR.. It appears at random times, sometimes it's there all day, sometimes it doesn't appear at all :eh:
Seems to be about 200mhz wide as it's non-existent below 60mhz and above 260mhz. The strongest point at around 170mhz.
It's constantly (but rather slowly) moving so it's hard to get an exact reading but seems to repeat at around 350khz intervals.

I'm connected to a 1/2 wave airband antenna, tuned at 127mhz.
Nothing is being turned on or off in my house when it appears or disappears, so I'm guessing it's outside interference from a neighbour or something near-by.

Anyone any idea what could be causing it and possible ways to get rid of it?
Also, it will disappear completely when disconnecting the antenna. Even with the gain set to maximum.

Thanks, Dave :thumbup:
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Re: Help identifying noise..

Post by radiosification » 29 Sep 2018, 12:37

I'm gonna guess it would be a TV. I have a similar kind of noise caused by a TV here, but any other electrical appliance could be causing it. The first thing to try is turn off everything in your home and see if you still get the noise. Run the SDR on a laptop off its own battery, if you can. Then turn things back on one by one.

But as you say, it could be external and if so then there is not much you can do.
If you're interested in digital voice, check out my YouTube channel:

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Re: Help identifying noise..

Post by Cornelius » 29 Sep 2018, 17:59

... or a led-light...

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Re: Help identifying noise..

Post by paulears » 30 Sep 2018, 12:17

switch mode power supply?

In truth - so many gizmos can cause it. If you are really keen to find it, first prove it is not being generated internally in the SDR by pulling out the antenna and replacing it with a small local antenna of any kind. If this doesn't produce the interference, you know it's 100% coming down the antenna cable, so go portable and wander around your area till you start to pick it up, then keep going until it gets stronger and stronger and leads you to it. A dipole made from coat hangers, held horizontally will let you spin it, and get a null - 90 degrees to it is the direction. Move locations and do it again. Where the bearings cross is the interference.

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