Help diagnosing interference issues
edited February 2018 in Installation, Antennas and Interference
I'm having quite a bit of trouble diagnosing interference issues on my KiwiSDR setup.
I'm not sure if this is intermod from a close-by AM broadcast station, or something in my house interfering.
As of today, I'm using an active MiniWhip antenna that I purchased as a kit on eBay and fabricated the rest myself, making sure to use lots of ferrite toroids and a clean 12V power supply. Before that, I was temporarily running on a 40M dipole and an ATX Walkabout (MFJ 1899T) extendable vertical antenna intended for 80M to 4M, depending on the positon of the flying lead.
In all cases, I get these horrible vertical bars across the entire 0-30 MHz range, and noise is pretty lit up across the whole thing, but really hot around MW broadcast and a few other spots.
If I turn the power supply off, it goes pretty much dark. If I unplug the antenna, it goes completely dark. Therefore I'm confident that it's something radiated, being picked up by the antenna (and any antenna I've used, for that matter).
First blip is power removed. Second blip is antenna removed.
I just got a KiwiSDR kit from OKDO in the UK. It has horrible birdies every 30kHz or so on the waterfall even with no antenna connected. These also radiate from the unit and I can see them on my X6100 with sniffer antenna. I tried several low noise switch mode psu's and the problem is still there but no battery supply yet. Apart from this I love the system !
I just shut down the system from its webpage and the noise still radiates from the board until I disconnect the power supply physically ! This suggests it might be a clock which is left running on the beagle bone green even in shutdown state. I saw the comment in this thread that early BBGs had a noise problem.
Do you have any suggestions ? I need to overcome this noise problem.
What kind of PSU are you using
I am using a Meanwell PSU which is recommended by kiwisdr as it is a lower noise switch mode psu. I also try it with a raspberry pi psu with the same result. I can't find a 5V battery here otherwise I would try that. It no longer seems possible to buy a single 7805 regulator otherwise I could hang one of those on a 12V battery. The birdies sound like fsk signals modulated with some raspy sounding data. If I can rig up a battery supply then I could go out into an open field with a laptop and see if the birdies are still there.
The black band is where I unplugged the antenna for a few seconds.
He sent me waterfall images in email. I've asked him to post waterfall + spectrum images here. I see all the classic stuff: Ethernet noise, SMPS, VDSL/BPL. Without spectrum images it's hard to tell how bad of a problem this really is. People often see anything other than black / dark blue in the waterfall and think the sky is falling without really understanding what the waterfall is showing.
Problem solved !!! Thanks to the extremely helpful comments from jks via email. I switched the ethernet speed from 100Mb/s to 10Mb/s and the birdies went away instantly. I had tried 3 different routers connected to the ethernet port and the problem was consistent. Perhaps the birdies emanated fom the ethernet adapter on the BBG itself ? Anyway - I am happy today so thanks once again for the excellent support !