Mitigating External Interference
Hi, in anticipation of receiving a new KiwiSDR2 I have some interference I wish to mitigate.
The interference is external to my property. Recently during a power cut and running an SDRPlay RSP1A, I quickly pulled out a battery to power my amplified loop and noticed that the interference was gone but as soon as the power was restored the interference was there immediately lending me to believe there was no 'turning on' process such as might be expected from a television or other electrical appliance but that may not necessarily be true fact.
All power utility is serviced underground so I expect no issues there and if I turn off the house mains the interference remains.
Attached is a graphic of the interference on the 8 MHz aeronautical band. Similar interference resides on 5911, 6650, 7401, 8141 and 8861kHz (approx. 740kHz spacing). The spikes drift up and down over a period of roughly three days by about +/-20kHz.
Since I have no apparent control over this I would like some options to mitigate this when using a KiwiSDR. I can reduce the amount of noise by turning my antenna but that is not a lot of reduction. I have a second loop that could be used for diversity but I see no real ability to effect that given that the KiwiSDR will be remotely located so no dual antenna input to the KiwiSDR nor able to be manually tweaked by some other hardware device.
If anyone has any ideas on:
a. the possible source of this interference, or
b. a way of minimising the level of noise
I'd be happy to hear your thoughts,
Comments
Have you tried to DF it to see which neighbor may be radiating that?
OK, so at least you have confirmed it's not something it your own property, which is always a good starting point.
It does seem like a switched mode power supply of some sort.
Does the noise vary during the day or night, or seem to match any other pattern like the amount of sunlight or EV cars not being parked and possibly recharged.
It gets progressively more complicated to trace noise sources, but walking around with a simple loop antenna to triangulate the rough location is probably the next thing to try.
Regards,
Martin
No, the noise is pretty stable throughout day or night 24/7. OK I'll have a think on progressing this matter. If it is a switchmode power supply it's not being turned off at any time in the last six months!
Do you have an ultrasonic air humidifier with built-in power supply at home? Mine generated identical double stripes in standby mode, which appeared several dozen minutes after turning off the steam. The fog generator board itself only made white noise around 28Mhz even though it was placed 2 floors down in the house. Therefore, I would bet on a device with a switching power supply that has become very worn out. Of all the +/- 20 power supplies I had at home, only 4 do not cause problems in HF