SOLVED: Identifying interference with oscilloscopes and software-defined radio
One final experiment for the night...

I still have my software defined radio dongle connected to my Blitzortung receiver's amplifier output.
  1. I turned all the (LED) lights on in my apartment, and switched on as many gadgets and devices as possible (my PC, fans, radio).
  2. I powered my Blitzortung receiver from a USB battery pack.
  3. I disconnected my laptop charger (the laptop that I used to record this data)  from its outlet. The charger generates significant interference, which tends to confound my measurements.
  4. I set up my software-defined radio dongle and GQRX to record a waterfall plot that was five minutes long.

Then I started recording...

After a couple of minutes, I turned off all the circuit breakers in my house.
(Lower on the waterfall is earlier in time.)
[Image: F7YYhA7.png]
Lots of noise is eliminated, but not everything! Those pesky 25 kHz and 60 kHz signals are still there..

Next, I left everything off for a couple minutes, then I turned the breakers back on.
[Image: PdA3bmj.png]
You can see interesting emissions as my devices powered back up. I suspect that this coincided with routers booting up, etc.

Messages In This Thread
RE: Identifying interference with oscilloscopes and software-defined radio - by djhuft - 2017-08-08, 04:50

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