SOLVED: Identifying interference with oscilloscopes and software-defined radio

[djhuft]

I recorded a bit more since last post. Keep in mind that you are seeing the spectrum between DC and 120 kHz.

10 hours of recording through the night:


Another 10 hours from the daytime:


There are lots of interesting signals here, in my opinion:

• Both images: There is broadband interference across the spectrum periodically.
  
• Both images: There is a signal that sometimes appears and drifts slowly from low 60 kHz range to steady-state above 70 kHz. Maybe this is some sort of thermal effect inside the interfering device?
  
• Both images: The signals at 25 and 60 kHz are very strong and still present all the time.
  
• Both images: There is a strong signal at 45 kHz that comes and goes.
  
• Second image: There is a broadband interferer between 8 and 15 kHz that occasionally appears.
  

I'm not sure what to conclude...

The next time I am away from the apartment, I plan to shut off every circuit breaker, except for the one powering my laptop and Blitzortung receiver. Maybe some of these strange signals will disappear. If not, I probably need to look outside my apartment.

Also, maybe I should make a 5V battery backup for my Blitzortung receiver, then pray for a neighborhood-wide power outage.    I could get a lot of interesting data then!