Hello,
I'm not sure what to call it, but I'm having a problem with certain
high frequency beeps that show up through the mains current in my
house when I record. I've been told that these pulses on top of the
normal 60Hz exist as a control method for refrigerators (?) but I
don't know for sure. Every few minutes, there are two very high
pitched tones about one second apart. They're barely noticeable. But
they are there. It's not a 60Hz hum.

Can anyone tell me what this beep is called? Could I get rid of it
with a notch filter? If so, what frequency?

Thanks,

-Mike Walters
www.mysterycircuits.com