The image below represents a type of ELF (extremely low frequency) persistent waveform which has been present in two different apartment buildings during the time raven1 has lived with the electronic harassment problem. This signal has been present non-stop for months at a time.
The extremely sharp sawtooth waveform is not natural to normal household appliances, and raven1 has no unusual equipment at home, not even a PC.
The detectors used were two very large (24" x 24" and 24" x 72") air core coils, about 75 and 260 turns respectively. It is raven1's experience that large flat coils detect very little of the 60 Hz AC power fields which are always present in a home with electricity. (The randomly oriented fields probably cancel when the coil size gets large.)
This field is usually highest in the vicinity of the bed, and makes tape recording nearly impossible.
When this unusual and strong waveform is NOT present, another type of sawtooth signal has been observed, in the form of a normal 60 Hz AC sine wave with a small sawtooth component impressed on it. The sawtooth component's amplitude is about 5 percent of the 60 Hz amplitude, and perhaps 100 times the 60 Hz fundamental frequency.
These signals are EASY to detect and display, and raven1 would like to hear from other victims who might make such observations in their homes.