The very first signal

After several years of failure with this project, I finally acquired a signal! The first hint at a signal came from averaging 128 scans (almost an hour of data collection!) down in the basement of the University of Nebraska chemistry building:

Blue shows the acquired signal without polarizing, and green is with polarizing.

The hump at 1775 Hz corresponds to a field strength of 41 microTesla, which was verified by my phones MEMS magnetometer. The peak is so broad because of massive field inhomogeneity caused by nearby iron structures that distort magnetic field lines. The sharper signals that appear in both spectra are (mostly) harmonics of the 60 Hz mains frequency.

While this was promising, it was nowhere near the expected performance of the PyPPM. So, I had to test it further...

Confirmation that the PyPPM works

A few weeks ago, I took the PyPPM out to a small field that was about 50 meters away from roads, electrical wires or buildings. After 32 scans, the resulting signal was (a) beautiful and (b) unequivocal proof that the PyPPM works! :)

The field here is roughly 54 microTesla, and even out in the field, I could still pick up sources of interference! The next step is definitely to design a humbucking sensor coil...