And here a little experiment: Extracted the 7.8Hz component with a low Q bandpass filter (Q=2) and modulated the VCO port of a function generator chip (XR2206), carrier frequency ~ 615Hz. This makes the otherwise sub - audible 7.8Hz Schumann resonance audible by "warbling" the 615Hz carrier. Unfortunately there are also occasionally high level transients (noise spikes), and these cause a sudden ,large frequen- cy displacement with some ringing. The .wav file is ~ 340kB long, the last 5 seconds of the 30 secs. recording have (for comparison) the signal modulation switched off. Schumann.wave |
Throughout the experimentations with Schumann resonance reception it was always obvious that the weather had a profound influence on the quality and appearance of the recordings, at least in my location here. This may well be tied in with the presence of H.V. power lines within a km of the sensing coil(s). So far I never had the opportunity to escape into the remote Australian interior with my induction coil and PC, and make a few days worth of recordings , but I'm tempted !! To illustrate the problems, look at the following spectra : Weather dry, but strong winds Spectrum 9 , note the strong spectral lines around 17 & 22Hz, also a weaker line ~ 5Hz. Reasons for the presence of those lines are not clear (as yet). Same again, but comparison between ind.coil and underground loop Spectrum 10 As before, the left section shows the 5,17 & 22Hz lines (induction coil), the right side (40 turn underground loop) shows different lines altogether, preamp 12Hz LPF. Same again, but comparison between ind. coil N-S, and then E-W alignment . Spectrum 11 This is more surprising, at least 50% of dominant lines change when orientation of the induction coil axis was changed through 90 deg. This one showing how the Schumanns get affected by sudden rain Spectrum 12 Same again, two rain showers Spectrum 13 And the extreme, continuos strong winds and rain Spectrum 14 |
On the 28th April the 8Hz resonance was much stronger than usual Spectrum8 |
Also tried recording with SPECTRAN ,showing first 5 resonances Spectrum7 |
Schumann resonances Recordings |
Detection and recording of Schumann resonances proved to be more difficult than first expected. Initially I wanted to use my large ground loop , but never managed to see even the slightest trace of the Schumanns. Renato (IK1QFK) showed me that it was almost impossible to receive them with horizontal loops. Vertical polari- zation was required; this needed a bit of a re-think..... That's why I built the 200 turn Octoloop next, which made Schumann resonance detection possible. But due to loop microphonics, reasonable interference free reception is only possible when there is not much wind. Finally the big induction coil was built; this enables reception unaffected by weather, but (there seems to be always a "but") daytime operation is still riddled with some forms of interference. I call this collectively " human activity" . Because during the early evening hours the various low frequency spectrum spikes (~2......25Hz) slowly disappear and during most of the night clean spectra are recorded. |
Below is a comparison trace between the induction coil and the 200 turn Octoloop : |
Recorded with PICOLOG and ADC-11 device |
Also tried recording with SPECTRAN ,showing first 5 resonances Spectrum7 |
On the 28th April the 8Hz resonance was much stronger than usual Spectrum8 |
Last updated : 8th July 2001. |
Throughout the experimentations with Schumann resonance reception it was always obvious that the weather had a profound influence on the quality and appearance of the recordings, at least in my location here. This may well be tied in with the presence of H.V. power lines within a km of the sensing coil(s). So far I never had the opportunity to escape into the remote Australian interior with my induction coil and PC, and make a few days worth of recordings , but I'm tempted !! To illustrate the problems, look at the following spectra : Weather dry, but strong winds Spectrum 9 , note the strong spectral lines around 17 & 22Hz, also a weaker line ~ 5Hz. Reasons for the presence of those lines are not clear (as yet). Same again, but comparison between ind.coil and underground loop Spectrum 10 As before, the left section shows the 5,17 & 22Hz lines (induction coil), the right side (40 turn underground loop) shows different lines altogether, preamp 12Hz LPF. Same again, but comparison between ind. coil N-S, and then E-W alignment . Spectrum 11 This is more surprising, at least 50% of dominant lines change when orientation of the induction coil axis was changed through 90 deg. This one showing how the Schumanns get affected by sudden rain Spectrum 12 Same again, two rain showers Spectrum 13 And the extreme, continuos strong winds and rain Spectrum 14 |
And here a little experiment: Extracted the 7.8Hz component with a low Q bandpass filter (Q=2) and modulated the VCO port of a function generator chip (XR2206), carrier frequency ~ 615Hz. This makes the otherwise sub - audible 7.8Hz Schumann resonance audible by "warbling" the 615Hz carrier. Unfortunately there are also occasionally high level transients (noise spikes), and these cause a sudden ,large frequen- cy displacement with some ringing. The .wav file is ~ 340kB long, the last 5 seconds of the 30 secs. recording have (for comparison) the signal modulation switched off. Schumann.wave |