A new portable ELF Schumann resonance receiver: design and detailed analysis of the antenna and the analog front-end

Constantinos I Votis,Spyridon K Chronopoulos,Giorgos Tatsis,Panos Kostarakis,Christos Repapis,Vasilis Tritakis,Vasilis Christofilakis

doi:10.1186/s13638-018-1157-7

Constantinos I Votis, Spyridon K Chronopoulos + Show 5 more

Open Access

https://doi.org/10.1186/s13638-018-1157-7

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Abstract

Schumann resonance oscillation detection is a complex procedure which requires customized and high-quality measurement systems. The primary objective of this work was to design and implement a stand-alone, portable, and low-cost receiver able to measure as much Schumann resonance harmonics as possible. Design, as well as detailed analysis of the efficient induction coil magnetic antenna and the low-noise amplifying-filtering chain, is presented. The detection system includes two coils back to back, resulting in a total coil length of 60 cm. The filtering and amplification chain exhibits an experimentally measured total passband gain equal to 112 dB at 10 Hz and as low as 2.88 nV/√Hz equivalent input noise. In order to validate the new portable ELF Schumann resonance detection and monitoring system, we took measurements at various spots “relatively” free from man-made electromagnetic pollution. Results have shown very clear Schumann resonance peaks for the first six modes with 10-min acquisition time.

Highlights

The Schumann resonances (SR) are electromagnetic oscillations of the Earth-ionosphere cavity at frequencies of 7.8, 14, 20, 26, 33, 39, and 45 Hz
We provide simulated results on noise figure (NF) in decibels at 10 Hz for each stage of our amplifying and filtering chain (Table 5)
5 Conclusions A new portable ELF receiver for Schumann resonance detection and monitoring is presented in detail in this paper

Summary

Introduction

The Schumann resonances (SR) are electromagnetic oscillations of the Earth-ionosphere cavity at frequencies of 7.8, 14, 20, 26, 33, 39, and 45 Hz. There is a very limited number of ELF measurement stations around the globe, based on synchronous electronic methodologies and techniques of signal reception, conditioning, and processing The contribution of this new ELF Schumann resonance receiver includes (a) signal conditioning stages with an equivalent input noise as low as 2.88 nV/√Hz and a total passband gain from 86 to 112 dB at 10 Hz, (b) monitoring and recording of six SR harmonics through a two back-to-back magnetic field antenna with total weight of 2.2 kg and 60 cm length, and (c) portability and over one and half month autonomy. The total simulated and measured frequency response of our amplifying and filtering chain is shown, in case the passband gain of the variable gain amplifier has a prefixed value of 1 From these curves, it is obvious that there are limited declinations between the simulated and experimental results. To verify that the primary aim of this work was achieved, which was to design and implement a standalone, portable, and low-cost system able to

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