Initial Results from SQUID Sensor: Analysis and Modeling for the ELF/VLF Atmospheric Noise

Abstract

Abstract:In this paper, the amplitude probability density (APD) of the wideband extremely low frequency (ELF) and very low frequency (VLF) atmospheric noise is studied. The electromagnetic signals from the atmosphere, referred to herein as atmospheric noise, was recorded by a mobile low-temperature superconducting quantum interference device (SQUID) receiver under magnetically unshielded conditions. In order to eliminate the adverse effect brought by the geomagnetic activities and powerline, the measured field data was preprocessed to suppress the baseline wandering and harmonics by symmetric wavelet transform and least square methods firstly. Then statistical analysis was performed for the atmospheric noise on different time and frequency scales. Finally, the wideband ELF/VLF atmospheric noise was analyzed and modeled separately. Experimental results show that, Gaussian model is appropriate to depict preprocessed ELF atmospheric noise by a hole puncher operator. While for VLF atmospheric noise, symmetric α-stable (SαS) distribution is more accurate to fit the heavy-tail of the envelope probability density function (pdf).

A comparative study of ELF and VLF noise characteristics of nor’wester at a low latitude tropical station

“…We now compare some other related observations taken in recent years using the ELF/VLF radiation sources. It has been reported that ELF noise appears almost similar to Gaussian distribution associated with occasional impulses while, on the other hand, VLF noise shows more impulsive characteristics [9]. The observations further permit modeling of wideband ELF/VLF communication performances, providing improved knowledge of the behavior of natural background noise.…”

“…Besides receiving the spectral patterns of sferics, we have simultaneously made audio recording arrangement, which provided interesting findings that can be divided into three categories: (1) short bursts of radiation, may be called radio atmospherics [8], (2) reducing sound pitch, popularly identified as whistling atmospherics [9] and (3) an extremely high pitched tone, mainly utilized for sensing remote ionospheric disturbances [10].…”

Precision Magnetometers for Aerospace Applications: A Review

“…SQUID (Superconducting QUantum Interference Device) magnetometers [ 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 ] consist of a superconducting loop split by one or two Josephson junctions (essentially, nonlinear inductors) [ 100 , 101 ], as illustrated in Figure 6 .…”

“…The current circulating in the superconducting loop, and the corresponding voltage drop across the Josephson junction(s), are sensitive to the magnetic flux threading the loop. SQUID magnetometers offer high magnetic field sensitivity (sub-fT/Hz 1/2 [ 97 , 102 ]), high dynamic range (they can operate in the Earth’s magnetic field [ 92 , 94 ]), a large range of spatial resolutions (down to the nanometer scale [ 103 , 107 ]), and broad bandwidth operation (DC to GHz [ 104 ]). To achieve superconductivity, the SQUID needs to be operated in a cryogenic environment; this incurs large operating costs and is usually incompatible with low SWaP applications.…”

“…[ 69 , 70 , 71 , 72 , 185 , 186 , 187 , 188 , 189 , 190 ]) are appreciably smaller and typically exhibit reduced sensitivity. Notably, superconducting magnetometers (SQUIDs [ 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 ]) and devices with optical readout (optomechanical [ 20 , 131 , 144 , 145 , 149 ], NV diamond [ 19 , 132 , 169 , 170 , 171 , 172 , 173 , 174 , 175 ], atomic vapor cell [ 130 , 133 , 134 , 135 , 136 , 137 , 191 ], and SERF [ 192 , 193 , 194 , 195 , 196 , 197 , 198 , 199 , 200 , 201 ]) are almost universally more sensitive than their conventional/electronic counterparts of comparable sensor size (we have displayed atomic vapor cell and SERF separately, despite their underlying similarities, because of their markedly different SWaP, dynamic range, and control requirements). Furthermore, these emerging technologies are still far from the ultimate perform...…”