scholarly journals A Positioning System Based on Low-Frequency Magnetic Fields

2021 ◽  
Author(s):  
Paolo Carbone ◽  
Valter Pasku ◽  
Alessio De Angelis ◽  
Marco Dionigi ◽  
Guido De Angelis ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Low Frequency ◽  
Outdoor Environment ◽  
Positioning System ◽  
Induced Voltage ◽  
Quality Factors ◽  
Large Area ◽  
Key Factor ◽  
Loop Antennas ◽  
Transmitting Antenna

This paper describes the design and the realization of a low-frequency ac magnetic-field-based indoor positioning system (PS). The system operation is based on the principle of inductive coupling between wire loop antennas. Specifically, due to the characteristics of the ac artificially generated magnetic fields, the relation between the induced voltage and the distance is modeled with a linear behavior in a bilogarithmic scale when a configuration with coplanar, thus equally oriented, antennas is used. In this case, the distance between a transmitting antenna and a receiving one is estimated using measurements of the induced voltage in the latter. For a high operational range, the system makes use of resonant antennas tuned at the same nominal resonant frequency. The quality factors act as antenna gain increasing the amplitude of the induced voltage. The low-operating frequency is the key factor for improving robustness against nonline-of-sight (NLOS) conditions and environment influences with respect to other existing solutions. The realized prototype, which is implemented using off-the-shelf components, exhibits an average and maximum positioning error, respectively, lower than 0.3 and 0.9 m in an indoor environment over a large area of 15 m × 12 m in NLOS conditions. Similar performance is obtained in an outdoor environment over an area of 30 m × 14 m. Furthermore, the system does not require any type of synchronization between the nodes and can accommodate an arbitrary number of users without additional infrastructure.

scholarly journals A Positioning System Based on Low-Frequency Magnetic Fields

2021 ◽  
Author(s):  
Paolo Carbone ◽  
Valter Pasku ◽  
Alessio De Angelis ◽  
Marco Dionigi ◽  
Guido De Angelis ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Low Frequency ◽  
Outdoor Environment ◽  
Positioning System ◽  
Induced Voltage ◽  
Quality Factors ◽  
Large Area ◽  
Key Factor ◽  
Loop Antennas ◽  
Transmitting Antenna

This paper describes the design and the realization of a low-frequency ac magnetic-field-based indoor positioning system (PS). The system operation is based on the principle of inductive coupling between wire loop antennas. Specifically, due to the characteristics of the ac artificially generated magnetic fields, the relation between the induced voltage and the distance is modeled with a linear behavior in a bilogarithmic scale when a configuration with coplanar, thus equally oriented, antennas is used. In this case, the distance between a transmitting antenna and a receiving one is estimated using measurements of the induced voltage in the latter. For a high operational range, the system makes use of resonant antennas tuned at the same nominal resonant frequency. The quality factors act as antenna gain increasing the amplitude of the induced voltage. The low-operating frequency is the key factor for improving robustness against nonline-of-sight (NLOS) conditions and environment influences with respect to other existing solutions. The realized prototype, which is implemented using off-the-shelf components, exhibits an average and maximum positioning error, respectively, lower than 0.3 and 0.9 m in an indoor environment over a large area of 15 m × 12 m in NLOS conditions. Similar performance is obtained in an outdoor environment over an area of 30 m × 14 m. Furthermore, the system does not require any type of synchronization between the nodes and can accommodate an arbitrary number of users without additional infrastructure.

Determining EMC Test Levels for Implantable Devices in Bipolar Lead Configuration

2021 ◽  
Vol 55 (3) ◽  
pp. 91-95
Author(s):  
Seth J. Seidman ◽  
Howard I. Bassen
Keyword(s):  
Magnetic Fields ◽  
Computational Modeling ◽  
Electromagnetic Compatibility ◽  
Low Frequency ◽  
Ring Electrode ◽  
Simulation Software ◽  
Implantable Cardioverter Defibrillators ◽  
Induced Voltage ◽  
Bipolar Mode ◽  
Lead Configuration

Abstract Certain low-frequency magnetic fields cause interference in implantable medical devices. Electromagnetic compatibility (EMC) standards prescribe injecting voltages into a device under evaluation to simplify testing while approximating or simulating real-world exposure situations to low-frequency magnetic fields. The EMC standard ISO 14117:2012, which covers implantable pacemakers and implantable cardioverter defibrillators (ICDs), specifies test levels for the bipolar configuration of sensing leads as being one-tenth of the levels for the unipolar configuration. The committee authoring this standard questioned this testing level difference and its clinical relevance. To evaluate this issue of EMC test levels, we performed both analytical calculations and computational modeling to determine a basis for this difference. Analytical calculations based upon Faraday's law determined the magnetically induced voltage in a 37.6-cm lead. Induced voltages were studied in a bipolar lead configuration with various spacing between a distal tip electrode and a ring electrode. Voltages induced in this bipolar lead configuration were compared with voltages induced in a unipolar lead configuration. Computational modeling of various lead configurations was performed using electromagnetic field simulation software. The two leads that were insulated, except for the distal and proximal tips, were immersed in a saline-conducting media. The leads were parallel and closely spaced to each other along their length. Both analytical calculations and computational modeling support continued use of a one-tenth amplitude reduction for testing pacemakers and ICDs in bipolar mode. The most recent edition of ISO 14117 includes rationale from this study.

scholarly journals Research on Permanent Magnet-Type Super-Low-Frequency Mechanical Antenna Communication

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Xiaoyu Wang ◽  
Wenhou Zhang ◽  
Xin Zhou ◽  
Zhenxin Cao ◽  
Xin Quan
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Radiation Power ◽  
Near Field ◽  
Low Frequency ◽  
Induced Voltage ◽  
Analysis Model ◽  
Large Area ◽  
Communication Structure ◽  
Radiated Power

In the super-low-frequency ( 30 ∼ 300  Hz ) band communication, the traditional antenna covers a large area and has low radiation efficiency. The excitation of electromagnetic waves by the mechanical motion of permanent magnets enables miniaturized technology for super-low-frequency communication. For this miniaturization technique, this paper proposes a super-low-frequency communication architecture framework. Theoretical analysis and experimental verification of each unit module in the structural framework are carried out to achieve high-quality communication. For the radiation unit, permanent magnet parameters and communication distances are introduced to establish a rotating permanent magnet radiation power analysis model and to study the radiation characteristics of rotating permanent magnets. For the receiver unit, a sensitivity normalization characterization method based on the ratio of the coil thermal noise voltage to the induced voltage is proposed. Based on the sensitivity analysis model, a square coil was developed that meets the communication requirements of a mechanical antenna and an experimental platform was built. Experiments are conducted on the factors affecting radiated power and coil sensitivity, and 2FSK signal modulation communication experiments are conducted to verify the feasibility of the communication structure framework. The volume of the mechanical antenna permanent magnets in the experiment is all below 10 cm3, and the operating frequency is continuously adjustable from 0 to 250 Hz. The experimental results show that the near-field radiated power of a rotating permanent magnet is proportional to square of the volume of the rotating permanent magnet; the sensitivity of the coil is proportional to the number of turns and the area of the coil. By controlling the speed in real time, you can control the frequency of the signal and modulate it.

A Positioning System Based on Low Frequency Magnetic Fields

2015 ◽  
pp. 1-1 ◽  
Author(s):  
Valter Pasku ◽  
Alessio De Angelis ◽  
Marco Dionigi ◽  
Guido De Angelis ◽  
Antonio Moschitta ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Low Frequency ◽  
Positioning System

Practical High Resolution Microscopy

1968 ◽  
Vol 26 ◽  
pp. 302-303
Author(s):  
P. A. Marsh ◽  
T. Mullens ◽  
D. Price
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Resolving Power ◽  
Careful Attention ◽  
Electron Microscopes ◽  
The Relationship ◽  
High Resolution Microscopy ◽  
New Facilities

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.

Natural and man-made low-frequency magnetic fields as a potential health hazard

1998 ◽  
Vol 168 (07) ◽  
pp. 767-791 ◽  
Author(s):  
N.G. Ptitsyna ◽  
G. Villoresi ◽  
L.I. Dorman ◽  
N. Iucci ◽  
Marta I. Tyasto
Keyword(s):  
Magnetic Fields ◽  
Health Hazard ◽  
Low Frequency ◽  
Potential Health ◽  
Potential Health Hazard

The characteristics and present state for Extremely Low Frequency-Magnetic Fields of metropolitan subway

2015 ◽  
Vol 14 (1) ◽  
pp. 7-15
Author(s):  
Dae-kwan Jung ◽  
◽  
Joon-sig Jung ◽  
Kyu-mok Lee ◽  
Hyung-kyu Park ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Present State ◽  
Low Frequency ◽  
Extremely Low Frequency
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