LOGARITHMIC AMPLIFIERS FOR SOFTWARE-HARDWARE MAGNETIC TRACKING SYSTEMS

Keywords: magnetic tracking, actuator–sensor, measurement range, logarithmic amplifier, logarithmic compression, SPICE model

Abstract

The work deals with the problem of signal conversion in magnetic tracking devices. Magnetic tracking technology is based on computing the spatial position of an object being tracked upon measuring reference magnetic fields in low-frequency electromagnetic radiation spectrum. Magnetic tracking devices are key components of navigation sensors for virtual and augmented reality. It has been shown that the main problem one faces when developing sensory devices for magnetic tracking is the fact that signals should be measured in a wide measurement range. We have analyzed possible ways to solve the stated problem by digital and combined methods. The latter have proven to be more efficient. They consist in signal amplification due to analog compression, which is performed by logarithmic amplifiers whose negative feedback circuits contain components with non-linear volt-ampere characteristics (typically, diodes or bipolar transistors are used). It has been shown that the parameters of logarithmic signal compression can be controlled by modified circuits with auxiliary resistance dividers. The resistance dividers scale the logarithmic volt-ampere characteristics of emitter p-n junctions of bipolar n-p-n and p-n-p transistors. A substantial advantage of circuits with resistance dividers is that they provide the possibility to expand the range of the output voltage of logarithmic amplifiers and optimize the transition between the linear and logarithmic amplification regions. The work presents the results of simulation and experimental
investigations into a logarithmic amplifier for a magnetic tracking system. Simulation was carried out using
SPICE (Simulation Program with Integrated Circuit Emphasis) models. We applied an integrated approach,
which provides collections of transient characteristics of logarithmic amplifiers at different sets of the
parameters of resistance dividers. The simulation results have been verified using our own softwarefirmware magnetic tracking tools Magnetic Tracking System Integrated Development Environment. The signal converter was built upon a programmable system-on-chip PSoC 5LP by Cypress Semiconductor.

Author Biographies

Роман Любомирович Голяка, Lviv Polytechnic National University

Dr. of Science, Professor,
Professor at Department of Electronics and Information Technology

Тетяна Анатоліївна Марусенкова, Lviv Polytechnic National University

PhD, Associate Professor, Senior Lecturer at Software Department

Дмитро Васильович Федасюк, Lviv Polytechnic National University

Dr. of Science, Professor,
Professor of Software Department

Published
2020-12-24
How to Cite
Голяка, Р., Марусенкова, Т., & Федасюк, Д. (2020). LOGARITHMIC AMPLIFIERS FOR SOFTWARE-HARDWARE MAGNETIC TRACKING SYSTEMS. Electrotechnic and Computer Systems, (33(109), 33-45. https://doi.org/10.15276/eltecs.33.109.2020.4
Section
Automation of control processes