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doc. Ing. Antonín Platil, Ph.D.

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Characterization of a Digital AMR Magnetometer for Space Applications

  • DOI: 10.1109/TIM.2020.3043867
  • Link: https://doi.org/10.1109/TIM.2020.3043867
  • Department: Department of Measurement
  • Annotation:
    In this paper, we present research, development, calibration and characterization of a novel concept of a digitally compensated, low-noise magnetometer based on anisotropic magnetoresistance sensors that is suitable for space applications. The main idea of the design was to reduce the number of precise analog components while using the digital signal processing power available in a modern microcontroller. Our most recent effort targeted lowering power consumption, enhancement of radiation hardness and overall improvement of the parameters. The principle of operation is presented in detail, along with a detailed description of the instrumentation used to characterize the real instrument, including its noise, linearity, and temperature stability in the range of -20 to +70 °C. The results of total ionizing dose (TID) testing at a gamma-ray irradiation facility are discussed at the complete magnetometer and part levels. This is an extended version of a paper presented at I2MTC 2020 that contains the results of a second radiation test done with a slightly modified design. The instrument worked well throughout the entire irradiation session (TID of 1.05 kGy over 72 hours), and the stability of main parameters was very good (50 pT/Gy offset and 1 ppm/Gy sensitivity stability).

AMR Magnetometer With Digital Feedback for Space Applications

  • DOI: 10.1109/I2MTC43012.2020.9129039
  • Link: https://doi.org/10.1109/I2MTC43012.2020.9129039
  • Department: Department of Measurement
  • Annotation:
    In this paper, we present research and development regarding a novel concept of a digitally compensated, low-noise magnetometer based on anisotropic magnetoresistance sensors that is suitable for space applications. The central idea of the design is to reduce the number of precise analog components while using the digital signal processing power available in a modern microcontroller. Our most recent effort targeted lowering power consumption and overall improvement of the parameters. Only commercial off-the-shelf components are used in the concept reported here, keeping costs manageable even for low-budget CubeSat missions. The principle of operation is presented in detail, along with a full characterization of a real instrument, including its noise, linearity, and temperature stability. The results of Total Ionizing Dose testing at a gamma-ray irradiation facility are discussed at the complete magnetometer and part levels; they suggest the instrument's good potential.

Cross-field Effect in a Triaxial AMR Magnetometer with Vector and Individual Compensation of a Measured Magnetic Field

  • DOI: 10.1109/TMAG.2016.2617121
  • Link: https://doi.org/10.1109/TMAG.2016.2617121
  • Department: Department of Measurement
  • Annotation:
    Magnetic field sensors based on anisotropic magnetoresistance (AMR) are widely used in many scientific and industrial applications. The AMR sensor sensitivity is superior to Hall probes and size and power consumption is superior to fluxgates. However, the noise properties and temperature stability of AMR sensors are typically worse than for fluxgates. These properties define the typical applications - less precise vectorial or gradient measurements of the magnetic field within <±1 mT range. AMR sensors are typically calibrated for sensitivity, offset, and orthogonality errors. However, there is another important source of error - sensitivity to the magnetic field applied in the perpendicular direction to the measurement axis. This so-called cross-field error is inherent to AMR sensors and can influence the measurements significantly. Flipping (set/reset pulses) and closed-loop operation of the sensor can reduce the cross-field error. In our paper, we present a novel approach of using full vectorial compensation of the measured magnetic field resulting in a complete elimination of the cross-field effect. The vectorial compensation provided superior results over alternative approaches that were also evaluated.

Construction of an AMR magnetometer for car detection experiments

  • Authors: Fúra, V., Ing. Vojtěch Petrucha, Ph.D., doc. Ing. Antonín Platil, Ph.D.,
  • Publication: Proceedings of 5th International Conference on Materials and Applications for Sensors and Transducers (IC-MAST2015). Bristol: IOP Institute of Physics, 2016. IOP Conference Series: Materials Science and Engineering. ISSN 1757-899X.
  • Year: 2016
  • DOI: 10.1088/1757-899X/108/1/012028
  • Link: https://doi.org/10.1088/1757-899X/108/1/012028
  • Department: Department of Measurement
  • Annotation:
    A new construction of magnetometer with commercially available AMR (anisotropic magnetoresistive) sensors intended for vehicle detection experiments is presented. For further experiments and acquisition of representative data, a new design of precise multi-channel magnetometer was developed. The design supports two models of commercial AMR sensors: the proven and reliable, but obsolete Honeywell HMC1021-series sensors and newly available Sensitec AFF755B sensors.

Simple estimation of dipole source z-distance with compact magnetic gradiometer

  • Authors: Ing. Michal Janošek, Ph.D., doc. Ing. Antonín Platil, Ph.D., Vyhnánek, J.
  • Publication: Proceedings of 5th International Conference on Materials and Applications for Sensors and Transducers (IC-MAST2015). Bristol: IOP Institute of Physics, 2016. IOP Conference Series: Materials Science and Engineering. ISSN 1757-899X.
  • Year: 2016
  • DOI: 10.1088/1757-899X/108/1/012025
  • Link: https://doi.org/10.1088/1757-899X/108/1/012025
  • Department: Department of Measurement
  • Annotation:
    A compact magnetometer/gradiometer with combined homogeneous and gradient outputs facilitates precise measurement of both H and G values with good spatial and temporal coherence. By evaluating combination of both signals, it is possible to estimate distance to a dipole source with relatively small error and largely independent from precise knowledge of source strength, orientation and lateral displacement.

Compact Full-tensor Fluxgate Gradiometer

  • Department: Department of Measurement
  • Annotation:
    Using full-tensor gradiometers has various advantages over simplified uniaxial gradiometers or even scalar measurements. The full-tensor information is used mainly in geophysical prospecting and in security/military applications. In our new design we combined 10 small (20-mm) fluxgate sensors operating in feedback compensated mode into one compact head in the form of 46-mm cube.

Compact magnetic gradiometer and its astatization

  • DOI: 10.1016/j.proeng.2015.08.841
  • Link: https://doi.org/10.1016/j.proeng.2015.08.841
  • Department: Department of Measurement
  • Annotation:
    We present a compact (10-cm head size, 3-cm base) axial magnetic gradiometer with a method of its astatization (i.e. suppression of false response to homogeneous field). For astatization, we use two integrated orthogonal sensors and a second-order polynomial correction; after astatization the gradiometer error is suppressed more than 1000×.

The Effect of Sensor Size on Axial Gradiometer Performance

  • DOI: 10.1109/TMAG.2014.2359960
  • Link: https://doi.org/10.1109/TMAG.2014.2359960
  • Department: Department of Measurement
  • Annotation:
    The case of a finite base gradiometer with ideal sensors is considered, then influence of finite-size sensing elements is modeled and finally, comparison with experimental results obtained with two ring-core fluxgates and two AMR sensors are evaluated. Some of the effects found may be counterintuitive and especially in the close proximity of dipole source, the gradient cannot be further modeled by simplified uniaxial approximation because of the sensor size. Full Biot-Savart field model was considered in those cases.

Dual-core fluxgate gradiometer with gradient feedback

  • DOI: 10.1109/ICSENS.2013.6688287
  • Link: https://doi.org/10.1109/ICSENS.2013.6688287
  • Department: Department of Measurement
  • Annotation:
    A fluxgate magnetic gradiometer with two fluxgate sensors and gradient feedback loop is presented. The two feedback coils, gradient and homogeneous, are common to both fluxgate sensors. The signal from the two sensors acts as regulating input in the two feedback loops, improving stability of the gradiometer. The presented gradiometer overcomes the problems of state-of-the art gradiometers which do not allow to decrease the sensor spacing.

Magnetopneumography Using Optical Position Reference

  • DOI: 10.1166/sl.2013.2805
  • Link: https://doi.org/10.1166/sl.2013.2805
  • Department: Department of Measurement
  • Annotation:
    The presented development utilizes a smart camera and retro-reflective optical markers for independent measurement of the subject body position during magnetic field scanning. This is critical in order to avoid distorting of geometrical ordering of the measured data by inadvertent movement of the subject on scanning bed in both lateral and angular way.

Temperature Drift of Offset and Sensitivity in Full-Bridge Magnetoresistive Sensors

  • DOI: 10.1109/TMAG.2012.2220535
  • Link: https://doi.org/10.1109/TMAG.2012.2220535
  • Department: Department of Measurement
  • Annotation:
    A typical commercially available magnetoresistive sensor, and particularly an anisotropic magnetoresistive sensor, employs a full bridge of the Wheatstone type formed by two complementary magnetoresistive elements in each branch. It can be shown that, theoretically speaking, the offset is temperature independent when the bridge is supplied with a constant voltage (but the sensitivity in that case is temperature dependent), and the sensitivity is temperature independent when the bridge is supplied with a constant current (but the offset in that case is temperature dependent).

Temperature Stability of AMR Sensors

  • DOI: 10.1166/sl.2013.2807
  • Link: https://doi.org/10.1166/sl.2013.2807
  • Department: Department of Measurement
  • Annotation:
    Magnetic sensors working in increased temperature range are required for many applications, such as: - down-hole orientation sensors for oil & gas exploration and production - angular position and speed measurement for turbines - engine sensors for automotive industry - electric current sensors and also for some planetary space missions (e.g. Mercury).

Fluxgate Sensor and Real Operating-mode B-H Curve

  • Department: Department of Measurement
  • Annotation:
    The core materials are usually characterized in well-defined modes. Either static B-H loops are measured or dynamic loops are recorded with sinewave H or better sinewave B waveform as required by IEC standard. Unfortunately, neither of these represents well the real operating conditions in fluxgate core, especially when the fluxgate is tuned and excitation current peak value is optimized by appropriate capacitor. Dynamic B-H loops can be recorded by digital acquisition and signal processing in real operating conditions.

Magnetopneumography - Incorporation of Optical Position Reference

  • Department: Department of Measurement
  • Annotation:
    Magnetopneumography is a non-invasive method for estimation of amount and spatial distribution of ferromagnetic dusts deposited in lungs of metal workers. Our setup consisting of a set of fluxgate probes is sensitive enough to detect remanent fields of small amounts of previously magnetized magnetite dust. Utilization of a smart camera and retro-reflective optical markers makes the scanning independent of operator's errors and helps to scan the magnetic field independently of the actual subject body position on the bed.

Magnetopneumography - Real-World Phantom Inversion

  • Department: Department of Measurement
  • Annotation:
    Magnetopneumography needs inversion of weak magnetic data in order to estimate amount and spatial distribution of ferromagnetic dusts deposited in lungs of metal workers. Our continuously improved setup is sensitive enough to detect remanent fields of small amounts (<8 mg) of magnetite dust. Fluxgate probes as the best room-temperature sensors are used. Estimation of distribution of 35 unit cubes of a simplified phantom based on SVD calculated calibration inverse matrix is demonstrated here. We still cope with background noise and positioning errors that severely limit the results. Preparation of electronic calibration phantom should enable successful inversion of more complex sources.

Multimedia Handbook of Sensors. Interactive Models on Web Pages

  • Authors: Fejt, R., doc. Ing. Antonín Platil, Ph.D.,
  • Publication: Proceedings of 15th Mechatronika 2012. Praha: Czech Technical University in Prague, 2012, pp. 205-208. ISBN 978-80-01-04987-7.
  • Year: 2012
  • Department: Department of Measurement
  • Annotation:
    This paper describes the development process of a multimedia handbook of sensors implemented as a website (on-line or off-line), from selecting the appropriate technologies to the realization. The focus is on the development of interactive models of sensors and on how to use modern methods for distributing and sharing information on websites. Each webpage in the multimedia handbook contains text description of specific sensor principle, basic physical equations, information about practical usage, an interactive animated Microsoft Silverlight model and links to other information sources for the specific type of sensor.

Suppression of Environmental Noise in Magnetopneumography by the use of Higher Order Gradients

  • DOI: 10.1109/TMAG.2011.2172200
  • Link: https://doi.org/10.1109/TMAG.2011.2172200
  • Department: Department of Measurement
  • Annotation:
    We use fluxgate magnetometer for measuring remanent field of contaminated volume (current experiments are mostly on phantoms). For earlier experiments we used simple 6-channel magnetometer with improvised probe holder and we used multiple 1st order gradients. However, geometrical and other instabilities forced us to upgrade both the mechanical assembly and the fluxgate electronics. The environmental noise from relatively close sources is apparent even in 1st order gradients and thus - now with more stable electronics - we evaluated 2nd order gradients in order to obtain better signal.

Magnetic Field Inversion for Magnetopneumography

Magnetic Markers Detection Using PCB fluxgate array

  • DOI: 10.1063/1.3074780
  • Link: https://doi.org/10.1063/1.3074780
  • Department: Department of Measurement
  • Annotation:
    PCB fluxgate sensors formed a sensor head for detection of ferromagnetic and paramagnetic markers. The sensors were arranged perpendicularly to the measuring plane and we measured the horizontal gradient of normal component of the measured field. When moving the sensor head, we were able to map field gradients smaller than 6 nT/mm, which was verified while measuring the magnetic markers on a dollar bill. With the help of perpendicular ac excitation at 30 Hz, we were able to detect a 0.1 ml Endorem iron-oxide superparamagnetic marker at 2 mm; volume of 0.6 ml was detectable at 10 mm.

Multiple Layer Scanning in Magnetopneumography

Short-range Navigation of Minesweeping Detector

  • Department: Department of Measurement
  • Annotation:
    The current paper deals with short-range (<1m) navigation of mine detector head around suspected location. The aim is building signal strength map for pinpointing of the underground metal object position and estimation of the object type from its signature. As the low-cost MEMS inertial sensors have unacceptable drift, various compensation techniques and navigation aids must be implemented.

Application of Neural Networks Inversion in Magnetopneumography

  • Department: Department of Measurement
  • Annotation:
    Application of Neural Networks Inversion in Magnetopneumography gives new opportunities for solvig of the inversion

Characterization of Ferromagnetic Powders for Magnetopneumography and Other Applications

  • Department: Department of Measurement
  • Annotation:
    Characterization of ferromagnetic materials in the form of powders and dusts is required in many practical applications. Among them are biomedical applications like magnetopneumography and magnetic hyperthermia. In both cases, specific problems make the accurate measurement difficult. We describe the practical experience with static and dynamic characterization of powder specimens.

Magnetopneumography - Advances in Measurement Procedure, Modeling and Inversion Using Artificial Neural Networks

  • Department: Department of Measurement
  • Annotation:
    For more precise measurements of remnant fields of dust particles in lungs (Magnetopneumography) non-magnetic positioning device was built and new computer model of experimental sources measurements was created. The inverse problem was solved partially using various types of neural networks (NN).

Magnetopneumography - Supression of Background Field Variations in Scanned Data for Inversion Using Multiple Fluxgates

  • Authors: Tomek, J., doc. Ing. Antonín Platil, Ph.D.,
  • Publication: The 6th IEEE Conference on Sensors. Piscataway: IEEE, 2007. p. 1020-1023. ISSN 1930-0395. ISBN 1-4244-1262-5.
  • Year: 2007
  • DOI: 10.1109/ICSENS.2007.4388578
  • Link: https://doi.org/10.1109/ICSENS.2007.4388578
  • Department: Department of Measurement
  • Annotation:
    In inversion of magnetic data the key task is the acquisition of sufficient number of measurements and suppression of the field variations in them. In Magnetopneumography (MPG) we scan very weak magnetic fields of ferromagnetic dust deposited in the lungs of affected workers in ordinary non-shielded lab. Variations of the background field during scanning time may bias the inversion. We present an innovative mathematical technique that enables by means of fitting to model equations to condense the information acquired and to eliminate the bias background fields. Six coaxially aligned fluxgates measuring five gradients are used for scanning of the field maps. The alignment and further errors given by non-homogeneity of outer field in the measurement area are the main limits of this method.

Simple Digitalization of Fluxgate Sensor

  • DOI: 10.1166/sl.2007.058
  • Link: https://doi.org/10.1166/sl.2007.058
  • Department: Department of Measurement
  • Annotation:
    The current paper describes implementation of fluxgate magnetometer using a universal data acquisition plug-in board for PC with a minimum of external components. The sensor excitation as well as the signal processing is performed using the board and software.

Application of Fluxgate Gradiometer in Magnetopneumography

Compensation of Accelerometer Drift for Improved Position Estimation

  • Department: Department of Measurement
  • Annotation:
    When direct position measurement is not possible, it may be estimated e.g. from integrated accelerations. However, the performance of most affordable devices is rather poor for this application due to unacceptable drift. With some restrictions, the drift may be compensated.

Errors of AMR Compass and Methods of their Compensation

  • Department: Department of Measurement
  • Annotation:
    The article deals with fully digital compass based on AMR sensors and accelerometers. The developed device gives information about actual azimuth, roll and pitch. The article is especially focused on errors caused by sensors misalignment, cross-axis effect and temperature offset drifts of the sensors.

Flow and Level Measurement

AMR Navigation Systems and Methods of their Calibration

  • Department: Department of Measurement
  • Annotation:
    The design of a navigation system with AMR and accelerometers is described in this article. The calibration methods of general triaxial sensor systems are discussed in this article and basic results are presented. The application of these calibration methods for developed navigation system is also included in this article.

Fluxgate Gradiometer in Magnetopneumography

  • Department: Department of Measurement
  • Annotation:
    Magnetopneumography (MPG) serves for examination of human lungs exposition to ferromagnetic dusts and fumes (e.g. in metal-workers in industry) through measurement of remanent magnetic field after magnetization of the subject in an electromagnet. Fluxgate gradiometer is used for measurement and various methods (neural networks, etc.) are used for evaluation and estimation of the inhaled dust amount and distribution.

Magnetic Field of the Lungs - Neural Network Inverse Models

  • Department: Department of Measurement
  • Annotation:
    Magnetopneumography (MPG) uses examination of remanent magnetic field for determination of amount and distribution of ferromagnetic dust respired into the lungs. Experimental physical model, fluxgate measurement setup including non-magnetic positioning bed and forward computer solver were built in order to provide data for training of neural network inverse model. Early results of the experiments are promising.

Precise Electronic Fluxgate Compass

  • Department: Department of Measurement
  • Annotation:
    AMR (Anisotropic Magnetoresistance) sensors were recently used for construction of an electronic compass and a simple calibration methods have been developed. Later, experiments were performed with application of this approach to calibration of higher-performance fluxgate compass. The comparison of results is provided and sources of errors are discussed.

Virtual Instrument - No Virtual Reality but Real PC Based Measuring System

  • Department: Department of Measurement
  • Annotation:
    Real measuring systems based on a host PC, where the PC is used for set-up and control of measurement, data acquisition, data processing and displaying results are usually called Virtual Instruments (VIs). Some examples of virtual instruments designed, realized or applied at CTU-FEE, Dept. of Measurement are given here.

Wattmeter with AMR Sensor

  • Department: Department of Measurement
  • Annotation:
    Analog multipliers comprising the Hall sensors have been used in electronic design, typically in powermeters. This article summarizes the results of experiments performed with a commercially available anisotropic magnetoresistive (AMR) sensor, used for the same purpose. The on-chip compensation coil can be successfully used in the function of the "current clamps" of the wattmeter. Periodical re-magnetizing (flipping) of the sensor structure performed by the flipping coil can improve the device parameters. This paper is not a description of a functioning, practice-ready device. It reports an experiment showing the feasibility of AMRs in the area of power measurements.

AMR Navigation Systems and Methods of Their Calibration

  • Department: Department of Measurement
  • Annotation:
    The article deals with fully digital navigation system based on AMR sensors and MEMS accelerometers. Described are used calibration methods: scalar calibration for finding sensitivities, offsets and non-orthogonalities and rotation in roll and azimuth for finding angular deviations (misalignments) of the sensor coordinate systems.. The device calculates actual azimuth, roll and pitch from measurement of Earth's magnetic and gravitational field vectors. Then the calculated azimuth is not influenced by actual roll or pitch.

AMR Navigation Systems and Methods of Their Calibration

  • Department: Department of Measurement
  • Annotation:
    The article deals with fully digital navigation system and method of its calibration using rotation in roll. The system calculates actial azimuth, roll and pitch from measurement of Earth's magnetic and gravitational filed vectors. Then the calculated azimuth is not influenced by actual roll or pitch.

Electronics for MI Current Sensor

Electronics for MI Current Sensor

Hysteresis Loop Measurements on Ring Cores with Small Cross-section

  • Department: Department of Measurement
  • Annotation:
    A digital sampling hysteresisgraph is used for characterization of fluxgate cores under various excitation conditions. Various sources of errors are discussed.

Wattmeter with AMR Sensor

Wattmeter with AMR Sensor

  • Department: Department of Measurement
  • Annotation:
    Commercially available AMR sensors can be used as simple analog multiplier devices, which can be used in real (active) electric power transducers. The electronics of such a device need not be complicated, when using the on-chip integrated coils. Periodical re-magnetizing (flipping) of the sensor structure can improve the device parameters.

AC Characterization of Materials for Fluxgate Cores

AMR Magnetometer

  • Department: Department of Measurement
  • Annotation:
    Simple anisotropic magnetoresistance magnetometer with improved parameters was developed. New flipping circuits deliver optimized current pulse with 2.8A amplitude. New type of signal processing uses switched integrator to avoid the most noisy time intervals. The achieved linearity is 0.2% in the ą200[mu]T range without feedback and 0.04% using integrated feedback coil. The magnetometer noise at 1 Hz is 2nT/Hz1/2, uncompensated temperature coefficient of sensitivity is -0.25%/K without the feedback and 0.01%/K with feedback. Temperature offset drift is typically 10nT/K.

Development of the GMI Permalloy Sensor and Its Practical Applications

  • Authors: doc. Ing. Antonín Platil, Ph.D., Malátek, M., Kubík, J.
  • Publication: Proceedings of Workshop 2003. Praha: České vysoké učení technické v Praze, 2003, pp. 408-409. ISBN 80-01-02708-2.
  • Year: 2003

Experiencies with Leonardo Pilot Project

  • Department: Department of Measurement
  • Annotation:
    CTU in Prague was participating in Leonardo da Vinci project CZ/PP-134026 Modular Courses on Modern Sensors. Gained experiences are shared.

GMI - MAGNETOMETER

  • Department: Department of Measurement
  • Annotation:
    GMI effect has been observed also in crystalline materials. This paper presents design of GMI sensor made of two Mo-permalloy strips with opposite biasing to achieve bipolar response. The measuring current frequency is 100 kHz. Either DC or AC biasing can be used. The achieved parameters comprise offset stability of 0.2 uT and linearity of 3.3 % in +/- 60 uT (1.3 % with AC biasing). The noise was approximately 9.5 nT/?ă Hz @ 1Hz. The greatest problem remains the relatively large temperature coefficient.

GMI Current Sensor

Permalloy GMI Sensor

  • Department: Department of Measurement
  • Annotation:
    GMI effect in permalloy can be used to measure DC magnetic fields. Impedance change of 50% at a field of 0.5 mT was observed at 200 kHz frequency. Magnetometer using biased two-stripe 10-cm long sensor achieved 10% linearity in open loop and 1% hysteresis error in the +/-80 uT range.

Precise AMR Magnetometer for Compass

  • Department: Department of Measurement
  • Annotation:
    AMR sensors gain growing popularity in linear applications such as compassing [1, 2]. We discuss techniques, how to achieve precision required for 0.2 deg azimuth error in wide temperature range. While linearity of 80 ppm FS and sensitivity tempco of 20 ppm/K can be achieved by using feedback compensation, offset drift and crossfield error can be lowered to nT level by periodical flipping.

Precise AMR Magnetometer for Compass

  • DOI: 10.1109/ICSENS.2003.1278983
  • Link: https://doi.org/10.1109/ICSENS.2003.1278983
  • Department: Department of Measurement
  • Annotation:
    AMR sensors gain growing popularity in linear applications such as compassing. We discuss techniques, how to achieve precision required for 0.2 deg azimuth error in wide temperature range. While linearity of 40 ppm and sensitivity tempco of 20 ppm/K can be achieved by using feedback compensation, offset drift and crossfield error can be lowered by periodical flipping.

Precise Magnetic Sensors

  • Department: Department of Measurement
  • Annotation:
    Can magnetoresitors replace fluxgate sensors in precise applications such as navigation and detection of metal objects? AMR and GMR can reach 10 nT resolution. It is possible to improve their stability by AC techniques, but the electronics becomes complex and consumes more power. If size is not limited, fluxgate sensors are still the winners.

Precise Magnetic Sensors and Magnetometers for Military and Space Applications

Sampling Measurements with Digital Hysteresisgraph

  • DOI: 10.1016/S0304-8853(02)00798-9
  • Link: https://doi.org/10.1016/S0304-8853(02)00798-9
  • Department: Department of Measurement
  • Annotation:
    Digital hysteresisgraph can be used for the measurement of dynamic hysteresis loops up to 100 kHz. Digital feedback allows achievement of sinusoidal flux density by iterative modification of the excitation voltage waveform. This approach is used for the measurement of closed (toroidal) samples at higher frequencies.

Calibration of Triaxial Magnetometers by Theodolite

  • Department: Department of Measurement
  • Annotation:
    Calibration and error-correction algorithms for several types of triaxial magnetometers are presented. The calibration method using theodolite is described in detail.

Fluxgate Can Replace SQUID for Lung Diagnostics

GMI Sensor

GMI Sensor

Improvement of AMR Magnetometer Precision

Improvement of AMR Magnetometer Precision

Industrial Applications of Programmable Hall Sensor

  • Department: Department of Measurement
  • Annotation:
    Although AMR and GMR sensors gradually penetrate many industrial applications, Hall sensors still remain the most widely used solution. However, developersof modern systems often require more added value than just plain sensor in order to satisfy specific needs in their construction.

Industrial Applications of Programmable Hall Sensor

Magnetic Sensors and their Temperature Testing

Magnetic Sensors and their Temperature Testing

  • Department: Department of Measurement
  • Annotation:
    The construction of temperature testing system is described. The description covers temperature chamber, cooling and heating system, testing methodology and complete testing system with computer control.

Magnetometer for the MIMOSA Satellite

Measurement of 3-Axial AC Magnetic Pollution

Permalloy GMI Sensor

Permalloy GMI Sensor

  • Department: Department of Measurement
  • Annotation:
    We report our work than contains investigation of attributes of permalloy GMI materials, construction of a magnetic field sensor based on GMI effect and its exploration, and design of GMI magnetometer. Achieved results of the work are presented in enclosed graphs, block diagrams and numerical results.

Phase Error Compensation in Sampling Hysteresisgraph

Phase Error Compensation in Sampling Hysteresisgraph

  • Department: Department of Measurement
  • Annotation:
    Digital dynamic hysteresisgraph for measurement in DC to 100 kHz frequency range was developed in out department. Among the errors influencing the measurement are also the phase shifts. This contribution deals with determination and software compensation of these phase shifts.

Precise Magnetic Sensors

Temperature Testing of Magnetic Sensors

Transmission of the Measured Data via SMS

  • Authors: Svoboda, M., Tipek, A., doc. Ing. Antonín Platil, Ph.D.,
  • Publication: Proceedings of Workshop 2002. Praha: České vysoké učení technické v Praze, 2002. pp. 394-395. ISBN 80-01-02511-X.
  • Year: 2002

Triaxial Magnetometers and their Calibration

AMR Magnetometer

Improving the Parameters of AMR Sensors Using Flipping Technique

  • Authors: Vopálenský, M., doc. Ing. Antonín Platil, Ph.D.,
  • Publication: Poster 2001. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2001, pp. E33.
  • Year: 2001

Laboratory of Magnetic Measurement CTU FEE Prague

Modern Sensors Modular Courses Education WWW System

Permalloy GMI Sensor

Remanent Field of Human Lungs

Sampling Measurement of Dynamic Hysteresis Loops

Sampling Measurements with Digital Hysteresisgraph

WWW Interface for Modular Courses on Modern Sensors

  • Authors: Tyml, P., doc. Ing. Antonín Platil, Ph.D.,
  • Publication: Poster 2001. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2001, pp. IC45.
  • Year: 2001

WWW System for Modular Courses on Modern Sensors

Dust Detection by Magnetopneumometry

Factor Limiting the Accuracy of Sampling Hysteresisgraph

Measuring of the Magnetic Field with the AMR Sensors

  • Authors: Vopálenský, M., doc. Ing. Antonín Platil, Ph.D.,
  • Publication: Poster 2000. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2000. pp. E30.
  • Year: 2000

New Types of Magnetoresistors

Precise Magnetometers

Testing of Synchronous AD Converters

The AMR Magnetometer

Two-Channel ADC System for Hysteresisgraph

VXI System Programming Using VISA Library

AC Digital Hysteresisgraph

Accuracy of Sampling Methods in AC Magnetic Measurements

Calibration and Stability of the Fluxgate Gradiometer

Calibration of 3-Axis Magnetometer

Calibration of AMR Magnetic Sensors

Design and Calibration of Satellite Magnetometer

  • Authors: Tipek, A., doc. Ing. Antonín Platil, Ph.D.,
  • Publication: IWCIT'99 International Workshop Control and Information Technology. Ostrava: VŠB-TUO, 1999, pp. 268-274. ISBN 80-7078-679-5.
  • Year: 1999

Magnetic Sensors

Magnetic Sensors for Space and Field

AC Digital Hysteresisgraph

Analysis of Data from 3-axis Magnetometer Calibrator

Calibration and Stability of the Fluxgate Gradiometer

Dynamic Hysteresis Loops Measurement System

Measurement of Angular Stability of 3-axis Magnetometer

  • Authors: doc. Ing. Antonín Platil, Ph.D.,
  • Publication: Poster 1998. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 1998. pp. 28-29.
  • Year: 1998

The Magnetometer Calibrator

Digital Hysteresisgraph Based on PC Plug-in Cards

  • Authors: doc. Ing. Antonín Platil, Ph.D.,
  • Publication: Poster 1997. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 1997, pp. 60-61.
  • Year: 1997

Fully Digital Magnetic Measuring System

Magnetic Projects at the Department of Measurement of FEE-CTU Prague

Responsible person Ing. Mgr. Radovan Suk