Now showing items 1-20 of 30

    • Fluxgate sensor with increased homogeneity 

      Author: Ripka, Pavel; Jireš, František; Macháček, Milan
      (IEEE, 1990-09)
      Several types of fluxgate sensors were developed for measuring microvariations of the earth's magnetic field. Sensor cores were produced by etching, leading to better geometric homogeneity and long-term stability. This ...
    • Fluxgate: Tuned vs. Untuned Output 

      Author: Ripka, Pavel; Billingsley, S.W.
      (IEEE, 1998-07)
      Fluxgate voltage output contains information about the measured DC magnetic field in amplitude of even harmonic components. Tuning the sensor output causes the concentration of output energy to specific harmonics (usually ...
    • Giant Magnetoimpedance Sensors 

      Author: Hauser, Hans; Kraus, Luděk; Ripka, Pavel
      (IEEE, 2001-06)
      Magnetoinductance and giant magnetoimpedance (GMI) sensors have greatly benefited from the development of amorphous wires. These soft ferromagnetic substances exhibit exquisite sensitivity (in the nT range) and wide bandwidth ...
    • Pulse Excitation of Micro-Fluxgate Sensors 

      Author: Ripka, Pavel; Choi, San On; Tipek, Alois; Kawahito, Shoji; Ishida, Makoto
      (IEEE, 2001-07)
      Miniature fluxgate sensors with symmetrical closed core elements on both sides of the planar coils were manufactured using standard microtechnology. The new sensors have shown substantial improvement over the standard ...
    • Current Sensor in PCB Technology 

      Author: Ripka, Pavel; Kubík, Jan; Duffy, Maeve; Hurley, William Gerard; O’Reilly, Stephen
      (IEEE, 2005-06)
      A novel DC/AC current sensor works on the fluxgate principle. The core in the form of a 7/10-mm ring made of electrodeposited permalloy is sandwiched in the middle of a printed circuit board (PCB), whereas the sensor ...
    • Double-Core GMI Current Sensor 

      Author: Malátek, Michal; Ripka, Pavel; Kraus, Luděk
      (IEEE, 2005-10)
      A novel design of the giant magnetoimpedance contactless current sensor is presented. A double-core structure is used in order to improve the temperature stability. The temperature coefficient of sensitivity and offset ...
    • Excitation and Temperature Stability of PCB Fluxgate Sensor 

      Author: Tipek, Alois; O’Donnell, Terence; Ripka, Pavel; Kubík, Jan
      (IEEE, 2005-12)
      Printed circuit board (PCB) integrated inductors have been adapted for operation as fluxgate sensors. A ring core is made from an electrodeposited permalloy thin film and is sandwiched between the layers of the PCB. The ...
    • Low-Power Printed Circuit Board Fluxgate Sensor 

      Author: Kubík, Jan; Pavel, Lukáš; Ripka, Pavel; Kašpar, Petr
      (IEEE, 2007-02)
      A new printed circuit board flat fluxgate sensor with integrated coils and amorphous alloy core was developed and its excitation parameters optimized for low-power consumption. The power consumption achieved with 10 kHz, ...
    • Two-Domain Model for Orthogonal Fluxgate 

      Author: Butta, Mattia; Ripka, Pavel
      (IEEE, 2008-11)
      In this paper a new model for orthogonal fluxgate is presented. A first attempt to explain the working principle of the orthogonal fluxgates was done in the 1970's. We show that this model does not work well on recently ...
    • Impact of Different Active-Speech-Ratios on PESQ’s Predictions in Simulated VoIP Environment 

      Author: Počta, P.; Holub, J.; Mrvová, M.
      (2009)
      In this work, we experimentally study how behaviour of the PESQ predictions varies with reference signal characteristic. In particular we investigate the impact of different Active-Speech-Ratios on speech quality ...
    • Multiple Layer Scanning in Magnetopneumography 

      Author: Tomek, Jiří; Platil, Antonín; Ripka, Pavel
      (IEEE, 2009-04)
      In magnetopneumography (MPG), we scan weak remanent magnetic fields (in the range of nT) of ferromagnetic dust deposited in the lungs of affected workers. This is carried out in an unshielded lab. Variations of the background ...
    • Linearity of Pulse Excited Coil-Less Fluxgate 

      Author: Butta, Mattia; Ripka, Pavel
      (IEEE, 2009-10)
      In this paper, we study the open-loop linearity of pulse excited coil-less fluxgate. Narrow current pulses can be used instead of classical sinewave for the excitation of the coil-less fluxgate. This method has shown several ...
    • Crossfield Sensitivity in AMR Sensors 

      Author: Ripka, Pavel; Janošek, Michal; Butta, Mattia
      (IEEE, 2009-10)
      We discuss the origin of the crossfield sensitivity of AMR sensors, the way how this error may influence the performance of an AMR compass and methods for its correction. Finally, we confirm the simple formulas experimentally. ...
    • Bi-Metallic Magnetic Wire With Insulating Layer as Core for Orthogonal Fluxgate 

      Author: Butta, M.; Ripka, P.; Infante, G.; Badini-Confalonieri, G. A.; Vázquez, M.
      (IEEE, 2009-10)
      In this paper, we examine the problems related to orthogonal fluxgates realized using magnetic microwires as core. Starting from a description of orthogonal fluxgates evolution, we give a theoretical analysis of the problems ...
    • Impact of Different Active-Speech-Ratios on PESQ’s Predictions in Case of Independent and Dependent Losses (in Presence of Receiver-Side Comfort-Noise) 

      Author: Počta, P.; Holub, J.; Vlčková, H.; Polková, Z.
      (2010)
      This paper deals with the investigation of PESQ’s behavior under independent and dependent loss conditions from an Active-Speech-Ratio perspective in presence of receiver-side comfort-noise. This reference signal ...
    • Double Coil-Less Fluxgate in Bridge Configuration 

      Author: Butta, M.; Ripka, P.; Navarrete, Joaquín Pérez; Vázquez, M.
      (IEEE, 2010-02)
      In this paper, a new method for excitation of coil-less fluxgate is presented. The purpose of this method is to reduce the spurious component of the output voltage, allowing us to increase the amplification. The method is ...
    • Sensitivity and Noise of Wire-Core Transverse Fluxgate 

      Author: Ripka, Pavel; Butta, Mattia; Jie, Fan; Li, Xiaoping
      (IEEE, 2010-02)
      Fluxgate sensors with cores made of amorphous microwire have low sensitivity due to the small cross-sectional area of the wire. Previous studies with multiwire cores have shown nonlinear increase of sensitivity with number ...
    • Advances in Magnetic Field Sensors 

      Author: Ripka, Pavel; Janošek, Michal
      (IEEE, 2010-06)
      The most important milestone in the field of magnetic sensors was when AMR sensors started to replace Hall sensors in many applications where the greater sensitivity of AMRs was an advantage. GMR and SDT sensors finally ...
    • Magnetic Microwires With Field-Induced Helical Anisotropy for Coil-Less Fluxgate 

      Author: Butta, M.; Ripka, P.; Infante, G.; Badini-Confalonieri, G. A.; Vázquez, M.
      (IEEE, 2010-07)
      We present a new method for production of magnetic microwire with helical anisotropy. Coil-less fluxgate sensors are generally composed of a bimetallic wire excited by an alternating current; in order for the wire to work ...
    • Predicting the Quality of Synthesized and Natural Speech Impaired by Packet Loss and Coding Using PESQ and P.563 Models 

      Author: Počta, P.; Holub, J.
      (2011)
      This paper investigates the impact of independent and dependent losses and coding on speech quality predictions provided by PESQ (also known as ITU-T P.862) and P.563 models, when both naturally-produced and synthesized speech ...