PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 7776358

Waveform generator for electrical impedance tomography (EIT) using linear interpolation with multiplying D/A converters.

B Blad·J Johannesson·G Johnsson·B Bachman·K Lindström
View original source ↗Export metadata ↓

Abstract

This paper describes the implementation of a multiplying digital-to-analogue (D/A) converter as a programmable waveform generator to be used in an electrical impedance tomography (EIT) system. Different digital techniques of generation waveforms are considered and the advantages and disadvantages of the chosen slope-plus-pedestal technique are presented. A wire-wrapped prototype system has been designed, and from measured frequency spectra the total harmonic distortion can be calculated to values between 1.1 and 2.9% depending on frequency.

Explore related subjects

Analog-Digital ConversionElectric ImpedanceElectronics, MedicalEquipment DesignImage Processing, Computer-AssistedOscillometrySignal Processing, Computer-AssistedTomographyJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

B Blad, J Johannesson, G Johnsson, B Bachman, K Lindström. Waveform generator for electrical impedance tomography (EIT) using linear interpolation with multiplying D/A converters.. https://doi.org/10.3109/03091909409030248

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1995

Outgrowing nerves in the foreleg of a mouse embryo as viewed by three-dimensional reconstruction from electron micrographs.

Electron micrographs from serial cross-sections of 12-day-old mouse forelegs were digitized and three-dimensional reconstruction of the data was carried out on an Apple Macintosh Quadra 700 computer using a program especially designed for this purpose. Two nerve endings of the palmar net of the median nerve were visualized together with their accompanying Schwann cells and the surrounding processes of fibroblasts. Naked axons invade straightly into the embryonic connective tissue and serve as contact guidance for the Schwann cells to follow. Fibroblasts with long processes extend around the axons with a parallel orientation. Contacts between axons and fibroblasts are occasionally observed. It is unclear whether the parallel orientation of nerve endings and fibroblast extensions have any biological significance.

Analog-Digital Conversion↗
PubMed1995

The calculation of linear dimension and image area using a digitising tablet and personal computer.

An inexpensive image-area and perimeter-length measurement system consisting of a personal computer and digital graphics tablet is described. A study to assess the efficacy of the system has shown that accuracy and reproducibility of area measurement increase with increasing size of cross-sectional area. The system generally underestimated all derived areas by less than 2%. Reproducibility of measurement, as defined by the coefficient of variation, was typically less than 2%; the greatest inaccuracies and variability occurring with shapes of smaller cross-sectional area. The system seems to be the least accurate when it measures shapes with rectangular symmetry. Neither direction of digitisation nor operator skill seemed to influence the measurement accuracy of the system.

Analog-Digital Conversion↗
PubMed1995

LabVIEW: a software system for data acquisition, data analysis, and instrument control.

Computer-based data acquisition systems play an important role in clinical monitoring and in the development of new monitoring tools. LabVIEW (National Instruments, Austin, TX) is a data acquisition and programming environment that allows flexible acquisition and processing of analog and digital data. The main feature that distinguishes LabVIEW from other data acquisition programs is its highly modular graphical programming language, "G," and a large library of mathematical and statistical functions. The advantage of graphical programming is that the code is flexible, reusable, and self-documenting. Subroutines can be saved in a library and reused without modification in other programs. This dramatically reduces development time and enables researchers to develop or modify their own programs. LabVIEW uses a large amount of processing power and computer memory, thus requiring a powerful computer. A large-screen monitor is desirable when developing larger applications. LabVIEW is excellently suited for testing new monitoring paradigms, analysis algorithms, or user interfaces. The typical LabVIEW user is the researcher who wants to develop a new monitoring technique, a set of new (derived) variables by integrating signals from several existing patient monitors, closed-loop control of a physiological variable, or a physiological simulator.

Analog-Digital Conversion↗