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Brno University of Technology

1. Kadlčík, Libor. Implementace rekonstrukčních metod pro čtení čárového kódu: Implementation of restoring method for reading bar code.

Degree: 2018, Brno University of Technology

Bar code stores information in the form of series of bars and gaps with various widths, and therefore can be considered as an example of bilevel (square) signal. Magnetic bar codes are created by applying slightly ferromagnetic material to a substrate. Sensing is done by reading oscillator, whose frequency is modulated by presence of the mentioned ferromagnetic material. Signal from the oscillator is then subjected to frequency demodulation. Due to temperature drift of the reading oscillator, the demodulated signal is accompanied by DC drift. Method for removal of the drift is introduced. Also, drift-insensitive detection of presence of a bar code is described. Reading bar codes is complicated by convolutional distortion, which is result of spatially dispersed sensitivity of the sensor. Effect of the convolutional distortion is analogous to low-pass filtering, causing edges to be smoothed and overlapped, and making their detection difficult. Characteristics of convolutional distortion can be summarized into point-spread function (PSF). In case of magnetic bar codes, the shape of the PSF can be known in advance, but not its width of DC transfer. Methods for estimation of these parameters are discussed. The signal needs to be reconstructed (into original bilevel form) before decoding can take place. Variational methods provide effective way. Their core idea is to reformulate reconstruction as an optimization problem of functional minimization. The functional can be extended by other functionals (regularizations) in order to considerably improve results of reconstruction. Principle of variational methods will be shown, including examples of use of various regularizations. All algorithm and methods (including frequency demodulation of signal from reading oscillator) are digital. They are implemented as a program for a microcontroller from the PIC32 family, which offers high computing power, so that even blind deconvolution (when the real PSF also needs to be found) can be finished in a few seconds. The microcontroller is part of magnetic bar code reader, whose hardware allows the read information to be transferred to personal computer via the PS/2 interface or USB (by emulating key presses on virtual keyboard), or shown on display. Advisors/Committee Members: Mikulka, Jan (advisor), Bartušek, Karel (referee).

Subjects/Keywords: PIC32; USB; PS/2; čárový kód; dekonvoluce; dvoujámová funkce; dvouúrovňový signál; hledání inflexního bodu; konvoluční zkreslení; metoda derivací; metoda nevydařené lineární aproximace; odhad PSF; rekonstrukce signálu; regularizace; stejnosměrný drift; totální variace; variační metody; PIC32; USB; PS/2; bar code; bilevel signal; convolutional distortion; DC drift; deconvolution; double-well function; detection of inflection point; method of derivatives; method of failed linear approximation; PSF estimation; regularization; signal reconstruction; total variation; variational methods

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APA (6th Edition):

Kadlčík, L. (2018). Implementace rekonstrukčních metod pro čtení čárového kódu: Implementation of restoring method for reading bar code. (Thesis). Brno University of Technology. Retrieved from http://hdl.handle.net/11012/25863

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Kadlčík, Libor. “Implementace rekonstrukčních metod pro čtení čárového kódu: Implementation of restoring method for reading bar code.” 2018. Thesis, Brno University of Technology. Accessed November 27, 2020. http://hdl.handle.net/11012/25863.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Kadlčík, Libor. “Implementace rekonstrukčních metod pro čtení čárového kódu: Implementation of restoring method for reading bar code.” 2018. Web. 27 Nov 2020.

Vancouver:

Kadlčík L. Implementace rekonstrukčních metod pro čtení čárového kódu: Implementation of restoring method for reading bar code. [Internet] [Thesis]. Brno University of Technology; 2018. [cited 2020 Nov 27]. Available from: http://hdl.handle.net/11012/25863.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kadlčík L. Implementace rekonstrukčních metod pro čtení čárového kódu: Implementation of restoring method for reading bar code. [Thesis]. Brno University of Technology; 2018. Available from: http://hdl.handle.net/11012/25863

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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