Semi-logarithmic and hybrid quantization of laplacian source in wide range of variances

Milan S. Saví, Zoran H. Perić, Stefan R. Panić, Aleksandar V. Mosić

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A novel semilogarithmic hybrid quantizer for non-uniform scalar quantization of Laplacian source, which consist of uniform quantizer and companding quantizer is introduced. Uniform quantizer has unit gain in area around zero. Companding quantizer is defined with a novel logarithm characteristic. Also an analysis of classic semilogarithmic A-law for various values of A parameter is provided. Comparation with classic semilogarithmic A-law is performed. The main advantage of hybrid quantizer is that number of representation levels for both uniform and companding quantizer are not unambiguously determined function of the A parameter value, as it is the case with classic semilogarithmic A companding characteristic. It is shown that by using hybrid quantizer, average of signal-to-quantization noise ratio SQNR quality obtained by using classic A companding law can be overachieved for 0.47 dB. Numbers of representation levels of hybrid quantizer are adapted to the input signal variances, in order to achieve high SQNR in a wide range of signal volumes (variances). By using this adaptation higher average SQNR quality of 2.52 dB could be achieved compared to classic A companding law. Forward adaptation of hybrid quantizer is analyzed and obtained performances correspond to adaptive classic A companding law case but possible advantage arises in simpler practical realization of hybrid quantizers. Obtained performances correspond to classic A-law companding case, because during the adaptation process, optimal values of parameter A are chosen. For each other A parameter values proposed hybrid quantizer provides better results. For value of A = 50 hybrid model has higher SQNR value for 0.79 dB.

Original languageEnglish
Pages (from-to)386-391
Number of pages6
JournalJournal of Electrical Engineering
Issue number6
Publication statusPublished - 11 Dec 2012
Externally publishedYes


  • Forward adaptive quantization
  • Hybrid semilogarithmic quantizer
  • Laplacian source

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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