REAL-TIME CORRECTION OF DC OFFSET OF LOW-COST AUDIO CODECS IN ACOUSTIC DIGITAL LOCK-IN AMPLIFIERS

Jan Fischer, Jan Vejdelek

Abstract

In design of the DSP for acoustic applications it is appropriate to integrate a low-cost audio codec into their structure. Audio stereo codecs are able to achieve a high resolution of measurement on low frequencies of the input signal. But audio codecs are able to digitalize only signals of the acoustic origin, it means the signal without the DC part of frequency spectrum. In the majority of available DSP there are 2 independent AD converters and also 2 DA converters. But most of audio codecs create the DC offset during the conversion to the digital form, it means 0V voltage amplitude of input signal doesn’t correspond to 0_HEX in hexadecimal form of output digital word. The solution how to achieve the required parameters with these low-cost audio codecs is founded in this project.

Keywords

audio codec, correction of DC offset, digital signal processing

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IMEKO-TC4-2002-037.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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