METHOD AND APPARATUS FOR ANALOG-TO-DIGITAL CONVERSION USING ASYNCHRONOUS SIGMA-DELTA MODULATION

摘要

The solution according to the invention consisting in the modulation of the analog signal using the asynchronous Sigma-Delta modulator, counting periods of the reference clock during each pulse of the previously obtained square wave and making the digital word available is characterized in that the square wave (z(t)) obtained in result of the modulation in the asynchronous Sigma-Delta modulator (ASDM) is subjected to conversion by counting the periods (T0) of the reference clock (RG) during subsequent pulses of that square wave (z(t)) by means of the counting module (CTM), and then each word obtained representing the number of periods (T0) of the reference clock (RG) counted during each given pulse of the square wave (z(t)) is recorded and stored in the intermediate buffer (TBUF); and the duration of the serial transmission of the digital word obtained in result of counting the periods of the reference clock (RG) during previous pulse of the square wave (z(t)) is simultaneously controlled by the control module (CM); and as soon as this transmission is completed, the content of the intermediate buffer (TBUF) is transferred to the transmitting buffer (TDR) of the apparatus; and after that a given digital word representing a given pulse of the squarewave (z(t)) is transmitted serially to the computer or to the communication network; then the cycle is repeated for the next pulse of the square wave (z(t)).