A method and system used in the barcode sensing process are disclosed, in which at least two instances of an optical signal are obtained from the same barcode in different time periods, and digitized by a first digitizer with a first threshold. The digitized results from the at least two instances are then applied with an AND algorithm to eliminate the noise, whereby create a correct digitized output. Preferably, the instances of the signal are also digitized by a second digitizer with a second threshold, which are used to synchronize the timing of the digitized results created by the first digitizer. The second threshold is preferably larger than the first threshold.