Methods to determine and selectively sample positive and negative peak values occurring within a scan reflectance profile signal

摘要

Methods and associated apparatus are provided to analyze and selectively sample scan reflectance profile (SRP) signals by producing corresponding first derivative and second derivative signals, as the SRP signal is generated. The methods employ the occurrences of zero crossings of the first and or second derivative signals, along with occurrences of the level of the first derivative signal rising above, or dropping below, predefined positive or negative threshold levels, respectively. Sample values, including positive and negative peak sample values, are produced and made available for post processing to determine one or more figures of merit (or quality parameters) that are indicative of the quality of a bar code indicia that was scanned to generate the SRP signal analyzed and processed.