Hand Held Products SV Series User Manual

Contents

Quick Check® SV Series User’s Guide A - 5Figure 3 - Examples of Scan Profile Parameters Out of RangeCalibration HintsCalibration is used to normalize reflectance calculations to known (and/ortraceable) values in absolute units of % reflectance. Calibration affectsreflectance calculations only. Calibration does not affect any other calculationsor ability to decode a symbol, etc. The scanner gain and offset settings have themajor effect on scanning performance. Keeping the scanner signal linear(between the yellow lines as described previously) is very helpful for gooddecoding, but is CRUCIAL for reflectance measurements. The calibrationprocedure will not be successful unless the bar code signal is proper.There may be cases in applications where the material being analyzed requiresa scanner gain and offset setting that will not allow calibration with the standardSV calibration symbol. In most cases this is due to a low contrast material (suchas brown corrugated) that will make the signal level on the calibration symbol gopast the yellow lines. In cases like this there are two basic choices to make:1. Do not use parameters that involve absolute units of reflectance as fail-ure criteria. These parameters include Symbol Contrast, Overall ISOGrade, PCS, Rmax, and Rmin.2. If reflectance parameters are required to be analyzed in the application,a calibration symbol can be created from the material being analyzed.Contact Hand Held Products Technical Assistance (see page 9-1) fordetails.All of bar codesignal notlinesBottom of barcode signalnot “flat”between yellow

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