HOW DO BARCODES WORK?
Different combinations of bars and spaces are used to encode characters into barcodes. Differences in light and dark and the width of the elements are the variables used for encoding. The barcode reader illuminates the symbol and measures the amount of light that is reflected back. The reader determines the pattern of light and dark or wide and narrow, then compares it to the encoding table for that type of barcode (called a symbology) and decodes the symbol.
HOW MANY KINDS OF BARCODES ARE THERE?
Hundreds of barcode symbologies have been created, but less than two dozen are widely used. Each symbology has its own pattern of bars and spaces and its own rules for encoding data. There are two basic types of barcodes: linear and two-dimensional (2-D).
Linear codes encode data in bars and spaces in a single line. The U.P.C./EAN symbol is the best-known example of a linear barcode.
Two-dimensional codes encode data in an additional dimension. The two principle types of 2-D codes are stacked and matrix symbologies. Stacked symbologies resemble multiple linear symbols stacked on top of each other. Matrix symbologies feature blocks or lines in a grid or geometric pattern. There are also hybrid 2-D symbologies and other variations.
HOW ARE SYMBOLOGIES DIFFERENT?
Symbologies differ primarily by the type and amount of data that they can hold. Some symbologies offer full alphanumeric encoding, while others only encode numbers. Symbologies may be fixed or variable length. However, size isn’t unlimited, because the symbol must remain compact enough to be recognised by the reader. Two-dimensional symbologies can hold significantly more data than linear codes.
WHAT KIND OF BARCODE SHOULD I USE?
The variety of barcode formats available practically ensures you can find a symbology that meets your needs. The most important variables that determine the optimal symbology are the amount of data that needs to be encoded, the space available to print the barcode and the type of data to encode.
HOW MUCH DATA CAN A BARCODE HOLD?
Variable-length symbologies can be used to encode only a few characters, if desired, while 2-D codes encode thousands of characters. The data capacity of variable-length barcodes is limited by the size of the symbol, which is in turn limited by the ability of the barcode reader. For reference, a standards U.P.C./EAN symbol encodes 14 numeric digits. Many barcode applications in warehousing, distribution, manufacturing, and inventory control require a serial number of similar length, which many common symbologies can easily encode into a compact symbol.