NLS-Glossary

A method of error detection that uses a polynomial calculation to compare the encoded check value with the calculated check value. If the CRC check values do not match, then the code contains a data error.

Dark current of a photodetector is the dc current that flows in the absence of light when it is carrying a bias voltage.

depends strongly on the temperature. There are two contributions to the dark current which are the diffusion of minority carriers in the neutral regions and the thermal generation of electron hole pairs (EHPs) in the space charge layer (SCL). Both depend strongly on the temperature and the dark current increases exponentially with increasing temperature, typically as a thermally activated process, i.e. Idark ~ exp(-Eg/$\mathrm{\eta }$kT) where $\mathrm{\eta }$is 1 if the reverse current is controlled by minority carrier diffusion in the neutral regions and 2 if it is controlled by thermal generation of EHPs in the SCL, Eg is the bandgap of the semiconductor material, k is the Boltzmann constant and T is the temperature (K). See reverese

Hardware interface standard for modems, protocol converters, and other communications equipment. To interface DCE devices with DTE (Data Terminal Equipment) devices such as terminals or PCs, a straight through serial cable is required.

A character (or set of characters) that uniquely defines the specific use of the data encoded in the bar code symbol following the data identifier. Also known as a Flag Character. 

In the Aztec Code symbol, a two-module-wide row of data and correction characters that wraps clockwise around the central finder pattern. Each data layer begins immediately beside the ending edge of the preceding layer and ends beside its own starting edge. As a result, a barcode scanner can read the data layers as a continuous spiral.

Data rate is the rate at which bits are transmitted per unit time according to a well-defined information coding system used, e.g. return-to-zero (RZ) or nonreturn-to-zero (NRZ). NRZ data rate is higher than the RZ data rate.