Continuous Signals and Frequency of Discrete Analyses

Sensors based on either electrical, optical or electromagnetic principles normally deliver a continuous signal which is very useful. The dynamics of the analyzed system can be resolved according to the time constants of the respective electronic equipment. In the general case, however, these data will nowadays be digitized but the information loss can normally be neglected because 12- or 16-bit converters are state of performance today. 

Further, data are stored in a computer in distinct time intervals resulting in discretion with respect to time and concomitantly in a possible loss of information. A data reduction algorithm should therefore be applied which must account for this fact raw data should be scanned with high frequency and the essential data - i.e. only recording when important changes take place - may be stored with the necessary frequency, i.e. variably or not equidistant with respect to time. 

Analytical instruments based on either physicochemical separation methods or relying on (bio)chemical reactions require a finite time to run these instruments are usually operated in repetitive, non-overlapping batch mode and deliver results with a certain non-negligible dead time. Generally, data density is low, for instance, in the order of 1 min 1 for FIA or 2 h 1 for HPLC. 

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