Signal processing digitisation

A block diagram of the experiment set-up is shown in Fig. 2.1. Both the acceleration and cutting force signals are recorded on a magnetic tape and then processed in the HP Fourier Analyzer, the output of which is plotted on the plotter or other peripheral devices. These acceleration and cutting force signals were digitised by an A/DC and then stored on the computer disc. 

A Fourier transform infrared spectrometer consists of an infrared source, an interference modulator (usually a scanning Michelson interferometer), a sample chamber and an infrared detector. Interference signals measured at the detector are usually amplified and then digitised. A digital computer initially records and then processes the interferogram and also allows the spectral data that result to be manipulated. Permanent records of spectral data are created using a plotter or other peripheral device. 

A spectrum in a specified ranalogue signals from eadi photodiode are digitised and transferred to a computer, where they e corrected for dark current response and transformed to absorbance. A number of digital techniques are available to increase sensitivity and to extend the use of rapid-scanning detectors to multicomponent analysis, reaction kinetics, tablet dissolution tests, process control, and detection in HPLC (A. F. Fell et al, Chrom-atographia, 1982, 16, 69-78). 

There are two main requirements for processing chromatographic data, accurate digitisation of the analogue detector signal and software to process the data. The software includes algorithms for detections of peaks, correction for base drift, calculation of peak areas and retention time, concentrations of components using stored detector response factors and production of the final analytical report. 

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