The family of processes: Discrete time, sampled processes
Many times the signals in the processes are only periodically available. The signals of vital processes, for example, are measured as practicable and if permitted by the circumstances.
In the case of technological processes, the circumstances may be similar. In a chemical process, for instance, the operators may examine the composition of a material periodically at predefined intervals and may decide to intervene depending on the results.
Examples of sampled, discrete-time processes include the control of blood pressure, the operation of the blast furnaces in metallurgy, cooking, etc.
The process is controlled by appropriate testing (in cooking generally by tasting), by adjusting the composition of materials in the process through rationing, and by modifying the signals maintaining the process (e. g. through heating).
Increasingly often, process signals are sampled in a way that the samples can be computer processed and then the process can be controlled through a computer. In this case, if the sampled signals are not directly available in a digital form, they are converted to digital signals with an analogue/digital converter (ADC).
With the spread of connected devices, by the use of the internet and by the use of wearable sensors, the sampling technique, computer methods assisting users and the processing of the resulting huge amount of information (Big Data) become more and more common.