ADC/DAC INTERFACE

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Electrical signals from a piece of medical laboratory equipment or clinical equipment may be processed by a digital computer and returned to an analogue output device (e.g. pen recorder) using an ADC/DAC. The ADC (analogue to digital converter) examines incoming voltage at regular intervals (e.g. every microsecond up to every second) and converts the voltage to a binary number. The computer can then use this binary number or a series of them to make calculations and to identify trends. The results of the calculations can be returned to the output device through a digital to analogue converter (DAC) which produces a voltage representing the binary number given by the computer.

Many medical instruments incorporate ADCs and DACs without any external presentation of the digital form in which the calculations are performed. If a commercial computer or microcomputer is used then an external device may be required to perform these functions. In this case the computer controls the sampling rate and timing of the calls for the input of information and meets the requirement for timing and scaling of the output information.