Asha Ganesan, Cypress
EDN (August 26, 2013)
Data acquisition systems (abbreviated with the acronym DAS or DAQ) measure real world signals (temperature, pressure, humidity etc.) by performing appropriate signal conditioning on a raw signal (amplification, level shifting, etc.), and then digitizing and storing these signals. This digital signals can then be transmit to another digital system for further processing, usually on a periodic basis.
Examples of data acquisition systems include such applications as weather monitoring, recording a seismograph, pressure, temperature and wind strength and direction. This information is fed to computers, which then predict natural events like rain and calamities like earthquakes and destructive winds. An example of a DAS in the medical field is a patient monitoring system that tracks signals like an ECG (Electro-cardiogram) or EEG (Electro-encephalogram).
A typical DAS consists of the following components:
- Sensors that convert real world phenomenon to equivalent electrical analog signals
- Signal conditioning circuitry that alters signals from the sensor to a form, which can be digitized
- Analog to digital converters that convert conditioned analog signals to a digital representation
- Store and forward memory, which is used to store digital signal streams for forwarding to another system at a later time
- A communication interface over which the digital streams are transferred to the other system
- A microprocessor system or a microcontroller to sequence and control all of the other components.
Figure 1 shows a block diagram of a basic data acquisition system. The details of these internal blocks are explained in the next section.
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