ABSTRACT
This chapter outlines many details of the process called digital data acquisition. The conversion of signals from an analog electrical wave to a table of numbers that can be further analyzed, using sophisticated signal-processing methods, is a delicate process. A broad dynamic range is needed when the signal contains both low- and high-amplitude data. On-line processing of digitized signals can substantially reduce the required volume of data storage. Many of the signal-processing methods applied to lung sounds assume certain properties of the signal. The most important of these properties is stationarity. The basic sounds may be considered as approximately random noise with close to Gaussian distribution. Lung sounds acquisition is particularly challenging due to the low signal-to-noise ratio. Correct strategies of breath sounds data acquisition and pre-processing are an essential ingredient in the process of their measurement and analysis.
