Digital data reflecting information carried by an analog signal can be represented either by the signal sample values given at the sampling instants or by the results of some preliminary signal processing procedure. Signal sample value preprocessing, carried out as data acquisition subroutines, is considered as signal parameter estimations in Chapter 12 and as complexity-reduced calculations of DFT estimates in Chapter 16.
The first category of the data acquisition systems considered here could often be realized on the basis of a single ADC with a few devices added for signal conditioning, data buffering and interfacing. However, this basic data acquisition scheme has to be diversified as soon as the conditions for data acquisition become more complicated and more demanding. Then some nontraditional approach, such as randomized sampling, might prove to be an interesting option. First of all, it concerns the methodology according to which signals are sampled and quantized. As shown in Part 1 of this book, these operations could be carried out in various ways so that they could be matched to specific functional and performance requirements. There are various signal digitizing techniques available and analysis of them is helpful in finding an appropriate approach to use in particular special signal digitizing and data acquisition problems. The structure and performance of data acquisition systems can be modified on the basis of the selected digitizing techniques ...