2.1 Introduction

This chapter is intended as a brief introduction to methods for acquiring and storing data. Although it may be tempting for the signal analyst to skip ahead to the chapters concerning the processing of the digital ECG, it is important to understand the etiology of a signal as far as possible. In particular, it is essential to know whether an observed anomaly in the ECG is due to a signal processing step (in either the hardware or software), an electronic artifact, an error in the storage of data, a disturbance on the sensor, or due to a pertinent physiological phenomenon. Furthermore, despite the diligence of the engineer concerning these issues, the error (or success/failure of a particular technique) may simply be due to the selection of the source of data itself.

Toward this end, the present chapter provides an overview of many of issues that should be considered before designing an ECG-based project, from the selection of the patient population, through hardware choices, to the the final signal processing techniques employed. These issues are intricately linked, and choices of one can restrict the analysis at another stage. For instance, choosing (either implicitly or explicitly) a population with low heart rate variability will mean that a higher acquisition sampling frequency is required to study such variability, and certain postprocessing interpolation techniques should be avoided (see Chapter 3). Apart from obvious confounding factors such as age, gender, and medication, variables such as lead...