4.1. Introduction

Correct measurements are crucial to the field of instrumentation. No matter what sensor is being used, many influence parameters or disturbances such as temperature, pressure, mechanical constraints and electromagnetic environment can contribute to measurement error. These kinds of problem are intrinsic to sensors. Furthermore, the acquisition chain must link an electronic device that can condition information and send it to a transducer. This information relates to the variable to be measured and provides the closest possible representation of the observed physical phenomenon.

Most analog possessing of a signal sensor contains filtering and amplification functions (Figure 4.1). These functions help us retrieve relevant information from signal sensors and take it to a compatible and sufficient electric level so that the information can be then used by the system or equipment. This process assures proper interface between user and displays, measurement devices and microcomputers.

Figure 4.1: Simplified functional schema of a measurement chain

Because measurement systems depend on reducing electronic noise in order to function correctly, in this chapter we will discuss in detail the aspects related to amplification functions, as well as the different sources of intrinsic noise in electronic devices. The concept of filtration will be dealt with in Chapter 5.

4.2. The Problem of Electronic Noise