Several chapters back, we began with the basic components used in electronics and then moved to exploring analog and digital electronics, and processing electrical signals. We can now begin to convert this understanding of basic electronics into an ability to design and plan more complicated instruments. Even the most complicated instruments are made up of simpler instruments and electronic circuits, so this will serve to bring more detail to our discussion of electronic instrumentation.
The instruments we will look at in this and future chapters are generally involved in performing sensing tasks and then processing that signal into the data we are interested in analyzing. In many scenarios, the input signal will be noisy or difficult to separate from other signals, meaning that a conditioning task will be needed. In optical engineering, we can make use of optical filters or gratings to separate specific light channels before the light reaches the detector. Once the light has been converted by the detector into an electrical signal, other techniques will be needed to improve the signal quality. Since our expertise is in working with the optical signals, we will focus here on the electrical side of the signals. While it is common to think of filters as being analog devices, and we will start there, the advent of digital signal processing has made it possible to use a wide range of mathematical functions available for use on signals.
In this chapter we will concentrate on electronic signal conditioning and filtering, and relating this to generic instrument design. The filters will include both analog and digital circuits, and some of the underlying concepts will be introduced as well. There is a great deal of literature on electronic filter systems, and it is common for electrical engineering programs to devote several courses to the topic.
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