Filtering: Extracting What We Want from What We Have
Engineers use filtering to extract the useful information from noisy signals.Copyright 2014 Michael B. Wakin and Dehui Yang, Colorado School of Mines</
Filtering is the process of removing or separating the unwanted part of a mixture. In signal processing, filtering is specifically used to remove or extract part of a signal, and this can be accomplished using an analog circuit or a digital device (such as a computer). In this lesson, students learn the impact filtering can have on different types of signals, the concepts of frequency and spectrum, and the connections these topics have to real-world signals such as musical signals. Students also learn the roles that these concepts play in designing different types of filters. The lesson content prepares students for the associated activity in which they use an online demo and a variety of filters to identify the message in a distress signal heavily corrupted by noise.
In electrical engineering, filters play a dominant role in speech, image and video processing. The concept of filtering also has a variety of applications in other types of engineering beyond electrical. In chemistry, membranes are used to block impurities while letting other materials pass through. Filters also play an important role in optics; they are used to alter the colors of light by blocking certain ranges of wavelengths. In addition, filters have applications for different purposes in the areas of mechanical engineering, geophysics and petroleum engineering.
After this lesson, students should be able to:
- Describe how filters process different kinds of signals.
- Explain the concept of frequency.
- Illustrate how to extract different frequency components of a signal using different types of filters.