|  | 4.1 |
| Background for Studying Frequency-Based Cable Testing
|  | 4.1.6 |
| Analog and digital signals in time and frequency
To understand the complexities of networking signals and cable testing, examine how analog signals vary with time and with frequency. First, consider a single-frequency electrical sine wave, whose frequency can be detected by the human ear. If this signal is transmitted to a speaker, a tone can be heard. How would a spectrum analyzer display this pure tone? Next, imagine the combination of several sine waves. The resulting wave is more complex than a pure sine wave. Several tones would be heard. How would a spectrum analyzer display this? The graph of several tones shows several individual lines corresponding to the frequency of each tone. Finally, imagine a complex signal, like a voice or a musical instrument. What would its spectrum analyzer graph look like? If many different tones are present, a continuous spectrum of individual tones would be represented.
|  | Interactive Media Activity
Interactivity: Fourier Synthesis In this activity, the user will draw sine waves by selecting the amplitude, frequency, and phase of each. Interactive Media Activity 4.1.6 is located in the CCNA 3.0 Bridge 1 Activities and Quizzes file. The Activities and Quizzes file can be downloaded in the Course Material section of your class homepage.
Web Links
Analog and Digital Signals http://www.smartcomputing.com/editorial/ article.asp?article= articles%2F1992%2Ffeb92%2F0215% 2F92n0215%2Eas