TABLE OF CONTENTS Though long experience with time-domain analysis has made many of us prefer that domain, there are very good reasons to also be competent in the frequency domain. The most obvious advantage is measurement capabilities. In the frequency domain, measurements can be made over a dynamic range of about 80 to over a 100 decibels. The high end of frequency available for typical network analyzers is in the range of 20 to 50 gigahertz. By comparison, the time domain reflectometer is capable of about a 30-decibel dynamic range and about 6-gigahertz equivalent frequency response.
In Chapter 2, methods to convert between frequency domain and time domain were presented. The main procedure in this conversion, is the Fourier transform and its inverse. These are usually implemented in the form of the fast Fourier transform, FFT, and its inverse, the IFFT. These are not perfect tools inasmuch as they make the presumption that the data being analyzed is actually a portion of a repetitive wave and that presumption introduces undesired artifacts. Dealing with those artifacts sometimes requires procedures that are unpalatable to purists. It was suggested that faking data could be made more palatable by assigning an alternative name completing the data set to the procedure.
In this section, applications and uses of frequency domain data will be discussed. There are some aspects of frequency domain data that are so obvious that, when you see the graphs, you will immediately recognize the utility of this data...
