Density trace measurement and triggering in frequency domain bitmaps

摘要

A "density trace" (730) is formed by measuring the density of each column of a frequency domain bitmap (720) above a user-specified "amplitude threshold" (725). The density of each column equals the sum of the densities of all of the pixels in the column that are above the amplitude threshold divided by the sum of the densities of all of the pixels in the column. A density trace (730) provides a convenient way to define and represent the occupancy for a large number of columns, and also allows density data to be quickly transmitted from one instrument or computer to another. In some embodiments, a density trace is incorporated into a trigger detector (700) of a test and measurement instrument and used to generate a trigger signal. The trigger detector compares the density trace (730) to a user-specified "density threshold" (735) and generates the trigger signal when the value of any point of the density trace violates the density threshold.