Method for operating a spectrum analyzer to display a marker of a signal of interest

Abstract

A method for operating a spectrum analyzer to provide a marker that follows a peak from sweep to sweep in a spectrum display. The method operates on first and second measured spectrums. The first measured spectrum includes a plot of the signal amplitude against frequency during a first time interval in which the marker has been assigned to a peak at a first frequency and first amplitude. The present invention assigns the marker to a peak in the second spectrum measured during a subsequent time interval in which the marker is to be assigned. Initially, a first frequency range is defined in the second measured spectrum centered on the first frequency. The first frequency range is searched for candidate peaks having amplitudes within a first range centered on the first amplitude. If more than one such candidate peak is found by the search, the marker is assigned to the candidate peak closest to the first frequency. If a candidate peak is not found, a second frequency range is defined centered on the first frequency, and the process is repeated with a different amplitude range. If more than one such candidate peak is found by the search, the marker is assigned to the candidate peak farthest from the first frequency. If no candidate peak is found, a third frequency range in the second measured spectrum is defined and this frequency range is searched for all candidate peaks regardless of amplitude. The marker is assigned to one of the candidate peaks based on a weighted sum of the differences in amplitude and frequency of the candidate peaks and the first amplitude and frequency.