Abstract: A signal processing method for identifying the type of a stored, digitized acquired signal according to a selected operating mode applies a hierarchy of tests to the stored data. The tests applied are determined by the selected operating mode--SPUR, PULSE or CW. Tests for threshold and width are applied in all operating modes, tests for left and right maximum values are applied in the PULSE mode, and a bandwidth test is additionally applied in the CW mode. Thus other signals than CW can be identified.

Abstract: An apparatus and method of using markers for identifying particular points on a quasi-3-dimensional display, such as a color spectrogram display or a waterfall display of multiple frequency spectra on an electronic spectrum analyzer, so that amplitude, time, and frequency values associated with a particular point can be conveniently read out, and so that differences in amplitude, time, and frequency between two points can be easily calculated and presented to the user. Two markers whose positions are ascertainable are generated on the quasi-3-dimensional display and are made subject to operator control. One of these markers is positioned by the operator on a particular point of interest and the values associated with that location are then displayed for readout with greater precision and convenience than would otherwise be possible. A second marker is placed at a second point of interest and the differences in the values of amplitude, time, and frequency between the two points are calculated and displayed.