In many signal analysis tasks, it is useful to focus only on the "good" parts of a signal - those segments that are clean, relevant, or contain key events - while ignoring unwanted sections.

Manually extracting these parts, performing spectral analysis on each, and combining the results can be time-consuming and tedious.


To simplify this process, SIGVIEW offers a Segment Selection and FFT Analysis feature, allowing you to easily select desired signal parts and perform FFT on them.


Selecting Segments from a Signal


You can control segment selection through the signal’s context menu (right-click on the signal), under the Segments section.



Available options include:


Start Segment Here: Marks the beginning of a new segment at the current cursor position.


End Segment Here: Marks the end of the current segment at the cursor position.


Create Segment from Selection:

Creates a new segment based on the current mouse selection range.


    • Delete This Segment: Deletes the segment currently under the signal cursor.
    • Clear All Segments: Removes all defined segments from the current signal.
    • FFT on Selected Segments: Performs FFT analysis on the selected segments (detailed below).



Visual Representation


Selected segments are highlighted with a green background behind the signal.


The start of an unfinished segment is indicated by a thin green vertical line.



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Saving and Reloading Segments


When you save a Workspace using File / Save Workspace... or Save as Tool..., all segment information is preserved along with the signal. Reloading the workspace will restore your segment selections.



Notes on Segment Behavior


If a new segment overlaps an existing one, SIGVIEW will automatically merge them into a single, larger segment.


You cannot manually edit segment boundaries. To adjust a segment, you must delete it and define a new one.



Performing FFT on Selected Segments


SIGVIEW performs FFT analysis on the selected segments by:


  • Dividing each segment into smaller, overlapping blocks.
  • Calculating FFT for each block.
  • Averaging the FFT results across all blocks and segments to create a final spectrum.


Setting FFT Parameters


After selecting your segments and choosing "FFT on Selected Segments", a dialog will appear where you can configure FFT parameters:



Single FFT Length: Defines the length of the FFT for each block. Options are limited by the size of the smallest segment (up to 512K samples).


FFT Overlap: Choose the amount of overlap between FFT blocks (25%, 50%, 75%, None)


Note: If perfect overlap settings do not fit into the selected segment length, SIGVIEW may slightly adjust the overlap percentage (e.g., from 50% to 48%) to match the available data.



Behavior of the Resulting FFT Window


The FFT result window created from segment analysis behaves like any other FFT window in SIGVIEW:


  • You can edit its properties (e.g., window function, scaling, averaging).
  • You can save it using “Save Workspace...” or “Save as Tool...”.
  • Each time you modify the selected segments, SIGVIEW automatically recalculates the FFT and updates the display.
  • You can create multiple FFT windows from the same segments but with different FFT settings to compare the effect of different parameters on the result.