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Spectrogram (time-frequency analysis)

Spectrograms are generated by the Short-time Fourier transform.

Right click on the signal name and select “Spectrogram".

Displays the following screen. Click “OK” to open analysis result of continuous wavelet transform.

(1) Window size​

Set number of samples per window.

(2) Step size​

Set step size. When step size is less than windows size, window ovelaps.

(3) FFT size​

Set FFT size. When window size is less than FFT size, data will be padded with zeros.

(4) Frequency limit​

Set maximum frequency.



The following time-frequency map is displayed (X-axis: time (s), Y-axis: frequency (Hz)).

The following mouse operation is possible on the chart.

OperationDescription
Scroll mouse wheelEnlarge/reduce horizontal waveform size.


(5) Color range: Min​

Specifies minimum magnitude to be colored.

(6) Color range: Max​

Specifies maximum magnitude to be colored.

(7) Auto​

Auto set display range

(8) Plot options​

Click to open color map setting screen. Color map (palette) can be changed.



(9) SAVE VALUES​

Export data to a binary file (*.dat).

(10) SAVE FIGURE​

Save spectrogram in an image file. Click to open “Figure editor”. See “Save image (figure editor)” for details.

(11) CLOSE​

Close this dialog.