Guralp-systems Scream Manual do Utilizador descarregar pdf (Página 39)

User guide

compare streams by placing one directly on top of another. The lane

used for selecting the streams stays the same.

4.2.5 Spectrogram

Scream! can perform real-time spectral analysis on incoming data. To

enable this feature, right-click on the stream of interest in the

Waveview window and choose Spectrogram from the pop-up menu.

The vertical axis of the spectrum is linear, with the Nyquist frequency

(= half the sample rate) at the top and 0 Hz (DC) at the bottom. The

colouring is logarithmic, giving a large total range whilst retaining

sensitivity at low signal levels.

The width of the spectrum can be changed in the Display options pane

of the Setup window. The and keys adjusts the colour

contrast of the spectrogram.

The spectrogram supports zooming in by dragging a selection on the

frequency scale. To apply the zoom to all spectrograms in the

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Guralp-systems Scream Manual do Utilizador Página 39