TS_SPECTROGRAM

The TS_SPECTROGRAM generates a spectrogram of a given vector.

This routine is written in the IDL language. Its source code can be found in the file TS_SPECTROGRAM.pro in the lib subdirectory of the IDL distribution.

Examples

t = findgen(100000)

data = sin(2*!pi*.02*t) + sin(2*!pi*.12*t) + sin(2*!pi*.22*t) + sin(2*!pi*.32*t) + sin(2*!pi*.42*t)

result = TS_SPECTROGRAM(data, window=512, overlap=128)

i = image(result, RGB_TABLE=colortable(72), title='TS_SPECTROGRAM')

IDL displays:

Syntax

Result = TS_SPECTROGRAM( X [, /DOUBLE] [, FREQ=value] [, SAMPLE_FREQ=value] [, TIME=value] [, OVERLAP=value] [, WINDOW=value] )

Return Value

The result is a [WINDOW/2, 1+(X.length - WINDOW)/OVERLAP] array which describes [time, frequencies].

Arguments

X

An n-element single- or double-precision floating-point vector.

Keywords

DOUBLE

Set this keyword to force the computations to be done in double-precision arithmetic.

FREQ

If set to a named variable, FREQ will contain the frequency vector for the spectrogram.

SAMPLE_FREQ

Set to the sample frequency of the input data.

TIME

If set to a named variable, TIME will contain the time vector for the spectrogram.

OVERLAP

An integer describing the number of points of window overlap. Defaults to WINDOW/2.

Note: OVERLAP is extremely data dependent.

WINDOW

An integer giving the size of the window. Defaults to 1024.

Note: WINDOW is extremely data dependent.

Version History

8.4	Introduced