DADiSP Online Help
Click here to see this page in full context

DADiSP Worksheet Functions > Function Categories > Fourier Transforms and Signal Processing > SONOGRAM

 

SONOGRAM

Purpose:

Calculates the 2D Spectrogram as a B&W image.

Syntax:

SONOGRAM(series, len, overlap, swin)

series

-

An input series

len

-

Optional. An integer, the segment length. Defaults to 512.

overlap

-

Optional. An integer, the number of points to overlap each segment. Defaults to len/2.

swin

-

Optional. An integer, the windowing function

0:

Hamming

1:

Hanning

2:

Rectangular (none)

3:

Kaiser

4:

Flattop

5:

Blackman

6:

Modified Flattop

7:

Dolph-Chebychev

8:

Taylor

9:

Blackman-Harris

Returns:

A table of Amplitude values in Frequency vs Time format.

Example:

sonogram(W1, 128)

 

divides W1 into columns of 128 points that overlap by 64 points. Each segment is multiplied by a Hamming window. The spectrum (i.e. magnitude of the FFT) of each column is calculated and the result is displayed as a Black on White image.

Remarks:

See the related SPECGRAM function for more details.

See Also:

FFT

RAVEL

SPECGRAM

SPECTRUM