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SignalProcessing

  

Periodogram

  

plot the periodogram of a signal

 

Calling Sequence

Parameters

Options

Description

Examples

Compatibility

Calling Sequence

Periodogram(f)

Parameters

f

-

string, rtable, list : a signal, the name of a file containing a signal, or a list of these

Options

• 

channel, column : posint, or list(posint) : channel or rtable column, or list of these

• 

compactplot : truefalse : indicates that multiple plots are to be displayed more compactly

• 

detrend : truefalse : indicates if the data should have any trend removed

• 

frequencyscale : anything

• 

powerscale : identical( "dB", "dB/Hz", "absolute" ) : indicates the power scale

• 

reduceplot : truefalse or posint : indicates that plot resolution is to be reduced

• 

samplerate : realcons : the sample rate

• 

timeunit : anything 

Description

• 

The Periodogram command plots the power spectrum for one or more signals. The input f can be the name of a file containing an audio signal, an rtable, or a list. See AudioTools:-Format for information about the kinds of files accepted.

• 

If f is an m by n Matrix (or 2-dimensional Array), then it is assumed to contain n signals of length m. In this case, all signals are plotted and displayed in an array plot. Similarly, if f is an audio signal with multiple channels, then plots for all channels are produced.  If you do not wish to plot all signals, the channel and column options allow you to plot a subset.

• 

If f is a list, then every element of the list must be a single-channel audio signal or a 1-dimensional Array.

• 

The compactplot option allows multiple plots to be displayed more compactly. When this option is set to true, it is assumed the x-axis labels for all plots are identical and thus they are displayed for the bottommost plot only.

• 

The detrend option specifies if the data should have any linear trend removed before being plotted.

• 

The frequencyscale option controls the scaling used on the frequency axis. The default is Hz.

• 

The powerscale option controls the scaling used on the power axis and can be one of "dB", "dB/Hz" or "absolute". The default is "dB".

• 

If the signal is particularly large and the reduceplot option is set to true, then the plot resolution is automatically reduced for efficient rendering. If reduceplot is a positive integer, then the plot is reduced by that factor. The default setting for this option is true.

• 

The samplerate option is used to specify a sample rate. Note that audio signals generated by the AudioTools package have the sample rate saved in their attributes.

• 

The timeunit option is used to specify the unit time of the sample rate. The default value is s.

• 

Additional plotting options as described on the plot/option help page may be included.

Examples

withSignalProcessing:

Generate a signal equal to the sum of two sinusoids with frequencies of 12 Hz and 24 Hz, sampled at 100 Hz:

f112.0:

f224.0:

signalVector210,i→sinf12Pii100+1.5sinf22Pii100,datatype=float8

signal2.181587199000001.186026578000000.7029176341000000.2477015962000000.8387995230000000.4301004243000002.201568505000000.9713203969000001.748245568000001.832734392000001024 element Vector[column]

(1)

Periodogramsignal,samplerate=100

audiofilecatkerneloptsdatadir,/audio/maplesim.wav:

Periodogramaudiofile,frequencyscale=kHz

audiofile2catkerneloptsdatadir,/audio/stereo.wav:

Periodogramaudiofile2,compactplot

Compatibility

• 

The SignalProcessing[Periodogram] command was introduced in Maple 2017.

• 

For more information on Maple 2017 changes, see Updates in Maple 2017.

• 

The SignalProcessing[Periodogram] command was updated in Maple 2019.

• 

The detrend option was introduced in Maple 2019.

• 

For more information on Maple 2019 changes, see Updates in Maple 2019.

See Also

LSPeriodogram

SignalPlot

SignalProcessing

Spectrogram

Statistics:-Detrend