plot the periodogram of a signal
string, rtable, list : a signal, the name of a file containing a signal, or a list of these
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
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.
Generate a signal equal to the sum of two sinusoids with frequencies of 12 Hz and 24 Hz, sampled at 100 Hz:
f1 ≔ 12.0:
f2 ≔ 24.0:
signal ≔ Vector⁡210,i→sin⁡f1⋅2⁢Pi⁢i100+1.5⁢sin⁡f2⋅2⁢Pi⁢i100,datatype=float8
signal ≔ 2.181587199000001.18602657800000−0.702917634100000−0.2477015962000000.838799523000000−0.430100424300000−2.20156850500000−0.9713203969000001.748245568000001.832734392000001024 element Vector[column]
audiofile ≔ cat⁡kernelopts⁡datadir,/audio/maplesim.wav:
audiofile2 ≔ cat⁡kernelopts⁡datadir,/audio/stereo.wav:
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.
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