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plotSpectrum

System object: phased.MUSICEstimator
Package: phased

Plot MUSIC spectrum

Syntax

plotSpectrum(estimator)
output_args = plotSpectrum(estimator,Name,Value)
lh = plotSpectrum(___)

Description

plotSpectrum(estimator) plots the MUSIC spectrum computed by the most recent step method execution for the phased.MUSICEstimator System object™, estimator.

output_args = plotSpectrum(estimator,Name,Value) plots the MUSIC spatial spectrum with additional options specified by one or more Name,Value pair arguments.

lh = plotSpectrum(___) returns the line handle to the figure.

Input Arguments

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MUSIC estimator, specified as a phased.MUSICEstimator System object

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Units used for plotting, specified as the comma-separated pair consisting of 'Unit' and 'db', 'mag', or 'pow'.

Data Types: char

Plot a normalized spectrum, specified as the comma-separated pair consisting of 'NormalizedResponse' and false or true. Normalization sets the magnitude of the largest spectrum value to one.

Data Types: char

Title of plot, specified as a comma-separated pair consisting of 'Title' and a character vector.

Example: true

Data Types: char

Output Arguments

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Line handle of plot.

Examples

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Estimate the DOAs of two signals received by a standard 10-element ULA having an element spacing of 1 meter. Then plot the MUSIC spectrum.

Note: You can replace each call to the function with the equivalent step syntax. For example, replace myObject(x) with step(myObject,x).

Create the ULA array. The antenna operating frequency is 150 MHz.

fc = 150.0e6;
array = phased.ULA('NumElements',10,'ElementSpacing',1.0);

Create the arriving signals at the ULA. The true direction of arrival of the first signal is 10° in azimuth and 20° in elevation. The direction of the second signal is 60° in azimuth and -5° in elevation.

fs = 8000.0;
t = (0:1/fs:1).';
sig1 = cos(2*pi*t*300.0);
sig2 = cos(2*pi*t*400.0);
sig = collectPlaneWave(array,[sig1 sig2],[10 20; 60 -5]',fc);
noise = 0.1*(randn(size(sig)) + 1i*randn(size(sig)));

Estimate the DOAs.

estimator = phased.MUSICEstimator('SensorArray',array,...
    'OperatingFrequency',fc,...
    'DOAOutputPort',true,'NumSignalsSource','Property',...
    'NumSignals',2);
[y,doas] = estimator(sig + noise);
doas = broadside2az(sort(doas),[20 -5])
doas = 1×2

    9.5829   60.3813

Plot the MUSIC spectrum.

plotSpectrum(estimator,'NormalizeResponse',true)

Figure contains an axes object. The axes object with title MUSIC Spatial Spectrum contains an object of type line. This object represents 1 GHz.

Version History

Introduced in R2016b