System object: phased.MVDREstimator
Perform spatial spectrum estimation
Y = step(H,X)
[Y,ANG] = step(H,X)
Starting in R2016b, instead of using the
to perform the operation defined by the System
object™, you can
call the object with arguments, as if it were a function. For example,
= step(obj,x) and
y = obj(x) perform
Y = step(H,X) estimates the spatial spectrum
X using the estimator
a matrix whose columns correspond to channels.
a column vector representing the magnitude of the estimated spatial
The size of the first dimension of this input matrix can vary to simulate a changing signal length, such as a pulse waveform with variable pulse repetition frequency.
[Y,ANG] = step(H,X) returns additional
ANG as the signal’s direction of
arrival (DOA) when the
DOAOutputPort property is
ANG is a row vector of the estimated broadside
angles (in degrees).
The object performs an initialization the first time the
is executed. This initialization locks nontunable
properties (MATLAB) and input specifications, such as dimensions, complexity,
and data type of the input data. If you change a nontunable property
or an input specification, the System
object issues an error.
To change nontunable properties or inputs, you must first call the
to unlock the object.
First, estimate the DOAs of two signals received by a standard 10-element ULA with element spacing of 1 meter. The antenna operating frequency is 150 MHz. The actual direction 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. Then, plot the MVDR spatial spectrum.
Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent
step syntax. For example, replace
Create the signals with added noise. Then, create the ULA System object™.
fs = 8000; t = (0:1/fs:1).'; x1 = cos(2*pi*t*300); x2 = cos(2*pi*t*400); array = phased.ULA('NumElements',10,'ElementSpacing',1); array.Element.FrequencyRange = [100e6 300e6]; fc = 150.0e6; x = collectPlaneWave(array,[x1 x2],[10 20;60 -5]',fc); noise = 0.1*(randn(size(x)) + 1i*randn(size(x)));
Construct MVDR estimator System object.
estimator = phased.MVDREstimator('SensorArray',array,... 'OperatingFrequency',fc,'DOAOutputPort',true,'NumSignals',2);
Estimate the DOAs.
[y,doas] = estimator(x + noise); doas = broadside2az(sort(doas),[20 -5])
doas = 9.5829 60.3813
Plot the spectrum.