System object: phased.MVDREstimator
Perform spatial spectrum estimation
Y = step(H,X)
[Y,ANG] = step(H,X)
Starting in R2016b, instead of using the
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
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 and plot the spectrum
[y,doas] = estimator(x + noise); doas = broadside2az(sort(doas),[20 -5]); plotSpectrum(estimator)