System object: phased.RootWSFEstimator
Perform DOA estimation
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
ANG = step(H,X) estimates the DOAs from
X using the
X is a matrix whose columns
correspond to channels.
ANG is a row vector of the estimated
broadside angles (in degrees). You can specify the argument
single or double precision.
The size of the first dimension of the input matrix can vary to simulate a changing signal length. A size change can occur, for example, in the case of a pulse waveform with variable pulse repetition frequency.
The object performs an initialization the first time the object is executed. This
initialization locks nontunable properties
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
release method to unlock the object.
Estimate DOA of Two Signals Using WSF
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 45° in azimuth and −5° in elevation.
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; 45 60]',fc); noise = 0.1*(randn(size(x)) + 1i*randn(size(x)));
Construct WSF estimator System object.
estimator = phased.RootWSFEstimator('SensorArray',array,... 'OperatingFrequency',fc,... 'NumSignalsSource','Property','NumSignals',2);
Estimate the DOAs.
doas = estimator(x + noise); doas = broadside2az(sort(doas),[20 -5])
doas = 10.0002 20.7934