Receiving a signal with Phased Array

Hi all,

I am trying to generate a signal, for instance a pure sine at 1 GHz, and see how that signal is received with different weights.

For that purpose, I found this documentation that creates weights aimed nulling a specific angle:

https://www.mathworks.com/help/phased/ug/array-pattern-synthesis.html

Now I want to use these weights in a phased array receiver, and plot the received signal before and after using these weights.

Assume I am using a uniform linear array with 10 elements:

ula = phased.ULA(10,lambda/2);

ula.Element.BackBaffled = true;

and that I already have the set of weights - 'w'

I could only find the objects like phased.Collector or collectPlaneWavem, which gets as input the signal magnitude over time, but both output the (time x elements) complex matrix.

How can I convert this matrix into an actual signal - magnitude over time?

Or is there any other way that I can compare how a signal is received before and after I changed the phased array antennas weights?

Thanks!

Answer 1

[Supraja]

To convert a matrix into an actual signal, the matrix elements can be considered as the magnitude of the signal over time. You can use the "plot" or "stem" function in MATLAB to visualize the signal. Following are the steps to create a magnitude over time signal from the given matrix in MATLAB:

1. Define a time axis for the signal. Depending on the sampling rate, you can determine the time axis as followss

`time_axis = 0:1/fs:(size(mag_matrix, 1)-1)/fs;`

Here, `fs` is the sampling rate of the signal.

2. Plot the signal using the "plot" or "stem" function in MATLAB. For example, using the "stem" function, you can visualize the magnitude over time.

`stem(time_axis, mag_matrix);`

3. Add axis labels, plot title, and legend if desired:

xlabel('Time (s)');

ylabel('Magnitude');

title('Magnitude over time');

legend('Channel 1', 'Channel 2', ..., 'Channel n');
    

Here, `n` is the number of channels in the input matrix.

Here is an example code snippet that demonstrates these steps

% Define the input matrix

mag_matrix = rand(1000, 5);

% Define the time axis

fs = 1000; % Sampling rate

time_axis = 0:1/fs:(size(mag_matrix, 1)-1)/fs;

% Plot the magnitude over time

stem(time_axis, mag_matrix);

% Add axis labels, plot title and legend

xlabel('Time (s)');

ylabel('Magnitude');

title('Magnitude over time');

legend('Channel 1', 'Channel 2', 'Channel 3', 'Channel 4', 'Channel 5');

This will create a stem plot of the magnitude over time of each channel in the input matrix with the corresponding axis labels and title.

For further reference you can follow the stem function documentation: https://www.mathworks.com/help/matlab/ref/stem.html?searchHighlight=stem&s_tid=srchtitle_stem_1