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This version (13 Nov 2023 03:15) was approved by Dongmin Lee.The Previously approved version (03 Nov 2023 16:10) is available.Diff

MATLAB Phaser setup guide

Getting started and setup

If the Phaser board is not yet assembled, please visit the Quick Start Guide and watch the Unboxing/Setup Video to see how to assemble the Phaser and related boards.

The Quick Start Guide also has instructions on installing an image of ADI Kuiper Linux onto the Raspberry Pi's SD card, which will be required.

After that is done, a few modifications need to be made to the setup from the quick start guide.

  • Disconnect the Pluto from the Raspberry Pi, and connect the Pluto to your computer using a microUSB to USB cable, or other compatible standard
  • Connect the Raspberry Pi to your computer via ethernet, using the onboard ethernet port on the Raspberry Pi

Once completed, your setup should resemble the image below:

Setting up MATLAB

Installing MATLAB

If you already have a recent version of MATLAB installed, please skip ahead to the Installing toolboxes section below.

For the hardware board support packages to work, you must use Matlab version R2022b or newer. You can go to the download page by clicking here, you may be required to sign in with your MathWorks account first.



Select the release version on the left, then click the download button.

After downloading the installer, open it to run the MATLAB installation tool. During the installation process, there will be a window to select which products and toolboxes will be installed, as shown in the image below. Ensure that all the products shown in the image have been selected.


Once this has been done, continue installing MATLAB through the installer as normal.

Installing toolboxes

Once MATLAB is installed, additional toolboxes can be downloaded through the built-in Add-On Explorer. It can be found by opening MATLAB, selecting the Home tab, and clicking the three colored cubes labeled Add-Ons located near the top.


This will open the Add-On Explorer. Here, you can search for toolboxes using the search bar in the top right corner, and install them.


  • If you have skipped here without installing any toolboxes while installing MATLAB, or already had MATLAB installed, get these first:
    • Antenna Toolbox
    • Communications Toolbox
    • DSP System Toolbox
    • Phased Array System Toolbox
    • Signal Processing Toolbox
  • Install these additional toolboxes:
    • Analog Devices, Inc. RF and Microwave Toolbox
    • Analog Devices, Inc. Transceiver Toolbox
    • Communications Toolbox Support Package for Analog Devices ADALM-Pluto Radio
    • MATLAB Support for MinGW-w64 C/C++ Compiler

The Communications Toolbox Support Package requires configuration, which can be performed either by following the prompt that appears after installation or by accessing the configuration tool from the add-on manager window.



Either of these options should open the configuration tool. It contains further directions for setting up the Pluto.

LibIIO package installation

The LibIIO package may be needed for MATLAB to communicate and work with the Phaser. If absence of LibIIO is causing problems with MATLAB/Phaser, it can be installed from here.

Running the labs

Verify connectivity

With Phaser connected to your local network or directly to your host machine with MATLAB installed, create an instance of the adi.Phaser class from the command prompt with the IP address of the Raspberry Pi.

bf = adi.Phaser;
bf.uri = 'ip:phaser';
bf()

This will connect and configure Phaser with a default set of parameters. If you receive a connectivity error verify the Raspberry Pi is powered up and you can at least ping the device. If you are having issues reach out to our support forums on EngineerZone.

If you get an error that refers to Could not find file ad9361-wrapper.h., manually install libad9361 by running the following commands in your MATLAB command window:
A=adi.utils.libad9361
A.download_libad9361

Next verify connectivity to Pluto with a similar method. Create and instance of the adi.AD9361.Rx class and run the operator method as so:

sdr = adi.AD9361.Rx
sdr.uri = 'ip:pluto';
data = sdr();

Like the Phaser system object this operation should not generate any errors. The data vector should contain non-zero data.

If there are errors while attempting to verify connectivity, please try the following options:

  • Check all the packages/toolboxes listed above are installed properly
  • Restart MATLAB and run the code again
  • Disconnect and re-connect the cable to the device in question
  • Ensure the Raspberry Pi's SD card has ADI Kuiper Linux installed (and that it works)

Running scripts

Once both the Phaser and Pluto are able to communicate with MATLAB, download and extract phasersteeringangle.zip

Then open the file Phaser_steeringAngle_rev1.m

This script functions to scan through a range of steering angles and output a plot of the array factor.


% Key Parameters
signal_freq = 10.145e9;  % this is the HB100 frequency
signal_freq = findTxFrequency();
plutoURI = 'ip:192.168.2.1';
phaserURI = 'ip:phaser.local';
 
% Setup the pluto
rx = setupPluto(plutoURI);
 
% Setup the phaser
bf = setupPhaser(rx,phaserURI,signal_freq);
bf.RxPowerDown(:) = 0;
bf.RxGain(:) = 127;

This segment of the code serves to initialize the Pluto and Phaser objects in MATLAB using the ADI toolboxes installed earlier, here labeled as “rx” and “bf” respectively. It also scans briefly to find the frequency of the HB100 emitter.

% Create the model of the phaser    
c = physconst('LightSpeed');
phaserModel = phased.ULA('NumElements',8,'ElementSpacing', ... 
    bf.ElementSpacing);
steeringVec = phased.SteeringVector("SensorArray",phaserModel, ...
    'NumPhaseShifterBits',7,'PropagationSpeed',c);

This segment creates a model of the antenna array on the Phaser, using the Phased Array System Toolbox (phased) from MathWorks. The Phaser features 8 uniformly spaced elements, which is modeled using the Uniform Linear Array object (phased.ULA) from the Phased Array System Toolbox. A corresponding steering vector is created using the SteeringVector object, also from the Phased Array System Toolbox.

%% Set all gains to max and phases to zero
bf.RxGain(:) = 127;   % max gain = 127, min gain = 0
bf.RxAttn(:) = 0;     % if RxAttn=1 then insert 20dB attenuator
bf.RxPhase(:) = 0;
bf.LatchRxSettings(); % write new settings to the ADAR1000s
 
% Load Phase calibration values
PhaseCal = [0; -8.4375; -5.625; -5.625; 67.5; 87.1875; 90; 101.25];

This segment just sets the gain levels and phase calibration values.

%% Sweep the steering angle and capture data
steeringAngle = -90 : 90;
ArrayFactor = zeros(size(steeringAngle));
for ii = 1 : numel(steeringAngle)
    arrayWeights = steeringVec(signal_freq,steeringAngle(ii));
    phases = rad2deg(angle(conj(arrayWeights(:))));
    phases = phases - phases(1);
    phases = phases + PhaseCal;
    phases = wrapTo360(phases);
    bf.RxPhase(:) = phases.';
    bf.LatchRxSettings();
    receivedSig_HW = rx();
    receivedSig_HW_sum = sum(receivedSig_HW,2);
    receivedFFT = fft(receivedSig_HW_sum);
    ArrayFactor(ii) = (max(abs(receivedFFT)));
end

Here is where the actual beam steering action happens in the code.
The code creates an array containing the angles that the beam will be steered through. Then, it performs a loop where:

  1. Takes a given angle from the array of angles
  2. Use the given steering angle to create another array containing the respective phase shifts to be applied to each antenna element
  3. Apply the phase shifts to the Phaser
  4. Collect data from the Pluto, perform FFT on the data to get the max amplitude, and record it
  5. Repeat for the next steering angle
%% Compare the measured array factor and model
[~,ind] = max(ArrayFactor);
EmitterAz = steeringAngle(ind)
figure(101)
arrayWeights = steeringVec(signal_freq,EmitterAz);
pattern(phaserModel,signal_freq,-90:90,0,'CoordinateSystem', ...
    'Rectangular','Type','powerdb','weights',arrayWeights)
hold on;
 
% Plot the measured data and the model
plot(steeringAngle,mag2db(ArrayFactor./max(abs(ArrayFactor))))

Here, the Phased Array System Toolbox is used to simulate the array factor for the Phaser. Then both the experimentally obtained array factor (from the data above) and the simulated array factor are plotted. The resulting plot that appears should resemble the image below. Note that differences between the simulated and obtained array factor are mostly due to the fact that calibration has not been performed yet.

phaser_matlab.txt · Last modified: 13 Nov 2023 03:15 by Dongmin Lee