% Define Parameters
N = 1000; % Number of bits
PW = 1e-6; % Pulse width in seconds
PRF = 1e3; % Pulse Repetition Frequency in Hz
Fs = 10e6; % Sampling frequency in Hz
numPulses = 128; % Number of pulses to simulate
target_velocity = 30; % Target velocity in m/s (example value)
% Generate a random binary sequence
binarySequence = randi([0, 1], 1, N);
% Create a pulse waveform
waveform = phased.RectangularWaveform('PulseWidth', PW, 'PRF', PRF, 'SampleRate', Fs);
% Generate a pulse train based on the binary sequence
pulseTrain = repmat(waveform(), 1, N); % Repeat the pulse for each bit
% Reshape the binary sequence to match the pulse train
binarySequenceRepeated = repelem(binarySequence, length(pulseTrain) / N);
% Modulate the pulse train with the binary sequence using BPSK
modulatedPulseTrain = pskmod(binarySequenceRepeated, 2, pi); % Binary Phase Shift Keying
% Set up transmitter and receiver
tx = phased.Transmitter('Gain',20);
rx = phased.ReceiverPreamp('Gain',20,'NoiseFigure',10);
% Simulate Transmitting and Receiving multiple pulses
received = zeros(length(modulatedPulseTrain), numPulses);
for p = 1:numPulses
% Each pulse in the train is transmitted separately
transmitted = tx(modulatedPulseTrain(:, p));
received(:, p) = rx(transmitted);
% Add Doppler shift to simulate target movement
doppler_shift = 2*(target_velocity/physconst('LightSpeed'))*waveform.PRF;
received(:, p) = received(:, p) .* exp(1j*2*pi*doppler_shift*(0:length(received(:, p))-1)/Fs).';
end
% Range-Doppler processing
rdmap = phased.RangeDopplerResponse('RangeMethod','FFT','DopplerOutput','Speed',...
'OperatingFrequency',300e6,'SampleRate',Fs,'DopplerFFTLengthSource','Property',...
'DopplerFFTLength',numPulses,'RangeFFTLengthSource','Property',...
'RangeFFTLength',length(modulatedPulseTrain));
% Generate and plot the Range-Doppler map
[resp, range_grid, speed_grid] = rdmap(received);
resp = abs(resp);
resp = 10*log10(resp/max(resp(:)));
imagesc(speed_grid, range_grid*physconst('LightSpeed')/2, resp, [-40 0]);
colorbar;
xlabel('Speed (m/s)');
ylabel('Range (m)');
title('Range-Doppler Map');
- Simulating Multiple Pulses: The code loops over numPulses to simulate the transmission and reception of multiple pulses. This creates a matrix where each column represents a different pulse.
- Doppler Shift: It applies a Doppler shift to each pulse to simulate the effect of a moving target over time.
- Range-Doppler Processing: The phased.RangeDopplerResponse function is used to process the 2D matrix (multiple pulses) and generate the Range-Doppler map.
Note
Assumes that each bit in the binary sequence modulates a single pulse of the radar signal. Depending on your specific requirements, the method of creating the pulse train and applying the modulation may vary. Ensure that the length of the modulatedPulseTrain and the dimensions of the received matrix match your system's needs. Additionally, make sure that the number of pulses simulated (in the numPulses variable) correctly reflects the design of your radar system.
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