86 lines
3.0 KiB
Matlab
86 lines
3.0 KiB
Matlab
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function [rxamp,rxphase] = helperSimulateAntennaSteering(fctransmit,rxpos,txpos,steerangle,analogweight,digitalweight,nullangle)
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% This helper function simulates antenna steering for the ADI workshop.
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% analogweight and digitalweight are optional inputs that default to 1.
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arguments
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fctransmit (1,1) double
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rxpos (3,1) double
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txpos (3,1) double
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steerangle (1,:) double
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analogweight (4,2) double = ones(4,2)
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digitalweight (2,1) double = ones(2,1)
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nullangle = []
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end
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% Setup the transmitter
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txelement = phased.IsotropicAntennaElement;
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radiator = phased.Radiator("Sensor",txelement,"OperatingFrequency",fctransmit);
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% Setup the Phased Array Receiver based on the Phaser specs
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frange = [10.0e9 10.5e9];
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sampleRate = 30e6;
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nsamples = 1024;
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element = phased.IsotropicAntennaElement('FrequencyRange',frange);
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hRange = freq2wavelen(frange);
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spacing = hRange(2)/2;
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subarrayElements = 4;
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subarray = phased.ULA('Element',element,'NumElements',subarrayElements,'ElementSpacing',spacing);
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array = phased.ReplicatedSubarray('Subarray',subarray,'GridSize',[1,2],"SubarraySteering","Custom");
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collector = phased.Collector("Sensor",array,"OperatingFrequency",fctransmit,"WeightsInputPort",true);
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% CW signal is used
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signal = ones(nsamples,1);
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% Set up a channel for radiating signal
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channel = phased.FreeSpace("OperatingFrequency",fctransmit,"SampleRate",sampleRate);
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% Setup geometry
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rxvel = [0;0;0];
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txvel = [0;0;0];
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[~,ang] = rangeangle(rxpos,txpos);
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% Radiate signal
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sigtx = radiator(signal,ang);
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% Propagate signal
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sigtx = channel(sigtx,txpos,rxpos,txvel,rxvel);
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% Create steering vector for the two subarray channels
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steervec = phased.SteeringVector("SensorArray",array);
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substeervec = phased.SteeringVector("SensorArray",subarray);
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% Receive signal while steering beam
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rxphase = zeros(1,numel(steerangle));
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rxamp = zeros(1,numel(steerangle));
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for steer = steerangle
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% Create the subarray weights.
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singlesubweight = substeervec(fctransmit,steer);
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% Create the replicated array weights
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repweight = steervec(fctransmit,steer);
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% insert a null if a null angle was passed in
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if ~isempty(nullangle)
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% Null the subarray
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nullsubweight = substeervec(fctransmit,nullangle);
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singlesubweight = getNullSteer(singlesubweight,nullsubweight);
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% null the replicated array
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nullrepweight = steervec(fctransmit,nullangle);
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repweight = getNullSteer(repweight,nullrepweight);
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end
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% Create the full subarray weights
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subweight = [singlesubweight,singlesubweight] .* analogweight;
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% Receive the signal
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sigreceive = collector(sigtx,[0;0],repweight,subweight) * digitalweight;
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rxphase(steer == steerangle) = mean(rad2deg(angle(sigreceive)));
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rxamp(steer == steerangle) = mean(abs(sigreceive));
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end
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end
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function nullsteer = getNullSteer(steerweight,nullweight)
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rn = nullweight'*steerweight/(nullweight'*nullweight);
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nullsteer = steerweight-nullweight*rn;
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end
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