59 lines
2.4 KiB
Matlab
59 lines
2.4 KiB
Matlab
function ChannelOut = apply_channel_effects(RadarParams)
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Target = RadarParams.Target;
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TxPos = RadarParams.Antenna.TxPos;
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RxPos = RadarParams.Antenna.RxPos;
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NumChirps = RadarParams.Waveform.NumChirps;
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Timing = RadarParams.Waveform.Timing;
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fs_adc = RadarParams.Waveform.fs_adc;
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f_start = RadarParams.Waveform.f_start;
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Slope = RadarParams.Waveform.Slope;
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c = RadarParams.Basic.c;
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NumTx = size(TxPos, 2);
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NumRx = size(RxPos, 2);
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NumTargets = Target.NumTargets;
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T_pri = RadarParams.Waveform.PRI;
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t_adc = 0 : 1/fs_adc : (Timing.AdcSampTime - 1/fs_adc);
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N_adc = length(t_adc);
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% [핵심] 처프 내 샘플별 순시 주파수 및 파장 계산
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% t_adc에 따라 주파수가 변하므로 파장(lambda)도 샘플마다 변함
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f_inst = f_start + Slope * t_adc;
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lambda_t = c ./ f_inst;
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ChannelOut.tau = zeros(NumTargets, NumRx, NumTx, NumChirps, N_adc);
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ChannelOut.space_loss_amp = zeros(NumTargets, NumRx, NumTx, NumChirps, N_adc);
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ref_point = (TxPos(:,1) + RxPos(:,1)) / 2;
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for k = 1:NumTargets
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az_rad = deg2rad(Target.az(k));
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el_rad = deg2rad(Target.el(k));
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rel_pos0 = Target.R(k) * [cos(el_rad)*sin(az_rad); cos(el_rad)*cos(az_rad); sin(el_rad)];
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target_world_pos0 = ref_point + rel_pos0;
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v_vec = Target.v(k) * (rel_pos0 / norm(rel_pos0));
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sigma = 10^(Target.rcs(k)/10);
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for m = 0:NumChirps-1
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% 처프 간 이동 반영
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target_pos_at_chirp = target_world_pos0 + v_vec * (m * T_pri);
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for tx = 1:NumTx
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for rx = 1:NumRx
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% 처프 내 샘플별 이동 반영
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curr_target_pos = target_pos_at_chirp + v_vec * t_adc;
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d_tx = sqrt(sum((curr_target_pos - TxPos(:,tx)).^2, 1));
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d_rx = sqrt(sum((curr_target_pos - RxPos(:,rx)).^2, 1));
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% TTD 지연 시간 저장
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ChannelOut.tau(k, rx, tx, m+1, :) = (d_tx + d_rx) / c;
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% [가변 파장 적용] 주파수 대역폭에 따른 공간 감쇠 변화 반영
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denom = (4*pi)^3 * (d_tx.^2 .* d_rx.^2);
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ChannelOut.space_loss_amp(k, rx, tx, m+1, :) = sqrt((lambda_t.^2 * sigma) ./ denom);
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end
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end
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end
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end
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end |