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[求助]
matlab仿真實(shí)現(xiàn)三階鎖相環(huán)路跟蹤高動(dòng)態(tài)多普勒變化出現(xiàn)問(wèn)題,急需指點(diǎn)[有源碼] 已有1人參與
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RT,最近在忙論文,但仿真出現(xiàn)問(wèn)題,結(jié)果總是不對(duì)。用的模型是JPL的高動(dòng)態(tài)模型,環(huán)路帶寬根據(jù)跟蹤門(mén)限設(shè)為90Hz,積分時(shí)間為1ms,但是好像就是一直沒(méi)法鎖相,鑒相誤差一直較大,有沒(méi)做過(guò)這方面的同學(xué)或前輩啊,急需指點(diǎn)和討論! clc; clear all; Chip_rate = 6.3*10^6; % 擴(kuò)頻碼速率(chips/s) Spreadcode_len = 63; % 擴(kuò)頻碼長(zhǎng)度(chips) Data_len = 240; % 數(shù)據(jù)長(zhǎng)度(symbols) Freq_carrier = 4*10^10; % 射頻載波頻率(Hz) Freq_sample = 6.3*10^6; % 接收機(jī)采樣頻率(Hz) Symbol_rate = 1*10^5; % 符號(hào)速率(sym/s) SNR = -5; % 信噪比(dB) load GoldSequence.mat; PNcode = 2*GoldSequence(1 ata_len,1:63)-1; % 偽碼長(zhǎng)度:數(shù)據(jù)長(zhǎng)度*63n_chip = 63; g = 9.8; % 重力加速度(m/s^2) c = 3*10^8; % 光速(m/s) ts = 1/1890; % JPL的采樣時(shí)間(s),所設(shè)置的值與擴(kuò)碼序列的長(zhǎng)度有關(guān) V0 = -500; % 初始速度(m/s) Theta0 = 2*pi*randn(1); % 初始相位(rad) Time = [3 0.5 2 0.5 2]; Total_length = round(Time/ts); % Jerk = [zeros(1,3/ts) 100*g*ones(1,0.5/ts) zeros(1,2/ts) -100*g*ones(1,0.5/ts) zeros(1,2/ts)]; Jerk = [zeros(1,Total_length(1)) 100*g*ones(1,Total_length(2)) zeros(1,Total_length(3)) -100*g*ones(1,Total_length(4)) zeros(1,Total_length(5))]; Acceleration = [-25*g cumsum(Jerk(1:end-1)*ts)-25*g]; Velocity = [V0 cumsum(Acceleration(1:end-1)*ts + Jerk(1:end-1)*ts^2/2)+V0]; Freq_Doppler = Freq_carrier / c * Velocity; Freq_Doppler_der1 = Freq_carrier / c * Acceleration; Freq_Doppler_der2 = Freq_carrier / c * Jerk; Theta = Theta0 + 2*pi*cumsum(Freq_Doppler)*ts + 2*pi*cumsum(Freq_Doppler_der1).*ts^2/2 + 2*pi*cumsum(Freq_Doppler_der2).*ts^3/6; %================== 數(shù)據(jù)序列 ===================% Data_sequence = randi(2,1,160)-1; %================== 信道編碼 ===================% trellis = poly2trellis([5,4],[23 35 0;0 5 13]); Data_sequence_conv = convenc(Data_sequence,trellis); %================== BPSK調(diào)制 ===================% Data_sequence_mod = BPSKMod(Data_sequence_conv); %================== 擴(kuò)頻調(diào)制 ===================% Spread_sequence = Data_sequence_mod(1) * PNcode(1, ;for i=2:1 ata_lenSpread_sequence = cat(2,Spread_sequence,Data_sequence_mod(i) * PNcode(i, );end %================== 加頻偏和噪聲 ===================% Spread_sequence_offset = Spread_sequence .* exp(1i*Theta); Spread_sequence_noise = Noise_Generate(Spread_sequence_offset,SNR); PNcode1 = reshape(PNcode.',1,[]); Signal_despread = Spread_sequence_noise.*PNcode1; w_nF_PLL = 90; T_IC = 1e-3; a3 = 1.1; b3 = 2.4; Simulation_len = length(Signal_despread); Signal_PLL = zeros(1,Simulation_len); NCO_Phase = zeros(1,Simulation_len); Discriminator_Out = zeros(1,Simulation_len); phase_third_derivate_temp = 0; phase_second_derivate1_temp = 0; for i=2:Simulation_len Signal_PLL(i) = Signal_despread(i)*exp(-1i*mod(NCO_Phase(i-1),2*pi)); I_PLL(i) = real(Signal_PLL(i)); Q_PLL(i) = imag(Signal_PLL(i)); Discriminator_Out(i)=sign(I_PLL(i))*Q_PLL(i)/abs(Signal_PLL(i)); % Discriminator_Out(i) = atan(Q_PLL(i)/I_PLL(i)); phase_third_derivate = T_IC*w_nF_PLL^3*Discriminator_Out(i); phase_third_derivate1 = phase_third_derivate + phase_third_derivate_temp; phase_third_derivate1_temp = phase_third_derivate1 + phase_third_derivate_temp; phase_second_derivate = a3*w_nF_PLL^2*Discriminator_Out(i) + 1/2*phase_third_derivate1_temp; phase_second_derivate1 = phase_second_derivate*T_IC + phase_second_derivate1_temp; phase_second_derivate2 = phase_second_derivate1 + phase_second_derivate1_temp; phase_derivate = 1/2*phase_second_derivate2 + b3*w_nF_PLL*Discriminator_Out(i); NCO_Phase(i)=NCO_Phase(i-1) + T_IC*phase_derivate; phase_third_derivate_temp = phase_third_derivate1; phase_second_derivate1_temp = phase_second_derivate1; end |
木蟲(chóng) (著名寫(xiě)手)
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哪敢說(shuō)指點(diǎn),我現(xiàn)在被逼著解決一個(gè)satcom下高動(dòng)態(tài)捕獲跟蹤問(wèn)題,根本沒(méi)有什么資料……嘗試這學(xué)習(xí)下高階鎖相環(huán)方法…… 發(fā)自小木蟲(chóng)IOS客戶端 |

木蟲(chóng) (著名寫(xiě)手)

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也不算GPS方面的,但很相似,偽碼用的是Gold碼。由于只研究跟蹤方面的,所以假設(shè)經(jīng)過(guò)捕獲后頻偏大概1k左右,JPL的高動(dòng)態(tài)模型是這樣的:速度變化的過(guò)程持續(xù)8s,其中在3s-3.5s以及5.5s-6s這兩個(gè)時(shí)間段內(nèi)產(chǎn)生100g/s的正加加速度和負(fù)加加速度,其余時(shí)間段則保持25g的常加速狀態(tài)。理論上來(lái)講三階PLL應(yīng)該可以跟蹤上的,但現(xiàn)在無(wú)法鎖相,程序看了幾次都覺(jué)得沒(méi)問(wèn)題,哥們你也是研究這方面的嗎,求指點(diǎn)啊。。 |
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