pmf-fft-acq.zip_FFT伪码捕获_PMF_FFT_acq_伪码 捕获_伪码捕获

clear; close all; % fd=500; %doppler corr_times=2; X=186*corr_times; L=20460*corr_times; P=L/X; fs=20.46e6; Ts=1/fs; Tc=1/fs; N=128; %FFT points %=============loc_code============ c_loc_ori = randi([0 1],1,10230); c_loc_ori(c_loc_ori==0) = -1; c_loc_ori = kron(c_loc_ori,[1 1]); %==============3bits============== c_loc = repmat(c_loc_ori,1,corr_times); t=Ts:Ts:L*Ts; SNR = -20; for fd=1:5:1000 %===========doppler========== rx_i_a = c_loc .* cos(2*pi*fd*t); rx_q_a = c_loc .* sin(2*pi*fd*t); %===========noise========== rx_i_a = awgn(rx_i_a,SNR); rx_q_a = awgn(rx_q_a,SNR); %===========quantiz_3bits========== if 0 [index,rx_i] = quantiz(rx_i_a,[-1 -2/3 -1/3 0 1/3 2/3 1],[-4 -3 -2 -1 0 1 2 3]); [index,rx_q] = quantiz(rx_q_a,[-1 -2/3 -1/3 0 1/3 2/3 1],[-4 -3 -2 -1 0 1 2 3]); c_loc_corr = c_loc_bit3; L_nom = L*16; else rx_i = rx_i_a; rx_q = rx_q_a; c_loc_corr = c_loc; L_nom = L; end pmf_result_i = pmf_test(rx_i,c_loc_corr,X,P); pmf_result_q = pmf_test(rx_q,c_loc_corr,X,P); pmf_result = complex(pmf_result_i,pmf_result_q); fft_result = abs(fft([pmf_result,zeros(1,18)],N))/L_nom; fft_result_all(fd,:) = fft_result; [max_v,max_p]=max(fft_result(1,1:N/2)); % if max_v >0.1 value_result(1,fd)=max_v; fd_result(1,fd)=fd-fs/(N*X)*(max_p-1); if max_p>1 F = 5*(fft_result(1,max_p-1)-fft_result(1,max_p+1))/max_v; V = fft_result(1,max_p-1)+fft_result(1,max_p+1); else F = 5*(fft_result(1,N)-fft_result(1,max_p+1))/max_v; V = fft_result(1,N)+fft_result(1,max_p+1); end mF= -4.135*F*F*F+204.5*F; fd_result(2,fd)=fd_result(1,fd)+mF; value_max(1,fd)=max_v; value_max(2,fd)=(max_v+0.35*V)*0.9; % break; % end % end end figure for i=1:2 plot(fd_result(i,:)); hold on end xlabel('doppler/Hz'); ylabel('frequency error/Hz'); hold off figure for i=1:1 plot(value_max(i,:)); hold on end xlabel('doppler/Hz'); ylabel('normalized amplitude');