www.gusucode.com > GPS仿真Matlab编程源码程序 > GPS仿真Matlab编程源码程序/tracking_CAUC3_1.m
function [trackResults, channel,ttime]= tracking_CAUC3_1(p,fid, channel, settings,ttime) % Performs code and carrier tracking for all channels. % wenguihong amend %[trackResults, channel] = tracking(fid, channel, settings) % % Inputs: % fid - file identifier of the signal record. % channel - PRN, carrier frequencies and code phases of all % satellites to be tracked (prepared by preRum.m from % acquisition results). % settings - receiver settings. % Outputs: % trackResults - tracking results (structure array). Contains % in-phase prompt outputs and absolute starting % positions of spreading codes, together with other % observation data from the tracking loops. All are % saved every millisecond. %-------------------------------------------------------------------------- % SoftGNSS v3.0 % % Copyright (C) Dennis M. Akos % Written by Darius Plausinaitis and Dennis M. Akos % Based on code by DMAkos Oct-1999 %-------------------------------------------------------------------------- %This program is free software; you can redistribute it and/or %modify it under the terms of the GNU General Public License %as published by the Free Software Foundation; either version 2 %of the License, or (at your option) any later version. % %This program is distributed in the hope that it will be useful, %but WITHOUT ANY WARRANTY; without even the implied warranty of %MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the %GNU General Public License for more details. % %You should have received a copy of the GNU General Public License %along with this program; if not, write to the Free Software %Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, %USA. %-------------------------------------------------------------------------- %CVS record: %$Id: tracking.m,v 1.14.2.32 2007/01/30 09:45:12 dpl Exp $ %% Initialize result structure ============================================ a=inf; skip=0; samplesPerCode = round(settings.samplingFreq / ... (settings.codeFreqBasis / settings.codeLength)); % Channel status trackResults.status = '-'; % No tracked signal, or lost lock % The absolute sample in the record of the C/A code start: trackResults.absoluteSample = zeros(1, settings.msToProcess); % Freq of the C/A code: trackResults.codeFreq = inf(1, settings.msToProcess); % Frequency of the tracked carrier wave: trackResults.carrFreq = inf(1, settings.msToProcess); % Outputs from the correlators (In-phase): trackResults.I_P = zeros(1, settings.msToProcess); trackResults.I_E = zeros(1, settings.msToProcess); trackResults.I_L = zeros(1, settings.msToProcess); % Outputs from the correlators (Quadrature-phase): trackResults.Q_E = zeros(1, settings.msToProcess); trackResults.Q_P = zeros(1, settings.msToProcess); trackResults.Q_L = zeros(1, settings.msToProcess); % Loop discriminators trackResults.dllDiscr = inf(1, settings.msToProcess); trackResults.dllDiscrFilt = inf(1, settings.msToProcess); trackResults.pllDiscr = inf(1, settings.msToProcess); trackResults.pllDiscrFilt = inf(1, settings.msToProcess); %--- Copy initial settings for all channels ------------------------------- trackResults = repmat(trackResults, 1, settings.numberOfChannels); %% Initialize tracking variables ========================================== codePeriods = settings.msToProcess; % For GPS one C/A code is one ms %--- DLL variables -------------------------------------------------------- % Define early-late offset (in chips) earlyLateSpc = settings.dllCorrelatorSpacing; % Summation interval PDIcode = 0.001; % Calculate filter coefficient values [tau1code, tau2code] = calcLoopCoef(settings.dllNoiseBandwidth, ... settings.dllDampingRatio, ... 1.0); %--- PLL variables -------------------------------------------------------- % Summation interval PDIcarr = 0.001; % Calculate filter coefficient values [tau1carr, tau2carr] = calcLoopCoef(settings.pllNoiseBandwidth, ... settings.pllDampingRatio, ... 0.25); % hwb = waitbar(0,'Tracking...'); N=500; %% Start processing channels ============================================== for channelNr = 1:settings.numberOfChannels % Only process if PRN is non zero (acquisition was successful) if (channel(channelNr).PRN ~= 0) % Save additional information - each channel's tracked PRN trackResults(channelNr).PRN = channel(channelNr).PRN; % Move the starting point of processing. Can be used to start the % signal processing at any point in the data record (e.g. for long % records). In addition skip through that data file to start at the % appropriate sample (corresponding to code phase). Assumes sample % type is schar (or 1 byte per sample) fseek(fid, ... settings.skipNumberOfBytes + channel(channelNr).codePhase-1, ... 'bof'); % Get a vector with the C/A code sampled 1x/chip caCode = generateCAcode(channel(channelNr).PRN); % Then make it possible to do early and late versions caCode = [caCode(1023) caCode caCode(1)];% caCode(1) %--- Perform various initializations ------------------------------ % define initial code frequency basis of NCO codeFreq = settings.codeFreqBasis; % define residual code phase (in chips) remCodePhase = 0.0; % define carrier frequency which is used over whole tracking period carrFreq = channel(channelNr).acquiredFreq; carrFreqBasis = channel(channelNr).acquiredFreq; % define residual carrier phase remCarrPhase = 0.0; %code tracking loop parameters oldCodeNco = 0.0; oldCodeError = 0.0; %carrier/Costas loop parameters oldCarrNco = 0.0; oldCarrError = 0.0; cPhaseold=channel(channelNr).codePhase; %=== Process the number of specified code periods ================= for loopCnt = 1:codePeriods %% GUI update ------------------------------------------------------------- % The GUI is updated every 50ms. This way Matlab GUI is still % responsive enough. At the same time Matlab is not occupied % all the time with GUI task. % if (rem(loopCnt, 50) == 0) % try % waitbar(loopCnt/codePeriods, ... % hwb, ... % ['Tracking: Ch ', int2str(channelNr), ... % ' of ', int2str(settings.numberOfChannels), ... % '; PRN#', int2str(channel(channelNr).PRN), ... % '; Completed ',int2str(loopCnt), ... % ' of ', int2str(codePeriods), ' msec']); % catch % % % The progress bar was closed. It is used as a signal % % to stop, "cancel" processing. Exit. % disp('Progress bar closed, exiting...'); % return % end % end %% Read next block of data ------------------------------------------------ % Find the size of a "block" or code period in whole samples % Update the phasestep based on code freq (variable) and % sampling frequency (fixed) codePhaseStep = codeFreq / settings.samplingFreq; % if channelNr==2 % [codePhase,carrFreq]=Wrelax1(p,settings,loopCnt); % blksize = ceil(codePhase-codePhaseold+6000); % codePhaseold=codePhase; % [rawSignal, samplesRead] = fread(fid, blksize, settings.dataType); % blksize % trackResults(channelNr).carrFreq(loopCnt) = carrFreq; % trackResults(channelNr).codeFreq(loopCnt) = codeFreq; % else blksize = ceil((settings.codeLength-remCodePhase) / codePhaseStep); % end % Read in the appropriate number of samples to process this % interation [rawSignal, samplesRead] = fread(fid, blksize, settings.dataType); %% for bupt if data rawSignal =rawSignal.'; % If did not read in enough samples, then could be out of % data - better exit if (samplesRead ~= blksize) disp('Not able to read the specified number of samples for tracking, exiting!') fclose(fid); return end %% Set up all the code phase tracking information ------------------------- % Define index into early code vector tcode = (remCodePhase-earlyLateSpc) : ... codePhaseStep : ... ((blksize-1)*codePhaseStep+remCodePhase-earlyLateSpc); tcode2 = ceil(tcode) + 1; a=find(tcode2>1025); b=find(tcode2<1); while tcode2(a)>1025 tcode2(a)=tcode2(a)-1; a=find(tcode2>1025); end while tcode2(b)<1 tcode2(b)=tcode2(b)+1; b=find(tcode2<1); end earlyCode = caCode(tcode2); % Define index into late code vector tcode = (remCodePhase+earlyLateSpc) : ... codePhaseStep : ... ((blksize-1)*codePhaseStep+remCodePhase+earlyLateSpc); tcode2 = ceil(tcode) + 1; a=find(tcode2>1025); b=find(tcode2<1); while tcode2(a)>1025 tcode2(a)=tcode2(a)-1; a=find(tcode2>1025); end while tcode2(b)<1 tcode2(b)=tcode2(b)+1; b=find(tcode2<1); end lateCode = caCode(tcode2); % Define index into prompt code vector tcode = remCodePhase : ... codePhaseStep : ... ((blksize-1)*codePhaseStep+remCodePhase); tcode2 = ceil(tcode) + 1; a=find(tcode2>1025); b=find(tcode2<1); while tcode2(a)>1025 tcode2(a)=tcode2(a)-1; a=find(tcode2>1025); end while tcode2(b)<1 tcode2(b)=tcode2(b)+1; b=find(tcode2<1); end promptCode = caCode(tcode2); remCodePhase = (tcode(blksize) + codePhaseStep) - 1023.0; %% Generate the carrier frequency to mix the signal to baseband ----------- time = (0:blksize) ./ settings.samplingFreq; % Get the argument to sin/cos functions trigarg = ((carrFreq * 2.0 * pi) .* time) + remCarrPhase; remCarrPhase = rem(trigarg(blksize+1), (2 * pi)); % Finally compute the signal to mix the collected data to bandband carrCos = cos(trigarg(1:blksize)); carrSin = sin(trigarg(1:blksize)); %% Generate the six standard accumulated values --------------------------- % First mix to baseband qBasebandSignal = carrCos .* rawSignal; iBasebandSignal = carrSin .* rawSignal; % Now get early, late, and prompt values for each I_E = sum(earlyCode .* iBasebandSignal); Q_E = sum(earlyCode .* qBasebandSignal); I_P = sum(promptCode .* iBasebandSignal); Q_P = sum(promptCode .* qBasebandSignal); I_L = sum(lateCode .* iBasebandSignal); Q_L = sum(lateCode .* qBasebandSignal); %% Find PLL error and update carrier NCO ---------------------------------- % Implement carrier loop discriminator (phase detector) carrError = atan(Q_P / I_P) / (2.0 * pi); % Implement carrier loop filter and generate NCO command carrNco = oldCarrNco + (tau2carr/tau1carr) * ... (carrError - oldCarrError) + carrError * (PDIcarr/tau1carr); oldCarrNco = carrNco; oldCarrError = carrError; % Modify carrier freq based on NCO command carrFreq = carrFreqBasis + carrNco; trackResults(channelNr).carrFreq(loopCnt) = carrFreq; %% Find DLL error and update code NCO ------------------------------------- codeError = (sqrt(I_E * I_E + Q_E * Q_E) - sqrt(I_L * I_L + Q_L * Q_L)) / ... (sqrt(I_E * I_E + Q_E * Q_E) + sqrt(I_L * I_L + Q_L * Q_L)); % Implement code loop filter and generate NCO command codeNco = oldCodeNco + (tau2code/tau1code) * ... (codeError - oldCodeError) + codeError * (PDIcode/tau1code); oldCodeNco = codeNco; oldCodeError = codeError; % Modify code freq based on NCO command codeFreq = settings.codeFreqBasis - codeNco; trackResults(channelNr).codeFreq(loopCnt) = codeFreq; %% Record various measures to show in postprocessing ---------------------- % Record sample number (based on 8bit samples) if channel(channelNr).PRN==13 % if mod((loopCnt-1),N)==0 % [cPhase,cFreq]=Wrelax1(p,settings,cPhaseold,skip,loopCnt); if loopCnt==1 % [t1_p,fd1]= tracking_CAUC_loop(channel,channelNr,settings,p,loopCnt); % t1_p=ftell(fid); % t1=mod(t1_p,samplesPerCode)/samplesPerCode*1e-3; fd1=carrFreq; else % t1=cPhase; fd1=cFreq; end t1_p=ftell(fid); [cPhase,cFreq]=Wrelax3_jinggu_1(p,settings,loopCnt,fd1); % [cPhase,cFreq]=Wrelax2(p,settings,loopCnt); trackResults(channelNr).absoluteSample(loopCnt) = cPhase+samplesPerCode*loopCnt; % blk=trackResults(channelNr).absoluteSample(loopCnt); % if loopCnt==1 % trackResults(channelNr).absoluteSample(loopCnt) = cPhase+samplesPerCode; % else % trackResults(channelNr).absoluteSample(loopCnt) = round(trackResults(channelNr).absoluteSample(loopCnt-1)+cPhase); % end if abs(trackResults(channelNr).absoluteSample(loopCnt)-t1_p)>5 trackResults(channelNr).absoluteSample(loopCnt)=t1_p; end trackResults(channelNr).codeFreq(loopCnt) = cFreq; %%%%%%%%% % blk = cPhase-cPhaseold+samplesPerCode*N; % blk1=cPhase-cPhaseold+samplesPerCode; % if abs(blk-samplesPerCode*N)>60 % blk=blkold; % end % % blk=samplesPerCode-cPhase; % cPhaseold=cPhase; % blkold=blk; %%%%%%%%% loopCnt if mod(loopCnt,50)==0 clc end % fd1 % cFreq % cFreq-fd1 % t1_p % blk % blk-t1_p % blksize %%%%%%%%%%% % if loopCnt==1 % trackResults(channelNr).absoluteSample(loopCnt) = settings.skipNumberOfBytes + channel(channelNr).codePhase-1+blk1; % else % trackResults(channelNr).absoluteSample(loopCnt) = trackResults(channelNr).absoluteSample(loopCnt-N)+blk; % end %%%%%%%%%%%% % skip=trackResults(channelNr).absoluteSample(loopCnt); % skip % else % trackResults(channelNr).absoluteSample(loopCnt) = round(trackResults(channelNr).absoluteSample(loopCnt-1)+blk/N); % if loopCnt~=1 % for ii=1:N-1 % trackResults(channelNr).absoluteSample(loopCnt-N+ii) = trackResults(channelNr).absoluteSample(loopCnt-N-1+ii)+... % round((trackResults(channelNr).absoluteSample(loopCnt)-trackResults(channelNr).absoluteSample(loopCnt-N))/(N-1)); % end % end % end % if mod((loopCnt-1),10)==0 % % [cPhase,cFreq]=Wrelax1(p,settings,cPhaseold,skip,loopCnt); % % [cPhase,cFreq]=Wrelax1(p,settings,loopCnt); % [cPhase,cFreq]=Wrelax2(p,settings,loopCnt); % blk = cPhase-cPhaseold+samplesPerCode*10; % blk1=cPhase-cPhaseold+samplesPerCode; % if abs(blk-samplesPerCode*10)>30 % blk=blkold; % end % % blk=samplesPerCode-cPhase; % cPhaseold=cPhase; % blkold=blk; % blk % blksize % loopCnt % if loopCnt==1 % trackResults(channelNr).absoluteSample(loopCnt) = settings.skipNumberOfBytes + channel(channelNr).codePhase-1+blk1; % else % trackResults(channelNr).absoluteSample(loopCnt) = trackResults(channelNr).absoluteSample(loopCnt-10)+blk; % end % % else % trackResults(channelNr).absoluteSample(loopCnt) = trackResults(channelNr).absoluteSample(loopCnt-1)+blk/10; % end else % end trackResults(channelNr).absoluteSample(loopCnt) = ftell(fid); end trackResults(channelNr).dllDiscr(loopCnt) = codeError; trackResults(channelNr).dllDiscrFilt(loopCnt) = codeNco; trackResults(channelNr).pllDiscr(loopCnt) = carrError; trackResults(channelNr).pllDiscrFilt(loopCnt) = carrNco; trackResults(channelNr).I_E(loopCnt) = I_E; trackResults(channelNr).I_P(loopCnt) = I_P; trackResults(channelNr).I_L(loopCnt) = I_L; trackResults(channelNr).Q_E(loopCnt) = Q_E; trackResults(channelNr).Q_P(loopCnt) = Q_P; trackResults(channelNr).Q_L(loopCnt) = Q_L; end % for loopCnt if channel(channelNr).PRN==13 ttime(:,p)=trackResults(channelNr).absoluteSample(loopCnt); end % If we got so far, this means that the tracking was successful % Now we only copy status, but it can be update by a lock detector % if implemented trackResults(channelNr).status = channel(channelNr).status; end % if a PRN is assigned end % for channelNr save result.mat trackResults channel % Close the waitbar % close(hwb)