Simulation of BOC modulation signal acquisition based on MATLAB

Catalog

1. Algorithm description

2. Partial procedure

3. Preview of some simulation drawings

4. Source code acquisition method

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1. Algorithm description

        With the rapid development of global navigation satellite system , The number of navigation systems is also increasing , For example, the most widely used GPS Navigation system , And China's Beidou navigation system, which has attracted more and more attention . Therefore, the navigation frequency band becomes more and more crowded , And the signals in each frequency band interfere with each other , In this case , A binary offset carrier (Binary Offset Carrier,BOC) The modulated signal is successfully proposed , To solve this problem . And with the right BOC In depth study of signals , A series of BOC Derivative signals have also been proposed and applied to various navigation systems . Besides , There are many disturbing factors in the actual environment , to BOC And the acquisition of its derived signals brings difficulties , Therefore, it has also become a hotspot and difficulty for scholars at home and abroad .
 

2. Partial procedure

for ii = 1:length(Visible_sv)
    % Output the visible star number to be assigned 
    PRN = Visible_sv(ii);
    fprintf('%02d ', PRN);  
    % Generate random Doppler shift frequency 
    frqshift(ii) = settings.acqSearchBand * 1e3 * rand(1,1) - ...
        (settings.acqSearchBand/2) * 1e3;       
    % At this time, the carrier frequency 
    frqBins(ii) = settings.IF  + frqshift(ii);  
    % Generate random navigation data as 1 or -1
    NavData = randi([0,1],1,ceil(navdatLength+1))*2 - 1;
    % Navigation data number corresponding to each sampling point 
    dataValueIndex = floor((ts * (1:settings.msToProcess*1e-3*settings.samplingFreq)) / ...
                               (1/50));          
    % Navigation data corresponding to each sampling point 
    NavDataS = NavData(dataValueIndex + 1);      
    clear dataValueIndex
    % utilize generateCAcode The function generates the corresponding C/A code 
    caCode1023 = generateCAcode(PRN);           
    % Corresponding to each sampling point C/A Chip serial number 
    codeValueIndex = floor((ts * (1:settings.msToProcess*1e-3*settings.samplingFreq)) / ...
                               (1/settings.codeFreq));
    % Generate the random phase corresponding to each sampling point 
    codePhase(ii) = floor(1023*rand(1,1));            
    % Corresponding to the sampling point under each random phase C/A Chip data 
    codePhase_o=codePhase(ii);
    longCaCode = caCode1023((rem(codeValueIndex + ...
        settings.CAcodeLength - codePhase(ii), settings.CAcodeLength) + 1));
    clear caCode1023                                 
    
    % The subcarrier is generated and multiplied by the pseudo code to obtain BOC Signal chip data 
    subCarr = square(settings.subcarrFreq * phasePoints); %sign(sin(settings.subcarrFreq * phasePoints));
    longBocCode = longCaCode.*subCarr;               
    clear longCaCode subCarr
    % Generate sine cosine carrier signal 
    sinCarr = sin(frqBins(ii) * phasePoints);         
    cosCarr = cos(frqBins(ii) * phasePoints);         
    
    % Produce orthogonal and isotropic BOC Modulation signal 
    I1      = cosCarr .* longBocCode .* NavDataS;
    Q1      = sinCarr .* longBocCode .* NavDataS;
    clear NavDataS longBocCode sinCarr cosCarr      
    
    % Several visible stars are orthogonal and in the same direction BOC Modulation signal superposition , That is to simulate the actual situation 
    signalI = signalI + I1;
    signalQ = signalQ + Q1;                          
    clear I1 Q1 
end

3. Preview of some simulation drawings

 

 

 

 

4. Source code acquisition method

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