[jorgeSigHound]

Thanks for the quick reply. I will work on your considerations. Thank you and congratulations to the Signal Hound Collective for their excellent work.
Greetings Jorge

[jorgeSigHound]

Hello
I am trying to represent with MATLAB, from the processing of the IQ values in a *.iq file recorded with SPIKE, the values of ‘IQ vs. Time ‘, ‘ AM vs Time ‘, ‘ PM vs Time ‘ and ‘ FM vs Time ‘. In the process I have had the following difficulties:
1. The values of the IQ data read from the recorded file of an X signal, differ from the values of the same signal but acquired directly using the bbgetiq () function.
2. The values of the parameters’ IQ vs. Time ‘, ‘ AM vs Time ‘, ‘ PM vs Time ‘ and ‘ FM vs Time ‘. calculated and represented with MATLAB, differ from the values represented by the SPIKE software in the reproduction of the same .iq file.
I am attaching the code in order to find out which error I am making.
Thanks for the help

% SCRIPT IQ signal representation recorded with SPIKE software. 
 
clear variables;
% clear functions;
%% ADD TEMPORARY FOLDERS 
addpath('SxIQ_REC');% Folder where the * .iq and * .xml files are located
 
%% PARAMETERS
fDir='IQREC-Test1';
%IQ file of recordings with Signal Hound BB60A 
fDir_iq=[fDir '.iq'];
fDir_xml=[fDir '.xml'];
 
%% Reading XML file. 
iqXMLDoc= xmlread(fDir_xml);
    %<CenterFrequency>
        CenterFrequency_List = (iqXMLDoc.getElementsByTagName('CenterFrequency'));
        CeFr = str2double(CenterFrequency_List.item(0).getFirstChild.getData);
    %<SampleRate>
        SampleRate_List = (iqXMLDoc.getElementsByTagName('SampleRate'));
        SaRa = str2double(SampleRate_List.item(0).getFirstChild.getData);
    %<Decimation>
        Decimation_List = (iqXMLDoc.getElementsByTagName('Decimation'));
        Dec = str2double(Decimation_List.item(0).getFirstChild.getData);
    %<ScaleFactor>
        ScaleFactor_List = (iqXMLDoc.getElementsByTagName('ScaleFactor'));
        ScFa= str2double(ScaleFactor_List.item(0).getFirstChild.getData); 
%% Reading and processing of the .iq file 
f=fopen(fDir_iq,'r'); 
    s=fread(f,'int16'); 
    n=length(s)/2;
    iq = reshape(s, 2, n);% Transform s into a two-row, n-column matrix. 
    vSh = iq(1,:) + 1i * iq(2,:);% Form the complex signal . 
   
    %2) Convert 16-bit integer max scaled values to floating point values between -1 and 1. 
    ScBin=2^16/2;
    vSh=vSh/ScBin;
 
   % 3) Multiply by the scale factor that the XML file has 
    vSh=vSh*ScFa;
    vI = real(vSh);
    vQ = imag(vSh);
        
%     % Calculate the power of the samples in dBm 
%     vS_dBm=10*log10(vI.^2+vQ.^2);
%% GRAPHICS 
iqdata = vSh;% Vector containing the complex values of the IQ signal 
iqlen=length(iqdata);% 
iqdata = transpose(iqdata);% perform the transpose 
Ts=1/SaRa;
 
    subplot(2,2,1);
        am = 10.0 * log10(abs(iqdata).^2);
        
        plot(am);
        title('AM vs Time');
        xlabel('Sample number');
        ylabel('Amplitude (dBm)');
              
    %
    subplot(2,2,3);
        x = linspace(1, iqlen, iqlen);
        plot(x, real(iqdata), x, imag(iqdata));
        title('IQ vs. Time');
        xlabel('Sample number');
        ylabel('Amplitude ()');
    
    subplot(2,2,2);
        pm=atan2(imag(iqdata),real(iqdata));
        dg_pm= diff ([0;pm]);% [0;pm] so that dg_pm has the same values as pm 
        fm=dg_pm*(SaRa/(2*pi));
      
        plot(fm/1e6);
        title('FM vs Time');
        xlabel('Sample number');
        ylabel('Frequency (MHz)');
        axis([0,length(x),-inf,inf]);

    
    subplot(2,2,4);
        plot(pm);
        title('PM vs Time');
        xlabel('Sample number');
        ylabel('Phase');
        axis([0,length(x),-inf,inf]);

%%
 rmpath('SxIQ_REC');% Delete the folder in the MATLAB paths 

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