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From: Jon on 9 Jun 2010 20:35
This is related to my previous post. I have 8 bit complex I/Q values (4 for I and 4 for Q) in binary format I need to read in and convert to real values and then save to wave file format. Each channel is in a separate file with the format: real, complex, real, complex.

These files are very large so this process must be done in a loop. I have appeared to have succeeded except that after the first loop there is a kind of a jump in the wave file and duplicates of the carrier signals show up when looking at the fft. I can't see anything wrong with this code. My guess is that it's something in
fseek(fid1, n2+4, 'bof'); the fseeks are to go back and read the complex values after I've read the real values.

out = fopen(outfile,'a+');
loop = 4;
fseek(fid1,0,'eof');
filesize = ftell(fid1);
frewind(fid1);

samples = filesize/8;
wavwriteheader(samples, channels, samplerate, 16, out);

loopsamples = filesize/(8*loop);

n1 = 1;
n2 = filesize/(8*loop);

while n2 <= filesize/8
realpart1 = sqrt(2)*fread(fid1, filesize/(8*loop), 'single', 4) .* cos(alpha*period* (n1:n2)')*multiplier;
realpart2 = sqrt(2)*fread(fid2, filesize/(8*loop), 'single', 4) .* cos(alpha*period*(n1:n2)')*multiplier;

if n1 == 1
fseek(fid1, 4, 'bof');
fseek(fid2, 4, 'bof');
else
fseek(fid1, n2+4, 'bof');
fseek(fid2, n2+4, 'bof');
end

wavesample1 = realpart1 - sqrt(2)*fread(fid1, filesize/(8*loop), 'single', 4) .* sin(alpha*period*(n1:n2)')*multiplier;
wavesample2 = realpart2 - sqrt(2)*fread(fid2, filesize/(8*loop), 'single', 4) .* sin(alpha*period*(n1:n2)')*multiplier;

n1 = n1 + filesize/(8*loop);
n2 = n2 + filesize/(8*loop);

wav = horzcat(wavesample1,wavesample2);

% interleave samples and scale samples
wav = reshape (wav', loopsamples*channels, 1);

wav = round (wav*32767);

fwrite (out, wav, 'int16', 0, 'a');

clear wavesample1 wavesample2 wav;
end
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