From .ogg audio data to IQ data?


#1

Hi, I don’t understand how to convert .ogg audio data that can be downloaded from the observations into complex IQ data.
Could you please explain which is the format?

For example I know that if I save a .wav file from gqrx setting “Raw IQ” for the demodulator I get a .wav file with two channels representing the I and Q branch (I obtain a Nx2 matrix if I open it in MATLAB).

In MATLAB .ogg files instead yield only one channel (Nx1 matrix); I tried to read it like if the format was interlaced IQIQ samples, but it didn’t seem to work.

I’m doing something wrong?


#2

The .ogg files do not contain any IQ information. Most of them are produced after a quadrature demodulation so they loose their quadrature (imaginary) part. If you want to handle them as complex, you can set the imaginary part to zero.

To achieve this quickly, use the OGG File Source block and connect it to the real input port of the Float to Complex block. Then store the result to an IQ file.


#3

@vinz87, hi, did you have any luck or success with this?