I’m trying to understand the receive filtering in sBitx. I’ve been studying and experimenting with Ashar’s well commented code in the function rx_process in sBitx.c. As I understand it, the incoming data along with the overlap data has undergoes a forward FFT to the frequency domain where it is multiplied by the filter coefficients. It then undergoes a reverse FFT to the time domain. However, in the time domain data the filtered audio is now in the imaginary part of the data. Why isn’t it in the real part?
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73,
Mark, N8ME
Mark Erbaugh