For my FPGA programming lab final project, I want to implement an audio spectrum analyzer. Since I won't be recreating any signals, I only need the frequency magnitude, and not the phase. I'm hoping that ignoring the phase will spare me the trouble of using complex arithmetic, and make the algorithm leaner. I found some references to the discrete hartley transform, which has "no intrinsic involvement of complex numbers" according to wikipedia. I also found the "real DFT" which splits the complex numbers into sine and consine parts. I was wondering, though, how the radix-2 fft butterfly method would be modified for the real DFT or the hartley dft. Or, maybe there's another method to get just the magnitude information that's better for hardware.
Thank you for any advice.