Just started looking into Xilinx Fourier transform ip and found out that there are three versions:
DFT: apparently useful for any resolution
FFT: power of 2 resolution, i.e. subset of DFT
LTE_FFT: looks like subset of FFT as I see equal resource for same configuration
If I am right then may I ask why LTE_FFT is made a subset. Can't we just configure FFT for that.
Thanks
Kaz
According to https://www.xilinx.com/products/intellectual-prope... LTE fourier transforms include one length which is non-power-of-2 (specifically a 1536 point DFT). That specific transform will have been carefully factorised to optimise performance and/or size compared to a naive DFT of 1536 points.
Thanks for that Martin but I noticed the same option for 1536 is available with fft ip setup.
Moreover I assume they could have done one ip for DFT and fft and lte configured as required.
I just was worried I may have missed something especially regarding matlab model for testing for example.
Ahh, I see what you mean.. In that case, it's probably just a hangover from when the FFT only did powers of 2?
As says The LTE FFT contains this 1536, which adds a radix-3 stage in the FFT. If you want to be able to change dynamically the FFT size you will have to include this radix-3 stage whenever you will use it or not.
The standard FFT IP is JUST for 2^N FFT length, the 1536 (3x512) is not possible in this IP. Some of my customers prefer to use a 2048 FFT size and then an interpolation to recompute the 1536 bins.
