With a Cyclone part with no dedicated multipliers, you are asking a lot of logic to create your multipliers. I would not suggest trying to do this type of calculation in this particular FPGA.
If you want to know how to do it in Verilog, you need to take into consideration your sample rate along with your clock rate. Given this, you have N clock cycles to perform the calculations. If you were to do something like this, you could possibly have a block that performs the two FFT's in parallel and puts the results into a BlockRAM. By the time this is done, the next frame is ready for the FFT, so while this is processing you can perform the cross correlation and store those results in the next BlockRAM. After doing this, you can do the IFFT out of that BlockRAM and pass the results into a small block to calculate the max value. You can get Altera tools to generate cores that will perform FFTs and IFFTs for you. The cross correlation would then be the handcoded part along with the max logic. http://www.altera.com/products/ip/dsp/transforms/m-ham-fft.html You can also try opencores.org and check out their FFT section, but as I said earlier - without dedicated multipliers, it would require a HUGE part and slow down your design significantly. Hope this helps! Brian On 11/3/06, Lin Ji <[EMAIL PROTECTED]> wrote:
Hi, I wonder what if the easiest way to perform real-time cross correlation in the FPGA on USRP? I've worked weeks on writing a close form algebra doing cross correlation,but since all my algorithms are based on floating points and multiplication/division, I'm afraid it's hard to convert that to Verilog code later. All I need to do is for 2 sequence A and B, perform this: max(ifft(fft(A).*conj(fft(B)))); It's really easy to do in MATLAB and relativly simple in C++, but in Verilog? I have no idea... Please people, if any one has done this before or anything related, share some information with me, I would really preciate that! /Lin Ji _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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