Hi Dan > > we used to use CORDIC for generating coefficients. > not sure how cordic comares to goertzel. > there are a few open source VHDL cordics.
Goertzel uses the coefficient factor of the previous calculation stage to calculate the coefficient factor currently required i.e rotate the previous factor by the phase increment associated with the frequency of the complex exponential I am multiplying with. CORDIC calculates the complex value associated with an arbitrary phase using a binary search style algorithm and no multipliers. It would be interesting to see if the Goertzel method could be modified to not have to use multipliers i.e use the CORDIC maths trickery to do the complex rotation. CORDIC combined with a BRAM lookup (to remove the need for the first N CORDIC stages) would also be interesting. Cheers Andrew
