We have used the radix 4 complex fft by ZHAO Ming ( cfft project ). It seems to work fine, but our simulators (ModelSim and ISE sim) give really a lot (1000's) of identical warnings. ISE sim gives: Warning: There is an 'U'|'X'|'W'|'Z'|'-' in an arithmetic operand, the result will be 'X'(es). I traced it back to cfft4.vhd, where signal RegAI is used in the case statement without being initialized properly (that is not all components are initialized in each case. Also,I cannot understand how you have implemented 64 point fft for OFDM. please do explain me in detail. __________________________________________________________ Yahoo! India Answers: Share what you know. Learn something new http://in.answers.yahoo.com/ -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.opencores.org/forums.cgi/cores/attachments/20070316/9f879888/attachment.htm