Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

IFFT odd behavior

I'm at the tail end of a design that uses 2D FFTs, does phase correlation calculation in frequency domain then does 2D Inverse FFT to get spatial shift between two images. I'm finding that the ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

thepancake

I did consider some type of dc offset going on. However, I don't see this zero position spike in the Verilog sim which is full of truncations. Actually, the Matlab core model sim is designed to truncate values exactly how/where I truncated the Verilog values so that I have exact match between the two. It just looks like a difference between the Verilog simulation model (.vo) and the Matlab core model.

Will crawl thru the two sims again to look for any difference.

I would just ignore it but a spike at the (0,0) point is valid for no shift between the two images which is a possibility.

Thanks for your input.