Well you must not have used Google or maybe you used Bing (gave a lot of bad results).
using google with the search string "fpga spectrum analyzer" produces a few good results and one result on the 2nd page, that would interest you. It's a senior design project for Indiana-Perdue Fort Wayne...
I'm not going to bother adding a direct link as it was far too easy to find. But here is the google search results link.