Vibrato(FM) effect on DE2

this post is old, i managed to change noise from this audio to worse noise :)

Standard delay and echo works good. Tremolo(AM) using this wave works good too. Vibratto is a problem, simulation in matlab works good too, but implementing it in hardware is to problematic for me. The noise i hear can be heard on this mp3 :

http://dark.art.pl/~kvasir/noise.mp3

It is 200hz sinus obtained from PC line out, modulated with 2hz triangle(50:50) with values 0 to 720. I think that what is heard in background IS frequency modulated signal. Any other ideas ?

ps: i use 2-port ram megafunction, with read before write.