Hi there, I setup that star.fru.me site awhile ago. The Weather Channel stopped using VBI with the STAR III, where they switched to only an audio subcarrier. You would be correct in that it uses FSK. Any audio (except for the beeps during warning scrolls) were broadcasted nationally, at one point they used the left and right audio channel to keep the product narrations relevant between the 4000 and the III. The data is using a derivative of UK teletext. I have been working with this old hardware for awhile with a few good buddies of mine. If you have any questions feel free to ask and I'll see if I can answer.