Cool, BCD seems likely.
However, I am having trouble differentiating the 1s from the 0s because all of my audio spectrum software can't give me a high enough detail picture. The closest i came to success was using a program called
CWGet.
Also, I don't think that it transmits the delta temperature because i can turn the receiver on after a minute or so after the transmitter and it will display "correct" data. (I say "correct" because it wasn't a good thermometer in the first place. That's why I took it apart.)