Simple way to decoding FSK
This should be a comment but there isn't enough room. 

Don't bother voting/down-voting on that basis.

The top trace looks like 1.6kHz (high) and the bottom trace looks like 1.1kHz (low). What equipment are you using for getting these spectrum traces? Also, where on the TDA7000 are you measuring? Also what carrier frequency are you using?

The top trace also shows a peak at about 3kHz and don't be surprised by this because your modulation method stinks and it will produce harmonics of the modulator frequency and the carrier frequency.

I'd say the distortion you are seeing on the top trace is at 3.2kHz and on the lower trace I'd say you are seeing 2.2kHz and 3.3kHz.

I'm not that certain because we don't know anything about the display with the green traces on?