Regarding Observation 134094 …This bird seems to be off target but still it decodes!
If I understood well AFSK is FSK over FM audio, and FM is relatively
immune to a shift in frequency (causing only a shift on demodulated signal level).
I approved the proposed drifting transmitter, though only -2 kHz. It’s only few days ago that I had one with +1 kHz so it is probably drifting back and forth.