No, it's not a typo: this FSK signal (kindly sent me by my friend cryptomaster) is truly modulated at the velocity of 6 Bd and 50Hz shift (Figs. 1,2).
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| Fig. 1 - modulation speed |
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| Fig. 2 - 50Hz shift |
The demodulated bitstream has a period of 696 bit (Figure 3): we do not know the origin and the user.
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| Fig. 3 - 696 bit period |
https://disk.yandex.com/d/d3Arg5sX2rXwhA
