Transmisja CIS-Navy i Akula

My friend Mario frequently monitors the frequency of 9201.0 KHz/USB in search of "Akula" signals: he mainly uses a KiwiSDR receiver located in Japan (Azumino-city, Nagano) [1] and it seems that this frequency (certainly 1 of the many) is rather active for this kind of transmissions, as collected by my friend Dave too. Most of the time it is usually a pair of signals that repeat at irregular intervals.
A fewer days ago he kindly sent me an interesting and "curious" recording of a transmission in which both an FSK 50Bd/1000 signal and Akula (FSK 500Bd/1000) are utilized with a central frequency of 9202 KHz (Figs. 1,2)

Fig. 1

Fig. 2

The first thing that catches the eye is the peculiar "shape" of the Akula signals in which the well-known first synchronization and preamble groups are missing but the EOM + EOT groups (101111 100010 100010 101111 011110) are precisely in their place, as can be seen from the demodulated bitstream in Figure 3. Just 1 year ago I had already come across these (let's call them) "anomalies" [2]. "It could depend on a malfunction of the modem or on the receiver's attack time" my friend cryptomaster says.

Fig. 3 - Akula bitstream