CIS MFSK-33 (here:15+∅+17), likely a "Serdolik" multimode waveform

Fig. 1 - "Serdolik" multimode waveform

The MFSK segments have the usual 40Bd and 40Hz (channels separation) values which are typical of the Serdolik waveforms family: a long-range radio system used by the Russian and CIS countries Diplomatic Service, possibly Serdolik V2. It's worth noting in Figure 2 - at least in this sample - that although the system provides a 33 channels grid, only 32 are the effective (used) ones: specifically, the first 15 lower channels plus the 17 higher ones (the 16th channel is not used).

Fig. 2 - MFSK segments

The FSK inserts too have usual Serdolik values, ie 40Bd/680Hz in this sample, and consist of short "01"s sequences (Figure 3).

Fig. 3 - FSK segments

This sample has been recorded on 20.8155 MHz/USB using a remote AirSpy server located in UK.

CIS MFSK-33 waveform is not the only one that does not always use all the available channels of the frequency grid: CIS MFSK-34 (aka Crowd-36) is another example in this regard (Figure 4).

Fig. 4 - frequency grid of some CIS MFSK-34 samples

https://disk.yandex.com/d/wgskeCZfRcz6Ow