1200Bd/800 Russian tactical datalink (2)

My friend UDXF @pir34 and I are monitoring different frequencies which are supposedly changed on a day/night basis, but not just that. We have noticed that the transmissions take place from at least two different sites (which I prefer not to indicate) and - more importantly - with two different data formats even if of the same transmission mode (1200Bd/800) bit length (69) and contents (radar tracks). In particular the transmissions on 6123.5 KHz/usb and 6232.5 KHz/usb (figures 2,3):

Fig. 1 - 6232.5 KHz transmission: spectrogram and modulation

Fig. 2 - 6232.5 KHz transmission: 69-bit period stream

I met such signal some years ago, as annoted here in the blog, on about 20 MHz: as you see, the waveform is very similar although its length is 165 bits (figure 3):

Fig. 3 - 165-bit frame length datalink

An anymous reader commented the post talking about the 165-bit "Akkord SS-PD" frame format, that he expected to see in the bitstream, and about the other more frequent frames of 69 & 117 bit lengths just as the ones discussed in the previous post. I did some research on the web about the Akkord format but getting very few results: the most interesting is precisely the frames of 165 bits in length (Akkord-165) of which a description of the framing is provided [1]:
4-bit SOM + 6 x 24-bit words + 1 sep + 16-bit CRC
That described framing corresponds to those used in the formats of 69 and 117 bits, in fact in those cases the part of the data is constituted respectively of 2 and 4 words of 24 bits. The only difference is in the polynomial used for the formation of the 16-bit cyclic code: in the Akkord-165 format it results to be x^16+x^12+x^5+1.

 A second interesting source seems to indicate an "Akkord SS-PD" data transmission equipment" and a "similar" one and also provides a data transmission equipment unit block diagram (figure 4) [2]:

Fig. 4