Transmissions on 9050.0 seem to be scheduled at 0830, 0900 and 0930 UTC Mon-Fri, almost all the sessions start with a ~ 15sec tone at 9051.8 KHz (sent about two minutes before) and they last the time necessary for interchanging/sending the messages, usually few minutes.
From previous recordings they used plain MIL-STD 188-110A and now they switched to RFSM (Radio Frequency Software Modem) with Data Masking (link protect) feature, an MS188-110 ST based software-modem by "RFSM-IDE Group".
Carrier frequency (1800Hz), symbol speed (2400Bd) and modulation (PSK-8) are the same as that standard (pic. 1) and may be misunderstood and wrongly identified as MS188-110 4800bps/uncoded (the RFSM 75bps/L) and 2400bps/voice (the RFSM 300bps/L), as it happens with both k500 and sorcerer; the 13ms ACF is a clue in favor of RFSM (pic. 2). The structure of the signal is quite complicated, the PSK-8 preamble is followed by the data transfer in PSK-8, QAM-32 or QAM-16 according to needed data-rate. Just as aside note, a sort of 2-ISB signal + carrier has been seen on 9050.0 as central frequency: signal is very week and is difficult to say it's nature.
The RFSM-2400/8000 is a software by "RFSM-IDE Group", it operates under standards MIL 188-110A / MIL 188-110B App. C, (also under a modified version) providing a maximum speed of 8000bps (standard mode), or 6670bps (non-standard "narrow" mode). Signal bandwidth: 0.3-3.3 kHz (standard mode) and 0.3-2.7 kHz (non-standard mode).
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