unid datalink protocol(s) over a PSK8 ST and STANAG-4539 (2)

I had the opportunity to record other transmissions on 3712.70 KHz/USB and - also following the comment of my friend KarapuZ - I can state with reasonable certainty that the waveforms analyzed in the previous post [1] come from Thales equipment. 
As mentioned, both Thales and L3Harris use the GMSK-MFSK8 waveform to handle HF links but the L3Harris bitmap/bitstream have a very recognizable pattern that is not present in the bursts recorded today (Figs 1,2): therefore, the GMSK-MFSK-8 signal is the Thales Systeme-3000 "Skymaster ALE", used in TRC-3500 and TRC-3600/TRC-3700 series radios (HF 3000 family).

Fig. 1 - Thales Systeme-3000 GMFKS+MFSK8

Fig. 2 - Thales Systeme-3000 GMFKS: bitstream after differential decoding and 50ms bitmap

As you see in Figure 2, I used the OQPSK "view" to demodulate the preamble of the Skyaster ALE signal: however, the differential decoding clearly show a 2-state keying (precisely GMFSK) that can be demodulated also using the "classic" FSK approach (Figure 3).

Fig. 3 - use of the SA MFSK dem

For what concerns the two PSK8 Serial Tone waveforms A & B [1], they also could be proprietary ones (Thales); indeed, quoting TRC-3600 datasheet: "Thanks to its digital advanced technology, the TRC 3600 offers new embedded services: secure high data rate and digital voice transmissions. It integrates a high data rate, multiwaveform, single tone modem (from 75 to 5400 bps) and a vocoder (800 - 2400 bps) associated to a high security digital COMSEC chip". 

The data link protocol could be the digital voice vocoder (new MELP/LPC10), given the similarity of the bitstream with its L3Harris analogue, but that is just an unconfirmed hypothesis of mine.

Fig. 4 - bitmaps of the two PSK8 ST waveforms

 

 https://disk.yandex.com/d/6NK6xYRAWzjzEw

 [1] http://i56578-swl.blogspot.com/2024/04/unid-datalink-protocols-over-psk8-st.html

THALES Skymaster, "skyhopper" mode

This is a fairly comprehensive list of the ALE waveforms provided by Thales' Systeme 3000 Series Skymaster and Skyhopper Modes, a set of procedures and adaptive waveforms that allow to offer reliable and real-time optimized links even in degraded ionospheric conditions of the HF channel. All the signals, kindly sent me by my friend ANgazu, belong to the same session, even if the recording is edited in the time axis. These Thales proprietary waveforms are used in TRC-3500/TRC-3600 and TRC-3700 series transceivers.

The first two parts are the Skyhopper mode, an intelligent frequency hopping and automatic hop band selection; the signals consist of a series of 40 ms MFSK-8 125 Bd bursts (figure 1) and 50 ms GMSK / OQPSK 200 Bd bursts (figure 2). It's interesting to notice that the MFSK-8 burst actually use 5-out-of-8 tones of the Skymaster ALE waveform (see the comparison in Figure 1 below).

 

Fig. 1 - MFSK-8 125Bd/250 (actually 5-out-of-8 tones)

The following 50 ms bursts, below in figure 2, are of difficult analysis given their duration and the used modulation, friends of  radioscanner suggest OQPSK modulation.

Fig. 2

The third part is the "classic" GMSK/OQPSK 2000 Bd & MFSK-8 125 Bd/250 part, see figure 3.

 

Fig. 3

The initial GMSK/OQPSK part has a 50 ms ACF that corresponds to a 100-bit frame: the waveform is similar to Harris RF-5800 selective call (figure 4).

 

Fig. 4 - framing' comparison of Thales (up) and Harris (down)  ALE

 

https://disk.yandex.com/d/owrO7l3R0MKEFQ

Thales Systeme-3000 Skymaster ALE

The signal reported here was heard on 2 May at 10.254.0 KHz on USB, around 0730z, and it is  Thales proprietary ALE protocol called Skymaster

The initial part of the signal SDPSK (Symmerical Differential PSK) modulation at 2000 Baud speed and carrier frequency ~1600 Hz; as you see, transitions do not traverse the origin and the information is stored in the transitions and not in the (four) states.

The initial part is followed by short MFSK-8  125 Baud segment that is not compatible with MS 188-141 2G-ALE although the scope be the same.

The initial SDPSK part exhibits a 50ms ACF that corresponds to a 100-bit frame.

This proprietary waveform is used in their TRC-3500/TRC-3600 and TRC-3700 series radios.