6 December 2021

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


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