5 May 2015

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 - at first glance - uses PSK-4 (OQPSK) modulation at 2000 Baud speed and carrier frequency ~1600 Hz but it's likely an MSK modulation 2000Bd/1000: OQPSK and MSK are strictly connected and difficult to discriminate. The absolute phase variation diagram of this part it's a clue in favour of MSK.

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 MSK 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.


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