RACAL/THALES PANTHER-H: Intelligent Frequency Hopper

Pic. 1: the 8-bursts train

I heard this signal several times, and today too on 20698.0 KHz on USB at 1445z. The waveform: 760 mSec spaced bursts (always eight), ~2500 Hz bandwidth, serial tone with sub-carrier at 1800Hz and PSK-4 2400 Bd manipulation, as shown in picture 2. Always a "train" of 8 bursts (pic. 1) during the SOC (Start Of Conversation) sync procedure, after synchronization the next hops are within 2 MHz.The signal belongs to the RACAL/THALES HF transceiver Pather-H, running in the Intelligent Frequency Hopper mode, and it is reported in radioscanner.ru at this address:
http://www.radioscanner.ru/forum/topic39959-65.html#msg1068885

Thanks to my great friend KrapuZ (radioscanner.ru) for pointing me to the right signal name.

Pic. 2: manipulation speed and serial tone sub-carrier

PANTHER-H is an intelligent frequency hopping transceiver and is the result of many years research to find a tactical HF radio system which provides a Low Probability of Intercept (LPI) and anti-jamming protection whilst delivering reliable, good quality communications on all types of HF link: http://www.railce.com/cw/casc/racal/panther-h.htm

Racal was purchased by Thomson-CSF (now Thales Group) in 2000.

RACAL/THALES-PANTHER-H.wav

Several times I noticed spread spectrum transmissions (hopping frequency spectrum transmissions, HFSS) after few seconds the end of the SOC sync: possibly it is the traffic just following that sync. Below an eaxmple of these HFSS