Interesting sessions recorded some days ago on 9072.0 KHz (CF) consisting of an initial THALES Robust MFSK-8 session followed by THALES TRC-1752 STANAG-4285 + STANAG-4539 encrypeted traffic, the latter used in QAM-16 6400bps mode (figure 1).The MFSK-8 waveform uses the same tone library as 188-141A/B 2G ALE but callsigns are limited to a maximum length of 2 figures only and can also be used as a robust-data mode. Aurally and visually it is easily mistaken for a normal ALE since the 250 Hz spaced eight tones and 125Bd speed.
 |
| Fig. 1 |
Direction Finding tests, TDoA method, point to center of France as shown below in figure 2:
 |
| Fig. 2 - Direction Finding tests |
It must be said that the TRC-1752 modem is a bit old and therefore has probably been replaced by the new TRC-177x multi-mode modems.