14 October 2017

TADIRAN HF modem running in scrambler mode

Tadiran/ElbitHF modem, probably the HF-6000 model, running in COMSEC mode using FSK 125Bd/300Hz Digital Coded Squelch (DCS) and scrambled voice-comms. Transmission heard on 5885.0 KHz/USB at 0755z with a very poor SNR. The sample marked as "A" is the "autocall" waveform: it precedes the MFSK/scrambler sessions, marked as "B", and terminates the link (Figure 1).
Fig. 1
The FSK segmentes (the DCS part) sent during the scrambled voice-comms have a speed of 125Bd and 300Hz shift, ie same parameters of the F7B (apparently MFSK-4) waveform, and cosists of 84 bit repeated strings:

Fig. 2

Fig. 3

2 comments:

  1. Hello Antonio, is there a way to reverse the scrambled voice? And, how does this scrambled voice generated?

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  2. Hi Antonio, is it possible to reverse the scrambled voice? What tools should I use to do that? Thanks, Fernando

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