an interesting sample of a 3G-2G switching copied on 7780.0 KHz/USB: the handshake is performed with FLSU bursts (ie 3G-ALE) and user data are sent using MIL 188-110A serial (a 2G HF waveform), last FLSU bursts terminate the link (Fig. 1).
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| Fig. 1 |
In
this scenario the traffic service is termed “Circuit Mode” in
STANAG-4538 and is used when an HF data continuous waveform (not a burst waveform) will be used to convey traffic after link establishment. The FLSU_Request specifies the traffic waveforms that will
be used during circuit mode, for example MIL 188-110A (as in this
recording), STANAG 4285, STANAG-4539 or other. Once
circuit mode begins, any station can initiate transmissions using the
specified traffic waveform. A CSMA/CA process is recommended to avoid
collisions (Fig. 2)
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| Fig. 2 |
Same operational contest was copied on 11132.0 KHz/USB (Figs. 3a, 3b): these are more likely test sessions that involves both the packet mode (the used datalink protocols are HDL+ and LDL over BW3-BW4 burst waveforms) and the circuit mode (the HF waveform is MIL 188-110A serial). These (test?) transmissions are probably from Algerian Military.
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| Fig. 3a |
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| Fig. 3b |
A STANAG-4538 circuit mode traffic was also copied by my friend Mike (ak mco) on 9003.0 KHz/USB (Fig. 4) who sent me his recording. The sample consists of n-transmissions, each composed of a MIL 188-110A transfer running at 300bps, preceeded and terminated by BW5 bursts which control the link. More precisely, 188-110A frames transport Harris proprietary Citadel encrypted data, Fig. 5, so it's difficult to say what sits behind.
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| Fig. 4 |
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| Fig. 5 |
(9003.0 KHz)
https://yadi.sk/d/GCq28TAjzSYzU
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