HFU HF Underground
Loggings => Utility => Topic started by: Retops on March 13, 2019, 0332 UTC
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Station 2HF (Two Hotel Foxtrot) sending series of EAM type encrypted messages 0315 03132019 USB. Very strong in Oklahoma. Calls ZMCUGW and ZMCUZO sends message of 36 characters to first and 30 characters to second. Repeats second message. No one answers the broadcasts except a Spanish freebander who comes up on frequency and says "Hello" in English a couple of times.
I have seen speculation that this is MARS. Might be, but big signal for typical MARS station.
At 0334, same message to ZMCUGW being transmitted on 6807 USB by station Y4S. This transmitter is weaker, fading quite a bit.
0340, Station 7RF on 6807 sends traffic to ZMCUZA. YL operator with male operator voice heard occasionally behind her.
0353 on 6988 C4K sends to ZMCUZO. Different YL operator, strong signal.
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EAM-like messages have been heard in the 6765-7000 kHz region before, often with very strong signals and various operators (similar to what you've logged).
It could be MARS, or it could be military operator training or a communications/SIGINT exercise type deal.
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When you hear LFL calls, LFL being Letter Figure Letter, think NATO military, ours, someone else's, etc as LFL is a NATO standard tactical callsign convention. USN/USMC come to mind in that freq range and rx location, I don't know of MARS sending eamish traffic, however.
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I also heard these comms, a little earlier, and had the presence of mind (? :)) to click the record button for later playback.
Here's my synopsis of a playback of the recording:
3 operators: 6903 kHz OM, pronounces 3 almost as “tree”, S9+ sig, ~2kHz pilot tone, call C3Q and 2HF
6988 kHz OM, S9+ sig, no pilot tone, call unkn
6988 kHz YL, vy poor copy and QSB, no pilot tone, slower cadence, call C4K
2 different messages, main one was 30 char, other one was 36 char, all were similar format
and sounded to be continuous chars, not in groups, first 6 char seemed to be
“To:” field, msg repeated 2X
005620: 6903 kHz, OM, call C3Q, 30 char msg Almost at same time: 6988 kHz OM, 30 char msg
012200: 6988 kHz, YL, 30 char msg
015120: 6988 kHz, YL, 30 char msg
022120: 6988 kHz, YL, 30 char msg
024335: 6903 kHz, OM, call 2HF, 30 char msg
024555: 6903 kHz, OM, call 2HF, 36 char msg
024845: 6903 kHz, OM, call 2HF, 30 char msg
025205: 6988 kHz, YL, 30 char msg
032140: 6988 kHz, YL, 30 char msg
--- Recording ended at 0330 ---
US Mil training exercise?
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EAM-like messages have been heard in the 6765-7000 kHz region before, often with very strong signals and various operators (similar to what you've logged).
It could be MARS, or it could be military operator training or a communications/SIGINT exercise type deal.
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It's a US Navy exercise. The same sort of exercise happens about 4 times a year. Different USN assets practice sending simulated EAMs.
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Also when you hear an obviously American voice send phonetics on hf and they say "tree" rather than three and "fife" rather than five you likely have the US military.