marine voice inversion

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313RADIO

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i head some scrambled comms on 157.025 ... anyone know what it might be? government ? i live near lake saint clair
 

iMONITOR

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That's marine channel 80, which is normally used for commercial use. US Customs/Border Patrol has been stepped up in the area recently. It's not impossible that they would be using this, but I'm not sure why.

You sure it wasn't some drunk captain?
 

Hooligan

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Along the Atlantic & Pacific coastlines, if you hear speech-inversion or time-domain 'scrambling' on VHF marine channels (& really, all over the 138-174MHz spectrum) it turns out to be small & large commercial fishing fleets, using crypto & no regard for FCC licensing/channel plans so that they can speak 'privately' amongst their vessels & share info on where the fish are.

But I've never heard of such activity on the Great Lakes, and I used to live less than 100' away from the Detroit River & thus monitored the VHF Marine Band channels regularly.


From high ground along the Pacific Coast during commercial fishing season, I've heard over a dozen freqs in & outside of the VHF Marine spectrum, clear-voice & 'secure' voice, in use by these foul-mouthed, feeble-minded fishermen.

I'm glad I'm a vegetarian, because I've even heard them talk about staying out at sea for a longer time in order to catch more fish/get a better price, even though it would mean that some of the fish they'd already caught would spoil (they planned on selling them anyway).

TV shows like 'The Deadliest Catch' make these guys seem kind of heroic, but after hearing many of them conversing on HF & VHF radio over the decades, I have a different opinion.
 

Hooligan

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That's marine channel 80, which is normally used for commercial use. US Customs/Border Patrol has been stepped up in the area recently. It's not impossible that they would be using this, but I'm not sure why.
?
ICE/CBP use DES-XL & P025 DES-OFB/AES, and also Nextels a lot for near-shore operations along the great lakes. It would be nice to know what sort of "scrambling" the guy heard. Sometimes for joint operations with Canadian authorities they've had no choice but to use a VHF Marine channel, but if they've gotten sophisticated enough for both US & Canadian parties to use secure mode, they should be smart enough to use a channel outside of the marine band for it.

So my guesses are still that it was an analog encryption system, and probably just some idiots (don't even have to be boaters -- supposedly, some truckers use VHF marine radios) with some radios they were told were "scrambled" & not having a clue what the freq is.
 

jsmeed

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A few years back I used to hear Michigan Marine Salvage using voice inversion all the time on Lake St. Clair. I assumed they used it so their customers wouldn't get poached. I think they used to be somewhere around Channel 18. I haven't heard them recently so they may have changed channels.
 
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