R4002: The last three major drug busts at Australian ports have originated in China, nearly one ton in a shipping container detected at Port of Melbourne last week, origin was China. So no doubt the radio spectrum would probably play some role in the scheme of things.
Late last year three yachts were also busted trying to bring cocaine into Australia from South America. Two didn't make it here, one intercepted in French Polynesia and the other in Fiji. So you are pretty spot on suggesting the marine HF frequencies would be at play too.
Being well cashed up the drug lords would have nothing but the best in comms, plus using old fashioned HF as part of the ploy to throw authorities off the trail.
We too, as monitors of the radio spectrum play a role too, last year I picked up some "weird conversations" on 8MHz SSB at 2.00am in the morning my time with coded type language (English) being used. I immeadiately contacted the authorities in Canberra alerting them in the instant.
The "weird conversations" vanished a week later. The authorities informed me that at any time I come across some "out of the ordinary" not to hesitate ringing them straight away on the 24 hour hot line.
As for ISIS and other Middle Eastern Islamic radical groups, most of the intercepts made by authorities here in Australia have been done via monitoring the internet, chat groups, links and Facebook etc.
Australia being an island nation is in a unique position when it comes to monitoring. It sounds like you've got some high-end monitoring capability and it sounds like you're using its full potential. Did you ever find out what the coded English language traffic in the 8 MHz band was? What frequency was it?
On top of using the traditional [read: legal] HF marine bands and the non-traditional [read: freebands / out of band frequencies], the drug traffickers have another advantage. It wouldn't be too difficult to assign code words that make use of fishing terminology as to camouflage drug smuggling related radio communications to sound like regular fishing fleet radio traffic. In a world where using encryption more or less equals "I have something to hide", innocent sounding communications are probably treated with much less suspicion. Another interesting thought that applies worldwide, especially considering the seemingly-unlimited Spanish and Portuguese voice traffic heard all over HF in the Western Hemisphere and the seemingly-unlimited Asian and Russian voice traffic heard all over HF in the Eastern Hemisphere (and, in the case of Russian language radio traffic...the Western Hemisphere as well).
Apparently 25-30 MHz is the de facto standard Russian taxi cab dispatcher radio band now. When 11 meters is open, CBers (and hams using 10 meters) have major problems with Russian taxi interference (almost always using FM mode too) booming in on basically every frequency available on the now-standard Chinese-designed "export" radios flooding the market. Before it was 25.615 to 28.305 MHz, or 25.165 to 28.755 MHz if you had a real fancy radio...now its 25.615 to 30.105 MHz, 25.165 to 29.695 MHz or even 24.265 to 30.555 MHz.
Things in Russia have gotten so bad that the Russian government has changed the CB radio rules from two sets of 40 channels [FM only] to six sets of 40 channels [AM/FM], and even this isn't enough. When CB traffic moved up towards 27.86 MHz or so, the taxi companies either went further up in frequency (into 10 meters) or further down in frequency (below 26 MHz, possibly into 12 meters.)
Former Russian CB Plan:
FM mode only.
Russian/Polish "R" Raster or "zeros" - 26.960 MHz - 27.400 MHz [40 channels]
European "E" Raster or "fives" - 26.965 MHz - 27.405 MHz [40 channels]
The former plan effectively gave 80 channels at 5 kHz steps, the European channels are considerably more popular in Russia compared to the "zeros", however the "R" channels or "zeros" are still heavily usedCurrent Russian CB Plan:
AM and FM modes allowed by law. SSB illegal but not enforced.
Russian Raster/Zeros:
B Band - 26.510 MHz - 26.950 MHz [40 channels]
C Band - 26.960 MHz - 27.400 MHz [40 channels]
D Band - 27.410 MHz - 27.850 MHz [40 channels]
European Raster/Fives:
B Band - 26.515 MHz - 26.955 MHz [40 channels]
C Band - 26.965 MHz - 27.405 MHz [40 channels]
D Band - 27.415 MHz - 27.855 MHz [40 channels]
The current plan provides for a total of 120 channels if 10 kHz steps are used or 240 channels if 5 kHz steps are used. Even with all these
legal channels now available in Russia, interference on frequencies above 27.86 MHz and below 26.5 MHz is a major problem. Buy a "multi-norm" CB radio in Europe, select the "RU" or "Russia" country setting in the radio's menu and it gives you 25.615 MHz to 30.105 MHz in 5/10 kHz steps right out of the box.
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But I digress... I'm sure you have similar issues with broadbanded 25-30 MHz radios operating out of Asian locations too...
Now that 11 meters isn't consistently providing the long-distance propagation it was a few years ago, I have a feeling a lot of the users who were using freeband 11/10 meter gear have moved down to the lower frequencies.