HFU HF Underground
Loggings => Utility => Topic started by: ChrisSmolinski on October 05, 2018, 1200 UTC
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I noticed a few transmissions like this around this time, starting with alternating beeping tones, then into a SS OM, here is a recording of one transmission: http://radiohobbyist.org/blog/mypics/6920usb-0106z-5Oct2018.mp3
My Spanish is rusty, I think I heard some numbers and maybe a mention of a frequency?
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Sounds like military or other land mobile traffic out of Latin America - its pretty noisy but I distinctly heard "frequency" and several series of numbers mentioned
EDIT: listened to it a couple more times
almost sounds like an alert or emergency type "broadcast" - the tones at the beginning aren't like anything I've heard the freebanders or peskies use before...."15" "frequency" "45", "75" and a possible mention of "la plata" (literally "silver" but a better translation is "money" or "cash" - could have been another similar sounding term though, perhaps "la playa" [the beach] or "la plaza" the plaza which is a term used by Mexican drug cartels to indicate areas of operation or influence of a particular cartel...) - heard "45" a couple times, could be a numerical ID for a station or a frequency/channel. Difficult to make out what else is being said. This could be related to the tropical storm developing in the Gulf of Mexico
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Thanks for your insights, R4002.
I don't recall hearing this before, not recently anyway. It stood out on the SDR recording vs random peskies due to the tones.
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The tones remind of me of a marine weather broadcast or something like that...or could be part of a land-based fixed/mobile network. Maybe oil rigs in the Gulf? I think I recall 6920 kHz USB being one of the frequencies they've been heard on in the past. Some sort of alerting system to get an operator's attention I would guess, or maybe some obscure selective calling system.
This doesn't have the characteristics of freebanders or the rural radiotelephone link systems that are often heard closer to 6700-6800 kHz which leads me to be believe its a more traditional "professional" HF radio network that you've stumbled upon. It could be net control "waking up" a net on the frequency or a reminder to switch to "frequency 15" at a certain time....something like that. So much of what's said is impossible to make out for sure though (and my Spanish is nowhere near perfect, especially if slang terms are used).
Yet another mysterious HF radio transmission out of Latin America :D
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Yet another mysterious HF radio transmission out of Latin America :D
There's a tremendous number of them. While other parts of the world are cutting back on HF use, it seems to be constant if not growing there. Lots of things to listen to!
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Their usage of 11 meters is insane too. Mexican taxicabs with Superstar 3900 export radios and 600 watt amplifiers to talk to their dispatcher 10 miles away. Latin America and Oceania are both still heavy users of HF. I imagine certain parts of Asia and Africa are too.
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6920 USB is active again at 1221 UTC Oct 8th not sure if this is the same group heard on the 5th but it sounds like it could be. Several mentions of two and three digit numbers....there are several other Spanish language QSOs going on in the 6765-7000 kHz range right now...
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I noticed this again last night, around the same time, 0103 UTC on 6920 USB. Hey - 7 days later. Is this a weekly net ???
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Sounds like it could be! We might have stumbled upon civil defense or another type of emergency service net (maybe the Latin American version of the FEMA SHARES network?)
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Hopefully somebody can keep an ear on or near 6920 kHz USB tonight and see if this is indeed a weekly net...would be further proof of organized HF-SSB networks mixed in with the fishing fleets and land-based freebanders/outbanders.
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It will be on my regular 43m SDR recording.
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Heard again at 0057 UTC on 20 Oct 2018 on 6920 USB, weaker signal this time, but the warbling tones are distinctive.
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We've discovered another regular net! Nice work, Chris
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I guess we can move this thread to utility?
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Indeed, Utility it is. I have a feeling its either part of a civil defense or government net (perhaps the Cuban or [insert Latin American country here] version of SHARES)?
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If someone can catch them on the air in real time, it would be educational to use TDoA to locate them. The transmissions are not very long, so you'd need to act quickly, and have some KiwiSDR's selected around the likely area in the Caribbean. Might take a few tries to get close.
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No sign of them last night.
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They were back again last night, 0100 UTC sharp with their warbling tones.
0100 SS OM with numbers and mentions of "frequencia"
This continued with good signals, and frequent breaks in the transmissions, until 0114 UTC.
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Heard again on the SDR recording a 0104 UTC 26 Nov 2018 with the alternating tones, then at 0107 what sounded like scrambled speech? That's new. Although it is possible it was just over modulated?
Around 0117 it was easier to understand, but with a lot of "clicking" in the audio.
Off at 0118.
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This is interesting. I wonder if they're using some sort of "scrambler" function or if, as you mentioned, its overmodulated or slightly off-frequency. Good to hear that they've been heard again.
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Back again last night, 0059 UTC 28 Nov 2018 with the alternating alert tones and SS OM with numbers and mentions of frequencias. Audio sounded normal. I thought I heard mention of Cuba/Cubanos but it could have been my imagination.
At 0103 I heard another, weaker, station.
Off at 0104.
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I think this is probably a Cuban public service or civil defense type net, going by what you've monitored. Hard to say for sure though - but I think with more monitoring we'll figure out it. Any chance you could get another recording next time you hear them?
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Here's a recording of last night's transmission: https://www.radiohobbyist.org/blog/mypics/6920usb28nov2018.mp3
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They sound just like Mexican speaking by the sound of there voice. Which has a sing songy style inflection.
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The cartels have actually kidnapped Mexican HAMs and forced them to create radio networks, not that there aren't likely to be cartel members with HAM licenses or military experience with hf, just that slavery is free labor.
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Indeed. Apparently there was/is a VHF/UHF digital DMR network built across various portions of Mexico for cartel comms. I'm sure HF is used extensively as well. Some of the "pescadore" comms seem suspect to me, but this isn't one of them. I think this is a civil defense net of some sort.
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Argentina, for sure. Calling several argentine towns (Santa Fe, Tucuman etc.)
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Indeed. Apparently there was/is a VHF/UHF digital DMR network built across various portions of Mexico for cartel comms. I'm sure HF is used extensively as well. Some of the "pescadore" comms seem suspect to me, but this isn't one of them. I think this is a civil defense net of some sort.
A friend's daughter was a coastie and her job was to fly around in some elint ship listening to those same guys radio traffic.
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Argentina, for sure. Calling several argentine towns (Santa Fe, Tucuman etc.)
Very nice! Proof that a lot of the stuff heard in the 6-7 MHz region is coming out of South America when the conditions are right. Reminds me of the rural radiotelephone activity centered in the 6700-6900 kHz region (most of it seems to follow the band plan for 6765 kHz being the bottom edge of the fixed/mobile band).
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Argentina, for sure. Calling several argentine towns (Santa Fe, Tucuman etc.)
Thank you very much for the confirmation!
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p.s. they were on again last night, 0105 UTC 12 Dec 2018 with the warbling tones, and then into the OM speaking. Good reception.
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Back again 0101 UTC 15 Dec 2018 with the warbling tones and then SS OM, but he only spoke for a minute or so.
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Heard again 0113 UTC 16 Dec 2018 - they were on later than usual. Alternating tones, then distorted OM speech. I now think this is more likely technical difficulties vs encryption.
Off at 0121
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Heard at 0104 UTC 18 Dec 2018 with the usual alternating tones and then SS OM. Good signal.
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0108 UTC - Heard the alternating tones and OM transmission then off at 0111 UTC Dec. 22, 2018. Signal was very weak but could make out the voice communication not sure of the language.
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Noted again on the SDR recording at 0107 UTC 31 Dec 2018 with the alternating tones and then announcements by a SS OM.
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0111 UTC 2 Jan 2019. Starting even a little later tonight. Usual format, alternating tones then SS OM.
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0058 UTC 3 Jan 2018 - On a little early last night. Very strong signal, but we had a good opening on 43m to South America with signals from Lupo Radio and the UNID pirate on 6934.8 kHz.
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On at 0100 UTC 4 Jan 2019 with a strong signal.
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I've noticed these transmissions nightly lately on the SDR recordings. Same format as always, and starting around 0100 UTC.
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Argentina, for sure. Calling several argentine towns (Santa Fe, Tucuman etc.)
This is the communications network that the Argentine federal police in HF to communicate with their delegations in the interior of the country 3 times per day at fixed times. The most stable is 6920 khz USB
Very nice! Proof that a lot of the stuff heard in the 6-7 MHz region is coming out of South America when the conditions are right. Reminds me of the rural radiotelephone activity centered in the 6700-6900 kHz region (most of it seems to follow the band plan for 6765 kHz being the bottom edge of the fixed/mobile band).