Format on 8983 and 17966 KHz ?

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Intellifax

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What type of digital signal is on 8983 and its x2 of 17966? It is not standard HFDL, although it looks similar. It has a pilot tone like HFDL, but the signal is slightly wider and usually a bit shorter in duration. It is repeated at 5 second intervals, with occasional added data making the signal a bit longer. It is a good signal on both freqs 24/7 in the Great Lakes area. The 17966 sits right next to the 17967 HFDL station from Al Muharraq Bahrain, but I can usually copy Bahrain in the local morning despite the interference.
 

Token

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I am listening right now on several remotes in the Lakes area, nothing heard digital on either freq. Is it only certain times of day / night? I do hear, and often do, CAMSLANT on 8983 kHz USB.

T!
 

Intellifax

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Its on 24/7 on 8983, and I can hear it most of the time on 17966. Its 2320Z now, both are going strong.

Is it possible its from a local airport? I'm 3 miles south of KTOL. I know they use a lot of data signals in the VHF area (lighting [various 172 mhz freqs], windshear towers 162.275, ANG barrier telemetry 139.875, etc).

Hear it on 3 different HF rigs here, Icom R8500, NRD525, SDR with HF converter, so its not a product of the radio.
 
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DaveNF2G

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Could it be ALE (Automatic Link Establishment) on an idle net?
 

vagrant

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I recognized the 8983 kHz after digging around for some U.S. Coast Guard frequencies recently. 17966 is also a known CG frequency. I'm listening to 8983 now and I hear the data burst. You're quite right that it does sound very similar to HFDL. Most of the bursts I heard were long like HFDL, or even longer.

As to the type of digital signal, I do not know. /speculating/ Perhaps it is a telemetry transmission.
 

Intellifax

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I was way up in the HF section looking around, rarely go up that high. Found this same signal on 26949, which is the x3 of 8983. It is VERY wide and strong. Makes me wonder if this is the actual originating signal, and the others are spurious emissions of that signal. I agree, it does sound like some sort of telemetry or data signalling, since it is regular at every 5 seconds with the occasional extra data thrown in.
 
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