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HFDL decoding

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rabrol

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#1
Hi Folks.

I've just been trying my hand at decoding HFDL with PC-HFDL trial version. I'm discovering something rather interesting.

I figured that since aircraft generally attempt CPCDL via VHF first, Satcom, then HF, I would not see position reports over or near land on HF. However I am receiving lots of position reports on the HFDL frequencies showing aircraft over the US, Canada, UK, Europe etc (in addition to the Oceanic / African stuff I was expecting to see).

Why are they not simply reporting position on VHF via ACARS when they are in VHF range?
Is it quite common to have position reports on HF when over Continental US or Europe?
 
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#2
Hello rabrol!

I believe this reports going direct to the home -base of the Airline! I decode Inmarsat Acars and I think thats the same.

regards G.
 

rabrol

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#3
Hello rabrol!

I believe this reports going direct to the home -base of the Airline! I decode Inmarsat Acars and I think thats the same.

regards G.
I was wondering if it had something to do with the changes made since MH370 went missing. A lot of the aircraft are giving quite regular HF position reports, all over North America & Europe. I've been really quite surprised.

I am preparing to move house this Summer, but once at my new place I think I'll want to feed HFDL data into the PlanePlotter ADS-B monitoring setup. I'll probably experiment with the VHF ACARS and VDL2 as well, but if most of that data is replicated via HF, then I might just stick with that.
 
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#4
Hi!
It make fun to decode ACARS -VHF maybe a range of 300 km here in Austria, HFDL- ACARS up to 10.000 km and Inmarsat Acars up to the last Corner of the world! I will say all Acars Decoding is interesting for me!
 
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#5
If I let a decoder go all day on hfdl, the mapping feature shows planes all over the US, Canada, and Central America/Caribean so it is perfectly normal. Sure they could use acars but they already have hfdl installed and running too.
 

DaveNF2G

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#6
Position reports are not replicated between the different services. Each flight sends reports on one mode and switches only if data are not getting through or if regulations/policies require it.
 

rabrol

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#7
Position reports are not replicated between the different services. Each flight sends reports on one mode and switches only if data are not getting through or if regulations/policies require it.
I understand that only 1 method would be used. I'm intrigued as to why so many aircraft are still on HFDL when the VHF & Satcom would also be possibilities.

I could understand some airlines in certain countries using HF because they don't want the expense of Satcom installation & monthly charges, but many of these aircraft have all 3.

So why would FANS opt to TX on HF over the other options? What regulations / policies would dictate that?

BTW I installed Sorcerer yesterday, hooked up to a web-based SDR in Massachusetts. That receiver was pulling in signals from Ground Stations in Bolivia, New York, San Francisco, Iceland, Shannon, Grand Canaria & Bahrain. Was amazing fun watching the reports come in and verifying location on flightradar24.

Received planes inbound to San Francisco from Hawaii, all across Continental US, Canada, Atlantic, Europe & Middle East. It is very interesting to see how a plane over Russia will communicate with the Iceland ground station, while a different flight will connect with Grand Canaria or Shannon from almost same location. Propagation is always fun!

I have also been impressed with the ability of HFDL decoders to perfectly decode the reports. Seems a lot more robust than HF voice.

Sent from my PH-1 using Tapatalk
 

ka3jjz

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#11
MultiPSK and Sigmira both also decode HFDL...and Sorcerer has a known bug that it will show incorrect site names because it's using a very out of date table listing. There's a way to make it use the latest tables, but unfortunately I don't know how that's done.

Mike
 

ka3jjz

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#17
You will need an audio, not a USB, cable from your R75 to your PC. USB really isn't meant for transfer of an analog audio signal. Also check your PC - it's not at all uncommon for inputs to be muted coming out of the factory. Check your system tray and make sure whatever you are plugging into is not muted.

It's best to use the REC jack on the back of the radio. Most software won't like having too much audio; overdriving can cause garbled junk where actual text is sent. When you make the connection, it's likely you will need to fiddle with the levels to get them right. This is perfectly normal and varies from PC to PC.

Mike
 
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