HFU HF Underground
Loggings => Other => Topic started by: ChrisSmolinski on October 23, 2013, 1151 UTC
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Mr Shrimper talking to Mrs Shrimper, asking if she got the email he sent. She could not hear him, so he said he would try the other channel.
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Also heard here with good signals, and I was quite surprised to hear an EE Shrimper Gal; first time here.
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Mr and the Mrs heard again last night around 0146z. I got the impression that the Mrs was on dry land with truck problems. Also ment they were moving to the alt freq of 8825.
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Also heard this as well - I know where that repair shop is they were talking about taking the truck to, lol.
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Also heard this as well - I know where that repair shop is they were talking about taking the truck to, lol.
So, you going for QSL #1?
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Shrimpers Swag Special: Bocephus, Budweiser & Beech-Nut :)
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Mr and the Mrs heard again last night around 0146z. I got the impression that the Mrs was on dry land with truck problems. Also ment they were moving to the alt freq of 8825.
Nice, now we know the alternate frequency - I never heard them say what it was. Isn't 8825 in the aviation band?
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I've figured out the selective calling system (the burst at the start of a QSO) they use, by the way. How much interest would there be in a decoder for it? Or, for those amongst you with a transmitter... an encoder? ;D
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Yes, 8825 is used by Gander and Santa Maria for the NAT's (North Atlantic Tracks).
Every aircraft has a decoder that's programed to a specific 4 letter 'tones' called SELCAL (Selective Calling)
The first two and the last two of the four tones are mixed (sent at same time like DTMF tones are made of two sets of tones) i.e. AD-HJ
Upon initial HF radio check in with Oceanic Control, we ask for a SELCAL check to make sure the decoder works and if there's propagation. After the controller sends the tones, we get chimes and lights, alerting us that ATC want's to speak with us. After check in, we turn the volume completely down so we don't have to listen to all the chatter and/or static for hours as we cross the Atlantic.
At the 30 degree longitude, we repeat the above for we are entering a different controlled airspace. i.e. Gander, Shanwick, NY, Santa Maria, etc...
The FEDs would love to know who they are, or where they are... QRMing aviation frequencies is not taken lightheartedly! Just look at all the fines the FCC dishes out to those to QRM aviation freqs.
From http://www.selcalweb.co.uk/faq.html#3
How do selcals work?
Each letter of the selcal code corresponds to a frequency in the audio range.
Alpha - 312.6 Hz
Bravo - 346.7 Hz
Charlie - 384.6 Hz
Delta - 426.6 Hz
Echo - 473.2 Hz
Foxtrot - 524.8 Hz
Golf - 582.1 Hz
Hotel - 645.7 Hz
India - not used
Juliet - 716.1 Hz
Kilo - 794.3 Hz
Lima - 881.0 Hz
Mike - 977.2 Hz
November - not used
Oscar - not used
Papa - 1083.9 Hz
Quebec - 1202.3 Hz
Romeo - 1333.5 Hz
Sierra - 1479.1 Hz
The frequencies are not harmonics, thereby reducing interference. The selcal is transmitted using Single Side Band, full carrier AM using an encoder such as the one shown below. Every aircraft HF radio contains a USB transmitter as well as an AM receiver in the same unit. The audio signal from the AM detector is connected to a decoding network that uses PLL (Phase Locked Loops) to identify the incoming signals (although many modern aircraft now have selcal decoders that use DSP circuits to decode the codes without the need for PLL). If the tones match what the aircraft is programmed for then a chime or gong will sound in the cockpit and a light will illuminate on the radio panel to signify which radio (HF1, HF2 etc) received the selcal tone. If the tones do not match then they are ignored and nothing happens
And No, I'm not a boat captain, just an aircraft captain! ;D
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Thanks, Captain...
Who do you fly for?
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One of those bankrupt ones! :-[
Well that narrows it down a bit eh? ;D
American Airlines
Presently now on B737, but was on B777 years back,
BOS-LHR and back every week.
73 de Kriss KA1GJU
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I've been working on my NECODE decoder. The shrimper transmission at 0146z on 25 Oct 2013 starting with this selcall: 3508 20
3508 20 was also noted at 0147z on 17 Oct 2013
3508 80 a little later at 0159z on 17 Oct 2013 and again at 0246z
I went back to some other recordings I had made, and found these:
3310 11
3511 10
3518 11
The 4 digit number is the station being called. The 2 digit number is the ID of the calling station: http://www.necode.com/322ARX_Manual.pdf
I'm going to try to document the selcalls they use, hopefully there aren't too many.
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I'll release a beta of MultiMode OSX with the NECODE decoder shortly. I'm working on adding a CODAN decoder to it as well.
In the mean time, I updated the SelCall desktop app (Windows and Mac) to properly send a NECODE call (previously I didn't have a field for the sender's 2 digit ID): http://www.blackcatsystems.com/software/selcall.html
It would be completely inappropriate to use this on 6925 with the Shrimper's call address. Especially when they're likely to be sleeping.
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It would be completely inappropriate to use this on 6925 with the Shrimper's call address. Especially when they're likely to be sleeping.
Yes, that would be inappropriate. The Shrimpers might have to vacate that frequency if someone were to abuse that feature.....