Teenager invents low-frequency radio for underground communications

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roadranger

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I wonder...

How "low" he had to go? I don't understand how different things would be at such a low frequency.
 

jackj

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No details in the short article. I wonder what frequency he is using? The navy has been using ULF radio for over 50 years to enable communication with their subs while submerged. But their system has a very low data rate because of the narrow bandwidth available at ULF frequencies.
 

kb2vxa

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"Texting" doesn't require a whole heck of a lot of bandwidth. One of the most efficient Amateur Radio digital modes, PSK31 requires only 31.25Hz for up to 50WPM (32bps), requires very little power and performs excellently under difficult propagation conditions.

Kids, texting, is there no escape??? YYYAAAAaaaa............

I live in a cave under the 99th floor of my block
And I sit at home where there ain't no window imagining the world has stopped
Then in flies a kid who's all dressed up just like a Union Jack
And says, I've won five pounds if I have his kind of detergent pack

I said
Hey, you, get outa my cave
Hey, you, get outa my cave
Hey, you, get outa my cave
Don't hang around texting underground!
 

Markinsac

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Built; Yes
Invented; No!
Maybe he didn't invent a new system. He did, however, find a use for an existing technology that could become a standard. Look at the avalanche transmitters people wear - old technology, new use.

What I do find interesting it the antenna system he built - lightweight, easy to assemble and take down. I'd never discourage someone from exploring new thoughts - always looking for new ways to accomplish something can lead to very interesting discoveries.

I'm hoping to hear more about his system - I'm sure the amateur radio magazines will have something before long.
 
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N_Jay

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Maybe he didn't invent a new system. He did, however, find a use for an existing technology that could become a standard.
No doubt it is a creative use.

I was taking more of swipe at the journalists who are supposed to know the meaning of words. (Even if they know little else). ;)
 

jackj

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"Texting" doesn't require a whole heck of a lot of bandwidth. One of the most efficient Amateur Radio digital modes, PSK31 requires only 31.25Hz for up to 50WPM (32bps), requires very little power and performs excellently under difficult propagation conditions.
Yes but my understanding of the navy's system is that a 3 letter code group takes around 5 minutes to transmit. It could be they are using a very narrow bandwidth to increase the signal-to-noise ratio, they are sending to the other side of the world after all.
 

jackj

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No Forward Error Correction at all. It's CW or morse code, at least the systems in the 70's and 80's were.
 

Delta

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I think that's pretty awesome. Art Bell should interview him that would be interesting. o.0;;
 

jackj

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Vlf; elf; ulf

I am fairly sure the VLF system has evolved beyond simple CW.

Communication with submarines - Wikipedia, the free encyclopedia
Per your Wikipedia link:

"Due to the limited bandwidth, information can only be transmitted very slowly, on the order of a few characters per minute (see Shannon's coding theorem). Thus it is reasonable to assume that the actual messages were mostly generic instructions or requests to establish a different form of two-way communication with the relevant authority."

CW was used because of the low bit count for letters with an average count of around 2.5 bits per letter. The maximum is 4 bits. ASCII requires at least 5 bits to cover all the letters. Yes, I read the article and I did learn quite a bit. Thank you for the link.

My understanding was that the system was only used for a very limited number of predetermined commands. i.e. contact by satellite. So there was limited need to encrypt the communication.
 
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N_Jay

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The old (cold war) joke, was it only said one thing; "Don't Shoot".

If it stopped . . .
 
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