Can radio-transmitted data be stored?

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Offline bbot23

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Can radio-transmitted data be stored?
« on: 12/11/2010 19:19:38 »
I am totally oblivious to how data transmission works, so bare with me.

My question is very general, so let me ask it more practically: a population in Northern Africa has no access to the internet because it's too expensive, but has access to radio frequencies. Theoretically, with the right device, could this population "download" information and store it via an antenna over-the-air? Not just audio, but video as well.

I know traditional tv broadcasting uses radio to transfer video and essentially "stream" it, but could it be stored in much the same way as a file is transfered to a computer from the internet?

Also keep in mind that i'm referring to over-the-air transmission via an antenna. No cabling whatsoever, and no internet.

And how fast would this transfer be if possible? (Or how slow, rather)

I apologize if the question screams an obvious answer...


Offline Geezer

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Can radio-transmitted data be stored?
« Reply #1 on: 12/11/2010 19:50:21 »
That's a good question.

It's quite practical to transmit large amounts of data over a very large area using radio frequency transmission. One way to do this would be from some satellites like the satellite TV transmission systems common in many parts of the World. They don't require much ground equipment to receive the signal.

The difficult part is that, to use the Internet, you need some sort of two-way communication, so the user also has to be able to transmit a signal into the Internet. This either requires some rather expensive radio transmission equipment, or a well established communication infrastructure.
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Offline techmind

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Can radio-transmitted data be stored?
« Reply #2 on: 07/12/2010 21:30:28 »
If you think back to the early 1980's we used to record computer programs and data on audio cassette-tape...
beeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep warble warble warble warble warble warble beeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep warble warble warble warble warble warblebeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep warble warble warble warble warble warblebeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep warble warble warble warble warble warble   etc  [:D]

You could (and people did) transmit this over mediumwave or FM radio (save your ears, turn off the speakers!). Those systems typically transferred data at 1.2k bits per second. Very slow.

In principle, you could use coding similar to a modern (c. late 1990's) dial-up modem, and transfer data at around 40-50kbps over a standard FM radio transmission. This would sound like white noise.

Digital terrestrial and digital satellite television systems could be used to broadcast digital "data" natively, at a rate of around 2-5 megabits per second per "TV channel" - they normally bundle 3~10 programs together in a "multiplex" transmission with a total data rate of typically 19 to 27megabits per second.

As a previous poster commented however, this would be non-interactive.
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Offline CliffordK

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Can radio-transmitted data be stored?
« Reply #3 on: 07/12/2010 23:28:16 »
There are a couple of types of wireless data transmission that are in use.

As mentioned, Satellite transmission is available anywhere one has the view, I think of the southern sky from the North.  There is supposed to be a few millisecond delay in the handshaking, generally not a problem when transmitting large packets of information, but it can be problematic for transmitting random small packets of information.

Another method.
Most new laptops are coming out with 802.11(a,b,g,N) WIFI wireless internet access.
You can take it to your nearest coffee shop, and access their internet.

There are some providers that go to a rural community, erect a tower on a hillside to broadcast the 802.11 WIFI, and then sell the access to the system to the neighbors.  The range is the "visible range" to the hillside, and can be several miles.  Special directional antennas are of course required to pick it up.

Sometimes when wiring a jobsite, the WIFI is easier to provide internet access to multiple users in diverse locations than hard-wiring the entire area.