IS LONGWAVE VIDEO TRANSMISSION POSSIBLE???/

[baker]

I was thinking since long waves travel so far, imagine if we could send movies on them. we could start a ring so the movie is passed around the world. One man recieves it, than re transmits it. It would take a bit of techniquell know how. But would be deadly. Shouldn't be too hard to build a reciever either. No more queued downloads are slow connnections. Everything would be done live.

Baker

[lattedfw]

There's a lot of talk about ultra-wideband networking. Your idea might be applicable to that somehow. Can longwave frequencies carry enough bits per second for a decent-quality movie/sound/data broadcast? 802.11b Wireless LAN hardware runs at 2.4GHz and only carries 11mbps,

[Xesdeeni]

When I was in the Navy, we used VLF at 10-50KHz (because it would slightly pentrate water for communication to the submarines), but it can only carry <100bits(!) per second (http://www.fas.org/nuke/guide/usa/c3i/vlf.htm).

Xesdeeni

[baker]

I think the WAY the signal is sent is important as the quailty of longwave radio is higher than telephone quailty and there are no gaps in the communication, a bitrate of over 56k should at least be possible.

Baker

[Mirror_Image]

If someone could explain how this has anything to do with "advanced conversion" we'd all be grateful.

[baker]

I would say modualting a digital signal then converting it to longwave radio with added protection bits is deffinetly advanced and is conversion of sorts.

Baker

[droolian01]

Hi there, what an interesting idea.
Unfortunately this idea is not practical, feasable or legal. It could also be dangerous.
The biggest problem as pointed out above is bandwith limitations. Listen to the audio quality of a longwave transmision. Trying to get just stereo cd quality audio down in the 200 khz area would use all the available band! (Don't think Radio 4 LW would be very happy with that!) You see there just isn't the space down there. E.g. Atlantic 252 is on 252 khz and Radio 4 is on 198 khz, so the space between them is only 54 khz (centre frequency). But up in the tv type bands (400 to 800 ish Mhz - can't remember exactly) there is so much space to fit all this data.

But of course these frequencies are strictly short range only. The limit for worldwide transmissions is around 30 Mhz, but this is VERY dependent on sun-spot cycle and the state of the ionosphere. Have you ever noticed that you can pick up distant medium wave transmissions at night but at sunrise they dissappear? Not only time of day but also time of year effects all this.

The radio spectrum is very tightly regulated because the potential of interference with services is not only restricted to close by frequencies, the disruptive effects can be felt way- way off from the base frequency due to harmonics. e.g. cb radio (27 MHZ) affecting tv reception (400-800 mhz). This is why the radio spectrum has to be controlled internationally (by the ITU - international telecomunication union) and very strictly.
An aside re: amateur radio - if you check the allowed frequencies they are almost exact multiples of eachother so that hams are less likely to cause interference to others - smart eh?

By the way i am a licenced radio ham. I had to pass a written exam the basic content of which is regulated and controlled by international treaty. I have a full class b licence which means that i can use all the amateur frequencies over the magic 30 Mhz. To become a class A ham i have to pass a morse code practical test - this would give me access to the shortwave and lower bands ond the possibility of world- wide coms. No one uses morse any more but to abandon this requirement requires international agreement and the ITU only meet every few years.

Radio hams launch their own satelites and i used to monitor some of them when i was an active ham but this is no good agiain due to bandwith probs.

Scott Spooner - M1 EPS (ham call sign)

P.s. Just setting up a usable antenna to do this sort of stuff (even a pre built one) is a technical nightmare ( or where the fun is!!).

[kwag]

Sorry guys, just won't work!.
You see, the carrier frequency must be higher than the information carried. In this case, low frequency waves, can only carry frequencies in the kilohertz range. If you look at the FCC's allocated spectrum, you'll see the maximum frequencies permited for each segment of the radio spectrum.

-kwag

[kwag]

Hey Scott Spooner!, how about a QSO down at 80 meters ( morse code, no voice )

73's
-kwag

[droolian01]

Hi there Kwag, i'll have to pass on the invitation i'm affraid for several good reasons:

-was only a B licence holder (is that equivalent to your no code tech licence)

-have let my licence lapse (didn't use the rig for over a year)

-my yaesu ft847 is thus boxed away.

-the only antenna i have is a homemade 2m dipole in the loft! (i think it's still there?!)

I will get back into this again one day, just got more into the computing over the last couple of years.

Hey, but just knowing another ham is around has got me interested again.
Writing my earlier post reminded me of how much i have forgotten/got out of touch with ham stuff.

Hmmm.... i wonder if they did get all the transponders on AO-40 working...........i wonder where my handheld is.......

[kwag]

Hi there Kwag, i'll have to pass on the invitation i'm affraid for several good reasons:

-was only a B licence holder (is that equivalent to your no code tech licence)

-have let my licence lapse (didn't use the rig for over a year)

-my yaesu ft847 is thus boxed away.

-the only antenna i have is a homemade 2m dipole in the loft! (i think it's still there?!)

I will get back into this again one day, just got more into the computing over the last couple of years.

Hey, but just knowing another ham is around has got me interested again.
Writing my earlier post reminded me of how much i have forgotten/got out of touch with ham stuff.

Hmmm.... i wonder if they did get all the transponders on AO-40 working...........i wonder where my handheld is.......

Great to hear all those familiar words
Well, my Kenwood TS-680 is boxed too and my long wire ( 90 feet ) is still hanging! But like you, I'm more into the Net, than hamming.
I still do practice my code ( Listened on 40 and 15 meters lately? ), as I did go up to 40WPM TX/RX speed, but now I'm around 20WPM again ( Way rusty ) But to me, it's like riding a bicycle, you just never forget, once you got to a level of expertise. And to me, morse code is music

So this is off topic now , if you want to add something, go ahead and PM me or see me at kvcd.net

Later,
-kwag

[baker]

I am still thinking of this. I still think digital transmission is possible

Baker

[BJ_M]

there is a power grid covering each land mass -- yes there are transformers and what not .. but if electrons can flow to any point --- so could a Carrier wave on the same grid ... it has even a built in clock signal -- 60hz or 50 depending ...

[kitty]

Baker - take a digital and/or analog information theory class and look up your country's spectrum limits (US it is the FCC). They have the whole spectrum planned out - if you go using someone elses frequency you'll get blasted.

Now if you go to Afghanistan I hear they don't have a government to regulate such things. If you go transmit longwave from there we'll be listening with our PCs over here.

[baker]

So in theory I could go to afghanastan devlope long range video transmissions and transmit films,football etc for free for everybody in europe to watch?

Baker