Digital TV Transmitter Using a VGA card

An anonymous reader writes "Yet Another Project from Fabrice Bellard : with any PC and a standard VGA card, you can build a real Analog or DVB-T Digital TV transmitter by directly generating the VHF signal. The provided example shows a Lena picture transmitted as a real Digital TV channel."

Now lets get some NTSC

[ankhcraft]

Once someone posts how to do this with NTSC (which you'll need if you're in the U.S. like me), I'll be all over this! Anyone? Enlighten me...

Has been done with music for a while

[m50d]

There's an X program that can transmit an MP3 to your radio by displaying pictures in certain ways. Quality's not too good, but it works. I guess it was just a matter of time before people did it with television.

It also goes to show TEMPEST attacks are real. Your screen is transmitting what's on it in a way that's detectable over quite a distance. Shielding is worth looking at if you're doing something sensitive.

very clever

[Anonymous Coward]

+1 point
shame he wont tell/show anyone how its done (ie. the source code)
-2 point

Re:Has been done with music for a while

[Evil W1zard]

TEMPEST based attacks have been proven as viable a long time ago and I'm not sure this would qualify as a TEMPEST issue as you are purposefully broadcasting a signal for reception... Now if you are only considering sending the signal to your TV set and only your TV set then TEMPEST would be a concern (but considering the cost of some TEMPEST equipment I don't think that is much of a worry for a home user trying to mod out their home equipment).

The Lenna Story.

[British]

....is more interesting than the main one. At my company when I started 6 years ago, I stumbled upon the Lenna picture, just thinking it was an ordinary pic. Few years later I saw the er, um "full" pictures. Didn't know she had a cult following.

Yes, that Lenna picture I assure you is still in use after all these years. A pretty "hello world" image.

ATV

[leighklotz]

You can do ATV [nasa.gov] legally in the US with NTSC, with a ham license.

You can see this the video for yourself, with stuff you have at home right now. There are cable channels that are on ham bands, but it's OK because their signals stay on the cable.

If you live in the SF ba area, hook a UHF antenna (vertically polarized) to your cable-ready TV or VCR with TV out, and tune to cable channel 57 (421.25 MHz), and aim it at Mt. Hamilton (east of San Jose).

Here are some tests on 1.2GHz [nasa.gov], which is also a ham band.

Re:crap ..

[harrkev]

The funny thing is that I saw the edges of that picture on the original web page. That looks just like the "lena" picture that I used to use at a target back when I took my image processing class. That "lena" was a picture of a girl's face wearing a fancy hat.

Is this new picture different?

Re:Has been done with music for a while

[UserChrisCanter4]

About ten years back, my brother had a very simple watch/PIM (Personal info manager, for those of you unfamiliar with term) made by Casio, IIRC. The unique feature was that you installed a driver which allowed the data input program to mess with your refresh rate (I'm guessing) and transmit the information to the watch. It usually took four or five tries to get it right, but I remember being pretty impressed with the unique method that helped avoid keeping track of a dongle/connector.

Re:Has been done with music for a while

[csnydermvpsoft]

I used to have one of these as well. I always thought that it worked by displaying a pattern of lines on the screen, which the device then picked up.

Guerrilla television in 2007

[Simonetta]

I suspect we may start to see illegal broadcasts in 2007 in poorer urban neighborhoods of the USA.

With all broadcast television on VHF/UHF scheduled to cease on New Years Day 2007, there are going to be a lot of pissed off people who don't have cable getting nothing but static on every channel.

This is assuming that UHF/VHF broadcasting actually does go off the air Jan 1, 2007. It doesn't seem likely at this time, but it is mandated by the TeleCom Act of 1996. And one never knows what the current administration is going to do.

Let's assume that it does happen. All the middle-class people won't notice it because they are paying monthly cable fees and cable TV will not be affected by the VHF/UHF shutdown. However, let's assume that in poor neighborhoods the convertor boxes don't work well, or are prohibitively expensive, or are too technically complex for the general population. Suddenly there's no television.

Well politics abhors a vacuum. We may find ourselves in a situation where people simply start pirate broadcasting on the unused television channels. This will probably cause problems with the new uses of the spectrum (private cell phone communications, I believe). The FCC will be really busy trying to track down pirate TV stations. Pirate TV stations are rare now because they can't compete with broadcast network quality, and there are outlets on local cable access for speciality and non-professional broadcasters.

But with the UHF/VHF channels gone off the air, people will start filling it up with DVD broadcasts. Maybe even porn broadcasts. Unregulated, and without commercials. All illegal.

These channels could become political if there is an economic downturn or a return of conscription into the permanent, endless war that the administration has promised the defense contractors and campaign contributors. Alternative broadcasts of police beatings at demonstrations made by tiny CamCorders alternating with current Hollywood movies downloaded from the DarkWeb could become common content on the new pirate channels.

I wonder if anyone is considering the possibility of this happening before they decide to shut down UHF/VHF broadcasting in 2007?

Re:Guerrilla television in 2007

[antrik]

Sorry for disspelling your very original fantasies... but nothing of that kind seems to be happening here in Berlin, where they did shut down analog TV broadcasts some two years ago.

The frequencies are reused for the new digital broadcasting -- there are now about five times as much stations available, and posing a considerable threat to cable television: As cable is still analog, you get the same number of channels in a better quality for free on air... Only thing you need to pay is buying the receiver (< $100) once.

Re:It Won't Be Long

[tylernt]

Consumer electronics that are unintentional radiators (FCCspeak for 'transmitters') are Part 15 devices. Actually, you can have intentional radiators under Part 15 was well, but the rules (power levels etc) are higher. Part 15 is usually where cordless phones and garage door openers operate.

You are allowd to build up to, I think, 5 homemade Part 15 intentional radiators without getting them certified by the FCC. The maximum power levels are pretty low though, 100mW IIRC. A 100mW signal will go a few hundred feet at best.

My understanding of Part 15 is limited to FM voice communications. I have no idea if images (TV) are also allowed under Part 15.