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."

Comments

ANOTHER one!!

[Anonymous Coward]

Wow, *another* project from Fabrice Bellard? DAMN!!!

By the way, who the hell is he?

Re:ANOTHER one!!

[gg3po]

I know he's the guy behind ffmpeg (used by most *nix media players) and the excellent qemu emulator that I use every day.

Re:ANOTHER one!!

[quinto2000]

Wow, your "mod the parent insightful" in the signature trick works pretty well. Second time I've seen it in action...

Re:ANOTHER one!!

[mlrtime]

It should have some html to make it look a little more original. Thanks for the reply too!

Re:ANOTHER one!!

[hostyle]

And your "miss the obvious, making a fool of yourself in the process" trick seemed to have a very similar effect.

Re:ANOTHER one!!

[gg3po]

This should be modded insightful ;-)

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...

Re:Now lets get some NTSC

[ebh]

I imagine that would be pretty tough, since NTSC is interlaced, unlike PAL or SECAM. but I can't say for sure having never hacked broadcast video RF signals.

Re:Now lets get some NTSC

[grub]

You can get progressive scan HDTV in North America, no?

Re:Now lets get some NTSC

[terrymr]

Both of those are interlaced too ... pal is really NTSC with some minor tweaks and I expect the same goes for SECAM

Re:Now lets get some NTSC

[ankhcraft]

You can get progressive scan HDTV in North America, no?

Yeah, but that would be even *harder* to do here. (read: impossible)

Re:Now lets get some NTSC

[bullitB]

PAL is also interlaced.

The correct analog (as in "analogy," not as in the opposite of digital) for this would be a mechanism for making an ATSC transmission. which could be tuned into from an OTA HDTV tuner. You could encode 1280x720 progressive ("720p") or 1920x1080 interlaced ("1080i") video signals into MPEG-2 then send that to an HDTV.

Not sure how far people have gotten rolling their own ATSC transmitters, tho.

Re:Now lets get some NTSC

[no_such_user]

a) NTSC wouldn't be a good comparison, as NTSC (AFAIK) only defines analog color broadcasting. ATSC would be the equiv here in the states.

b) The interlaced part wouldn't be the stumbling block -- 720p (aka progressive scan) is one of the ATSC standard modes. The hard part would be the 8VSB modulation, which is a totally different creature than the 16QAM modulation used in the european standard.

That said, WHAT A NICE HACK!

Re:Now lets get some NTSC

[no_such_user]

Hmm... wait. I guess he does provide analog PAL and SECAM modulation. Oh well -- yeah, NTSC would be cool too.

Re:Now lets get some NTSC

[b1t r0t]

HDTV in North America uses ATSC/8VSB, not DVB-T/COFDM. It also sounds like the guy in the article "cheated" by using a DVB-T modulator. I can't see anywhere that shows where the MPEG stream to feed into the modulator came from.

The best part of TFA is at the end where he gushes about "This project can be the basis for foo, bar, and baz", then at the end "Where is the source code? It is currently not available, although I plan to release it someday, provided enough people ask me to." Sounds like "this project" can be the basis for approximately zilch right now.

Re:Now lets get some NTSC

[b1t r0t]

Oh gee whiz... I think I figured it out now. What he did was make a grayscale image that resulted in a signal which was equivalent the unmodulated data stream. So the VGA card was esentially being used as an enormous shift register. In that case, it would definitely take some work (and an 8VSB modulator) to make it generate ATSC.

Re:Now lets get some NTSC

[nightznoe]

Actually no. PAL is pretty different from NTSC, PAL used 50Hz and NTSC is on 60HZ (interlaced). This has to do with the electrical system used in Europe vs. NA. Also PAL and SECAM uses different scanning velocities than NTSC, mainly due to the fact that PAL has more lines. Another major difference is PAL and NTSC signal bandwidth, IRC from my digital video compression course. PAL has an 8MHz per channel bandwidth, and NTSC only has 6Mhz.

Re:Now lets get some NTSC

[Anonymous Coward]

I guarantee you, your time and money would be better spent buying an existing item to do such a job. A couple good products for such a job are sold from a little company in South Dakota named Sencore, the HDTV 996 or a ATSC 997 would do the job pretty well. They have some newer things, even a PCI card, shame the catalog hasn't been updated in a while.

Re:Now lets get some NTSC

[Anonymous Coward]

You might want to mention the primary difference, the very reason why PAL is called PAL (Phase Alternating Line). Contrary to NTSC, PAL inverts the phase of the signal every other line. This cancels out phase errors and provides a much more stable color reconstruction. NTSC is jokingly referred to as "Never The Same Color" because it uses a manual tint control to correct phase errors.

Re:Now lets get some NTSC

[Anonymous Coward]

Actually NTSC and PAL are related, SECAM is totally different. Notably PAL includes some protection against phase-disturb that make it a lot stronger than the Never Twice Same Color

Re:Now lets get some NTSC

[Khyber]

Just as a side note for those that don't know.. NTSC is standardly 60hz (60 fps for those not that able to comprehend the other uses for the word hertz) while PAL is 50hz. Done in computer video, it's 29.97 and 25 FPS as digital.

Re:Now lets get some NTSC

[taniwha]

you're both right - PAL and NTSC's colour encoding is similar (PAL reverses its phase every other line to help with the sort of interferance caused by your neighbour's electric drill). PAL does use more bandwidth and a slightly different color space and can render more saturated colors than NTSC (think bright eye grabbing adverts). PAL also has more pixels/screen (better resolution) but a lower frame rate (not so good for sports) - this has more to do with the underlying B/W TV standards they were built on top of though, which in turn were based on the local power line rates (in order to avoid AC humbars on those old B/W sets

Re:Now lets get some NTSC

[ltbarcly]

NONONO PAL is significantly different then NTSC. There is more color information inm the PAL signal but a lower frame rate.

The resolution is also slightly different.

Re:Now lets get some NTSC

[Cramer]

You're confusing fields and frames... NTSC has 60 interlaced fields per second generating 30 frames per second. The reason you generally cannot see that flickering is due to the retentative properties of your eyes and the phosphor pixels in the TV. PAL is the same at 50 fields / 25 frames.

Re:Now lets get some NTSC

[jelle]

Actually black-and-white was 60Hz, NTSC is 60*1000/1001 Hz (which results in the ~29.97Hz frame rate). The reduction was done to remove some interference for the color signal.

Re:Now lets get some NTSC

[spaceyhackerlady]

Then there is Séquentiel Couleur avec mémoire (System Essentially Contrary to the American Method to its critics).

It sends the luminance signal on every line, but only sends one of the two colour subcarriers on each line, getting the other subcarrier from the preceding line.

Invented in France, popular in the former Eastern Bloc. Dunno.

...laura

Re:Now lets get some NTSC

[JLF65]

No, 60*1000/1001 Hz is just a close approximation made by video player programs. The actual frequencies are derived in this manner:

The color sub-carrier is 3,579,545 Hz. This was chosen because it makes all the harmonics work to interleave the color and luminance spectrums.

There are exactly 227.5 phase changes per horizontal line. This is the source of the saying Never The Same Color. It is also why PAL inverts the phase on every other line. Their sub-carrier isn't the same frequency, but it's derived in a similar manner.

3579545/227.5 = 15,734.26374 Hz which is the number of lines per second. There are 525 lines in a frame yielding 29.97002616 frames per second. Since NTSC is interlaced, this yields 59.94005233 fields per second.

Now you know where all the numbers come from. :)

Re:Now lets get some NTSC

[connorbd]

NTSC is easy. You can get a kit from Ramsey Electronics and plug a camcorder into it -- whole thing comes out under $300 if you use a Hi8 instead of a DV camcorder.

Re:Now lets get some NTSC

[connorbd]

Depends on who's transmitting. 720/30p is the common progressive scan format, while interlaced is 1080/60i. You have the same choice with camcorders -- JVC is 720p, Sony is 1080i.

Re:Now lets get some NTSC

[Goth Biker Babe]

Actually the tweaks to NTSC are relatively minor. PAL was derived from NTSC once the problems with NTSC were seen. The basic signal is not that different and apart from frame rate (see below) the monochrome signals are compatible.

The reason there are more lines is because the frame rate is lower (because, as you say, the frame rate was linked to the mains frequencies - 60 interlace frames per second in North America and 50 virtually everywhere else) and there's longer time to display the lines. Essentially the same amount of information is handled in a second on both systems.

On PAL they've reversed the phase of alternate colour lines compared with NTSC although the lines are produced in the same way. This means that systematic phase shifts, caused by same atmospheric effects, are cancelled out removing the need for the Hue knob.

Finally the bandwidth comes from NTSC originally being broadcast on VHF and PAL on UHF. The higher frequencies allowing a greater bandwidth.

Re:Now lets get some NTSC

[ThJ]

PAL and SECAM are interlaced as well. PAL frames have 576 lines at 25 FPS. PAL fields have 288 lines at 50 FPS. Same goes for SECAM.

Re:Now lets get some NTSC

[N Monkey]

imagine that would be pretty tough, since NTSC is interlaced, unlike PAL

Errrr....
IIRC, PAL stands for "Phase Alternate Line" which basically means interlaced....

Re:Now lets get some NTSC

[marcansoft]

Except 3.579545Mhz, the color subcarrier.

The color subcarrier has to be between about 2Mhz and 4Mhz to prevent interference with the luminance signal and the audio carrier (4.5Mhz above video). 3.58 is chosen as a good number giving little interference and a very small response in old B/W sets, while still having enough bandwidth for color and not getting into the audio subcarrier space.

The old line frequency is 15,750Hz. Then you get the audio carrier, 4.5Mhz, and divide by 286 which gives 15,734.2657Hz. 286 is the even number that results in the closest approxmation to the old frequency. The frame and field numbers are calculated as you said. Then, the color frequency is the 455th harmonic of half the line frequency, or 15,734.2657/2*455 = 3579545Hz. 455 is the odd number that gets it closest to 3.58Mhz. All this helps minimize interference.

Some of my numbers are slightly different from the parent's, but those are just rounding errors.

Re:Now lets get some NTSC

[rec9140]

SECAM was designed by the Russians & French for the exact purpose its not so elegant acronym stands for. It was designed so those persons in Communist Block countries and especially East Berlin could not receive outside bourgeois propaganda.

Re:Now lets get some NTSC

[terrymr]

The phase alternation only applies to the color signal not the luminence information.

Re:Now lets get some NTSC

[JLF65]

Nice description. I was going to cover that, but thought it a little beyond most folks.

Re:Now lets get some NTSC

[canavan]

Not quite correct. PAL and NTSC are just standards for color coding, and have not much to do with the Black&White picture that goes along with this. They are erroneously associated with 480i and 576i video signals, respectively. However, Brazil uses 480i with PAL Color as their broadcast standard, which is called PAL-M (the M is essentially a standard for transmitting a 480i b&w picture), as opposed to the NTSC-M used throughout the rest of the americas. I think the most common broadcast standard in Europe is PAL-G (again, the G is a standard for 576i).

Re:Now lets get some NTSC

[taniwha]

actually I think this is exactly the 2nd point I was trying to make - that the differences between 'NTSC' and 'PAL' (as most of us think of it) as far as pixels/screen and frame rate are more to do the underlying B/W standard they were built on

Kill those Utah lawmakers!

[garcia]

coming right after the story about Utah? Slashdot, are you trying to cause the Utah law to fail?

Re:Kill those Utah lawmakers!

[Anonymous Coward]

In Soviet Russia, Lena has pictures of you.

Re:Kill those Utah lawmakers!

[garcia]

This coming right after the story about Utah? Slashdot, are you trying to cause the Utah law to fail?

Sorry for the bad link in the original. I should have previewed first, I know :(

Re:Kill those Utah lawmakers!

[Anonymous Coward]

How about "sorry for slashdotting lenna.org?"

This coming right after the story about Utah? Wayback, are you trying to cause the Utah law to fail?

Re:Kill those Utah lawmakers!

[NitsujTPU]

Quick note, the parent is a little NSFW.

Re:Kill those Utah lawmakers!

[Anonymous Coward]

Nah, they're just doing it all for Lenna.

Re:Kill those Utah lawmakers!

[the arbiter]

Most subtle Billy Joel reference ever. I tip my hat to you, good sir.

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.

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).

Re:Has been done with music for a while

[Rei]

You're talking about Tempest For Eliza". I never got the "broadcast an mp3" function to work, however - only the broadcast using their special midi-like files. A shame, really. Still, even the midi-like broadcasts make for a neat geeky party trick, and demonstrate the power of tempest ;)

Re:Has been done with music for a while

[Anonymous Coward]

He didn't say this was a TEMPEST attack. He said it shows that they are real. In other words, it demonstrates to the unbelieving that there is a link between EM waves and what shows up on your tube.

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.

Re:Has been done with music for a while

[UserChrisCanter4]

Now that you mention it, I think you're correct. It's been a while, and I only remember seeing my brother holding it up to the screen. I suppose the line method would probably be easier to implement, as well.

Re:Has been done with music for a while

[Tokerat]

I'm not sure this would qualify as a TEMPEST issue as you are purposefully broadcasting a signal for reception.

I think he meant the fact that this works in the first place proves the concepts behind being able to perform a TEMPEST attack are entirely plausible.

Re:Has been done with music for a while

[wolrahnaes]

I had one as well (It was Timex, by the way), and it did work by a pattern of flickering lines, but your parent post is right as well. When I upgraded from a Rage Pro to a Rage 128, I had to install a TSR (this was on Win98 btw) from Timex that allowed the DataLink software to override the graphics driver and use a pure VESA mode that matched a certain refresh rate the watch wanted.

I always thought that thing was pretty cool, even if a dongle would have likely worked faster (not to mention that NT systems and LCDs did not work, so you had to get a serial dongle with a flickering LED anyways).

Re:Has been done with music for a while

[hawk]

How much more does it prove than a 360 era machine playing tones on an AM radio???

hawk

Neat Idea

[wackysootroom]

This is a great idea. If there is a way to make the signal just a bit stronger you can hack your own wireless media center.

Re:Neat Idea

[connorbd]

Your mileage may vary depending on location, but the only thing you could get away with in the US is doing it on an amateur frequency. The Friendly Candy Company might turn a blind eye on a pirate TV operation that doesn't extend past a city block, but it's technically illegal.

Re:Neat Idea

[dascritch]

In fact, he is xcustomer at Free (a french ISP) as I, and this one gave to every ADSL subscriber a Linux modem called "Freebox" that permits IP/Telephony/TVoADSL .... but Free is promoting for monthes about a mysterious "Armageddon". Last rumours wants that "Aramgeddon" stand for sending video from the pc to the tv via Freebox's SCART plug. As every Free subscriber, he was too impatient, so he looked at his ATI spare card, an unuseful DVB-T receptor and...

It Won't Be Long

[geomon]

Until this project is rendered illegal in the US under some DMCA-style bullshit. After all, you might be able to (gasp!) record something off of your incoming television signal.

Of course, only pirates and pedophiles will have a use for this project.

(The last part of this post is a JOKE, gawddammit!)

Re:It Won't Be Long

[HTH NE1]

Until this project is rendered illegal in the US under some DMCA-style bullshit.

More likely it would be something originating from the FCC. Unlawful use of radio bandwidth without a license, use of a class B device to intentionally generate interference (a competing unlicensed coherent signal is interference, but I may have the wrong class of device).

Re:It Won't Be Long

[SomeoneGotMyNick]

My HAM Radio license allows me to use a small portion of the UHF band to broadcast video at low power. However, I must have my call sign in the picture or as a 'bug' in the video image.

Whatever method I use to generate the signal, as long as I remain within the power and frequency band, there's not going to be any major problems.

I'd love to be able to generate an NTSC signal like this. Some of the transmitters for HAM radio are expensive.

Re:It Won't Be Long

[M1FCJ]

They are not that expensive but I never did any ATV work myself either.

Re:It Won't Be Long

[gl4ss]

..or maybe you should have read the project page?

it's not exactly.. hmm. shall we say, useful for anything. but a very fucking neat hack never the less.

(not about recording at all - but creating tv signals from your vga cards vga-output...).

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.

Re:It Won't Be Long

[glitch23]

It better be a joke because I have a use for it and I refuse to be labeled a pirate.

Re:It Won't Be Long

[connorbd]

The rules are somewhat different for TV, and fairly complicated for Part 15 in general (the 100mW rule applies only on the AM broadcast band, for example). You might get away with a small local link that doesn't interfere with anyone else, but if you want to experiment with this stuff you're far better off getting an amateur radio license and doing your experimenting on the 70cm band -- that's where most of the ATV people in the US hang out (the allocation is different in Europe). The power limits are a lot less stringent at that level, and you can use an analog cable box to tune in the analog signals.

Re:It Won't Be Long

[connorbd]

Ramsey Electronics sells a couple of ATV transmitters as well. They're interesting -- sort of like video bugs, though they don't come with a camera.

very clever

[Anonymous Coward]

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

Re:very clever

[pslam]

shame he wont tell/show anyone how its done (ie. the source code)

The only thing he hasn't explained is how he generated the raw unmodulated DVB and PAL signals. PAL is pretty text book and there's no need to explain it. Creating a DVB signal is a huge project in itself. You can look up the details relatively easily and freely, and I think the GNU Radio project even has one.

As for the signal generation, he's given you the XFree86 timings, and explained the calculation behind it. What more could you want?

The clever bit is the way he's worked out the correct VGA timings and used harmonics to place the DVB signal at just the right frequency to be received. It's an underused trick you can do with DACs and ADCs: if you turn off the filter (or just have a crappy one like VGA cards do!) then you can reach frequencies far above half the sampling rate, with certain restrictions. It doesn't defeat nyquist - you basically move the "band" you're looking at to somewhere other than starting at 0Hz (DC). If it's a hack like this one which doesn't have an appropriate bandpass filter, you get a lot of crud in your signal, but presumably it's not enough to destroy the signal altogether.

I assume there's an issue with the Hsync and Vsync which aren't eliminated - but at a 76.5MHz pixel clock, it's probably a small enough glitch to not matter.

It's a nice trick I've been thinking of using for DAB (digital audio) receive and transmit, but I never thought of using the VGA in this way!

oh man..

[p373]

The slashdot effect + a nudie photo. Say goodbye to that server.

what the..

[Bauguss]

who in their right mind would post a link to a site with a playboy nude on it to Slashdot???

Talk about asking for a slashdot "effect"

Mass panic

[parasonic]

Now if I had some DV software and a little time, I could do a re-play of the "Martians are attacking us!" program. A re-creation of that 50's-ish alien invasion hysteria to my roommate or next wall neighbor. What advanced alien race wouldn't transmit digital TV?

Re:Mass panic

[ScrewMaster]

Pretty much all of them wouldn't ... I mean, a truly advanced race would have evolved beyond the need for sitcoms, "Reality TV" and the 5 o'clock news anyway. The SETI project tried to use radio-frequency emissions to detect the presence of intelligent life elsewhere in the Cosmos, because they couldn't find any here.

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.

Re:The Lenna Story.

[ettlz]

I've been tinkering with that business of hiding a greyscale image in the spectral data of audio (a la Aphex Twin, etc.). At the moment, it's still in Mathmatica code, and I've been looking for a decent test image.

Seems like I've found it.

Oh, and Lena looks nice on my desktop. I wonder what her image sounds like.

Re:The Lenna Story.

[m50d]

I'm wondering about getting it on a tshirt (with a program encoded in using dataglyphs), thinking it would be an instantly recognisable geek thing. Is it not so well known?

Re:The Lenna Story.

[Qzukk]

The story of her pictures is apparently very well known in video processing circles, and /. ran an article some time ago about it which introduced her to everyone else ;)

I had never heard of her before, but then again, I've never dealt with any kind of photography or video processing.

Re:The Lenna Story.

[kureido]

Lenna is one of the many "standardized" images used in image processing research, akin to the well-understood strains of Norway rats used by medical researchers all over the world so that their peers can reproduce their experiments. For more examples of standard research images, see the USC-SIPI image database.

Re:The Lenna Story.

[bill_mcgonigle]

Everybody who's done image processing knows Lenna. Noone else does.

It Won't Be Long-People start to learn.

[Anonymous Coward]

"(The last part of this post is a JOKE, gawddammit!)"

Actually both parts are because it relies on the readers ignorance of what the DMCA actually says.

Re:It Won't Be Long-People start to learn.

[geomon]

Thanks for chiming in, Orrin. Here's the latest amendment to the DMCA for you to peruse.

Its only ten pages, so you should be able to wade through it in about two days.

Watch out internet!

[Toe, The]

Watch out internet!

Porn just found a whole new outlet. :/

Aw, c'mon guys...

[Anonymous Coward]

Stop hogging the bandwidth with the full size Lenna image! All I want to do is read the text (honest) and it's taking ages...

crap ..

[macaulay805]

I clicked on the link while I was at work, now I'm waiting for the network security people to remove me from my workstation.

On a side note: WARNINGS PLEASE!

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:crap ..

[Anne_Nonymous]

Don't worry, you'll be retirement age by the time the naughty image loads.

Re:crap ..

[_anomaly_]

Is this new picture different?

No. This "new" picture is the same one you used, just possibly a different crop of the original.
You probably should have followed the other link in the article summary before posting.

Re:crap ..

[harrkev]

You probably should have followed the other link in the article summary before posting.

I was afraid of following ANY link for fear of getting fired.

Re:crap ..

[Bishop]

a naked shoulder will get you fired? Where the hell do you work?

Re:crap ..

[Sloppy]

He works for a dressmaker.

Re:crap ..

[Anonymous Coward]

Did it release some of that internets glue and now you're stuck there?

Re:crap ..

[Anonymous Coward]

Did you not hear about the Janet Jackson fiasco? they must work somewhere in the U.S.

I can't see it!

[n6kuy]

Internet access to the requested website
has been denied.
URL: www-2.cs.cmu.edu/%7Echuck/lennapg/lenna.shtml

C AT: GPORN

Link

[emkman]

It's called Tempest for Eliza. I remember it being pretty cool when I tried it a few years ago in high school.

this is all you need to see...

[bob_greatguy]

unless you like "reading the articles" :)
http://www.lenna.org/full/len_full.html/ (nudity)

Re:this is all you need to see...

[jo42]

Way to go - slashdot Lena why don't y'all...

Re:this is all you need to see...

[Anonymous Coward]

Most Important Mirror Ever

ATV

[leighklotz]

You can do ATV 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, which is also a ham band.

Re:ATV

[leighklotz]

I forgot to mention that the NASA Ames folks plan to re-transmit live space shuttle video from STS-114 over the K6BEN repeater, so you can pick it up on cable channel 57.

Re:ATV

[Anonymous Coward]

Cool! So instead of pounding out morse code, you can instead send pictures of dots and dashes!

(Hey mods, I keed, I keed!!)

Re:ATV

[leighklotz]

< Cool! So instead of pounding out morse code, you can instead send pictures of dots and dashes!

The original post has some questionable legality issues; I'm showing you a way to do it legally, and get peer support. It's still bog-standard TV modulation, not morse code. And you don't need to learn morse code to get a license to do ATV.

Probably the biggest problem is the use of harmonics -- the proposed system uses the 5th harmonic of a VGA output, which happens to fall in the VHF TV band. What about the 2nd, 3rd, and 4th, (and higher?) Doing this with the support of other people who know what they're doing will help you avoid these problems:

Let's see:

• Fundamental: 25.71Mhz
  25.550-25.670Mhz is assigned for radio astronomy. So you'd be interfering with SETI research (slightly away from the band but close enough to interfere if the signal isn't clean, which it won't be).
• 2nd harmonic mixed with 76.5: 178.71MHz
  The article said TV channel 5, but it's not so in the US. See this chart.
• 3rd harmonic mixed with 76.5: 153.64MHz
  Police and fire VHF radio frequencies, in the US.

The list goes on, since mixing both adds and subtracts the frequencies and their harmonics.

And who can forget the plasma TV transmitting the 121.5 MHz international distress signal?

Bottom line: don't hook this thing to an antenna.

Re:ATV

[mikeydb]

430-440MHz in the UK is not so popular for ATV, mostly due to the fact any ATV operation on this band pretty much wipes out all simplex and repeater operation within a few miles of the ATV transmitter (not enough bandwidth for decent separation), although slow scan tv on HF (short wave) seems to be a constant source of semi pornographic images, that and old men sat at desks full of junk metal.

Re:ATV

[M1FCJ]

My Yaesu is not junk and I am not old, you insensitive clod!

Re:ATV

[Anonymous Coward]

The original post has some questionable legality issues

Only if one were to hook an antenna directly to the output. Even the article itself discourages that. In the requirements:

"A cable connecting the VGA output to the set-top box RF input. It is possible to use antennas, but since the transmit power is very low, it is better to begin with a cable connection."

He's basically using relatively cheap hardware to replicate the functionality of much more expensive hardware. With the right filtering, this would be a very useful thing - imagine if you could replace a costly NTSC/ATSC transmitter with something akin to this, properly filtered and amplified? This could greatly reduce the cost of building a television station (or subsequently replacing a failing transmitter). It's almost akin to the original Video Toaster, which could replace a 4-input switcher for live work, while also providing a CG, paintbox, framestore, 3d modeler, and DVE, including ChromaFX, at a fraction of the cost of obtaining all of those components separately.

Re:ATV

[connorbd]

I never understood the point of SSTV porn. You can get much better quality stuff on the net (hell, I'm sure there's a couple of packet BBSes left with a decent quantity of the stuff), so why would you want to transmit over SSTV?

Thank You!!!.

[MisanthropicProgram]

'Nuff Said

NSFW?!?

[natron 2.0]

Hey editors, how about a NSFW warning on stories such as this!

Re:NSFW?!?

[xlv]

What are you talking about? Yes, some of the Lenna pictures that can be accessed indirectly from the site are not safe for work but all the pages you open when clicking on the links in the story description are safe for work unless a portrait picture of a woman is not safe and in that case, please let us know where you work so we can avoid that place...

Re:NSFW?!?

[British]

My workplace blocked the website, citing malicious software could come onboard.

*sigh*. A digital tv tuner I don't have, being hosted on free web page service in France.

It just simply wasn't meant for me to read this article.

Re:NSFW?!?

[Anonymous Coward]

What, are they monitoring you there?

-Bob

Re:Mormons, beware:

[msdschris]

Hey, not all of us residents of Indiana are natives. How on earth did I end up here?

Thank you Sir! , May I have another!!

[MisanthropicProgram]

'Nuff siaid

Slashdot lawyers.

[Anonymous Coward]

Here's some reading for you. It's only one page. You should be done in about a week.

http://www.radioshack.com/product.asp?catalog_name =CTLG&product_id=15-2572

Guess their lawyers understand the DMCA better than yours.

Re:Slashdot lawyers.

[geomon]

You go to Radioshack for legal advice?

I'm bookmarking your post for posterity. It is a classic.

I also said, if you cared to read the original post, that it would be illegal in the future. That would mean this device would *also* be illegal.

And Radioshack's attorneys would just advise the production staff to quit making them.

Radioshack - for legal advice... That's good.

Re:Slashdot lawyers.

[harrkev]

You've got quesions. They've got answers.

What was the subject again?

Re:Slashdot lawyers.

[mink]

I always thought it was "You've got questions, we've got blank stares."

Never Twice the Same Colour

[Anonymous Coward]

...as we call it over here.

Do I Understand correctly?

[Anonymous Coward]

This only transmits, but does not encode the signal. What is outlined on this page is just the easy part.

Dude.

[Anonymous Coward]

It's not even full frontal. What kind of work do you have where they are that hard-ass?

Other famous pr0n

[gr8_phk]

Now can someone turn up the original photo that Tim Skelly used for the starfield in Star Castle... The stars are nice, but I'd like to see the actual photo he happened to have in the drawer to pick coordinates.

Re:Other famous pr0n

[pyrrhonist]

Now can someone turn up the original photo that Tim Skelly used for the starfield in Star Castle...

Tim Skelly was the designer. Scott Bodden actually programmed "Star Castle".

Scott traced the starfield from the February 1980 issue of OUI magazine.

I don't know which model it was, Cleo Bergssen or Nelia Cozza.

Re:Other famous pr0n

[gr8_phk]

"I don't know which model it was, Cleo Bergssen or Nelia Cozza."

Right. Now if someone could produce the pictures from OUI we could just look and you'd know which one it is. Having written the first functional Cinematronics emulator, and having talked to both Tim and Scott, I've always wanted to see the original picture. At least it's a good excuse to check out some porn ;-)

Re:Other famous pr0n

[pyrrhonist]

Now if someone could produce the pictures from OUI we could just look and you'd know which one it is.

Yeah, that was kind of the problem. I was unable to find the requisite nudie pics on the net.

However, I was able to find places that sell the actual magazine issue. So, you could buy the print version, and have a collector's item!

I don't understand...please explain.

[zutroy]

I'm interested in this, but I don't understand the practical implications (mainly because I have no idea what most of the acronyms mean). Does this mean I could plug my computer into my digital TV tuner somehow and be able to watch it on my TV? If so, does it work with US digital TV equipment (such as the Motorola set-top boxes that Comcast provides)?

Re:I don't understand...please explain.

[Anonymous Coward]

Answers are: yes and no (for now).

Re:Mormons, beware:

[Anonymous Coward]

Are there a pair of legs wearing ruby slippers sticking out from under your house? Trust me, steal the shoes, you'll thank me...

This is great

[Bruha]

Just hook everything up to the pc and let it do the conversion and display your video at the native resolution on your DTV.

It's a digital stream .... not NTSC

[taniwha]

it would be an MPEG2 encoded stream, not PAL nor NTSC ... the picture size and/or frame rate may be different but with any reasonable system you should be able to do exactly the same thing in the US

First Edition: 9/27/96

[trakta]

Can you all stop visiting lenna.org please? I'm trying to get me some nekid goodness and it's taking, like, forev-her. Though on a nostalgic note, it is rather like almost-ten-years ago...

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

[tomhudson]

Guess youy'll be watching a LOT of Canadian TV in 2007, eh? http://www.cdtv.ca/en/faq/index.htm#13

How Long will Conventional Analogue TV Signals Be Available?
...

The earliest that analogue stations may be allowed to shut down in Canada has yet to be determined but it is likely to be beyond the year 2010.
...

Re:Guerrilla television in 2007

[CohibaVancouver]

We may find ourselves in a situation where people simply start pirate broadcasting on the unused television channels

I think it's more likely that you'll see a lot more people "stealing" cable. The incentive to "steal" cable TV is reduced if you can still watch WWE Smackdown! on your rabbit ears. However, if that disappears then people will probably start splitting cable ten ways to Sunday.

Re:Guerrilla television in 2007

[Anonymous Coward]

Not quite, it is still relatively easy to trace down a broadcast signal. So it wouldn't take long before the fcc comes knocking with their rabbit ears.

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:Guerrilla television in 2007

[StikyPad]

In the US, many cable providers offer digital cable already, so that wouldn't be as much of a factor. Similarly, many cable boxes also have custom PVR/DVR capabilities and offer a much broader range of channels than broadcast stations in any locale in the continental US. Among people who watch TV, just about anyone who can afford cable (any many who can't) fork out the cash rather than watching broadcast, which generally consists of 4 to 8 channels, depending on where you live. (Although the only channels I ever watch are History & Discovery.. and The Learning Channel, back before it turned into the home improvement/women's channel).

Re:Guerrilla television in 2007

[antrik]

Seems my comment was confusing...

Of course, cable is much more desirable than *analog* TV broadcast. My point was that, with broadcast switching to digital and cable still being (mostly) analog, the situation changes quite a lot: Digital broadcast offers about the same number of stations as analog cable (something around 30), and offers a better quality. Many people ask: Why still pay the fees for cable, when they can get something comparable or even better for free?

(Of course, with cable getting more digital, it will get an advantage again... But the incentive won't be nearly as big as it used to be. Which in turn makes the cable companies reluctant to do the necessary investments :-) )

Re:Guerrilla television in 2007

[eraserewind]

Well, I think that rather a lot of people in urban areas that have shall we say, a more liberal interpretation of copyright and broadcasting laws, are not paying for cable anyway, but that doesn't stop them from getting the pictures.

Re:Guerrilla television in 2007

[toddestan]

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.

I would be tempted to get satellite TV or something and rebroadcast the channels exactly as they were. I bet they would never see that coming!

Re:Guerrilla television in 2007

[StikyPad]

I understood you correctly.. what I meant to say was that there's less incentive for companies to set up more broadcast channels. It's not as if the analog spectrum is close to saturated by current VHF/UHF broadcasts. Further, the reason is not because of signal quality, but because it's cost prohibitive to set up all the necessary transmitters. With cable, it's one piece of infrastructure for all channels. Not so for broadcast, nor does cable have to vie for suitable real estate upon which to build a tower.

If the lack of available frequency spectrum were the limiting issue, then certainly I'd expect to see more channels with a switch to digital. It's simply not the biggest prohibitive factor in most markets, nor is picture quality, but rather the much higher earnings potential for cable, with it's lower cost of service and revenues from both advertisers AND viewers.

Re:Guerrilla television in 2007

[modecx]

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.

That's a joke, in my experience. My family rents out many (small) appartments, and several houses. Many of the tenants certianly qualify as poor, certianly they're on fixed incomes... And the overwhelming majority have cable today, and always have had it in the past. You can't blame it on poor reception, either. It's fine.

A couple of tenants have even gone as far as losing their water service, but they still had to have their $60/month cable service. It's like goddamned crack. They'll do anything, as long as they have a roof over their heads, food in their bellies, and America's Funniest Home Videos on the TV.

My family dosn't belive in much TV. We're too busy managing our small corner of the universe, and actually having fun when we're not doing that. I only got cable a year ago when Qwest pissed me off to the point where I had to ditch DSL through them.

For $3 extra than the cable internet service I get basic, anaglog cable, and that's fine because I get a few chanels that I do enjoy. Discovery (love them motorcycles!), Food Network, and I think TBS. There's some others but they mostly have crap/reruns(crap).

I think many Middle Class Americans hold off on overly superfluous things like pay-TV. Not to sound clichéd, but do people really need more than 64 channels? Unless you spend all day in front of the boobtube, you can't remotely hope to watch enough to justify it--if you don't have money to throw away, that is.

I suspect that this phenomenon echos throught our country. I think many lower-class people (from the Blacks in the ghetto, to the whites in the trailer courts) are either too lazy to do anything else, unable (by injury, or illness, including mental--including TV addiction), or they just don't know what the hell else to do.

Having that said, I doubt pirate broadcasts will pop up all over. There's the thing about the price of the equipment (unless they steal it that is), the knowledge of how to hook it up, and, well, it takes effort. People don't like effort.

Re:Guerrilla television in 2007

[Anonymous Coward]

I bet you thought the old Max Headroom TV Series was a documentary. Or, maybe a prophecy?

Re:Guerrilla television in 2007

[isdnip]

The Telecom Act does not shut down analog TV in 2007.

The FCC does have a mandate to shut down analog TV -- TV stations now have two channels, one analog and one digital, and once the transition is complete, new users of former channels 52-70 (some of which have already been auctioned off) can go ahead with them.

But the date is not firm yet. The current rule is that it will be delayed a year at a time, until 2010 at the latest, until 85% of households have digital reception capability. That includes DTV sets, as well as cable boxes that convert.

The FCC has just passed a rule requiring most TV sets to have digital tuners by 2006. The channel election process (by which stations choose which of their two channels to keep and which to give up -- for instance, some VHF stations will stick with UHF DTV, some won't -- is being accelerated. See the FCC web site.

But it's highly unlikely that analog will be shut down before 2008. And since that's an election year....

Re:Guerrilla television in 2007

[serutan]

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

Don't worry! I'm sure more prisons are being planned as we speak. Meanwhile, the War On Spectrum Piracy can share the prisons that are being built for the War On Copyright Infringement, because the War On Drugs already filled up the prisons for the War On Crime. The War On Everything marches on!

Re:Guerrilla television in 2007

[bobcat7677]

Sweet! As much as I like the pretty HDTV singals, the pricing of HDTV recievers is still rediculous. I guess I'll just have to move to Canada. I hear they have some tech jobs up there and last time I was to B.C. I met some fine looking women. Given that the U.S. has gone all socialist on me anyway I see no downside:)

Re:Guerrilla television in 2007

[Simonetta]

Sorry for disspelling your very original fantasies... but nothing of that kind seems to be happening here in Berlin

This may be cultural. Traditionally Germans do exactly what their superiors tell them to do.
My comments were about American poor urban centers, primarily black and latino. The African-Americans have been resisting the destruction of their culture and their enslavement for 400 years. The Latinos are isolated by language and citizenship issues. Their only television is the ultra-conservative Mexican-American cable TV networks like UniVision. The poor whites, the European-Americans, live on the outskirts of the cities and are sustained by cheap gasoline.
None of these groups can be expected to act like 'good Germans' when their television is shut down.

Re:Guerrilla television in 2007

[Simonetta]

Thank you for taking the time and effort to make a response to my post. Your comments are well-written, well-thought-out, and perceptive.

Re:Guerrilla television in 2007

[Anonymous Coward]

Yeah, but traditionally Americans hate community efforts as communism and all share a simple view of the world.

Re:Guerrilla television in 2007

[hawk]

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.


"Hey, get in here! It's going to drop!"

10 . . . 9 . . .[muffled by cheers] 7 . . . 6 . . . 5. . . . [lost to starlet's babbling] . . . 3 . . . [supposedly witty response to dingbat starlet by just as dingy star] . . 1 . . .[crackle-hiss]"

"Hey, what happened???"

[Which in turn leads to massive late-night sales on the west coast]

hawk

Re:Guerrilla television in 2007

[modecx]

I'm never one to turn down a compliment, but I have a strange feeling that you may have had Chinese food last night :P

Re:Guerrilla television in 2007

[antrik]

There seems to be some misunderstanding here. It's not like the people here generally don't like the switch to digital broadcast, and only do not oppose it because they are "good Germans". While there is some inertia about anything new, most people actually consider the move to be a *very good* thing. At least that's my impression.

Americans may have a stronger tendency to oppose things they do not like; but I doubt they will have a fundamentally different opinion about the merits of digital broadcasting.

Re:Guerrilla television in 2007

[antrik]

> It's not as if the analog spectrum is close to saturated by current VHF/UHF broadcasts.

Actually, TV broadcasting is the single application eating up by far the biggest part of the available spectrum. Even with only a few channels available.

> but rather the much higher earnings potential for cable, with it's lower cost of service

This pretty much contradicts about anything I have heard about that matter so far.

The general opinion is that central, wireless solutions are considerably *cheaper* than serving each and every single customer individually with wires. Many see wireless solutions as the only realistic way to provide people in thinly settled areas with fast internet connection, for example.

I don't think it's a coincidence that you get broadcast for free, while cable needs to be funded by considerable monthly fees...

The advantage of wires is higher bandwith (because they can use the whole frequency spectrum, and also the transport media are generally more optimal); but certainly not price.

Re:Guerrilla television in 2007

[riprootin]

We should all be so lucky, that would be worth watching, quite unlike the 98% of the news and entertainment marketing propaganda we get now. And to think, people are actually worried about establishing a legal right to make more copies.

All about Lena (Lenna)

[alphakappa]

A brief history of Lena. The page is worksafe, but if you wish to click, there are links to non-worksafe images of Lena over there.

Guys, this is no small feat

[o'reor]

and yes, I am a (former) DVB-T engineer (and a consultant in digital video broadcasting at large -- yes, I know a bit about the US and Japanese standards too).

What Fabrice is telling us here is that he has managed to produce a real-time (or close-to-real-time) DVB-T/DVB-H software COFDM modulator, the output of which may be broadcast via the DAC converters of the video board. Given the complexity of the generated signal (more than 6000 subcarriers, not including pilot subcarriers which are used as beacons for the demodulator, and paying respect to the guard interval -- sorry for the technical gobbledygook), this usually requires a dedicated ASIC. Don't forget to include the preliminary phases of the encoding : creating an MPEG-2 video channel, an MEPG-2 transport stream (OK, he did it using a modified MPEG library), then encapsulate this into MPEG-2/DVB frames, add the Reed-Solomon code, perform the interleaving procedure, pour in some Viterbi encoding for redundancy, and feed it to the input of the DVB-T modulator, phew ! you're done.

I want to say hats off, ladies and gentlemen, to this outstanding performance. The Free Software movement definitely needs more guys like Fabrice, and we all need to encourage him into publishing more of his code.

Chapeau bas, mon cher Fabrice !

Re:Guys, this is no small feat

[Anonymous Coward]

It's not realtime. He's rendering to a PGM file, and then by displaying it. Not easy, but it's not a replacement for custom hardware.

Re:Guys, this is no small feat

[o'reor]

My mistake, I got a little carried away with what I was reading... Still, that is one of the possibilities for his project, as he mentions at the bottom of the page :"This project can be the basis of a real time low cost DVB-T and DVB-H modulator."

Re:Guys, this is no small feat

[timecop]

what do you mean by "Japanese standards"?
They don't even use DVB-T, they use their own customized abortion called ISDB-T, and they use OFDM modulation instead of COFDM. Another words equipment that nobody else in the world cares about, incompatible receivers, etc. And what's the japanese fear of AC3 audio? AAC is shit, especially the currently broadcasted incarnation of it wiht cut off frequency of like 10khz.

propz to fabrice for pulling this off, it does seem like the method can be done "realtime" though I wonder on what kind of machine.

Re:Guys, this is no small feat

[o'reor]

That's right, they use ISDB-T; this standard requires a special twist on the basic MPEG-2 transport stream, and custom headers for the transport packets, plus a special multiplexing of the packets for the channels broadcast in that system. When I coded a measurement tool for Japanese clients a few years ago, I had several headaches trying to understand how it all worked (plus at that time, most of the documents on that standard were still written in Japanese only, you had to understand the oral explanations of the clients in order to get all the picture).

Concerning AC3 : it's fine and cool, but there is a patent on that system (Dolby), and asian countries hate to base their standards on patented algorithms, especially when those patents are not owned by a local company.

video instead of images

[felipe.ledesma]

is there any way I could use this to output video instead of still images? I would like to watch that DiVX flicks I have in my HD...

Re:video instead of images

[Anonymous Coward]

Haha, hooking up your computer to your HD with a VGA or DVI/HDMI cable will be easier if watching Divx movies is your goal.

Apple zealot!

[Anonymous Coward]

The slashdot effect + a nudie photo. Say goodbye to that server.

Given that the photograph of this nude model "Lenna", is the most used photograph used to test image compression algorithms, I think you intended the Photoshop audience to glaze over your post with no suspicsion. But to correctly raise the verry stenographical element, I believe you meant to type iNude and not nudie. Did you just make up that word? Is "nudie" even a word, or is it more hidden words to conceal your thoughts of "GNU DIE"? I think you are one of those Apple zealots...am I, for seeing it?

Here is the photo in dispute. Bring here down, bots errm I mean boys.

9200SE DAC's

[Ge10]

There's a small mention in the article about the PLL used for clocking in the 9200SE being capable of up to 400Mhz. If the DAC's could be run fast enough, the carrier could be generated directly and you would get a much stronger signal. Does someone have any details?

Annoying

[Anonymous Coward]

Any old ham will know that a computer can generate a TON of RFI (Radio Frequency Interference), and these brand new video cards generate so much RFI that building a faraday cage around the blasted thing just isn't enough!

We don't call it useful in any sense - we call it INTERFERENCE! Get your facts straight! And don't call me old geezer!

Wait...

[ImaLamer]

I think you mean ATSC

Re:Mormons, beware:

[M1FCJ]

And what's the problem with that? I love smut.

Killing a Cop to See Lena

[Anonymous Coward]

"As we did not want to generate a 176 MHz signal directly, we use the fact that the VGA DACs generate a lot of harmonics. The real generated DVB-T signal has a central frequency of 25.71 MHz. Then the second harmonic has a frequency of 25.71+2*76.5 = 178.71 MHz which is almost exactly the central frequency of the VHF TV channel 5."

Really bright there Fabrice Bellard. Hook this up to an antenna, as you suggest, and trash communications in your neighborhood every 25.1 MHz up the spectrum. Who cares if there's a cop, wounded and lying face down in a nearby alley, Yah gotta have that Lovely Lenna picture.

Yes, the signal is low power and won't get far, not nearly as far as the 80-meter ham transmitter I had as a kid who's second harmonic was picked up 800 miles away. But I wasn't trying to do that and quickly fixed the problem. You're deliberately trashing the spectrum for those around you who want to watch the real channel 5 or whatever. Show some responsibility and use a coax cable.

--Mike Perry, Seattle, Untangling Tolkien

Re:Killing a Cop to See Lena

[Ge10]

You're glossing over several issues. * high frequencies are decay very quickly (by distance)Even with an antenna connected, it would be very short range * he's using the harmonic of the 76.5 Mhz pixel clock, so the harmonics will repeat in multiples of this. If you're talking about sidebands, the bandwidth is limited to 25.1Mhz so you will only have to worry about harmonics of the sidebands * The second harmonic of an 80m rig is only 7.5Mhz - still in that shortwave region used by hams FOR LONG DISTANCE TRANSMISSIONS * Interference would be primarily AM in nature, and (since all police radios use FM) will be mitigated by the AM rejection circuitry in their receivers * the power output is incredibly small - bear in mind that a direct connection is being used and it still comes up as only 60%.

its simple, just reverse the polarity of the phase

[Anonymous Coward]

inverters and fire a beam of neutrons into the main deflector dish.

*smile* n/t

[Bishop]

*smile*

Re:SLASHDOT MYSOGYNY

[Anonymous Coward]

Yea, I could feel the hate dripping off that.

Actually, no fuck off, an amusing ditty from a man's perspective is not mysogyny.

About Lena;

[Anonymous Coward]

I'd hit it!

Re:About Lena;

[Anonymous Coward]

Crawl back off to Fark. We mod down comments like that (wish I had mod points, gotta keep the /. sane(ish)).

Re:its simple, just reverse the polarity of the ph

[o'reor]

Sort of. But I dare you to do this with just a PC and a measly VGA board ;-)

Who the hell is he?

[Anonymous Coward]

My housemate suspects that he's a front for a group of very talented coders, sort of like DVD Jon...

I think he's just a very clever Frenchman (*gasp* go all American right-wingers...)

won't somebody _please_ think of the bandwidth

[jamesh]

When I opened up the image in GIMP, I could vaguely see two identical-looking images (only at 16% scaling though, the image being visible must have been an artifact of my laptop screen).

Assuming that the two copies are the first and second frames of one interlaced tv frame, then we are talking about 4096 x 2048 x 8 bits = 8388608 megabytes of data to generate one tv frame.

For motion picture, at 25 interlaced frames per second, thats just under 210 megabytes of data you'd have to move every second. And, moved with enough consideration to timing that you're not wiping out a frame while it's being drawn.

We can take into account that there is overscan, vsync and hsync 'signal' that doesn't need to be refresh each scan, which might eliminate some data requirements for refreshing, it's still going to be a fair bit of data.

Is that feasible?
(or am I wrong about 1 VGA frame being 1 PAL image?)