Microcasting Color TV By Abusing a Wi-Fi Chip (hackaday.com) 63
szczys writes: The NTSC standard has effectively been replaced by newer digital standards, but most televisions still work with these signals. This can be done through a composite video connection, but more fun is to broadcast video directly to your television's analog tuner. This is what cnlohr has been working on, using a lowly ESP8266 module to generate and transmit the color TV signal. This board is a $3 Wi-Fi module. But the chip itself has a number of other powerful peripheral features, including I2S and DMA. This hardware makes it possible to push the TV broadcast out using hardware, taking up only about 10% of processor time. Even more impressive, cnlohr didn't want to recompile and flash (which is a relatively slow process) during prototyping so he used a web worker to implement browser-based development through the chip's Wi-Fi connection.
Speaking of chip-abuse in the interest of hyperlocal signal propagation, reader fulldecent writes to point out a project on GitHub that "allows transmission of radio signals from a computer that is otherwise air gapped. Right now this could be useful for playing a quick tune or for pranks. But there are more nefarious uses as this could also be used to exfiltrate information from secure networks."
chip 'abuse' !? (Score:3)
'abuse' ?!
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"ab-use" to use something in a manner not originally intended
overclocking the I2S fifo to the megahertz range is clearly "ab-use" unless you have some sort of miracle eardrum that can vibrate at that frequency
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Actually, abuse explicitly includes that the use is bad or harmful.
If the chip fails in a few minutes of that, it is abuse.
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Hacking in that context has never meant removal of anything but a problem or task. Though hack in that context can mean solving a problem through using things in a positive but unintended way.
Drug abuse very much is meant to identify that use as bad. Your values may vary but among those who don't see it as bad I have only heard the word abuse used sarcastically or ironically. Abuse of authority is most certainly meant to indicate that that unintended use is bad.
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Sure. But since the chip isn't made of wood, we can guess that one of the other shades of meaning it evolved to applies.
One day, abuse may evolve to lose it's explicitly negative meaning and then you'll be correct. But not today.
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Actually, abuse explicitly includes that the use is bad or harmful.
If the chip fails in a few minutes of that, it is abuse.
Except for self abuse. Then it's just fun.
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Sorry to hear about your failure problem. There are drugs that might help that.
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Sorry to hear about your failure problem. There are drugs that might help that.
Now now, A sense of humor, so lacking in many these days, is a great help in getting through life happily. And alas, there are no drugs for that.
Well, maybe Nitrous oxide.
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It's just an example, there's not a true bright line there since even run within specs, the failure prediction is just an average.
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Well, it's spectrum abuse at least. You're explicitly not supposed to be using that spectrum for this shit.
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Nobody else appears to be using it.
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> [heavily paraphrased] Running the program on an Apple MacBook Air (13-inch, Early 2015) uses the _mm_stream_si128 instruction to write through to a memory address, causing electromagnetic radiation to be emitted from the computer at 1580 KHz.
> By tuning an AM radio tuned to this frequency, you should hear "Mary had a Little Lamb" played over and over.
Shades of Don Lancaster's "TV Typewriter"! (Score:4, Interesting)
This is beautiful. It takes me back to my late teens, building out TTL divider chains and 2K CMOS static RAMs to make a higher-resolution (30 rows of 100 characters) alphanumeric display for the TRS-80. Maybe I won't toss that 1970s 13" color TV just yet...
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Outstanding! (Score:5, Insightful)
This is the coolest little hack I've seen on /. since...probably dice bought it. More of this please!
One minor quibble, no need to editorialize the "POTENTIAL SECURITY VULNERABILITY". We already know everything is a weapon for terrorists these days. How about instead of "speaking of chip abuse" we have "speaking of $3 computers with tons of hidden functionality"?
Re:Outstanding! (Score:5, Informative)
Agreed - cool hack.
There *should* be a big, huge warning, though - about violating FCC rules. The hack broadcasts on restricted frequencies; replicate at your own risk.
Re:Outstanding! (Score:5, Informative)
your car's starter motor violates FCC rules when the brushes get old, so you too will join the others in the gulag for violating the rules
The phrase "intentional radiator" has a significance here. Google it if you are confused.
It would be a good question to research if this intentional radiator met the limits of a Part 15 device, like the unlicensed AM and FM broadcast transmitters that you can buy or build.
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The FCC doesn't care anymore. You have to be interfering with commercial stations for months before they do any investigating. I still hear people talking on the CB with illegal amplifiers. Even if they do fine you, you can appeal it down to a fraction of what they asked.
Re:Outstanding! (Score:4, Informative)
It would be a good question to research if this intentional radiator met the limits of a Part 15 device, like the unlicensed AM and FM broadcast transmitters that you can buy or build.
FCC OET Bulletin No. 63, October 1993:
With the exception of intermittent and periodic transmissions, and biomedical telemetry devices, Part 15 transmitters are not permitted to operate in the TV broadcast bands.
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The FCC also explicitly bands the amateur broadcast of music for any purpose
You are talking about licensed Amateur Radio here, FCC Part 97. That is completely different from unlicensed low power transmissions under Part 15, which have no such restriction. Amateur transmissions are prohibited in the broadcast television frequencies.
The plug-in dongle to transmit from your iPod to the FM radio in your car, for example - a Part 15 device, and it clearly does allow music.
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Keep in mind that intermittent transmissions are specifically *not* broadcasts, which are defined (roughly) as sustained transmissions to no particular endpoint.
Along with your confusion between the amateur radio service (Part 97) and unlicensed operation (Part 15), you have an unusual definition of broadcast. Broadcasting is not defined by it's "sustained" nature, but by the intended recipients.
with the sole exception of repeating an amateur transmission from a space station that happens to include some music.
This, too, is not correct. 47CFR97.113(c) permits the retransmission by amateur operators of:
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FCC OET Bulletin No. 63, October 1993:
Do you notice that this bulletin is 23 years old, perhaps?
47CFR15 [ecfr.gov] has an entire subpart H that deals with "white space transmitters". That subpart covers an AWFUL lot of Part 15 transmitters that are none of intermittent, periodic, or biomedical telemetry, but live in the TV broadcast bands, all unlicensed.
The times they is a changin', Jeb. Next thing you'll know, they'll have phones that you don't need to jingle Mable to get you connected to someone else. What is the world coming to?
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This is slashdot, not fark. Some minimal level of civility is common.
White space devices need type approval (and are quite complex, generally needing an internal GPS and a database). The "unlicensed" part means that the end purchaser does not need a FCC license to operate, not that the device doesn't need to be tested and approved prior to sale.
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This is slashdot, not fark. Some minimal level of civility is common.
I was quite civil. I used humor to point out that relying on a 23 year old FCC bulletin instead of the 2106 regulations is a bad way to determine what is and is not legal.
White space devices need type approval
Are you going to be selling or manufacturing these low power TV transmitting devices? Was that question uncivil?
not that the device doesn't need to be tested and approved prior to sale.
And if the device is never sold?
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Wow *sniff. Never in my wildest dreams did I think the conversation would end up this way *sniff *sniff. Arguing regulation sub-parts and outdated FCC bulletins. (wipes tear). Does /. really have a chance of going back to the "good" ol days?
And yes I read a few paragraphs of the eCFR to see what yall are on about. Thanks for providing a link to true entertainment!
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That sounds like the perfect theme for a comedy sci-fi movie: FCC gulags spread across the country. Inmates detained for reasons ranging from failing to maintain starter motors, keeping old washing machines and electric drills, refusing to hand over old multi-sync CRT monitors.
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The hack broadcasts on restricted frequencies; replicate at your own risk.
Same as taking an FM transmitter meant for linking to a personal vehicle stereo and hooking the antenna to an amplifier.
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Actually, no. The FCC has excluded low-power FM transmitters from requiring licensing, thus making those little FM transmitters for your car perfectly legal. The FCC basically limits their power to 200 feet or less range (the FCC measures output not by mW, but by complete system, so if you have a 200W transmitter with a piss-poor antenna that gives you 200 feet max, that works. Same goes f
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If you're doing it from your mom's basement (like any self respecting slashdoter should) the signal will not be powefull enough to get outside.
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Check the FCC regulations first (Score:4, Informative)
If you are relying on Part 15 FCC regulations, be sure to read them first. Using a device in a way not contemplated by the manufacturer can turn your "approved" device into a "home-built transmitter [that is] not for sale" which puts the onus entirely on you to comply with the rules.
Having said that, if nobody complains, then you almost certainly won't be hearing from the FCC, and even if you were to use a device "as intended" and it caused harmful interference, you are still required to cease using it.
https://www.fcc.gov/Bureaus/En... [fcc.gov] has an interesting item on page 7:
With the exception of intermittent and periodic transmissions, and biomedical telemetry devices, Part 15 transmitters are not permitted to operate in the TV broadcast bands.
I guess that means if you are only going to transmit "intermittently" or "periodically" then this is fine, but it's probably not okay to use this for your home-security system that runs 24/7.
Channel 3 is in the 54-70MHz band, which is okay but only at very low power, 100 microvolts/m measured at 3 m away ("quasi-peak").
It is almost certainly legally safe to use this over low-VHF channels over coax rather than "over the airwaves," and you'll probably get a stronger signal to boot. But it won't be as much fun.
There may be some opportunity to use this under other parts of the FCC rules, such as part 18 (industrial, scientific, and medical) and, on applicable frequencies, part 97 (amateur radio license-holders only, and only in ham bands, and even then NTSC is not an acceptable "mode" in many bands).
Okay, that document was very out of date (Score:2)
Oops, I just got egg on my face. That document is 20 years old. Please consult the current FCC Part 15 regulations, which should be widely available.
My Google-fu is obviously not working well today.
Re: Okay, that document was very out of date (Score:2)
You can tell the slashdot crowd has matured when it starts to look up the rules pertaining to something when a hack is posted. While it may be for the better, I like the days when we could push the bounds without question. I don't think the new kids these days are pushing the limits anymore.
Whatever happened to pirate radio?
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I don't think the new kids these days are pushing the limits anymore.
Whatever happened to pirate radio?
They put Kevin Mitnick in jail for 5 years for hacking the phone system.
excuse me for pointing this out (Score:1)
but doesn't radio transmission implicitly imply that the devices are air gapped....
oh well, anything to keep the sheeple busy running around and wondering. Better than them coming after you and tearing you a new one.
good grief.
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Wifi uses (wait for it) radio transmission. You would have to be a complete moron to consider a device with active WiFi to be 'air gapped'. Even more shocking (to you) is the fact that even wired devices can also have radios!
The remainder of your post appears to have been written by a random word generator.
Context (Score:1)
The term "radio transmission" is sometimes loosely used to mean "radio frequency transmission" which can mean over a coax or other wire carrying the signal rather than as photons through the air (or free space or water or what-not).
The Hack-a-day link specifically mentioned non-over-the-air applications using TV ("RF") frequencies.
Didn't work for us in the late 1970s (Score:4, Funny)
I forget why, but we had an RF modulator, possibly to connect some early VHS deck to a TV. We also had a video camera and a giant antenna on the roof of our house, and we thought it would be awesome to make our own local channel 3.
Try as we might, connecting the RF modulator to the TV antenna did not allow our broadcast to be received by anyone in the neighborhood, denying them the ability to see me lipsync AC/DC with a tennis racket for a guitar.
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You didn't have enough power. I mean, most of those RF modulators didn't even have external power sources, and were only designed to work through a few feet of coax.
If you'd tried to hack one of those Rabbit cable TV/VCR signal extenders instead, it at least would have been designed to transmit over air and maybe you would have had enough power to do something.
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Here's the formula for easy NTSC broadcasting on Channel 3:
1. NTSC device (VCR, camera, etc.) outputting via composite or S-Video and RCA R-L audio
2. RF Modulator with output via RG-59 or RG-6 coax cable
3. Channel Master or Winegard VHF-LO preamplifier with lots of gain
4. Matching transformer ("balun") for converting 75 coax unbalanced to 300 twinlead balanced signal
5. DIY dipole antenna with end-to-end width of 2.38095m (93.74in) and attachment points for balun leads
6. connect device to modulator to preamp
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Maybe the range was too far? I found I could use my 8 bitter to drive the TV across the room by connecting a TV antenna up to its RF out port. That was only a few meters though.
Now do it with ATSC (Score:2)
Right now, I think the cheapest ATSC "modulator" (probably not the right term) is in the neighborhood of $1000. Would be nice to connect something like this to in-home wiring to stream video over existing wiring.
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You also would need a properly formatted MPEG stream before you even got a "modulated signal", which would add a second or two of delay if you started with analog or uncompressed video content. There are good reasons why an "ATSC modulator" is not a consumer product. One of them is the lack of reasons why NTSC modulators are a consumer product: ancient TV sets that had no other input. A TV set that can decode ATSC also has multiple other uncompressed video inputs, both analog and digital.
An NTSC modulator
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