When I was an undergraduate student the lab I was working in had a computer donated from a defense contractor. The PC case and keyboard were very impressive for how heavy they were. When we looked more closely, the keyboard circuitry was wrapped in copper mesh to prevent signals getting out into free space. And this was a late 80's computer, so I can only imagine what can be done now.
@@kreuner11 I think I'll stick with believing what the person from MITRE who donated the equipment said about signals intelligence. If a nuclear strike had happened the operation of these computers would have been irrelevant. But the design work being done on them certainly would have been of interest to the Soviets. BTW I have been involved in RF circuit design for two decades. I can confidently say that anything with a mechanical switch will absolutely radiate. You'd have to be crazy clever to figure out a way to interpret the RF pulses coming out but I'm sure the cold war spooks were up to that task.
One problem of this concept is that ferrite material saturates very quickly and is really only usable for very low field strengths (as in receivers). Using a different inductor on the transmitter side should improve the range. Another problem is that the direct drive of the LC circuit limits its possible peak voltage to the voltage range of the AVR pins (which have protection diodes and load the resonance circuit non-linearly). An isolating buffer stage (transistor with high voltage rating) would be beneficial.
It is not that difficult to increase the power and range but at some point there will be a risk that it will interfere with someone's radio and authorities may get involved.
Maybe I could have achieved a little better coverage with a loop antenna and a good impedance match. But I don't think it would make much difference, and I don't see much practical use in it anyway. So I didn't want to put too much effort into it.
what would be the best inductor to use? the using of a voltage and current boosting transistor is indeed a logic thing to do, and at this low frequency it isn't to hard to find a suitable part. also the antenna I searched up the name but got nothing, so am I right to assume it is just one of those LC oscillator antennas. or that it is just a coil around a rod through which the current is passed and a second coil around the same rod but connected to gnd on one side and air on the other side? kind of like one of the old long range radio antennas. or is it one coil with a center tab?
You are obviously not a ham radio guy. I personally have used ferrite in an antenna system at the 100 watt P.E.P level. Other hams have used ferrite at levels up to a kilowatt.
You mean high-pass filtering? With a HPF you could get the signal’s centre almost exactly halfway between the rails. I think he should also add an AGC circuit of some kind. And a Schmitt trigger comparator assuming he doesn’t already have one. I think 10b/8b encoding would get the DC offset to zero, and is more effective than the Manchester I was thinking of.
@@Scrogan Both work. If you lowpass the signal, you get the DC offset and can use that as a reference. If you highpass, the signal is centered around 0V, but you end up with negative voltage.
I saw someone hack a SATA cable to send data. Yes, I know, that's what it's supposed to do, but this person wrote some code that wrote data to the drive periodically to transmit 1s and 0s with the RF noise. It was a proof of concept for malware to exfiltrate data from an air-gapped computer, and it wasn't particularly practical outside just being a poc since the range isn't great, but it was interesting nonetheless.
I did something similar following some research paper but with USB 2.0 protocol. I never made video public :) Maybe one day I will get back to that project and write decoder to :) th-cam.com/users/shortsZivNEi4GbVM @@dafoex
Another way of increasing the distance would be to instead use error correcting codes. Though I'm sure that's out of scope of this, it's something that would be necessary even over very short distances, given how susceptible to interference RF communication is.
Now you have to import IPv4, IPv6, TCP and UDP and a conection that is duplex for wifi but its still an interesting Video. Why you dont use metric? Even USA try to switch to metric system.
The Arduino just has too little memory to handle all that OSI layer 3 and 4 stuff, when a MAC frame alone takes up to 1514 bytes... And handling all the header overlay would make it even slower. I use both feet and meters, but I find feet more convenient when describing short distances. And most of my viewers are from the US anyway.
@@DoctorVolt this wasn't seriouse i know how hard OSI comunication can be. cnlohr did a great project on Ethernet with an attiny 85 but this dude is an insane good hardware programmer. I realy like your project its simple to umderstand but still interesting i love RF stuff and like to think alot about this topic but i sometimes feel lost with all this things to considere when designing real world applications.
I think what he means is that Arduino is capable of generating RF signals all by itself without an intentionally designed transmitter. The ferrite- core coil is simply there so you can get a clean signal.
That secret "wifi" is not so useful, except when you want to annoy the cat or bats, it is told they can listen to very high frequencies. By the way bats are protected animals, you mustn't harm them.
It definitely isn't a 2.4/5.0 GHz RF transmitter, but "wifi" (as opposed to the trademarked "Wi-Fi") isn't about the frequencies per se. --- I think it might qualify as primitive 'packet radio' of a sort, though.
You could probably increase the range fairly trivially, but you don't want to run afoul of regulatory authorities. Radio transmission is tightly regulated.
@@jnharton I used to play with scart video to uhf transmitters with more range than that still got the box but also got sky slx box does the same thing just newer lol
When I was an undergraduate student the lab I was working in had a computer donated from a defense contractor. The PC case and keyboard were very impressive for how heavy they were. When we looked more closely, the keyboard circuitry was wrapped in copper mesh to prevent signals getting out into free space. And this was a late 80's computer, so I can only imagine what can be done now.
google TEMPEST to learn more.
en.m.wikipedia.org/wiki/Tempest_(codename)
thats EMP hardening since it was during the cold war
Keyboard releases no signals, as the other comment says likely EMP
@@kreuner11 I think I'll stick with believing what the person from MITRE who donated the equipment said about signals intelligence. If a nuclear strike had happened the operation of these computers would have been irrelevant. But the design work being done on them certainly would have been of interest to the Soviets.
BTW I have been involved in RF circuit design for two decades. I can confidently say that anything with a mechanical switch will absolutely radiate. You'd have to be crazy clever to figure out a way to interpret the RF pulses coming out but I'm sure the cold war spooks were up to that task.
One problem of this concept is that ferrite material saturates very quickly and is really only usable for very low field strengths (as in receivers). Using a different inductor on the transmitter side should improve the range. Another problem is that the direct drive of the LC circuit limits its possible peak voltage to the voltage range of the AVR pins (which have protection diodes and load the resonance circuit non-linearly). An isolating buffer stage (transistor with high voltage rating) would be beneficial.
It is not that difficult to increase the power and range but at some point there will be a risk that it will interfere with someone's radio and authorities may get involved.
Maybe I could have achieved a little better coverage with a loop antenna and a good impedance match. But I don't think it would make much difference, and I don't see much practical use in it anyway. So I didn't want to put too much effort into it.
what would be the best inductor to use?
the using of a voltage and current boosting transistor is indeed a logic thing to do, and at this low frequency it isn't to hard to find a suitable part.
also the antenna I searched up the name but got nothing, so am I right to assume it is just one of those LC oscillator antennas.
or that it is just a coil around a rod through which the current is passed and a second coil around the same rod but connected to gnd on one side and air on the other side? kind of like one of the old long range radio antennas.
or is it one coil with a center tab?
You are obviously not a ham radio guy. I personally have used ferrite in an antenna system at the 100 watt P.E.P level. Other hams have used ferrite at levels up to a kilowatt.
Nice concept! For the threshold, lowpass filtering the RF signal may help to get an automatic threshold. Also consider 10b8b encoding. Cheers!
You mean high-pass filtering? With a HPF you could get the signal’s centre almost exactly halfway between the rails. I think he should also add an AGC circuit of some kind. And a Schmitt trigger comparator assuming he doesn’t already have one. I think 10b/8b encoding would get the DC offset to zero, and is more effective than the Manchester I was thinking of.
@@Scrogan Both work. If you lowpass the signal, you get the DC offset and can use that as a reference. If you highpass, the signal is centered around 0V, but you end up with negative voltage.
Impressive, nicely done.
The real art of airgapped transmition. Reminds me of RPiTX. Don't even want to know what can be done to PC motherboards so they "leak" data ;)
That RPiTX project looks rather cool! I have to give it a try!
I saw someone hack a SATA cable to send data. Yes, I know, that's what it's supposed to do, but this person wrote some code that wrote data to the drive periodically to transmit 1s and 0s with the RF noise. It was a proof of concept for malware to exfiltrate data from an air-gapped computer, and it wasn't particularly practical outside just being a poc since the range isn't great, but it was interesting nonetheless.
I did something similar following some research paper but with USB 2.0 protocol. I never made video public :) Maybe one day I will get back to that project and write decoder to :)
th-cam.com/users/shortsZivNEi4GbVM
@@dafoex
Might be able to increase range with custom designed antennas and help from a ham radio person.
orientation of the two coils will make a huge difference to range .
This is sincerely amazing. This is marvelous!
Another way of increasing the distance would be to instead use error correcting codes. Though I'm sure that's out of scope of this, it's something that would be necessary even over very short distances, given how susceptible to interference RF communication is.
Your receiving antenna must be parallel to the transmitting antenna to get the best distance
Interesting project!
This is fantastic. I love your videos. How would you increase the range?
Maybe with an amplifier and/or better antenna.
Thank you for sharing knowledge.
Thanks great video I have subscribed.
Sweet! Thanks muchly. :) U rock.
Now you have to import IPv4, IPv6, TCP and UDP and a conection that is duplex for wifi but its still an interesting Video. Why you dont use metric? Even USA try to switch to metric system.
The Arduino just has too little memory to handle all that OSI layer 3 and 4 stuff, when a MAC frame alone takes up to 1514 bytes... And handling all the header overlay would make it even slower. I use both feet and meters, but I find feet more convenient when describing short distances. And most of my viewers are from the US anyway.
@@DoctorVolt this wasn't seriouse i know how hard OSI comunication can be. cnlohr did a great project on Ethernet with an attiny 85 but this dude is an insane good hardware programmer. I realy like your project its simple to umderstand but still interesting i love RF stuff and like to think alot about this topic but i sometimes feel lost with all this things to considere when designing real world applications.
This is next level hacking here. very impressive.
question, at 4:53, that brass plate, and nixiey tubes, would not need to earthed some how, unless it like not high, mains power or something?
That's no problem, because the anode voltage of the VFD tube is around 24V and there is no mains power in it at all.
Very cool, does the powder consumption change over normal operation?
Of course. If it's not transmitting (no serial data to be sent), power consumption is less.
It's kiloHertz (uppercase/lowercase)
Seems like the hardest part is getting a coil and figuring out how it works!
Ferrite antennas are easy to find on Ebay etc. But figuring out everything is the fun part.
What's that magnetic coily thingy ad how can i find it
It's a ferrite antenna. You can find them in old radios, on Ebay, Aliexpress...
add a flyback diode across the coil to protect the arduino
on the transmit side
This would cost some transmit power and my Arduino survived anyway.
This isn't really Arduino's Internal Hidden WiFi
You added a ferrite antenna, that KINDA changes everyything LOL
I think what he means is that Arduino is capable of generating RF signals all by itself without an intentionally designed transmitter. The ferrite- core coil is simply there so you can get a clean signal.
@@jnharton
I know what he means, but it still......... ummm yeah you know
That secret "wifi" is not so useful, except when you want to annoy the cat or bats, it is told they can listen to very high frequencies. By the way bats are protected animals, you mustn't harm them.
I doubt that Bats can really hear radio waves.
This is very cool but I don't get how this can be used for wifi
A bit clickbatish
I think I just found Andreas Spiess’s brother 😊
Maybe regarding topics, but without the swiss accent 😎
This has absolutely nothing to do with WiFi! It's just an RF transmitter. Where exactly is the WiFi and network stack?
try turning the antenna sideways || . I don't think lengthwise is correct - -
i tried different orientations. It worked best when the rods were aligned lengthwise.
As cool as it is, this aint wifi.
Yes, I have to admit...
It definitely isn't a 2.4/5.0 GHz RF transmitter, but "wifi" (as opposed to the trademarked "Wi-Fi") isn't about the frequencies per se. --- I think it might qualify as primitive 'packet radio' of a sort, though.
Cool, but its neither wifi nor secred.... So its pretty much clickbait...
Make sure you are allowed to use the frequencies and are not adding extra interference for others
These frequencies are no more used in many countries, and with that low transmit power i is extremely unlikely to disturb anyone.
@@DoctorVolt that's good
So its facking useless 2m range 😂😂😂😂 and the point in this video was 😂
You could probably increase the range fairly trivially, but you don't want to run afoul of regulatory authorities. Radio transmission is tightly regulated.
@@jnharton I used to play with scart video to uhf transmitters with more range than that still got the box but also got sky slx box does the same thing just newer lol