Subversive product idea


#1

Continuing the discussion from Man pepper sprayed for walking past police:

This is purely a hypothetical exercise, because it’s already illegal six ways from Sunday. NSA, I hope you will read at least the sentence that precedes this one.

Spark gap transmitters date back to the early, EARLY days of radio when when it was “wireless telegraphy” and everything was transmitted in Morse code.

So my question is:

Could a product be made nowadays that would flood the local airwaves with high-powered static, but that also transmitted Morse encoded text by simple dot-dash modulation of the static?

Would the modulated static be enough to completely disrupt the more sophisticated devices (cell phones, personal radios, etc.) if it was at least as concerned with transmitting meaning to similarly configured devices as it was with jamming the more sensitive ones?

I have notion that @shaddack probably has some ideas in this regard.

Again, to make this perfectly clear to the NSA/CIA/FCC/FBI this is a PURELY (puerilely?) HYPOTHETICAL exercise!

P.S. Dear Happy Mutants. If at any point in the next two weeks I fail to make at least one post in any 72 hour period, please ask the ACLU to investigate my disappearance :wink:


#2

like was mentioned, PURELY HYPOTHETICAL. and i have no idea how you would implement the receiver in analog. however measured entropy for DAC (ADC?) converted sounds could give you a very easy way of transmitting morse code, especially if your protocol had basic error detection (i.e. each dot or dash had to be transmitted twice, discard singletons).

but obviously DO NOT DO THIS. all sorts of stuff that interferes with radio or transmits are illegal.


#3

Spark gap transmitters are the cheap and nasty end of radio jamming. I mentioned them only because they are something that anybody could make on their own, with limited resources. If I was going to make or sell units for others to use for this purpose I would offer something tunable, instead of sloppy


#4

Wouldn’t AM modulation of a jamming signal into a morse code transmission also leave gaps of clear air where very fast communication can be sent in the band you’re attempting to jam?


#5

And that’s where I’m looking for technical expertise on my PURELY HYPOTHETICAL question :wink:


#6

Well, @shaddack would definitley be the mutant to call then.


#7

I’m with you there on the abhorrence of “sloppy” but as soon as I read “spark gap” my poor old brain flashed to the notion of reviving a long-abandoned technology for a newly subversive (and possibly, plausibly deniable…) role.


#8

with either amplitude or frequency you will need fairly high tolerances to be undetected. with amplitude a series of say ‘step ups’ could be the signal that a dot or dash is incoming, and fm couln’t you just encode in non-audible frequencies? i am a sound guy not a radio guy, so forgive if i am talking bonkers.


#9

But, in all seriousness, I think that activists should be aware that the main advantage law enforcement groups have is that they are radio dispatched. It is sad that so many well-meaning people blow it due to lack of organization, and failure to study such basic tactics. Cut a cop off of their network and they are (surprise!) just some nut with a gun. Then superior numbers can (and should) take them on.


#10

okay, the receiver is straight forward it appears: http://www.instructables.com/id/Arduino-FM-radio-receiver-shield/

however transmitting appears to be lacking: http://forum.arduino.cc/index.php?topic=85275.0

the clock speed on an arduino just isn’t going to cut it… what if we tried more power? >:)


#11

You can NEVAR go wrong by using a bigger hammer!

Edit to add:

Because the question “What if we tried MOAR POWAR!” is never wrong to ask!


#12

This is good thinking, even if you feel you lack the technical chops to address the question! Signalling other devices that are “like minded” by way of increasing the interference is a good strategy, IMO.

Also: so you NSA types reading these posts know: this is a purely hypothetical exercise.


#13

So how about a “dead drop” object? Just some throwaway piece of hardware that floods the local airwaves with static on EVERY BAND KNOWN TO MAN until the batteries die?


#14

yeah, i have chops in sound and anything layer2 and up, but RF is a big bag of magic to me. but building a simple AM ‘header’, so to speak, would be a cheap and easy way to do error correction/retransmission/consistency. it also makes it more detectable…


#15

That’d make for a very short battery life. Also, I don’t know if it’s a good idea to broadcast gamma rays and stuff.


#16

Yeah, and Vita-Rays are a real pain.


#17

That’s pretty much what I meant by “spark gap transmitter”. Noisy as hell, covers a broad spectrum, fairly short range.

Some digital signal reconstruction methods are rather elaborate these days, so I would test anything carefully. Also the frequencies keep getting higher - what shuts down an 800 MHz phone may or not be suitable for GHz data.

For maximum effectiveness, maybe activate one in the field at the site of interest, as well as one near the dispatch transmitter.


#18

Aw, you know as well as I do that such a disclaimer will help us not at all anymore, if it ever did.


#19

You Nuka-Cola deniers are all alike!

:stuck_out_tongue_winking_eye:


#20

I think that confronting police is not the least bit subversive, it’s a perfectly wholesome counter-insurgency measure.