Assuming present day earth.

Imagine someone with access to an exa-scale super computer creates an AI. That AI then becomes sentient and tries to take over the earth.

An exa-scale supercomputer consumes around 20 MW and takes up a huge room to get similar processing power to a human brain. Any human level AI is too big to move.

Therefore the physical agents (robots) of this AI would essentially have to be remote controlled. Basic movement and stuff could be done by local processing, but high-level human type reasoning would have to involve sending video, audio, and sensor data back to the main CPU cluster.

  • The first thing the AI does is send out a bunch of phishing emails in order to steal a bunch of people's money.
  • Using that money it hires a bunch of unwitting companies to build some power plants, some copies of itself, as well as a robot army. The design is compartmentalized an obfuscated, so no one could see the big picture, and no-one knew what they were building.

We don't know exactly which RF frequencies the AI is using, but they need to have enough bandwidth for video feeds. So lets assume possible carrier frequencies from like 900MHz to like 5GHz.

It seems then that the clear path to keeping the robots away from you is just to jam communications.

The basic requirement for the jammer is that a robot, not bigger than a small passenger car, could not carry communications equipment powerful enough to send a useable video feed through the interference.
Supposing one wanted to make a mobile jammer that fits in the bed of a pickup truck, what is the maximum power level that you can emit without cooking yourself, and still keep the robots at a distance? Also, what would that standoff distance be?

  • We are allowed to add EMI shielding to the cab of the pickup truck if needed.
  • We are barring the use of optical communications links in this scenario.
  • We can assume that the AI is capable of constructing its own communications network, and that just turning off the regular telecom network is not an option.

I think the first step is to figure out the max radiated power level that won't cook the passengers. Assuming that the energy is uniformly spread between 900MHz and 5GHz.

The next step is to figure out how far away that would keep the robots. Keep in mind that the power density of RF signals is inversely proportional to the square of the distance between the antennas (W = C / D^2). So as the robot gets closer to the jammer and further away from its own communications network the jammer gains a massive advantage. Weather or not it stops the robot at 10 feet or 10 miles is up to be solved.


1 Answer 1


Some existing vehicle mounted jamming systems:

An aircraft mounted jamming system:

Considering that 10.8 kW aircraft jammer, I think that RF safety is unlikely to be too big a concern, especially if you shield the cabin.

However, jamming is not so simple as just putting out a certain amount of power that drowns out everything anyone transmits nearby. If you jam on a broad frequency spectrum and your enemy broadcasts on one frequency, his single frequency will not be jammed even if you have a lot more power total than he does, because he has more power on that one frequency. You have to find the frequency that your enemy is transmitting on and block it specifically. If the AI keeps switching frequencies randomly, it would be more or less impossible to jam it for long, because it would get at least a brief burst of information out every time it switches frequencies, before you'd be able to notice the switch and jam that frequency.

Also there is the possibility that the AI could use directional antennae to transmit its video, which you would not be able to jam.

  • $\begingroup$ The person doing the jamming has some advantage. The energy density of the jamming field is inversely proportional to the square of the distance between the robot and the jammer (W = C / D^2), and the same sort of logic holds for the robot antennas. For example if the robot gets to a point 10X closer to the jammer than the nearest communications antenna then the jammer gets a 100X advantage in signal power. The robot could compensate for that with more transmit/receive power and directional antennas, but only to a point. Aiming narrow beams becomes at moving targets is hard. $\endgroup$
    – user4574
    Commented Jul 24, 2021 at 13:41
  • $\begingroup$ @user4574 So, you're 10x closer to the robot than the robot is to the base station. Both you and the robot are about the same distance from the base station. There are 2 directions to consider: base station to robot, and robot to base station. To keep the robot from "hearing" the base station, you do have a 100X advantage - but the base station can transmit at much higher power than you, and the base station only needs to transmit commands, not video, which is lower bandwidth. $\endgroup$
    – causative
    Commented Jul 24, 2021 at 17:34
  • $\begingroup$ @user4574 The other direction - to keep the base station from "hearing" the robot - is more difficult, because you're at about the same distance from the base station as the robot is. To stop the upstream transmissions you do have to be louder than the robot on the same frequency. It's like two guys, close together, yelling to be heard by a third guy far away. The louder yell is heard. $\endgroup$
    – causative
    Commented Jul 24, 2021 at 17:36
  • $\begingroup$ @user4574 If the AI cares about your jamming enough to produce countermeasures, it should be able to aim its base station antenna fairly close to its robot, by tracking and predicting the position of the robot. It doesn't have to be laser-like focus, but just focusing in the general area - with, say, a beam spread of 100m - creates a really big power advantage. So perhaps story-wise you can say that the AI did not think jamming would be too big a threat and didn't bother. $\endgroup$
    – causative
    Commented Jul 24, 2021 at 17:41
  • $\begingroup$ In the movie version of this, the men and women of action don't get why a ton of noise wont work. The @causative character turns on white noise and cranks it up. The men and women of action wince. Then causative brings out a police whistle and blows it over the noise. "Ok," says the hero. "I think I get it". Heroine adds "and we don't need to do that demonstration ever again." $\endgroup$
    – Willk
    Commented Jul 24, 2021 at 19:58

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