Hacker News Reader

Comment by ChuckMcM | Hacker News Reader

See Steve Perlman's efforts at making a cellular radio system that can focus a 'bubble' of cellular energy around the user.[1] Call 'pCell' or 'pRadio' in various press releases it basically is a MIMO setup that uses many cell towers to transmit a pre-distorted signal that converges into a power signal at a particular point in space. At the time it was announced I suggested it sounds like something that could be weaponized if you wanted to. Being able a turn a microwave on around a person without anyone nearby noticing anything is a pretty capable thing.

[1] https://patents.justia.com/patent/20080130790

View on HN

Parent comment still applies. A detector would be cheap, small, and could be issued to everyone on a team.

If the signal is strong enough, you can easily design a pocket detector. A PCB attached to a pocket protector with antenna tracings for multiple spectrums and a buzzer. No need to get fancy, a few passives off the shelf will do the trick. Or just get a SDR scanning multiple spectrums and have a threshold trigger above a specific power level. This is beginner radio stuff, I am sure their local hardware tech support can whip one up under a day.

I wonder if you could just have a calorimeter and a block of material with similar properties to human tissue? That way you cover the EHF/THF(>30GHz) ranges as well?

I guess semiconductors are covering pretty high frequencies these days though(http://www.semiconductor-today.com/news_items/2019/may/knu_2...).

Terahertz doesn't penetrate walls particularly well but if they managed to get it to work, then that would be very interesting.

Yeah, also if anyone wants external proof of the concept:https://dl.acm.org/doi/10.1145/3214268

Sure but then you have a targeting problem, which in the radio range is not trivial particularly when you've got intervening objects and no receiver providing feedback about signal strength.

I don't suppose the embassy received any gifts of plaques recently? Is playing the Theremin a popular pastime among diplomats?

Embassies are constantly swept for bugs and transmitting radio devices. The security officer in an embassy is always going to be an intelligence officer. Particularly US embassies, are not lax security targets along any dimension.

Sort of right? I mean how big is the field? How often does someone move the bed in a hotel room? If you were set up outside a hotel where you knew targets slept, you could program constants for the bed in each room right?

Further if you knew what you were trying to do, you could set up your feedback transmitter in a room, record all the parameters for that room, then move to the next room, Etc.

The problem that Perlman was solving was a lot harder (a moving target) but hitting a nominally stationary target?

Reply on news.ycombinator.com