Wi-Fi Doppler Radar (and lots of Snowden updates)

It looks like some researchers have figured out how to encode a signal in the space of a single WiFi channel (using a USRP as transmitter) and thereby created a quite simple-to-build doppler radar. The trick lies in structuring the signal so that it nulls out at the receive antenna (given a static environment). Any movement within range towards or away from the receiver creates a Doppler phase shift that disturbs this nulling, and creates a trace on the receiver.

Nothing *hugely* new, but it’s been getting a ton of press coverage (ZOMG see through walls with wifi!) and could theoretically work with commodity hardware. Sometimes I wonder if there isn’t a conspiracy to blast vaguely-creepy but non-earth-shattering research in the headlines.

Snowden updates:
No new leaks, but lots of talk — including from the man who’s said the least yet been discussed the most.

Everyone’s favorite “infrastructure analyst” [dude in charge of finding weaknesses in everyone’s systems[5]] released a statements through Wikileaks, noting that rather than fearing whistleblowers, “the Obama administration is afraid of you. It is afraid of an informed, angry public demanding the constitutional government it was promised — and it should be.” [0]

Snowden also changed his mind about the correctly-rumored Russian asylum, dropping his application in light of Putin’s stop-the-leaking terms.[1] This came around the time Snowden sent a long letter to Ecuador’s president, thanking him for his support at least early on in the Sheremetyevo Saga. [2] Ecuador has nevertheless backed away from Snowden, presumably after Biden told Correa the NSA knew all about his porn habits. [6]

That said, there is at least a faint ray of hope — with his airplane presumably still in Moscow, Venezuelan president Maduro has said he’s “ready to help Snowden” if the people are in favor. [3] Maduro nevertheless denies having had any “official communication” asking for asylum. Bolivia has also invited an asylum application and denied receiving any so far. [7]

The Venezuelan and Bolivian denials come despite both being listed on Wikileaks’ statement giving the countries to which Snowden put in asylum bids. [4]

[0] http://wikileaks.org/Statement-from-Edward-Snowden-in.html
[1] http://english.ruvr.ru/2013_07_02/Snowden-asked-Russia-for-asylum-reconsidered-after-learning-Moscow-s-terms-Kremlin-0774/
[2] http://www.guardian.co.uk/world/2013/jul/01/edward-snowden-letter-president-ecuador?CMP=twt_gu [3] http://rt.com/news/maduro-snowden-asylum-venezuela-565/
[4] http://wikileaks.org/Edward-Snowden-submits-asylum.html
[5] http://www.nytimes.com/2013/07/01/us/job-title-key-to-inner-access-held-by-snowden.html
[6] http://www.guardian.co.uk/world/2013/jul/02/ecuador-rafael-correa-snowden-mistake [7] http://rt.com/news/morales-bolivia-asylum-snowden-534/


“Wi-Fi signals are typically information carriers between a trans- mitter and a receiver. In this paper, we show that Wi-Fi can also extend our senses, enabling us to see moving objects through walls and behind closed doors. In particular, we can use such signals to identify the number of people in a closed room and their relative locations. We can also identify simple gestures made behind a wall, and combine a sequence of gestures to communicate messages to a wireless receiver without carrying any transmitting device. The paper introduces two main innovations. First, it shows how one can use MIMO interference nulling to eliminate reflections off static objects and focus the receiver on a moving target. Second, it shows how one can track a human by treating the motion of a human body as an antenna array and tracking the resulting RF beam. We demon- strate the validity of our design by building it into USRP software radios and testing it in office buildings.”

%d bloggers like this: