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Mobile Telephone Mast Signals Usable As Radar
caveman writes "In this article at ElectronicNews.com, BAE systems have joined forces with Roke Manor Research (part of Siemens) to further develop a method of using mobile telephone base station signals as a form of radar, capable of detecting periscopes, boats, and aircraft up to several kilometers offshore, as well as detecting vehicles and people moving into and out of areas within range.
The company doesn't say exactly how accurate the system will be, but they have a similar system which calculates height which is accurate to ten meters. The parts necessary to build a receiver cost about $3000, which is extremely cheap as radar systems go."
The system appears to have a few uses. Detecting stealth planes has been mentioned, so its a cheap alternative to an air traffic/air defence system.
But according to the article, it could also be used as a people tracker. Such as the people moving through a parking lot as mentioned in the article. Track them going to the car park, track them breakin in to cars, track them going to dispose of their ill gotten gains and track them trying to escape whem the police turn up to arrest them.
Given the processing power available today on the sorts of computers a government can afford, it ought to be possible to keep track on a fair portion of people living in the urban areas of the world... at least while they are outside, and especially when they are in highly reflective objects like cars. Something some governments will no doubt relish. Something many other people will be very wary of.
This all depends on whether it could be made to track in a person in a crowd of people or a specific vehicle in traffic. Maybe it'll allow missing individuals to be tracked from the last known point to wherever they have ended up.
I wonder if enough detail can be gained from the return signals to actually identify the person. Maybe the frequencies used are too low for much more than determining the build of the person being tracked. On the other hand, anyone who has seen themselves on an ultra sound based scanner in hospital will know that considerabel detail may be seen with frequencies well below 0.9 to 1.8 Ghz.
And due to the fact the radio signal is there whether you are being tracked or not, there is no way to know if someone is watching your movements or not.
quite old technology really. The U.S. has had, for years, the capability to exploit such "emitters of opportunity" to precisely locate aircraft and even trace back projectiles to their launch point. It's a form of triangulation that involves resolving the time difference of arrival and Doppler difference of arrival of reflected signals to give both position and velocity information. The math is not too hard, but doing it in real time is real hard (at least it was back when I first learned of it).
What surprises me is that it would work with something with as intentionally small a radar cross-section as a stealth aircraft (with electronic counter measures to boot).
or china, who claimed something similar a few years ago. from this 1999 article:
The Chinese appear to have turned things around. Their new Passive Coherent Location system allegedly tracks fluctuations in normal or civilian broadcasts, which function at a different frequency, and looks for distortions, reports Newsweek.