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."