At 01:08 PM 7/8/04 -0400, Sunder wrote: >I recently visited the Canadian side of Niagra falls. On the return entry >to the US customs, etc. meant driving through penns that look like toll
>booths. But I noticed little sensors in pairs and large square sensors as >well. 1. I've seen adverts for linear sensors which image the bottoms of cars as they drive over. Sort of a scanner where the paper does the moving. Installed in the road. 2. There are companies developing sensors that bombard your car with neutrons (don't have to open the trunk), and detect the N from the temporary neutron-activated gamma emissions. 3. Obviously license plate OCR is trivial. 4. I've read papers on recognizing vehicles by their inductive signature as they drive over regular road sensors. This was to passively measure road speed for traffic control. The idea is that a VW Beetle has a different inductance vs. time than a Ford-250 or an 18 wheeler. You correlate between roadloops at known distances apart and infer road speed. 5. One could call terahertz "hard RF" in same way that hard x-rays bleed into soft gammas. But calling anything "hard" implies danger, and we mustn't scare the proles. Perhaps soft IR is better. Whatever, its still pornography if the resolution is high enough.
