Message posted by Joerg (Webmaster) on June 04, 2004 at 14:36:58 PST:
Well, the sensor really does not calculate the size or speed of a vehicle. This is (very simplified) how magnetic induction works: A metal object, moved perpendicular to the center axis of a coil, indices an electric current in the coil, which can be measured as voltage difference at its ends. Among other things, the voltage depends on the mass of the metal object, the speed of its movement and the distance between the coil and the metal object. So, if you are moving very slowly, you can sneak by a larger metal object without tripping the sensor (exceeding the voltage threshold). If you are further away you can move faster, or have a larger metal object (vehicle), before you trip the sensor. The sensor itself only knows "on" or "off". It only trips when the preset voltage is exceeded. As for direction, you need two sensors to determine the direction of travel based on the sequence they are tripped. The sensor unit also has a built-in shock sensor. However, it is not very sensitive. You literally have to jump up and down on the buried sensor to trip it. Its main purpose it to detect when someone handles the sensor. Darkstar was a stealth UAV development supposedly cancelled in the late 90's in favor of the Global Hawk. However, there are persistent rumors that the knowledge gained from the Darkstar project was used in a new, larger black project UAV. See the attached link for more information.
In Reply to: Re: Questions posted by Iroquois on June 04, 2004 at 13:53:18 PST:
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