we used some of these in yosemite, its basically a seismic sensor. we would place them at remote trail crossings into the park in hopes of catching poachers when they entered the park.
the sensor was buried under ground, and the radio antenna was usually hidden in bushes nearby. When someone, or something, would walk over, the radio was programed to transmit to a repeater, and said ranger's radio would get a signal of a computer voice saying a number designated for that sensor.
pretty freakin cool if you ask me, the technology that is. so if they use them in yosemite, i'm sure forest service peeps have them as well.
in fact, just remembered this, we had borrowed these from the forest service law enforcement guys, those nazis
[ 08-21-2002, 02:11 PM: Message edited by: gapertimmy ]