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| Re: Possible new 76th Street Evidence and summary (1383849) | |||
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Re: Possible new 76th Street Evidence and summary |
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Posted by SelkirkTMO on Tue Feb 2 07:06:29 2016, in response to Re: Possible new 76th Street Evidence and summary, posted by Dyre Dan on Tue Feb 2 06:49:58 2016. The red box is the radar unit and control electronics itself. In order to provide valid measurements and height calibration, it needs to actually be ON the ground to work properly. Yeah, you could probably sneak it, but the metal of a car's trunk could screw up what you're measuring. The way it works is the electronics sends a microwave signal straight down, and then sees what reflects off it in a "time domain" which indicates depth and interpretation of the amplitude (color?) of the reflection is then analyzed to determine what it was down there that reflected back.Metal gives the best reflections, but is it iron? Steel? That's what you pay the experts to give you in the final report. But since we're looking for rails, steel beams and other iron about 35 or more feet down, any metal found at a depth of 20 feet or less has to be water, gas, etc. Find echoes further down, and we might have rails and rebar around concrete. That's how it works. GPR is about the only thing that's going to settle this other than a really large backhoe and lots of explaining. :) |
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