Three other thoughts to add to John Gastineau's comments:
1. Faulty grounding can make for strange results. We found that one of
our lab tables had the third-pin on the outlets floating. This seemed to
result in the detectors on the computer connected to those outlets not be
able to 'see' anything beyond about 1.5 meters.
2. If you have multiple detectors in the room, they can 'talk' to each
other, when they are within each other's active "cone."
3. Sometimes isolating the detector from ambient vibrations can help. We
find putting a paper towel under the detector when we are using it on
something like a ramp helps.
A variation on one of John's comments: often another student is the object
giving off the strongest echo. You have to help the students 'see' when
this is happening.
Good luck.
Dewey
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Dewey I. Dykstra, Jr. Phone: (208)385-3105
Professor of Physics Dept: (208)385-3775
Department of Physics/SN318 Fax: (208)385-4330
Boise State University dykstrad@varney.idbsu.edu
1910 University Drive Boise Highlanders
Boise, ID 83725-1570 novice piper
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