[ayeckley]

Just to add another data point, when we first tested the sensor we found huge intermittent drops in the measured range when more than 8' from the target wall, even with a properly-initialized sensor, perpendicular target, clear range to target etc. Two days later the problem did not recur even with no changes to the hardware or software. The leading theory so far (which we will test at the next opportunity) is that all of the grinding noise from the welding class going on next door had a high ultrasonic spectral content which interfered with the unit. Without the grinding noise two days later, the sensor was well-behaved.