Ultrasonic Sesnor Accuracy

Here’s the spec sheet for the sensor.

Each time after the LV-MaxSonar®-EZ1™ is powered up, it will calibrate during its first read cycle. The sensor uses this
stored information to range a close object. It is important that objects not be close to the sensor during this calibration
cycle. The best sensitivity is obtained when it is clear for fourteen inches, but good results are common when clear for at
least seven inches. If an object is too close during the calibration cycle, the sensor may then ignore objects at that distance.

I found when testing the sensor that the signal is very susceptible to interference from other irregular obstacles (i.e. it ignores walls unless directly facing them) in its field of vision (which I estimated to be roughly 60 degrees, centered on its line of sight). The waveform is highly erratic when there are multiple objects in its field of vision, and oscillates between the closest and farthest object it can see.