[Al Skierkiewicz]

The diamond plate will produce unusual reflections due to surface texture for IR and ultrasonic. In addition, objects striking the surface of the diamond plate may also produce ultrasonic signals that can confuse or overwhelm the transducers. It is best to take a series of readings and either average the results, do some noise filtering or reject readings that are outside the realm of your environment. i.e. if the readings have been in the 3-4 foot range and you suddenly get a few inches reported, wait for more data. If you have several reporting inches then you might be inches. If you only get one and then it goes back to feet, the later is likely true. Remember in both cases, the rangefinders are looking for reflections.