What are the two modes of operation for ultrasonic sensors?

• A. Transmitted and received
• B. Transmitted and diffuse
• C. Analog and digital
• D. Opposed and diffuse

Answer: (D)

Ultrasonic sensors detect objects by emitting a sound pulse and listening for its echo, and they can operate in two configurations: diffuse reflective mode, where the single sensor transmits and relies on the target reflecting energy back to it, and opposed (through-beam) mode, where transmitter and receiver are positioned opposite each other and the target’s presence alters or interrupts the beam between them. In diffuse mode, detection depends on the target’s surface reflecting enough energy back to the sensor, which works with many shapes and materials but can vary with angle and texture. In opposed mode, the transmitter and receiver are separate and aligned so that the beam must travel directly to the target and back; detection is based on the beam path being interrupted or strongly affected by the target, offering stable sensing in setups where diffuse reflections are unreliable. The other options mix aspects of transmission with output types or reference incorrect pairings, whereas the two true modes describe how the ultrasonic energy interacts with the target.