The length of time required to complete one pulse is called what?

• A. Duty cycle
• B. Frame rate
• C. Transmit time
• D. Pulse duration

Answer: (D)

The main idea here is that pulse duration is the length of time the transducer is actively emitting during a single pulse. It starts when the pulse begins and ends when the pulse ends, so it’s the actual time span of the burst. If you have a multi-cycle pulse, the duration grows with the number of cycles and the period of each cycle (the inverse of the frequency). Shorter pulse durations give better axial resolution because echoes from different depths are less smeared together.

Duty cycle, by contrast, is about how long the system transmits within a repeat cycle—it's the transmit time relative to the total cycle time. Frame rate refers to how many image frames are produced per second, and transmit time is another way some contexts describe the duration of the pulse, but the standard term for the length of one pulse is pulse duration.