The time for one pulse to occur is known as the:

The time for one pulse to occur is known as the:

• A. Duty factor
• B. Spatial pulse length
• C. Wavelength
• D. Pulse duration

Answer: (D)

Pulse duration is the time from the start of a pulse to its end—the length of time the transducer is actively emitting. It depends on how many cycles are in the pulse and how long each cycle lasts. In formula form, pulse duration equals the number of cycles in the pulse multiplied by the period of each cycle (period = 1/frequency). So higher frequency shorten the cycle period, and with a fixed number of cycles the pulse duration becomes shorter. This is distinct from spatial pulse length, which is a distance: the number of cycles in the pulse times the wavelength, telling you how far the pulse travels in space. Wavelength itself is the distance of one cycle, determined by the speed of sound in tissue divided by the frequency (λ = c/f). Duty factor is a ratio describing how much of the total time is spent transmitting (pulse duration divided by the pulse repetition period), not the actual length of the pulse in time.

Pulse duration is the time from the start of a pulse to its end—the length of time the transducer is actively emitting. It depends on how many cycles are in the pulse and how long each cycle lasts. In formula form, pulse duration equals the number of cycles in the pulse multiplied by the period of each cycle (period = 1/frequency). So higher frequency shorten the cycle period, and with a fixed number of cycles the pulse duration becomes shorter.

This is distinct from spatial pulse length, which is a distance: the number of cycles in the pulse times the wavelength, telling you how far the pulse travels in space. Wavelength itself is the distance of one cycle, determined by the speed of sound in tissue divided by the frequency (λ = c/f). Duty factor is a ratio describing how much of the total time is spent transmitting (pulse duration divided by the pulse repetition period), not the actual length of the pulse in time.