Axial resolution is improved by increasing which parameter?

Axial resolution is improved by increasing which parameter?

• A. Pulse duration
• B. Pulse length
• C. Frequency
• D. Period

Answer: (C)

Axial resolution depends on how short the pulse is along the beam direction. A shorter spatial pulse length allows two echoes that are close together along the axis to be distinguished. Spatial pulse length is the product of how many cycles are in the pulse and the wavelength. Since wavelength is inversely related to frequency, increasing frequency shortens the wavelength, reduces the spatial pulse length, and therefore improves axial resolution. If you increase pulse duration or pulse length, you’re making the pulse longer along the axis, which worsens axial resolution. A longer period (lower frequency) lengthens the wavelength and also degrades axial resolution.

Axial resolution depends on how short the pulse is along the beam direction. A shorter spatial pulse length allows two echoes that are close together along the axis to be distinguished. Spatial pulse length is the product of how many cycles are in the pulse and the wavelength. Since wavelength is inversely related to frequency, increasing frequency shortens the wavelength, reduces the spatial pulse length, and therefore improves axial resolution.

If you increase pulse duration or pulse length, you’re making the pulse longer along the axis, which worsens axial resolution. A longer period (lower frequency) lengthens the wavelength and also degrades axial resolution.