Which term below most correctly describes the Doppler waveform?

Which term below most correctly describes the Doppler waveform?

• A. Aliasing
• B. Spectral mirroring
• C. Spectral broadening due to sample volume size
• D. Reverberation

Answer: (B)

Spectral mirroring describes the mirrored appearance of the Doppler spectrum that occurs when velocities exceed the Nyquist limit and wrap around. When the sampling rate (PRF) is too low to capture high velocities, the aliased parts of the spectrum flip to the opposite side of zero velocity, creating a mirror image about the baseline. That mirrored display is the hallmark of spectral mirroring. Aliasing is the underlying cause, but the term that best captures what you visually see in the waveform is spectral mirroring. Spectral broadening due to sample volume size would widen the spectral line, not produce a mirror image, and reverberation creates multiple echoes, not a mirrored velocity spectrum.

Spectral mirroring describes the mirrored appearance of the Doppler spectrum that occurs when velocities exceed the Nyquist limit and wrap around. When the sampling rate (PRF) is too low to capture high velocities, the aliased parts of the spectrum flip to the opposite side of zero velocity, creating a mirror image about the baseline. That mirrored display is the hallmark of spectral mirroring.

Aliasing is the underlying cause, but the term that best captures what you visually see in the waveform is spectral mirroring. Spectral broadening due to sample volume size would widen the spectral line, not produce a mirror image, and reverberation creates multiple echoes, not a mirrored velocity spectrum.